Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Willabe on March 03, 2015, 04:30:37 pm
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Well I have made some progress but I'm still thinking about a few things.
I wired the 9 pin sockets for 12.6v.
Here's a few pictures;
Brad :icon_biggrin:
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looking good so far, (looks like fun to have one)
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I bought some meters from Weber some years ago for future projects like this and dug them out. I'm not sure how to hook them up.
I have 2x100mV large, 2x200dcmA small, 2x100dcmA small and 2x1000dcv.
I'd like to use the large, their easy to read, not sure if I have the room thou, 100mV for bias current, 1 for each tube. (I don't see myself building any 4x power tube amp. If I do I could always put in a couple of switches to change between tubes.)
1. The large dcv meters, do I just put them across the 1 ohm K resistor, + to K?
2. I'd like to use the smale 200dcv meter to monitor the power tubes plate (A) B+, so I hook up the + on the meter to plate B+ and the meter - to ground?
3. And I think I should put in a switch to lift the + connection on the K and A meters when playing through the amp after biasing it?
4. Should I fuse the meters? If yes, how?
Brad :think1:
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looking good so far, (looks like fun to have one)
Thanks Jojo. :icon_biggrin: I get the feeling that after I work with it some I'll want to make some changes.
I want to play around with some things without cutting/drilling out a chassis and face plates.
Brad :icon_biggrin:
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I want to play around with some things without cutting/drilling out a chassis and face plates.
Over the years at various times I've just used existing chassis, iron, sockets, and pots into various designs and/or experiments. This is where turret boards can be nice but eyelets actually can be easier/faster.
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1. The large dcv meters, do I just put them across the 1 ohm K resistor, + to K?
2. I'd like to use the smale 200dcv meter to monitor the power tubes plate (A) B+, so I hook up the + on the meter to plate B+ and the meter - to ground?
3. And I think I should put in a switch to lift the + connection on the K and A meters when playing through the amp after biasing it?
4. Should I fuse the meters? If yes, how?
I'm sure PRR, Sluckey, or HBP have specific answers but how I've used them in the past on things: since voltage readings should be only taken/used across various points like a volt-ohm meter you're only worry would be not to exceed the voltage scale reading you're planning on applying them too. On the ammeter(s) you would definitely fuse in-line with a fuse rated no higher than the highest scale reading. Following these simple "rules" and you should be fine.
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Thinking out loud;
I really want to use the analog meters I have for the bread board to monitor voltages and current in different circuits and save my hand held meter for what ever else I might want to check. Since it's test bed for circuits it's makes sense to me to have these in place and not have to keep moving the hand held meter probes around to different parts of the circuit that I know I need to keep an eye on. I will also be able to just glance up and take a look at a few important parts of the circuit at once.
And, as I don't have multiple meters, and even if I did, these will always be set up in place and I'll have no extra meter leads/alligator clips to deal with, plus their way less expensive to have multiples of.
So, I was trying to figure out how to mount the analog meters and I remembered that I have a compass/circle cutting arm for my Dremel that will cut holes as small as 3/4" and up to 12".
It will take a few try's on some scrap to get the size adjustment correct but I think it will work. :icon_biggrin:
I have some 1/4" plywood that I think will work or I might use some 1/8" fiberglass board.
The problem is the trim skirt on the meters is pretty small, so the meter will have to fit pretty tight so I can still use the mounting holes on the trim skirt to bolt it in place. If the meter hole is just a little too big the mounting bolts hole will cut into the meters hole and weaken the meters mounting to the panel.
Then I have to figure out where and how many switches I need. I'll need at least 2 power switches, 1 for the main PT and the 2nd for the 9 pin tubes heater PT. And I want a stand by for the main B+ PSU.
For the Carling switches I'll have to either enlarge the holes in the angle iron with a step bit or depending on where I need to mount them, I might need to make/find/buy different mounting brackets. I don't see the whole picture yet as far as layout.
I do have some fuse blocks that I stashed away for a build like this and I need to incorporate them in the PT's and OT, both primaries and secondary's.
Brad :think1:
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> a switch to lift ... meters when playing through the amp...?
No. Watching the meters while using/abusing the amp is a KEY development tool.
When building your race-car, do you disconnect the tachometer before you drive it?
With self-bias power stages, you expect current to rise 0% to 20% from idle to FULL wail.
Fix-bias MAX power stages may double or triple their idle current when you smack them good.
Any sudden or large deviation from the trends is a sign of trouble.
Large power amps (more than 2*6V6) will exceed 100mA at full power. You got a 100mA meter. Add a shunt for large currents. A small resistor across the meter to divert some current. Get any darn amp running <100mA. Say 88mA. Now tack 1 or 2 Ohms across the meter. You want the value which makes the meter say 44mA (half of the total). Or any reasonable multiplier: big 6L6 amps can suck over 250mA, so a 3X multiplier (29.3 indicated on 88mA actual) may be useful.
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Ahhh, Ok, thank you PRR.
(Oh, put the current meter in the - return leg.)
Brad :icon_biggrin:
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I'm sure PRR, Sluckey, or HBP have specific answers but how I've used them in the past on things: since voltage readings should be only taken/used across various points like a volt-ohm meter you're only worry would be not to exceed the voltage scale reading you're planning on applying them too. On the ammeter(s) you would definitely fuse in-line with a fuse rated no higher than the highest scale reading. Following these simple "rules" and you should be fine.
Ok, makes sense, thanks Jojo.
Brad :icon_biggrin:
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If you have a spare voltmeter my council is to use it as to keep under control G2 voltage
this may be useful in general and very useful if you use power tubes that requires a very lower G2 voltage respect to plate voltage
(EL500 - EL504 - GU50 - 6DQ6 ........)
Franco
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Ok, thanks K, I'll keep it in mind.
Brad :icon_biggrin:
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Blundered into this article on how to wire & use panel meters: http://sound.westhost.com/articles/meters.htm (http://sound.westhost.com/articles/meters.htm)
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Hey, thanks jjasilli!
Brad :icon_biggrin:
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Got some more done.
The dcv current meters board, for the power tubes cathodes came out pretty good using the Dremel router/compass arm.
I'm still trying to figure out how I want to make a few common circuit separate modular boards that I can plug in and not have to use the barrier strips.
I have some different barrier strips and fuse blocks laying around that I want to use up, pics below. I have more of both, single, doubles, triples, 4x, 5x and 6x.
I included a rough layout schematic for the bread board.
Here's a couple of pics and drawings.
Brad :icon_biggrin:
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I'm working on the bread board and I have a few questions.
1. In the drawing PRR posted, the current meter is hooked up the the PT secondary CT?
2. To get the current meter's needle to swing correctly, on the back of the meter, there are 2 terminals, 1 has a + sign, so...... then the - (negative) meter solder tab, should be soldered to the ground end of where the B+ filter cap/PT CT meet with the B+ negative rail? (Look at my drawing below, I'm not saying this very well.)
3. To fuse the current meter the fuse goes before the meter?
4. Can I hook up the B+ negative rail to ground from anywhere along the negative B+ rail without affecting/bypassing the current meter?
I'm thinking all the B+ current has to come from ground and go through the CT.
Thanks :icon_biggrin:
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This is a great thread. I wonder if it could be preserved in the "Amp Tools/Tech Tips" section?
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Maybe, if I ever finish it! :rolleyes:
Dummy Load, with Richard, (board zilla?) and Silvergun (Let's build a bread board and Son of bread board) have great threads on the bread boards they built. (Their threads would be included in with mine if we put it in favorites?)
