TOS Build Diary

[SLW]

In the picture you have posted, the pin 8 wiring on the power tube socket on the right side doesn't look very solid?
However, that might just be the picture angle?  But if it's not a solid solder, that would account for too much current, I think?

Also look at the pin 2 heater wiring on that same socket on the right. That doesn't look solid either?

I am wondering if the VVR is playing a factor in this also?  Does anything change with the light glowing if you change the VVR setting? 

I hit the pins again and put more solder on them.  I took the VVR out of the circuit.  I removed both of the connections of the VVR (in and out) and bypassed it with a wire.  No difference with the dim bulb tester.  I would have to put it back to answer your question.

I got the idea to use pin one as a support here on the forum.  My 5881's don't even have a pin in position one.  I don't think that is a problem but I don't have any other answers either.  I will probably try to rig up something for a test. 

I just finished tracing out the wiring for the output tube portion of the circuit and did not find any issues.   Could something in preamp portion of the circuit be causing this?  I don't think so.

I was thinking about the loud hum coming from the speaker so I went looking for a short to the heaters on the output tubes but did not find anything.

All of these things are bound to be telling me something but my inexperience keeps me from seeing the answer.  I am grateful for your input and hope to get more questions from you.

SLW

[tubenit]

You may have already answered this ......... but have you tried those two tubes in another amp and know for sure that the tubes are good?  Have you tried other tubes known to be good in this amp?

Have you tried the bulb limiter with another amp that you know is a perfectly good working amp?  Did it do the same thing?  Let's make sure the bulb limiter is working correctly.

If the cathode pins aren't grounded or there is no bias resistor to ground, then that could be an issue?  IF you are using a PPIMV as a dual ganged pot in the TOS also ......... is the dual gang pot grounded?  

Have you tried NOT using the negative feedback and just grounding the LTPI section without NFB?

Have you double or triple checked the cathode resistor value for the power tubes?

Is the VVR grounded?  

Any chance a filter cap is NOT grounded?  

Do all the voltages on the B+ rail look correct or reasonable?

When you had the tubes in ....... did you try playing the guitar thru the amp and IF so, did it sound OK or did it make an odd noise?   IF all the voltages look right through out the amp, I would be tempted to play the guitar thru the amp and see what happens?  BUT there is a risk in doing that certainly and it might not be a good idea.

Did you try it with NO preamp tubes in and ONLY the power tubes in with the lamp limiter?

Just grasping for straws here ..............

PLEASE keep working on it!  The Tweed Overdrive Special is a great sounding amp and your layout and chassis work is just fantastic!
I know you can and you will get this resolved.

With respect, Tubenit

[Willabe]

PLEASE keep working on it!  The Tweed Overdrive Special is a great sounding amp and your layout and chassis work is just fantastic!
I know you can and you will get this resolved.

+1 on this quote - and - every thing else Tubenit said. Your pics look great on the work you have done, you'll find that bug.

Tubenit, IMO is a very good amp trouble shooter, safe to say he's been around the block more than a few times.      

I never would have said to you to make sure/check out that the bulb limiter is working on another amp. (Very well could be your problem?)

On the OP tubes cathode R, have you actualy measured it with a meter?


          Brad    

[SLW]

Thanks for all of the questions.  I will answer what I can.

You may have already answered this ......... but have you tried those two tubes in another amp and know for sure that the tubes are good?  Have you tried other tubes known to be good in this amp?

I have not tried those tubes in another amp.  The only other amp I have is a 5F2A (SE tweed Princeton).  I guess I could try the 6V6 form that amp in each socket.  I will do that and report back.

Have you tried the bulb limiter with another amp that you know is a perfectly good working amp?  Did it do the same thing?  Let's make sure the bulb limiter is working correctly.

  I have not.  I will have to rig up something to do it.  I think I made the limiter properly.  I cut a IEC type cord in half.  I inserted the lamp socket so that it is in the hot path.  I reconnected the neutrals and grounds.

If the cathode pins aren't grounded or there is no bias resistor to ground, then that could be an issue?  IF you are using a PPIMV as a dual ganged pot in the TOS also ......... is the dual gang pot grounded? 

The amp has no PPIMV.  The cathode pins connect to the cathode resistor and caps then to ground.  All connections have been checked. 

Have you tried NOT using the negative feedback and just grounding the LTPI section without NFB?

  No I will try that and report back.

Have you double or triple checked the cathode resistor value for the power tubes?

Yes.  It measures 356 ohms.

Is the VVR grounded?   

