lego's spin on Sluckey's AC15

[lego4040]

That looks just like the switch I got at RS but I wasn't sure if non grounding was right one

[lego4040]

Found your link for the switch, will order w new caps

[sluckey]

On the other hand someone has a case of Icehouse.  I ain't mentioning no names.

Ugh, OK. Ed, I'm baaaack. Now what was it you wanted to discuss?   

  

[sluckey]

Sluckey you changed the 220k on the speed control, was that to ?  ...Where did you put your standby switch?

I originally used a 100K. But the oscillator would drop out when approaching the fast limit. Changing to 220K prevented the dropout. It also means the top speed is reduced slightly, not enough to be concerned about.

My standby switch is exactly halfway between my Power switch and the pilot lamp.

[Ed_Chambley]

On the other hand someone has a case of Icehouse.  I ain't mentioning no names.

Ugh, OK. Ed, I'm baaaack. Now what was it you wanted to discuss?   

 

I am done for the evening, but glad you thought of me.  I am tired and relaxing, but I will be back to you soon.  You know I am a sponge.  Have a great evening and have fun.  You deserve it.


Have another one.

[lego4040]

Thanks, I'm multitasking here. Watching Bruins loose, ordering parts, drinking a beer and typing.

[lego4040]

My bad Sluckey, I shouldve been more descriptive. I meant electronically not physically

[sluckey]

My bad Sluckey, I shouldve been more descriptive. I meant electronically not physically

Ah, OK. Look on page 3... http://home.comcast.net/~seluckey/amps/VAC15/Vox_AC15.pdf
I keep forgetting. I'm updating the long board file, but not the original file. You may want to keep a copy of both. Sorry.

[lego4040]

I do go back and forth and look at pics as well. I was reading Merlin's view on standbys on tube rectifiers. He said something about them being after the main caps and not in between rectifier and choke. He called it back flash ? Above my knowledge but it was interesting

[sluckey]

A better STBY switch would be a DPST switch between the PT HT leads and the rectifier tube plates. The switch will last much longer. However, unless you are in a gigging environment and taking a break every hour, you don't need a STBY switch on a 15 watt amp. My STBY switch has remained in the operate position ever since I measured total B+ current back on the first day I powered up. Remember, the original had no STBY switch.

[Ed_Chambley]

Sluckey,
Back from debate and the real world.  I am mounting transformers.  Does it matter where I place the choke?  I think I will have room behinf both transformers and will probably allow for the shortest wire length and best lead dress in the power section.

[sluckey]

Choke placement is not critical. But if you can mount it very close to that dual cap can that would be ideal. That's why I asked if it would fit under the hood.

[Ed_Chambley]

Choke placement is not critical. But if you can mount it very close to that dual cap can that would be ideal. That's why I asked if it would fit under the hood.

I am planning it there if I can get it.  It should and work well. Thanks!

[sluckey]

If you have doubts about putting the choke under the hood, look at the old Sunn amps.

[lego4040]

I got some iron time in today and I feel better now. I was a little overwhelmed for a second on where to begin. I started with the tube sockets. I'll neat them up when I'm done, on the output tranny, the brown/yellow and blue/yellow get cut and capped, correct.

[sluckey]

on the output tranny, the brown/yellow and blue/yellow get cut and capped, correct.

That's right. I left them full length and put heat shrink on them. Do you have the OT just like mine or is it the newer style with user friendly secondary winding?

It's beginning to look like an amp now. Won't be much longer.

[lego4040]

I got the Hammond 1650F OT. Not exactly sure what your mentioning but I can either use the black and green wire for four ohms or the second set black/yellow stripe and the green/yellow(4ohm) and yellow(8ohm). Which will allow me to save on the selector switch I believe

[Ed_Chambley]

Looking good Lego, won't be long now.

I had a pleasant surprise.  I mounted my transformers and the PT wires are all long enough, just long enough.  I am getting ready to run my heaters.  Looks like I won't be far behind.

[Ed_Chambley]

Sluckey,
you have your CT for your heaters with the chassis ground and all others together.  Is there a reason to separate the heater CT?  I can no problem, just wondering the reason mostly.

[lego4040]

I don't like this Teflon wire tho, it's a pain in the ass to wrap around turrets. I bought 10feet of every color in the old school cloth wiring for next build

[sluckey]

I don't like this Teflon wire tho, it's a pain in the ass to wrap around turrets. I bought 10feet of every color in the old school cloth wiring for next build

I've never had that problem. What gauge? Are you tinning it as soon as you strip it?