Do a search. If you use the search button on the top left, that search lets you enter a members name with the search, works better for some searches.
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1. In the drawing PRR posted, the current meter is hooked up the the PT secondary CT?
PRR will have to confirm, but I see the current meter after the first filter cap, negative side connected to 1st filter cap -, positive side connected to the ground lead of whatever comes next (probably a screen filter cap - and output tube cathode R ground lead).
The current meter is not between the CT and the 1st filter cap ground, but after the 1st filter cap ground. Otherwise, you'd also be measuring big charging current pulses going into that cap.
2. To get the current meter's needle to swing correctly, on the back of the meter, on the 2 terminals, 1 has a + sign, that goes before the B+ filter cap/CT ground connection? Or the negative side of the meter goes to the CT going to the PT. (Look at my drawing below, I'm not saying this very well.)
In accordance with the above, meter "-" side to CT/1st cap "-"/Ground, meter "+" side to 1Ω cathode resistor "common"/2nd filter cap "common".
3. To fuse the current meter the fuse goes before the meter?
It would seem like "6 of one, half-dozen of the other" since the fuse and meter are in series. Maybe PRR has a reason for a preference of which side of the meter gets fused.
4. Can I hook up the B+ negative rail to ground from anywhere along the negative B+ rail without affecting/bypassing the current meter?
No. Sorta...
If you have a 3-wire power cord, with the 3rd wire connected to chassis, PT center-tap and 1st filter cap ground, then that's "(Chassis) Ground". You need all output tube current to flow through the current meter, so the stuff to the right of the meter in the drawing which would normally be "grounded" are all connected to a "common" buss. The fuse and the meter complete the path to chassis ground. If you didn't do this, output tube cathode current could flow through the chassis instead of the meter, probably failing to produce a reading at all.
If you don't want preamp tube current measured in the same 1 meter, then preamp filter caps and common buss could be connected via a wire from the preamp common buss to the power cord ground/1st filter cap ground/PT CT. That would be a 2-legged star to chassis ground.
BTW, thinking of "circuit ground" or "circuit common" as something separate from the chassis ground and the power cord 3rd-wire helps you envision how to lay out an amp for a ground-lift switch. Pretend your chassis was all plastic and you couldn't bolt a ground wire to it; you could still have a wired circuit common (all filter cap - leads, PT CT, all circuit 0v returns), which functions effectively at completing the circuit. You'd only get buzz due to lack of a grounded metal shell shielding the circuit from picking up noise in the air....
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If you have a spare voltmeter my council is to use it as to keep under control G2 voltage
And G2 voltage in relation to G1 voltage is what sets the idle current. I suppose you could ignore G2 voltage if you always have a choke-filter G2 supply node and assume G2 is roughly-same voltage as the output tube plate (in other words, lacking a separate variable G2 supply voltage or not using some of the schemes to keep G2 well below the plate, as in the Standel amps or some 6550 amps).
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Thanks for the reply HBP. :icon_biggrin:
I thought about this and I think I understand what your saying.
I'm going to try it like in the drawing below.
Edit; Added OT.
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I've made some good progress, I stacked the B+ DCV and mA current meters with some zip ties and weather stripping to save some space and tilt them back a little to see them, new pics below;
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B+ power switch and mounting bracket;
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I can see the 2 meters very well even though they are small, their tilted back just right and B+ DCV on/off is well in reach;
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:icon_biggrin:
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More;
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I ditched the din rail and bolted the 8 pin relay sockets down to the plywood.
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You can see the nice tilt back I have on the B+DCV and mA current meters.
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Looking at the back/side of the power tube K current meters. I installed 2 octals so I can play around with PSE;
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3 rows of EU style 600dcv barrier strips for the 9 pin sockets;
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19 is from the back;
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3 speaker jacks and barrier strip for OT secondaries;
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Last;
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I need to do a few more things;
1. Hook up the power tube heater wires to the 8 pin power tube relay sockets.
2. Hook up the dual 3AG fuse holder to the power tube K current meters.
3. Hook up and fasten down a few B+ star grounds, the B+ -A- node ground wire to the ACV 'in' barrier strip where the safety ground wire is, hook up the B+ -B- node ground wire to the B+ -A- node ground and the pre amp ground node to the -B- node ground.
4. Solder/wire up the speaker jacks to the OT secondary barrier strip.
5. Fasten down the EU style barrier strip, with wood screws, that goes between the power tube sockets and the power tube K current meters.
6. Install/solder up the input jack.
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I moved the B+ stand by switch so it's after the B+ DCV and current meters so I can keep an eye on the 1st B+ filter cap at turn on.
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Here's the link for where I started this, has more good info and more pictures;
http://el34world.com/Forum/index.php?topic=18922.msg194284#msg194284 (http://el34world.com/Forum/index.php?topic=18922.msg194284#msg194284)
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I finished up all the wiring. :icon_biggrin:
I hooked it up > variac > lamp limiter > IEC input box, power switch/150vac meter/fuse > Hammond torid 12.6 heater PT.
No smoke, set the variac to 120vac, and I'm getting 13.3vac on the heaters (pins 4/5) with 6x 12A_7's installed. The PT say's; 12.6vac @ 1.19A.
I have some zener diodes 12v/1w here, can I use a pair of those to knock down the heater acv to 12vac?
If so, will they be noisy?
And to hook them up, 1 to each leg, banded side to leg other end of the zener to ground?
Or am I better off getting a couple of resistors to run is series with the heater leads? If so what value to knock the 13.3vac down to 12.6? As it is now I have all 6 sockets filled to draw the max current I can. If I can knock it down some I wont have to keep all 6 9 pins in all the time.
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You can't connect the zeners like you're suggesting. Just crank the variac down a bit more.
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Here's a couple of pics of the underside. I ran a few wires underneath to keep the top side clutter down.
I'm trying to use up some things I bought over the years on this. So I to help protect the under carriage wire runs I used some of the spaghetti tubing I got from AES along with some 1/4" plastic clamps. To get the clamps to hold tight, I used 2 and 3 different sizes of tubing nested inside of each other. 1 full length and 1 or 2 more short pieces just the width of the clamps. Worked very well. :icon_biggrin:
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You can't connect the zeners like you're suggesting. Just crank the variac down a bit more.
Can't, then the main PT will be low.
Hmmm......... maybe I can because the main PT will be under used on it's heater wind too. Might kill 2 birds with 1 stone. :icon_biggrin:
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Looking real good Brad. Won't the heater voltage drop a bit once you get a load going? What are you going to build first?
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Thanks Jojo. :icon_biggrin:
I put in all 6, 9 pins to load it.
I think what Sluckey suggested will work.
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Ain't no thang! It's only 5.56% high.
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What are you going to build first?
It's time for me to find out about Champ amps! Some love them some not so much. :dontknow:
Then I'm going to use the champ set up on the board to see if that Gibson GA55V's (true pitch shift) vibrato works. (Gibson's schematic could be wrong.)
Then the Gibson/Vox AC15/30 vibrato. :icon_biggrin:
Then maybe mix Sluckey's Warbler vibrato with the Gibby vibrato, run them in series. :undecided:
Then a 1 tube verb.
Then......... :laugh:
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Ain't no thang! It's only 5.56% high.
Yes, but that's with all 6 pre amp tubes in. :laugh:
I could just leave them in with nothing else hooked up to them to keep the same current draw?