It was when it was hooked up.  It is still out of the circuit.

Any chance a filter cap is NOT grounded? 

 
I just checked them all again.  They are all grounded.

Do all the voltages on the B+ rail look correct or reasonable?

I guess so.  Using the lamp limiter with all tubes installed I measure:
A=266, B=243, C=220, G=212, D=205, E=149 and F=147 all DCV.   The letters correspond to a node on the rail.

When you had the tubes in ....... did you try playing the guitar thru the amp and IF so, did it sound OK or did it make an odd noise?   IF all the voltages look right through out the amp, I would be tempted to play the guitar thru the amp and see what happens?  BUT there is a risk in doing that certainly and it might not be a good idea.

No I have not tried this.  I have been too chicken. :)

Did you try it with NO preamp tubes in and ONLY the power tubes in with the lamp limiter?

Yes.  The limiter gets brighter after the initial flash and dimming.  This is the same behavior I have reported.

I am not going to give up.  I am going to my mother-in-laws for a week,  it will be here calling me when I get back.  :)  Keep the questions coming.

SLW

[sluckey]

Do all the voltages on the B+ rail look correct or reasonable?

I guess so.  Using the lamp limiter with all tubes installed I measure:
A=266, B=243, C=220, G=212, D=205, E=149 and F=147 all DCV.   The letters correspond to a node on the rail.

I think the light bulb has served it's purpose. It's time to plug the amp straight into the wall and do a few checks.

Plug straight into the wall and turn power off. Turn standby off (switch open). Pull the output tubes and set aside. Connect a voltmeter across the first filter cap. Turn the amp on but keep your hand on the switch and be ready to kill power at the first sign of smoke or arcing or stinky smells or unusual noises. Hopefully your meter will read your B+ which will be higher than expected because of the the open standby switch. If B+ looks OK then turn the standby switch on and measure the plate and screen voltages on the empty output tube sockets. What are the readings?

[SLW]

I thought a video of the lamp might be useful http://youtu.be/LT5RXu96omA.  Since I have never used a limiter before.  It could be that I just don't know what to expect.  It is a 100W lamp.  The first click is going into standby.  The second click is into full power mode.  The buzz at the end is what happens all the time.  What do you think?

SLW

[sluckey]

Without knowing what that light bulb looks like at full brightness, I'd say it's behaving normally and you no longer need the light bulb. The hum I hear sounds like an open grid near the input, kinda like a guitar cord plugged in the amp but no guitar connected and volume pots maxed. Turn all pots to zero and leave the VVR disabled for now. Does the buzz go away? Check voltages on the output tubes and report.

[SLW]

Thanks for the input fellas.

Well I did it.  I plugged it straight the wall after reading sluckey's comment.  Good news!  No smoke or fire!  With all pots on zero the buzz goes away.  Here are the voltage readings on the tubes with all of the pot on zero. http://www.el34world.com/charts/valve/ValveData.php?e=view&f=12274

The VVR is still out of the circuit.  V3 is a 5879 and the readings I got are 150 volts on pin 8 and 41 volts on pin7. 

As soon as I turn the level pot the buzz is back.

What now?

SLW

[sluckey]

You have a lot of relay contacts and circuitry that could be part of the buzz problem. Since the amp is quiet with the level control set to zero, I suspect the PI and output stages are OK. It's time to divide and conquer. I would disconnect the wire from the wiper of the level pot P4. Then disconnect the wire labeled FX Loop return from the PI input cap C26. Now connect the wiper of the level pot P4 directly to the PI input cap C26. This will remove the OD circuitry and the FX Loop circuitry. Your signal path will now be V1a, V1b, V2a, V5, V6, and V7. This is a simple amp. How does a guitar sound thru this configuration? If my suspicions are correct, you will still have the buzz.

Also, since the amp is quiet with the level control set to zero, I suspect the problem lies between the input jack and the level control. Make the changes above and report back. I have some more suggestions based on your findings.

[tubenit]

This will remove the OD circuitry and the FX Loop circuitry. Your signal path will now be V1a, V1b, V2a, V5, V6, and V7. This is a simple amp.

Listen to Sluckey!  He has given me more answers to amp problems than anyone I can think of.  He just has a knack of walking you thru to the solution.

 

With respect, Tubenit

As a side note, I've had the passive effects loop jacks cause buzz before & needed to replace them.

[TIMBO]

Stick with it SLW, Try a 50 ohm resistor to ground off one leg of your 5vac relay power supply. Worked a charm on my MSJ relay PSU.    

[sluckey]

Here are a couple things to try before you bypass the OD and FX circuits...