[Willabe]

I bought 10feet of every color in the old school cloth wiring for next build

There's at least 2 kinds of the 'old school wire', ie, cloth covered.

I like the kind Doug has for sale. The other type has a thicker covering that I don't care for, to be fair some guys like it. I don't think it's what they call 'push back braid'. Not as easy to work with IMO. 

To me, I think Doug's is much easier to work with.

22 ga Cloth wire - solid core;

http://hoffmanamps.com/MyStore/catalog/parts18.htm

                 
                                Brad       

[Willabe]

Hey Lego, man that's beautiful work!!!!!!!

Very, very nice!!!!!!


             Brad            

[lego4040]

Yeah I bought Doug's cloth wiring for next build. I should rephrase that about the Teflon, the small gauge is nice but the green and blue is was giving me a headache. I think the green was 18, I would strip with my new Klein auto stripper, twist it tight, clean and tin. Then prebend and wrap around lug, maybe it's cause it's the first time I'm using this stuff or that gauge is to thick

[sluckey]

I should rephrase that about the Teflon, the small gauge is nice but the green and blue is was giving me a headache. I think the green was 18

Ah, now I see. Any kind of 18AWG would be tough installing on a turret, especially when using the pass thru holes. I use 20AWG for B+ and ground wires on the board. All other board wires are 22AWG, except for the 20AWG green wires that connect to tube socket grids (only because I don't have any green 22AWG).

I've got lots of 18AWG but seldom use it for anything.

[sluckey]

you have your CT for your heaters with the chassis ground and all others together.  Is there a reason to separate the heater CT?

T thought it looked purty.

[lego4040]

Will keep that in mind Sluckey. I don't think I'll get to more of this this weekend

[Ed_Chambley]

Sluckey,
Running my heaters, question, what is the proper phase between a 12AX7 and an EF86, 4 to 4 and 9 to 5?

[lego4040]

Ed the pin 4 for EF86 is on same phase as 4/5 for 12Ax7. Pin5 on EF86 is on phase of pin9 of 12ax7

[sluckey]

I always run my heaters 180° out of phase.

[Ed_Chambley]

I always run my heaters 180° out of phase.

Not possible, or is it?
One end of the Heater is the intake and the other is the exhaust, right?  I right, one is the positive and the other is the negative.  Which one is the positive on the green wires.

Please ignore my above comments.  Meant as a joke.

[sluckey]

One end of the Heater is the intake and the other is the exhaust, right?  I right, one is the positive and the other is the negative.

Well I never thought about it as intake and exhaust, but I follow you. But that's only right half the time.

Which one is the positive on the green wires.

OK, I'll quit messing with you. Right now the green wire is positive and the green wire is negative. 16.7mS later the green wire is negative and the green wire is positive.

[SILVERGUN]

Right now the green wire is positive and the green wire is negative. 16.7mS later the green wire is negative and the green wire is positive.

[lego4040]

 

[sluckey]

16.7mS later the green wire is negative and the green wire is positive.

Crap, that's wrong too. It should be 8.3mS. Next time I'm gonna paint one of those green wires yellow like I did in my Revibe. That should eliminate all my confusion.

[Ed_Chambley]

Lego, you are the recipient of an inside joke between Slucky and me.  Please don't take any of this to mean anything.

[Ed_Chambley]

16.7mS later the green wire is negative and the green wire is positive.

Crap, that's wrong too. It should be 8.3mS. Next time I'm gonna paint one of those green wires yellow like I did in my Revibe. That should eliminate all my confusion.

8.35ms


You want the job of explaining the joke, or you want me to do it?

[lego4040]

That's ok, no need to explain

[Ed_Chambley]

Well, I am down to making the board connections and hooking up the OT and hopefully we will hear music.  Lots of wires left, but the PT wiring wend well and everything fit very nicely.

[Ed_Chambley]

She fired up first try.  Have not had a chance to play through a decent speaker, but so far it is nice.

I did measure and dropped the voltage to get the plates to 303-304 vdc, resistor gets a little hot for my liking.  10 watt, 250 ohm.  Just wanted to see what t was like.  Probably get everything put together and see what I finally end up with.

I will report more, just wanted to let you guys know the layout works well.  More later.

[Ed_Chambley]

Awesome!!  Speakers and NOS amperex and Blue Celestion.  I will be finished soon.

[sluckey]

You know we want pics. And since you have some darn good chops we want some sound samples too. I'm very interested to hear your impression of the Celestion Blue.