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There are lot's of things you 'could' do. You could use a dedicated variac just for the filaments. You could wire the tubes for 6.3v. But it's just a breadboard and in the end it still ain't no thang! :icon_biggrin:
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But it's just a breadboard and in the end it still ain't no thang! :icon_biggrin:
Very true. :icon_biggrin:
Ain't no thang! :laugh:
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Sluckey I want to make a little substitution box loaded with several K bypass value caps.
I have a few C&K 2P/6T rotary switches.
I thought I could wire it up like your tone switch for your Vox AC15.
You tied all the caps together on 1 side and also tied that side to 1 of the in/out poles, why? To stop pops when switching?
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and also tied that side to 1 of the in/out poles, why?
No particular reason other than I wanted to. It serves no purpose. My switch is a MBB so popping is not an issue.
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No particular reason other than I wanted to. It serves no purpose.
:w2: ??????
What about why you tied all the positions together on 1 side?
Must be a reason for the extra work.
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No particular reason other than I wanted to. It serves no purpose.
Must be a reason for the extra work.
"The ancient ways carry purpose and may not be forborne."
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Convenience of mounting the caps. It's fine to have one side of every cap tied together. Notice my schematic shows a cap connected between pins 6 and 6, or 5 and 5, or 4 and 4, etc. While this looks neat and orderly on a paper schematic, it would be a jumbled mess to actually mount the caps like that on the real switch. Impossible to do! Connecting all the pins of half the switch together allows you to connect the caps in a more manageable orderly fashion. Look at the layout. For example, you'll see that 220pF really connects between pins 6 and 3. And the 500pF connects between pins 5 and 2.
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Wait........If all the positions on the left side/gray in the drawing are tied together then only the right side/yellow has to have the correct cap value soldered to the correct pin/position.
So the left side cap ends can go anywhere they fit.
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Convenience of mounting the caps.
Hah! I figured it out while you where posting. :icon_biggrin:
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It's fine to have one side of every cap tied together.
Yes, because their still isolated from each other on the other side.
Notice my schematic shows a cap connected between pins 6 and 6, or 5 and 5, or 4 and 4, etc. While this looks neat and orderly on a paper schematic, it would be a jumbled mess to actually mount the caps like that on the real switch. Impossible to do! Connecting all the pins of half the switch together allows you to connect the caps in a more manageable orderly fashion. Look at the layout. For example, you'll see that 220pF really connects between pins 6 and 3. And the 500pF connects between pins 5 and 2.
I saw that and started to think you made a mistake on the drawing. I should know better by now!
That's how I figured it out. :icon_biggrin: Messed me up for a little bit. :laugh:
Thanks!
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"The ancient ways carry purpose and may not be forborne."
:laugh: I've been here 5, 6 years?
Sluckey always has a reason why he does what he does. :icon_biggrin:
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Hah, and on the left side/gray their hard wired to the pole so if the switch contact ever gets corroded or even fails it won't matter. :icon_biggrin:
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Here's another way to do exactly the switching. This totally frees up the second section of that switch. This is from my AC-15 Lite conversion.
http://home.comcast.net/~seluckey/amps/hammond/closeup.jpg (http://home.comcast.net/~seluckey/amps/hammond/closeup.jpg)
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I get it, Nice! Thanks. :icon_biggrin:
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"The ancient ways carry purpose and may not be forborne."
:laugh: I've been here 5, 6 years?
Sluckey always has a reason why he does what he does. :icon_biggrin:
Exactly! :wink:
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All right, I think I'm done! :icon_biggrin:
I'm putting a Champ SE on the bread board (BB) 1st. And then I'll use that to try some true pitch shift vibratos (TPSV) .
Even though this is a BB, I wanted to change the K bypass cap and the plate coupling cap (CC) very fast to really hear the difference in real time and not from my ear's memory. I want to take out any second guessing.
To me this was very important especially for the CC's. I bought several different brands to see IF/how much different they might sound.
So, for the 1st preamp gain stage, I made up a couple of brackets from some parts I had laying around to mount a couple of rotary switches. They both are movable so I can use them on other gain stages too. I did test and mark the outside foil on the CC's. (They don't look real pretty but they work fine.)
For the K bypass caps I used a 2P6T rotary set up like this;
Position's;
1. Open/No bypass cap.
2. 0.68uF.
3. 2.2uF.
4. 4.7uF.
5. 10uF.
6. 26uF.
For the plate CC I used a 1P8T rotary (I had this here, bought it from Weber years ago, BIG honkin rotary :laugh: ) I measured each cap for capacitance and I went through the Mallory 150's I had on hand and found a yellow (old) and white (new) that were both 22.02nF. All the other cap brands I had at lest 2 each and measured for the closest to 22.00nF. Rotary switch set up like this;
Position's;
1. Mallory 150/white/630v/22.02nF.
2. Mallory 150/yellow/630v/22.02nF.
3. Jupiter/yellow/600v/20.39nF.
4. Jupiter/red/600v/19.28nF.
5. SoZo/blue/400v/22.02nF.
6. Musicap/600v/23.00nF.
7. AuriCap XO/600v/20.78
8. Mojo Mustard/630v/22.05nF.
I didn't have room for the OD 225 and 715. I also don't have a SoZo mustard, I'll test those later.
Here's a few pics;
Now back to my CUBS playoff game against the St. Lou. red birds. :icon_biggrin:
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I also added a Fender Princeton 5F2A/tweed Deluxe 5E3 single tone control and installed a 2P1T switch to take it completely out of the circuit. :icon_biggrin: Just to hear the gain loss.
I did this because a Champ has limited gain with only 2 stages before the output tube.
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Those switching pots look monstrous.
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Yeah, 1 is. :laugh:
I only used it because it's 8 throw and I had it here already, it came with the knob. The other is about the same size as a standard pot, after you trim the shaft.
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Yowza, that is crazy. I hope you dont have to move that once its done either.
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Yowza, that is crazy. I hope you dont have to move that once its done either.
It's only 2'x2'. The close ups might be making it look much bigger? :icon_biggrin:
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You can really tweak a circuit before you build, prototyping too
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You can really tweak a circuit before you build, prototyping too
Yep, that's 1 of the reasons I built it. :icon_biggrin:
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All right, I took the maiden voyage tonight with the bread board (BB) set up with a Champ 5wSE amp. :icon_biggrin:
Everything worked! No smoke, and full sound at the speaker! ALL the BB meters are working too.
I played for ~1 hour flipping the 6 throw K by pass switch and the 8 throw 1st coupling cap (CC) switch, and kicking in/out the single tone control (tweed Deluxe 5E3).
To start with, I ran it through a NOS 5Y3/new EH 6V6/new Tung-Sol 12AX7, 15" alnico WGS with a MoJo 759EX/290/0/290/75mA/PT, Classic Tone 40-18030/5w/50mA/8K/8ohm, SE OT.
My 1st thoughts are, switching the 1st stage CC, all the caps sound very, very, similar to me so far. Any little twist of the pick/accents or playing with my fingers/accents, made as much difference or way more than changing the CC. (Now, that was for lead and not full chords yet. :dontknow: )
As I try different tubes, power/rectifier/pre amp and different speakers I'll post more with ACV's/DCV's.
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I played for ~1 hour flipping the 6 throw K by pass switch and the 8 throw 1st coupling cap (CC) switch ...
My 1st thoughts are, switching the 1st stage CC, all the caps sound very, very, similar to me so far. Any little twist of the pick/accents or playing with my fingers/accents, made as much difference or way more than changing the CC. ...
But changing the cathode bypass cap made a big difference, right? All the coupling caps you used are polyester film & foil (though they have construction differences) except for the Auricap XO which is a polypropylene dielectric. With value and dielectric material being the same, I'd expect little if any difference, resulting mainly from construction details. It's nice to see your experiment is arriving at similar results.
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With value and dielectric material being the same, I'd expect little if any difference, resulting mainly from construction details. It's nice to see your experiment is arriving at similar results.
That is what I'm hearing so far, have to play through the amp some more.
But changing the cathode bypass cap made a big difference, right?
Yes! Big difference in gain at lower and lower frequencies as you use a larger cap.
I also added a by-pass switch for the 2nd gain stage K cap. Right now I have a 10uF in there and pretty dramatic change in switching it in/out.
The tone control works well and is not dropping any gain that I can hear. I switched out the tone pot and the amps volume decreased. (I used a 2P/2T switch to take it fully out of the circuit.) So it's acting more like a boost at most any volume setting less than full up. Makes sense because it's by passing the hi end around the volume pot.
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Anybody have an idea about what to use to lube the 8T ceramic rotary switch?
It's difficult to get the switch to seat correctly by itself so it makes full contact so the cap is in the circuit. I have to wiggle it to get it seated properly. :BangHead:
I'm not sure if it's the little brass(?) wheel that's not turning smoothly or if it's getting hung up on the ceramic bumps or a little of both. :dontknow:
I have a can of spray silicon lube that I could spray on a Q-tip and apply it. Or maybe some of that brake white silicon lube they sell at the auto parts store? ~$1 for a little tube that I could use a tooth pick or thin wire to apply?
The wheel is pretty close to the pole contacts.
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.
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Look for electronic lube, I can take a picture of the canned stuff we use for our contacts and moving coils when I get to work today
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Is that different than pot cleaner/lube? Is it conductive?
I have a spray can of pot cleaner/lube but I don't think I should get anything that's conductive on the ceramic as the pole contacts are mounted in it.
Think of a ceramic tube socket, you can use contact cleaner on it but not cleaner with a conductive lube in it.
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It's non conductive, either that or I'm living in Bettlejuice land and don't know it yet :icon_biggrin: :icon_biggrin:
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Caig deoxit
http://store.caig.com/s.nl/sc.2/category.188/.f (http://store.caig.com/s.nl/sc.2/category.188/.f)
--pete
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We use the CRC 2-26 cleaner/lube for our electrical work
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Caig deoxit
http://store.caig.com/s.nl/sc.2/category.188/.f (http://store.caig.com/s.nl/sc.2/category.188/.f)
Isn't it conductive? Maybe I'm misunderstanding them. Maybe they mean by cleaning the contacts their more conductive? See below from the Deoxit page;
KEY FEATURES:
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DeOxit is not conductive. Otherwise every device with switch contacts that I own would have blown sky-high.
It cleans the oxidation from the contacts
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Since I think you're trying to get the switch mechanism to turn more smoothly, I'd go with your original idea of a tiny bit of brake lube on the brass wheel & ceramic bumps.
The whole assembly looks spring-loaded. Is the spring not pulling the switched contact back in place? Could that mechanism/switch shaft be a little bound?
On second thought, I might just replace it with a better switch... :dontknow:
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Auto parts store also has hi-voltage grease for plug wires, pretty sure is non - conductive, pricey, silicon based.
Is that a *push-rotate-release* instead of just rotate?
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Caig deoxit
http://store.caig.com/s.nl/sc.2/category.188/.f (http://store.caig.com/s.nl/sc.2/category.188/.f)
Isn't it conductive? Maybe I'm misunderstanding them. Maybe they mean by cleaning the contacts their more conductive? See below from the Deoxit page;
KEY FEATURES:
you don't really think I'd recommend a product that was conductive to use on electronics, right?
it imporives conductivity of the. ontacts by deoxidizing.
--pete
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you don't really think I'd recommend a product that was conductive to use on electronics, right?
it imporives conductivity of the. ontacts by deoxidizing.
Your right, I know you better than that. :icon_biggrin:
Ok, deoxidizing the contacts. Thanks Pete and thanks lego and all the guys!
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Is that a *push-rotate-release* instead of just rotate?
Just checked, you had me worried, it's not a push-rotate-release.
Since I think you're trying to get the switch mechanism to turn more smoothly, I'd go with your original idea of a tiny bit of brake lube on the brass wheel & ceramic bumps.
The whole assembly looks spring-loaded. Is the spring not pulling the switched contact back in place?
I think it's the wheel hanging up (maybe on it's shaft?) and not rolling down into the bottom of the valley under the spring pressure. The spring U clip should force the contact to seat in the bottom of the valley.
I think you can see it in the pics, there's a U shaped bracket, 1 end/side is press fitted to the rotary shaft the other end/side moves up/down, because of the hills/valleys as you rotate the switch. So somethings binding.
Could that mechanism/switch shaft be a little bound?
I not sure, but maybe that's part of it? I'll try and get some silicon spray down in there.
Here's a pic of the white silicon brake lube, $1.46.
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these will work better... (http://www.mouser.com/ProductDetail/Alpha-Taiwan/SR2511F-0112-19R0B-E9-S-W/?qs=sGAEpiMZZMvNbjZ2WlReYnqYHrQfuERsVVYwe2wXwFk%3d)
$2.77 each from our uncle mouser.
--pete
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Thanks! I'm gonna buy a few. :icon_biggrin:
Edit; Just bought 4.
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I'm too slow. AES has them for $1.75.
https://www.tubesandmore.com/products/switches?filters=Type%3DRotary (https://www.tubesandmore.com/products/switches?filters=Type%3DRotary)
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Oh well, that's all right, not much more, <$1 each, thanks anyway. :icon_biggrin:
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Wd40 is non conductive as well and everyone has that one
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Wd40 is non conductive as well and everyone has that one
Ok, thanks Lego, I was wondering about that. :icon_biggrin:
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I realized yesterday that I forgot to install the B+ dropping R in between the screen B+ cap. So I had 22uF for the screen cap and 10uF for the pre with no dropping R between them so 32uF for the screen and pre.
It was motor boating (oscillating) when I turned up the volume past ~7 to full up, but I thought it was because of long runs on the bread board (BB). Because of the BB set up and since I don't play that distorted I didn't really care. Just put in a 22K dropping R, as per a 5F1, and fixed that. :icon_biggrin:
I also forgot the 470 ohm screen R. I had it (470R) where the B+ plate to screen dropping R (10K) should go. Fixed that. :icon_biggrin:
Will take some dcv's with tubes being used and post them next.
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I was testing the heater DCV stand off and the humdinger pot.
I have a pretty good swing of DCV with the pot I put in on the DCV stand off board. With the B+ C node at 205.5dcv, which is where I tapped the DCV, I get 40.5dcv to 73.0dcv. I'm shooting for 70dcv to 80dcv. So that's pretty good, if I have a higher dcv from the tap/take off point I'll get a higher swing, might need to play with the voltage divider values, but fine for now.
BUT, the humdinger pots, I have 2, 1. for the 6x12A_7's and a 2nd for the power tube(s), (I have 2 @ 8 pins set up, to go with either a SE, PSE or a PP) didn't do any thing. :BangHead:
So I tracked it down to the extra 50 ohm R's I put in series with the end legs of the humdinger pot.
I by-passed the pre-amp humdinger with short gator clip leads and then it worked. I could hear it very easily by ear. But tried the same with the power tubes heater humdinger pot and nothing, no change in hum that I can hear.