[Ed_Chambley]

Sluckey
Couple things.
When I am plugged into the wiggle channel I have to ground the footswitch to make it wiggle.  Fine, as I am making a pedal anyway, but I thought you said your worked the other way.  Maybe just bad recall on my part.


Second, if I jump channels and plug into the wiggle channel the both work, but not if I am plugged into the normal channel.  Nothing at all.  Both are very nice.


I have a high pitch squeal on the vibrato channel only when the cut is up all the way.  I can find it, but wanted to know if you have tried this and noticed anything.  Should be something simple.


Finally, I get whet you mean by the tremolo much stronger, but I think there should be something that can be done to get more vibrato.  Vibrato seems a little weak overall.


I believe the tone is better on the normal and more apparent harmonics when turned up with the voltages lower.  I tried just lowering the EF86 alone does not do it, I plan to drop whole thing.  I do not like the heat coming off the resistor.  I was using a ceramic block. I plan to use a nice ohmite I have.  Do you see the heat as any problem?  If so, I will just get the correct PT.


I cant remember, but I posted a method of checking the bias on cathode bias amps and you offered another method or a revision to it.  I have the 1ohm in place.  Mind reminding me your method of checking bias on cathode bias with the 1 ohm resistor.  I did not keep your method, but it has something to do with not having to move you probe as much.


I changed the place of my open socket between both inputs.  I have an idea, but it will be down the road a tad.

[Ed_Chambley]

You know we want pics. And since you have some darn good chops we want some sound samples too. I'm very interested to hear your impression of the Celestion Blue.

I will get some photos before I button it up and yes I will play some too. You are going to appreciate my lead dress.


The blue is a great balanced speaker.  I have one in my modded 5E3.  They are very smooth and compressed and really help with any shrill and ice pick sounds.


I play every day and have since I was 6.  I love to play anything as long as it is talented.  I sould be able to play a song or 2.  I will just do a at home recording to my computer this time and I will play some ROCK.


What would you like to hear?

[Willabe]

You know we want pics. And since you have some darn good chops we want some sound samples too. I'm very interested to hear your impression of the Celestion Blue.

Yes, Yes and Yes!!!!!


I've heard you play befor and You Sir have some great chops!!!!!

Maybe somth'in like this;   


 

The Mavericks - Dance The Night Away

          

                       Brad       

[sluckey]

When I am plugged into the wiggle channel I have to ground the footswitch to make it wiggle.  Fine, as I am making a pedal anyway, but I thought you said your worked the other way.  Maybe just bad recall on my part.

The tip of the footswitch jack must be grounded for the wiggle to work. I used a Switchcraft 12A to short the tip to ground when no footswitch is plugged in.

Second, if I jump channels and plug into the wiggle channel the both work, but not if I am plugged into the normal channel.  Nothing at all.  Both are very nice.

You need to insert a plug into the 'unused' input jack when jumping channels as we discussed a while back. There's probably a more complicated switching arrangement that will break the ground on the unused input jack but I like simplicity.

I have a high pitch squeal on the vibrato channel only when the cut is up all the way.  I can find it, but wanted to know if you have tried this and noticed anything.  Should be something simple.

I don't have that squeal. But I've only had the volume turned up about half way so I can't say if the cut causes a squeal at full volume. I'll check that today.

Finally, I get whet you mean by the tremolo much stronger, but I think there should be something that can be done to get more vibrato.  Vibrato seems a little weak overall.

I've looked but don't find anything wrong. I think that's just the nature of the circuit. Someone posted earlier confirming the trem was stronger than the vibrato. You should be able to get more vibrato by increasing the Depth control.

I believe the tone is better on the normal and more apparent harmonics when turned up with the voltages lower.  I tried just lowering the EF86 alone does not do it, I plan to drop whole thing.  I do not like the heat coming off the resistor.  I was using a ceramic block. I plan to use a nice ohmite I have.  Do you see the heat as any problem?  If so, I will just get the correct PT.

Power resistors are supposed to get hot. Give it plenty of 'breathing' room. If your amp draws 100mA at idle like mine does, then a 250Ω/10W resistor will be fine.

           P = I²R = .1 x .1 x 250 = 2.5 watts

I cant remember, but I posted a method of checking the bias on cathode bias amps and you offered another method or a revision to it.  I have the 1ohm in place.  Mind reminding me your method of checking bias on cathode bias with the 1 ohm resistor.  I did not keep your method, but it has something to do with not having to move you probe as much.

I used two 1Ω resistors. Here's how I check idle dissipation...