I take this to mean that the pre's benefited from it because the input signal is so low that the little bit of ripple(?) from the ACV heaters is leaking through and being amplified where as the power tubes signal is large enough to squash/kill that leakage?
Why did by-passing the extra R's make the humdinger work? :think1:
Schematics posted below,
(Edit; Fixed spelling errors.)
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Test voltages, set up with a Mojo PT 759EX, 290/0/290 @75mA, 6.3/?A, 5v/3A, input to BB set to 120acv with variack, with CLC B+ filter input before the B+ plate A node, Doug's Fender 2x6L6 choke@90mA, 5Y3 NOS JAN/PhillipsECG rectifier, JJ 6V6, new made Tung-Sol 12AX7, WGS 15" alnico, all at idol;
Reservoir B+; F&T/22uF/500v; 305dcv.
After choke, B+/A, plate node; Panasonic radial EH(?) series, 22uF/450v; 301.3dcv
B+/B node, screen; Panasonic radial EH(?) series, 22uF/450v; 257.2dcv.
Screen dcv taken off B+/B node with 470R, 256.2dcv.
B+/C node,Panasonic radial EH(?) series, 10uF/450v pre-amp; 205.3.
BB meters;
Total current, measured at reservoir B+, just under <40mA.
Power tube 6V6 K current; ~23mA, with volume full up and bashing a full 6 string chord, just under 40mA. 6V6/250R/25uF bypass K cap.
Odd thing, I measure for ACV ripple at the reservoir B+ node (F&T/22uF/500v), NO ACV?????? Maybe because it's SE/class A and only ~23mA at idol?
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Oh, when I added the B+ screen to pre-amp dropping R that lowered the B+ screen to pre-amp dcv.
Now it sounds WAY fuzzy after 5 on the volume.
The higher pre-amp B+ sounded WAY better to me, just a taste thing.
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So I tracked it down to the extra 50R's I put in series with the end legs of the humdinger pot.
I by-passed the pre-amp humdinger with short gator clip leads and then it worked
I got lost here(not hard for me :BangHead:)
why did you add the 50R's?
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The pot I bought was only 100 ohms so I added some extra resistance after reading a Merlin article on humdinger pots, so as not to bleed as much current to ground through it.
I would have liked a 250 ohm or 500 ohm pot.
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Great stuff, thanks for sharing!
Why the fuse? Just cause? Do you fuse your heaters in your amp builds?
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Why the fuse? Just cause? Do you fuse your heaters in your amp builds?
Just in case I do something wrong. :laugh: I had those fuse holders sitting here for years, might as well use them.
I've never fused heaters in an amp.
Hey, my 1P12T rotary switches just got here. :mail1:
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I need to order a couple small switches from Mouser. About $12. How bad were the shipping charges on your small order?
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I got 3 day UPS and the shipping was a buck or 2 more than for the 4 switches.
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I was hoping for a dollar amount?
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4 switches $11.08, UPS 3 day $12.99. :icon_biggrin:
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I usually get about $12 Shipping from Mouser if I do not use my UPS account number. If I use my account number it is $7.75 for business delivery. Home will be more.
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Thanks.
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Well, I changed out that coupling cap (CC) 1P8T rotary switch (RS) that was giving me problems with the new Alpha 1P12T RS, it's working GREAT! Very smooth and very fast. Play something and reach with my left hand for the switch and then play the same thing, very easy to hear any change in tone. :icon_biggrin:
I also added the 2 OD caps I had, 1@ 715/400v, 1@ 225/400v.
I played another hour or so and I am hearing some differences BUT NOTHING where I can say this cap is the best hands down.
Tests were done with the set up in reply #93, I had my Fender stand alone Reverb feeding the Champ 5F1 (with a Fender single knob tone control engaged). All test's this round were with the volume set at ~11:00, tone set at ~2:00, no change in those settings;
1. One of the differences I'm hearing is the overall frequency response across the full frequency spectrum. Some had less bottom bass end, so they sounded more bright. BUT at the same time, the brighter caps had less bottom end distortion.
2. Second difference I'm hearing is depth/3D sound. Some sound more flat/lifeless, not frequency so much but depth, more like adding a slight amount of reverb.
3. The 3rd thing I'm hearing is some seem to sound better with single notes and some seem to sound better with cords when left to sustain/ring out. There's a smoother sustained 'grind' and a very nice 'swirl' that sounds real good to me. Sounds like a big amp, Marshall/HiWatt, that's not over the top with a fuzz before it or on 10. Real nice for some things.
I only did all these test with only 1 guitar so far (re-issue 80's rosewood fret board Strat, stock PUPs, neck PUP, volume/tone full up).
As I said this is with 1 guitar/PUP's and no change in the amps/guitars volume/tone controls.
So...... so far I think that for the same reasons that I might reject some of the caps, I believe others would love those same caps. :dontknow:
PS: I had a hearing test last month that came back as both ears being very close in full frequency spectrum/volume and the hearing of an early 20 year old, at 56.
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That's a great rundown! I'd be interested in seeing this last post with the specific caps mentioned under each of the categories you've outlined (perhaps in its own thread?).
Since I've used some of those caps but not others, having the names added to the observations would help as it would give a sense of how a given cap is different from a known reference.
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I'd be interested in seeing this last post with the specific caps mentioned under each of the categories you've outlined (perhaps in its own thread?).
I'll post them here. :icon_biggrin: I want to play through them a little more 1st, to be sure.
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I was briefly thinking about a prototype box to test different caps based on this thread. It would have 3 switches, for each of 0.022uF, 0.047uF and 0.1uF caps, to hear the different brands/types. Add a 4th 3-position switch to select the value-switch in use. The idea was to have not just ployester-dielectric caps, but oil, polypropylene and polystyrene, too (I already have a mess of 0.1uF polystyrene caps).
I think I'm starting to talk myself out of it because of the cumulative cost of switches, caps, box and binding posts. But I was very excited to try it for an hour or two... :laugh:
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A friends over and playing through the amp, sounds pretty good, it's starting to grow on me. :icon_biggrin:
I popped in an NOS Philips ECG JAN 6V6 last night and it sounds much smoother than the new EH 6V6 I had in there.
Amps got plenty of chime with the strat, very nice harmonics and the verb gives a nice depth to it. It's set at ~11:00 (tone ~2:00) and that's plenty of distortion for me. :laugh:
The WGS 15" alnico sounds real good to me. :icon_biggrin:
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I was briefly thinking about a prototype box to test different caps based on this thread. It would have 3 switches, for each of 0.022uF, 0.047uF and 0.1uF caps, to hear the different brands/types. Add a 4th 3-position switch to select the value-switch in use. The idea was to have not just ployester-dielectric caps, but oil, polypropylene and polystyrene, too (I already have a mess of 0.1uF polystyrene caps).
That would work great. :icon_biggrin:
I think I'm starting to talk myself out of it because of the cumulative cost of switches, caps, box and binding posts. But I was very excited to try it for an hour or two... :laugh:
That's a problem with trying this kind of thing. Some of these caps are well over $12 a piece. But I really wanted to get to the bottom of this with my own ears.
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Oh, I replaced the NOS 5Y3 with a TAD GZ34/5AR4. Reservoir dcv is now ~360dcv and preamp B+ C node is ~230dcv. Sounds better to me. Next I'm going to lower the B+ dropping R going to the C node from 22K to 10K maybe 5K and see if I like that better.
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Here's the caps I tried, uF value tested before soldering them up to an Alpha 1P12T rotary switch so I could compair them instantly and not from ear memory;
1. Mallory 150/white/630v/22.02nF.
2. Mallory 150/yellow/630v/22.02nF.
3. Jupiter/yellow/600v/20.39nF.
4. Jupiter/red/600v/19.28nF.
5. SoZo/blue/400v/22.02nF.
6. Musicap/600v/23.00nF.
7. AuriCap XO/600v/20.78
8. Mojo Mustard/630v/22.05nF.
9. Orange Drop/400v/22.74nF.
10. OD 715/400v/22.30nF
Here's what I think so far after 3 different rounds of playing on 3 different days, playing single notes and full chords, both with -FB and without -FB;
1st, I think ALL the caps would definitely work fine for different people, in different builds, with different guitars, different PUP's and different music/playing styles. (Remember I'm testing these caps in a SE Champ, 5F1, 1x6V6, V1a/b ~150dcv plate, 6V6 ~360dcv and the 12T CC rotary switch is connected to the 1st CC from V1a plate to V1b volume control, with a Strat. And I only tested 1 of each as a sample.)
Also, and I don't know what it means, was when I tested for the caps outside foil lead, some were way noisier than others. (I mean how noisy the cap is with the outside foil lead hooked up to the test amps input.) The Mallory's were the nosiest with the white being the worst. The Musicap and AuriCap were by far the quietest. The quite 1's had very little difference in noise when flipping the switch to flip the caps leads. And on the outside foil cap lead to the test amps input they were way quieter than the other caps on their outside foil lead. Big difference.
I was thinking, before these tests, that the fatter the cap the more shielding it would have from outside foil lead to the inside foil lead. So larger values/larger voltage rating(fatter cap) would have more difference when switching leads. A 0.1uF cap is way easier to hear a difference than a .0047uF cap, I have a very hard time hearing any difference in leads on a Mallory white 150. (I know that Tubenit and Gezzer have posted they hear the opposite. :dontknow: ) But the Musicap was the quietest and is the thinnest.
So far, for the sound I'm wanting, my least liked sounding cap (to me) is the white Mallory 150. Flat , no/not much depth(3D depth) and thinner/less bottom end, yet clean(er) sounding and a little more forward/aggressive sounding? And the yellow Mallory's 150 sounds different than the white. It's fuller and has some better depth to it. But is not as clean on the bottom, because it has more bottom extended range?
(I noticed that the shape and size/dimensions changed on the 22nF 150's but not on the other values I have of the 150's. The yellows are just a little shorter and fatter. I'm gonna have to try a few other white/yellow 150 values and see if they sound closer to the same rather than different on the bottom end.)
(I have a couple of old Fender blue tubular caps from the BF amps around here somewhere. I'll see if I can find them then test them to make sure there not leaking any dcv. Might be a good base line?)
The Musicap was/is the most balanced to my ear, top/middle/bottom end, very nice sounding, maybe the nicest mid range, had the most 3D depth of sound, smoothest distortion and had the best ringing sustain smooth growl/swrill on a full cord left to ring out. I think it has/lets the most harmonics through? It's also, unfortunately, the most expensive.
AuriCap was very good too, although a little cleaner/less bottom end but clearer because of it?
The blue SoZo, another pricey(er) cap, sounded pretty thin to me and pretty flat sounding too. But again very clean/clear sounding. (Might sound great with a big Jazz box guitar?)
The Jupiters sounded good, pricey(er) caps, the yellow sounds pretty good, fuller and some/more depth than most. But the red costs more than the yellow, red has a tube/sleeve it's in and they sound close but less bottom and cleaner/clearer.
I can hear why Tubenit likes the OD 225's. They sound more like/close to the yellow 150 and yellow Jupiter caps. Fuller bottom, more depth, nice mids, a little less bottom that the yellow 150 and yellow Jupiter. (Might be that the mids are a little more apparent because there's a little less low end?) The OD 715 is cleaner and brighter with less bottom end distortion. For a cleaner amp, maybe for a Jazz player with a big body git box, they might sound very good?
Mojo Mustard was good, maybe a good in between cap from a bright to bassy(er) cap? I like it.
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I have to say that at 1st I didn't like this little 5F1 Champ at all!
But........ after playing through it more and changing the rectifier from a 5Y3 to a GZ34/5AR4 (this raised the 6V6 plate dcv to ~360 and the 12AX7 dcv to ~150dcv, much better sound to me) and changing the (new) EH 6V6 to a NOS Philips ECG JAN 6V6 (smoother distortion), I'm really liking this little amp!
Then........ I added the -FB loop........ at 1st I hated it! I thought I had something wired wrong, maybe the tap point. But I tried it again tonight and with a fresh set of ears and played with the amps volume/tone controls, it's fine.
If/when I build a Champ I will absolutely add a on/off -FB switch, as I found great sounds with both -FB on/off. This really surprised me. :icon_biggrin:
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Over all the caps with more bottom end sounded better to me on single note leads and the thinner sounding caps sounded better on full cords. Which makes sense to me. :dontknow:
Now with some of these comments remember I didn't play with the amps volume/tone controls or the guitars volume/tone controls. Some of the possible shortcomings(?) might vary well be compensated for by dialing in/shaping the sound with them.
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you don't really think I'd recommend a product that was conductive to use on electronics, right?
it imporives conductivity of the. ontacts by deoxidizing.
Your right, I know you better than that. :icon_biggrin:
Ok, deoxidizing the contacts. Thanks Pete and thanks lego and all the guys!
Before I tried DeoxIT I thought I could just use any old lubricant spray, WD40 etc. were already on my shelf so why bother with an expensive can of this other stuff?
Now that I have used it, I think it is some kind of miracle spray. It has brought frozen pots and numerous switches/contacts back to life for me.
DeoxIt is a must have item on my shelf now.
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There is more than one kind of Deoxit.
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Out working on the BB doing some tests.
There's a little calibrator screw on the face of the panel meters just below the needle vain. So I set the input acv to 120acv with my variac and my hand held meter (HHM) then adjusted the panel meter to read the same, easy enough.
Then I tried to set the input B+ dcv meter to what my HHM read and that's at the 1st/reservoir filter cap and it would go up in it's reading but not down enough.
HHM said 338.5dcv could only get the panel meter down to ~ 350dcv, 1K dcv scale. Close enough.
Now I'd like to calibrate the B+ power supply (PSU) current meter (monitors the whole PSU B+ current) and the power tube K current meter.
I'll thinking, I'll either put my HHM in series with the B+ dcv or pop in a 1 ohm R and measure across it. That should work.
But on the K current meter there's a 1 ohm R across it already.
So can I use my HHM to measure across it safely? Will it give a false reading doing that?
PSU current panel meter, at idol, reads ~41mA, but the K panel meter, at idol, is reading only ~28mA's. Champ set up, 1x6V6, 1x12AX7. That's 13mA's difference. With only 1 more tubes current draw, a 12AX7, maybe 2mA, the rest is filter cap charging current and/or the panel meters are off?
1st/reservoir/22uF = 338.5dcv > then fender 6L6 choke > A node/22uF = 334.5dcv > then 470 ohm > B node/ 22uF = 297.0dcv > then 10K; C node/10uF = 239.6dcv.
6V6 plate = 308.6dcv, K = 17.61dcv, 250 ohm K R, screen R = 470ohm.
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There's a little calibrator screw on the face of the panel meters just below the needle vain.