1. Measure plate voltage (black lead on ground).
2. Measure cathode voltage. (black lead on ground)
3. Subtract step 2 from step 1 and record results here.
4. Measure millivolts ACROSS the 1Ω resistor. This directly converts to mA.
5. Multiply step 3 and step 4. This is your idle dissipation in watts.
6. Repeat step 4 and step 5 for the other tube.

I changed the place of my open socket between both inputs.  I have an idea, but it will be down the road a tad.

Are you talking about the extra tube socket?

What would you like to hear?

I've been in the mood for Moody Blues lately. I also want to hear whatever you think really shows off the sound of the normal channel and the vibrato channel.

[Ed_Chambley]

Sluckey,
I meant by posting about channel jumping that I do not have to insert a grounding jack if I plug into the wiggle channel.  I have a switch on back connecting both just like you used the jumper wire.  I plug into the wiggle channel and turn on the switch and the EF86 is added and both volumes work.  If I plug into the normal channel it will not work unless I put a grounded plug into it.


Try yours and see.  I also found the normal channel will swamp the Vibrato channel completely, but if you turn up the wiggle channel a lot and bring the normal channel up it adds a cool overdriven tone to the Vibrato/Tremolo.  The cut adds a TON of overdrive when doing this and the 12 position switch I have allows me to add a lot of punch when doing this.


The Celestion helps out a lot as well as they tend to compress before they get shrill.  Also, I have only used closed back.  When I get the bug out of the cut control I will try opening up the back.  I think it need the back open some as it does not have much volume, but I remember my original did not have loudness anywhere near a 18 watt.  It is basically like putting a 12" in a princeton except much more open.


I am using a NOS Tesla EF86 which is not as smooth or as dark as a Mullard.  I tried the mullard, but the Tesla is the clear winner.  All my 12Ax7's are RCA except for the PI.  There I have a balanced Russial Tungsol.  I really like these.  The RCA pan getters for the EL84 hold together longer then simply break off into distortion.  Not much transition, but are durable.  The Amperex Bugle Boys begin breakup early, but still have a very nice sound and they simply distort more the more you give them.  I did not have to pay to going price, but I will when I need some new ones.  I like them that much.  If you can find a pair without breaking the bank, do it.


Tonight I am going to drop the voltage back and figure out what that the issue is with the cut.  Like I said, I am sure it is simple.


Steve, you did a magnificent job on recreating a valid piece of history.  I would have to say it is quite an undertaking to build this thing and I am not speaking from a Honeymoon perspective, since I have owned one.  This is why the Vox name is still valid today and the new Vox amps cannot light this one's candle.  It is not a bedroom amp, but it is not far from one.


More later after I have time to fiddle around more with it.

[Ed_Chambley]

You know we want pics. And since you have some darn good chops we want some sound samples too. I'm very interested to hear your impression of the Celestion Blue.

Yes, Yes and Yes!!!!!


I've heard you play befor and You Sir have some great chops!!!!!

Maybe somth'in like this;   


 

The Mavericks - Dance The Night Away

          

                       Brad       

Brad, you know I dig the Mavericks.  Nice simple solo on guitar, but the horns make this tune.  I will listen to it and see if I can rearrange some of it and pick up the melody with the progression.  The guitar is fairly simple and as is I do not think it can hold its own.


Play a groove to it on your new Gibby and send it to me and I will counter if you want.  I still have to figure out how to make a good recording on the computer the simple way.


I don't want to Hijack the thread with discussion on recording.  We still have amps to build.

[Ed_Chambley]

I changed the place of my open socket between both inputs.  I have an idea, but it will be down the road a tad.

Are you talking about the extra tube socket?


Yes the extra tube socket.  My brain was stuck on trying to use it with the normal channel because I was only thinking of the Vibrato Channel for effects.  While building it, when I installed the board I began to notice the values of the Vibrato preamp.  I never used it much one the one I had when I was younger as I was not interested in clean tones.  I guessed with the Vibrato I would not need any reverb and the amp doesn't really need reverb.


So I may add an additional tube to get a richer tone, not to add a "Gain" stage even though it may appear that way.  I have some reading to do, but I have a bassman I did this to and it really sweetened up the clean tones.


Like I said, I plan to play it a while in its stock form and it will probably stay that way.

[lego4040]

Awesome Ed, I feel better knowing another amp has fired up. I thnk I'll be the only one with the two board version tho. Details on your tweaks for lowering the voltage, it's not that I can't look it up but I'd rather see it from you guys. I should order my cabinet so it's here when I'm done. I think I want a combo now , but how would I do that with the way the chassis is built