That's a mechanical zero. With no power applied place a short across the meter terminals and turn that screw clockwise until the needle is below zero. Continue slowly turning clockwise until it reads zero. Don't back up. If you go past zero just keep turning until below zero again.
You can check the meter full scale by applying the correct current. Any other calibration has to be done with external circuitry.
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2 other things;
I've tried to measure for ac ripple voltage at the 1st reservoir B+ filter cap with my HH meter and I can't get any reading of acv? If I watch the HHM and as I 1st touch the red probe to the reservoir node/positive end of the 22uF cap, the meter flashes ~3. something acv's.
So my meter's not good enough/can't read it or there's no ripple because the it's a class A amp with only ~41mA of current draw?
The other thing is I noticed that when I had my Fender stand alone reverb plugged was in the front end input jack of the BB, that when I didn't use the ground lift adapter on the verbs power cord, the B+ panel current meter would drop to ~10mA.
At 1st I thought the panel meter was bad, :BangHead: :cussing: ...... but put the ground lift adapter on the verb's power cord and the B+ current panel meter goes back up to ~41mA.
I guess without the ground lift adapter on the verbs power cord that gives the BB another path for the B+ ground return current to flow, so the panel meter doesn't see it?
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That's a mechanical zero.
Ohhhh..... I'll try it. :icon_biggrin:
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Yes it works just like you said. :icon_biggrin:
Tried my HHM in series with the B+ from the 1st reservoir filter cap, set for mA's, red lead to filter cap positive end, black lead to down stream B+, got ~0.49mA's. So that doesn't work. (Unless the meter leads need to be flipped?)
Then I put the HHM in series with the PT CT, set for mA's, red lead to PT CT, black lead to ground, reads 56.8mA's.
Panel meter still worked with both tests and read ~41mA's(200mA scale). 56.8mA - 41mA = 15.8mA.
So is the way I have the panel meter set up in the B+ PSU not seeing that 1st 22uF filter cap? Or my panel meter is not very accurate? Or both?
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You can check the meter full scale by applying the correct current.
How?
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On the K current meter there's a 1 ohm R across it already.
1. Can I use my HHM to measure across it safely?
2. Will it give a false reading doing that?
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What is an HHM?
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What is an HHM?
Sorry, because I'm talking about the panel meters and my bench/hand held meter, I abbreviated it to HHM a few posts back in ( ). I wanted to be clear which meter I was referring to.
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I measured across the 1ohm R on the back of the panel dcv meter and my test meter read 29.3mA's, panel meter read ~28mDCV's. Not bad, close enough. :icon_biggrin:
Odd thing though, I 1st disconnected the 1ohm R from the panel meter and measured for dcv across the 1ohm and read 37.7mA. :dontknow:
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I would get a handful of 1Ω/1W resistors to use in conjunction with a breadboard. For example, put one between your rectifier and the first filter. The voltage drop across it represents the entire B+ current load. Put one almost anywhere you want to measure current.
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Odd thing though, I 1st disconnected the 1ohm R from the panel meter and measured for dcv across the 1ohm and read 37.7mA.
The meter coil has resistance too. It's in parallel with your 1Ω resistor and should skew your readings.
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The meter coil has resistance too. It's in parallel with your 1Ω resistor and should skew your readings.
37.7 - 29.3 = 8.4 That much? That's close to what, 25%?
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Probably not. Why don't you measure the resistance of your meter coil?
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I would get a handful of 1Ω/1W resistors to use in conjunction with a breadboard.
I have a bunch here I got from Doug.
But it's nice to be able to look up at the BB's panel meters and see what's going on with out having to move my test meter's gator clips/probes around. That was the whole point of using the panel meters and to free up the bench test meter. :BangHead:
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With 1 end of the 1ohm R disconnected from the back of the panel meter, coil = 3.8 ohms.
With 1 ohm R across panel meter coil = 0.6 ohm.
1 ohm R = 0.9 ohm.
Test meter leads shorted = 0.0 ohm.
Test meter = Klein tools, MM2000.
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Some of the panel meters say 'Class 2.5' on their face panel.
I did a search and the best I can figure out is that "Class 2.5" means +/- 2.5%?
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With 1 end of the 1ohm R disconnected from the back of the panel meter, coil = 3.8 ohms.
That's very significant.
I'm not suggesting to abandon the panel meters. I'm suggesting to use the 1Ω resistors to get a feel for how accurate your panel meters are. If you have a multimeter that you trust the current function, then you don't even need the 1Ω resistors. Just put your multimeter in series with your panel meter, connect to a variable power supply with current limiting resistor, increase the power supply output until the panel meter reads exactly full scale, and compare to your multimeter reading. IE, if you have a panel meter that says full scale current is 100mA, then use a power supply to pump 100mA through that meter with your multimeter connected in series. They should give the same reading. If not, then your multimeter calibration is no good or the panel meter is not calibrated.
If you want consistent accurate readings from those panel meters then you will have to calibrate them against some other standard that you trust. That can be your DVM or it can be a NIST standard. I would be happy if the panel meter matched my uncalibrated Fluke 87-V. Unfortunately, panel meters either are accurate or they are not accurate. There is really nothing you can do to change the fullscale reading of the meter itself.
But if the meter is being used as a current monitor or a voltage monitor you can provide external circuitry to make the panel meter readings agree with your DVM.
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Doh, that's the word I wanted, multi meter instead of hand held meter. :BangHead: :laugh:
Thanks Sluckey, I will try a few more things, including using the 1 ohm R's I have.
Earlier, I did try my multi meter in series with the B+ from the 1st reservoir filter cap, set for mA's, red lead to filter cap positive end, black lead to down stream B+, got ~0.49mA's. I don't know why that didn't work. (Unless the meter leads need to be flipped?)
Then I put the multi meter in series with the PT CT, set for mA's, red lead to PT CT, black lead to ground, reads 56.8mA's.
Panel current meter still worked with both tests and read ~41mA's(200mA scale, coil reads, 0.1 ohms).
But..... 56.8mA - 41mA = 15.8mA.
I also did try putting my multi meter in series with the 6V6's K R, (but I think it was with the panel meter still connected?) set for mA's and got no reading/0.0dcv. I'll try again.
6V6 conditions, panel K meter read ~28mA;
6V6 plate = 308.6dcv, K = 17.61dcv, 250 470 ohm K R, screen 295.7dcv, screen R = 470ohm.
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I would be happy if the panel meter matched my uncalibrated Fluke 87-V.
I would too. :icon_biggrin:
Not saying my multi meter is as good as a Fluke but still I think it's in the ball park.
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6V6 plate = 308.6dcv, K = 17.61dcv, 250 ohm K
what am I missing? I get 70mA (17.6/250) and 20W plate. Isn't a 6V6 like 9-11W?
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Seems very hot to me for a single 6V6.
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Don't single 6V6s usually use a 470'ish ohm K resistor?
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Yes.
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Yes, my mistake. I just double checked, it's 470R.
Actual = 463 ohm.
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Now the resulting plate+screen current seems much more reasonable; so does the dissipation.
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Yes and the math is very close to what my multi meter reads for K current. :icon_biggrin:
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Good news! :icon_biggrin:
I took out the large power tube K current panel meters and put in 1 of the small 100mA panel meters I have. I also put in a 1 ohm R in from the 8 pin power tube (relay) socket to the top of the 470KR.
Test results with SE 6V6;
Panel meter coil; 0.6 ohm, 100mA scale. Read; 40mA. (The large panel meter was reading only 28mA, way lower.)
Multi meter across the 1 ohm (measured 0.9 ohm with my multi meter), set for dcmV. Read; 36.2mV = 36.2mA.
Multi meter in series with the K ground wire, set for dcmA. Read; 36.8mA
Panel meter seems a little hotter then the other 2 ways I tested but for the BB I can live with it. If I need to I can measure across the 1R as I will leave it in place on the 8 pin socket.
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I also figured out why I couldn't get a mA reading before when I put my multi meter in series with the power tube, SE 6V6, K ground wire.
I've never used the mA setting on my meter before and there's a function button I didn't push that switches uA/mA/A readings to ac or dc.
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Just finished playing for an hour/hour 1/2 after changing the power tube K panel meter, SE/6V6.
What I noticed is this;
The 1st panel meter I had in there would sit at ~28mA at idol, but when I would hit hard on the strings that meter would jump up to ~40mA.
Now the replacement panel meter sits at idol ~40mA, but now when I hit the strings hard, the power tube K current panel meter AND the B+ current panel both drop down to ~37mA.
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I also added 3 more coupling caps (CC) to the rotary switch.
I bought them from Angela and they are the new Fender CC's. I'll post more later on their construction.
I want to play through them more before I can say what I think.
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From a PM I sent to HBP today;
I know at 1st I posted that I wasn't hearing much of a difference at all then posted that I was. I think here's what happened;
The 1st rotary switch was not seating right and I was having to wiggle it to get it to seat. That was long enough for me to loose my ears focus. The new rotary switch works perfectly, bam!
I do hear a deference but I have to listen for it giving it my full attention. If I were talking with my wife and playing guitar and she was changing the switch while we were talking I don't think I'd hear it.
Maybe if she was flipping from the Malory white 150 or SoZo blue (the 2 thinnest and least amount of 3d caps sounding to my ears, least amount of harmonics?) to the MusiCap or yellow Jupiters (the fullest with the most 3d sound, largest amount of harmonics?) I would still hear it? (http://el34world.com/Forum/Smileys/default/dontknow.gif)
I need to get my friend to play through the BB test rig set up as I flip positions on the switch and see if I can still hear it.
I think, maybe, that what I might hear is the 3d depth coming from the speaker but it's just a wild guess? (http://el34world.com/Forum/Smileys/default/dontknow.gif)
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I just was playing for ~hour or so with the same set up as noted before. I don't know why but some days I hear a bigger difference then other days. And the differences are definitely more pronounced on some days. :dontknow:
I've been thinking about this and I thought maybe it has to do with the Champs volume/single tone knob settings?
Not how loud dB wise, I can hear the amp/speaker just fine volume wise.
But I'm thinking that distortion is having an effect in hearing any differences in the different caps? I'm going to go with the word artifacts because there are extra bits/harmonics I'm hearing? I'm wondering if you have to push the cap enough to make these artifacts heard? Going past the caps linear range? That's when I hear them more clearly? I'm going to move the CC rotary switch to V1b's CC and see if that position in the circuit pushes the CC's a little more? :dontknow:
Also if having V1b's K bypass cap, 10uF, in or out, I have it on a 1P1T switch.
So I tried it at different volumes and different tone settings with V1b's K bypass cap in and out. It did make more of a difference.
I'm hearing the most difference, most artifacts, on the B/G/D/A strings with the amps volume up ~50% and the tone control up to ~2:00 with V1b's K bypass cap in the circuit. Cords and double stops on those strings are the easiest to hear the differences/artifacts/the extra bits/harmonics?
There's a 'grind' and a 'depth' on cords and double stops on these strings and settings that I'm hearing. It's more pronounced with some caps then others AND I hear it in different parts of the frequency range.
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I also added 3 new caps to the 1P12T rotary switch that changes the coupling caps going from V1a to V1b.
I bought them from Angela Instruments ~ $14 each. Their Fender brand caps, 660v/5%;
Red; measured; 21.48nF; Kraft paper/Tin foil/Resin. (Red Astron/early tweeds) Sounded the fattest/warmest/full range break up.
Yellow; measured; 20.22nF; KP/Tin/Wax. (Yellow Astron/late tweeds/some brown face amps) Sounded not as fat but had the most 'hair' in the upper mid to treble. Pronounced picking attack, clicky sounding.
Blue; measured; 22.22nF; Mylar/Tin/Wax (Blue Astron/BF amps) Sounded the brightest and cleanest, least amount of 'hair'.
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Man if I didn't know what it is all about, I would say you were reviving/rebuiding Frankenstein!!
This is one awesome project, I've never seen/heard anything like that before, this is really amazing !!
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I also added 3 new caps to the 1P12T rotary switch that changes the coupling caps going from V1a to V1b.
I bought them from Angela Instruments ~ $14 each. Their Fender brand caps, 660v/5%;
Red; measured; 21.48nF; Kraft paper/Tin foil/Resin. (Red Astron/early tweeds) Sounded the fattest/warmest/full range break up.
Yellow; measured; 20.22nF; KP/Tin/Wax. (Yellow Astron/late tweeds/some brown face amps) Sounded not as fat but had the most 'hair' in the upper mid to treble. Pronounced picking attack, clicky sounding.
Blue; measured; 22.22nF; Mylar/Tin/Wax (Blue Astron/BF amps) Sounded the brightest and cleanest, least amount of 'hair'.
Are you liking all these? Do you feel like the blue ones are close to the blue molded and will add to the scooped tone of a Blackface?
Are any of them similar to the 715 OD's? Some say the 715 are a good sub for the blue molded, but I have simply used the blue molded since I have a few around.
From your findings if you were building, what caps do you find you prefer. Like if you were going to build another 5G9?
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Those are all good questions, answer, I'm not sure yet. Sorry. :dontknow:
I thought today that the Fender blue was a little more scooped sounding than the Fender Red and Yellow and also the other 11 caps. And I haven't found my old blue Fender caps I have a few around here somewhere. :BangHead:
I think I like the Red 1 the best of the 3 new Fenders.
If I were to build another 5G9, I think I would try the Jupiter yellow, Musicap, OD 215, Fender Red and the Mallory yellow. Not in any particular order. I'm still leaning towards the Musicap.
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This might help explain a little better about the differences in caps I'm hearing.
I play slide and I have ~ a dozen different slides. Glass, ceramic, steel, brass, and their different in length, diameter, weight and density. They do sound different but some sound much closer in tone to each, harder to hear a difference, but it's there.
BUT, a thin steel slide sounds way different than a thick ceramic slide to me. These 2 are the far end of the extremes for the slides I own. The glass slides sound scooped in tone compared to the steel/brass/thin or thick and the ceramic, ie, has less fundamental tone and more harmonics mixed in. The thin steel slide sounds the brightest, with the least amount of low mids and bottom end, so it's the sharpest, harshest, ie, has the most fundamental tone and the least amount of harmonics, or maybe has the most amount of hi end harmonics?????? :dontknow:
I would say at this point, I think that it's easier for me to hear the difference in slides, at the 'extremes' of slides I have, then with the CC's. The slides in the 'middle of the pack' tone wise are more/much more subtle in tone difference. Same with the CC's.
Changing the 6V6 in the BB Champ from a new EH 6V6 to an NOS Phillips/JAN was clear to hear but not huge.
I know that changing the speaker would make the largest change in tone over all.
At this point I think, at least with the caps I have to test with, that although they DO make a difference, they are perhaps the least in tone change.
Maybe I'll know more when I change the 12T rotary switch from V1a position CC to V1b position CC?