1. Turn the volume pot to zero. Does this kill the buzz even when the level pot is turned up?

2. What is your purpose for the switch and R57 at the input? And what is the value of R57? If it's large it will likely cause a buzz such as you have. Set the switch to bypass R57. Does the buzz go away?

Here's a spliced pic showing only the input circuit...

[tubenit]

I am wondering if a heater wire is touching a plate wire on a preamp or power tube?  AND check for solder drops that wedge between the heater pin and plate pin also.

IF that is it, it would account for the hum not being there initially but building up after it has been turned on for a second or two.  It makes a hum similar to that noise.

With respect, Tubenit

[SLW]

Here are a couple things to try before you bypass the OD and FX circuits...

1. Turn the volume pot to zero. Does this kill the buzz even when the level pot is turned up?

2. What is your purpose for the switch and R57 at the input? And what is the value of R57? If it's large it will likely cause a buzz such as you have. Set the switch to bypass R57. Does the buzz go away?

Here's a spliced pic showing only the input circuit...

I will try that before I bypass anything.  I am at grandma's (my mother-in-law)house for a week.  The kids are wound up tight.  I am happy to be here also.  Every day at 5pm my mother-in-law brings me a beer!

The switch and R57 are my attempt to have a switchable form of high/lo input.  R57 is 33K.  I need to update the schematic.  My engineering mentor would chew me out for not having my documents in order.  I hope it is obvious what is going on with the switch.

Even though I am not finished with the amp yet I want to publicly thank all of you for your input and time invested in following and helping with my project.

Merry Christmas to all of you!

SLW
 

[stingray_65]

sounds like 120Hz not 60

http://www.soundsnap.com/tags/120hz

http://www.soundsnap.com/search/audio/60hz/score

[SLW]

Back home now.  Happy new year!  Here is what I found.

Here are a couple things to try before you bypass the OD and FX circuits...

1. Turn the volume pot to zero. Does this kill the buzz even when the level pot is turned up?

2. What is your purpose for the switch and R57 at the input? And what is the value of R57? If it's large it will likely cause a buzz such as you have. Set the switch to bypass R57. Does the buzz go away?

Here's a spliced pic showing only the input circuit...

The buzz is there with the volume pot at zero.  The buzz is gone when the level pot is at zero.  Does this imply a problem with v1b?

The input level switch has no effect on the buzz.  I get the same buzz with R57 in or out of the circuit. 

SLW

[sluckey]

The buzz is there with the volume pot at zero.  The buzz is gone when the level pot is at zero.  Does this imply a problem with v1b?

Yes, but it could also be V2A. Pull V2 to narrow the buzz source.

[SLW]

Thanks.  Here is what I found.  Pull V2 and still have buzz.  Pull V1 and still have buzz.  Pull both V1 and V2 and still have buzz.  I plugged in a guitar and the amp plays but the buzz is still there.  What do I look at now?  Do I start to bypass stuff to make it as simple as possible or do I check some parts?

SLW

[tubenit]

Can you please look carefully to make sure there is NO contact between a heater wire and a plate wire or anything else and report back that you have done that?   Also please  look for any solder drops connecting heater to something else.

The symptoms you're describing can be there with a single strand of heater wire touching a  preamp or power tube plate. The report of it sounds OK until you flip the stand-by (to allow sound) then it sounds OK for a second or so then hum will happen with heater wires touching plates.

Double check that no shielded wiring got grounded on both ends.  Check the pots grounding also. That can cause hum if the pot is not grounded well.

Then report back again, please.

with respect, Tubenit

[sluckey]

Do I start to bypass stuff to make it as simple as possible or do I check some parts?

That's what I would do. Refer to reply 58.

[tubenit]

Do I start to bypass stuff to make it as simple as possible or do I check some parts?

That's what I would do. Refer to reply 58.

How about going straight from V1a to LTPI?    Skip the V1b, DPDT, OD & FX.

Would you please reply to the concern about heater wires touching plates also?  Thanks.

With respect, Tubenit

[sluckey]

I think the heater/plate short is a possibility and can be easily confirmed/ruled out by closely inspecting the socket wiring. It's worth the effort to do so. I am more suspicious of the wiring for the relay board or maybe the 5vdc power supply for the relays. That's why I suggested bypassing all that stuff and get to a simple straightforward circuit. If still have hum with all that stuff bypassed, it will be much easier to track down. And if the hum disappears, well then look to the relay and FX circuitry.

[SLW]

Would you please reply to the concern about heater wires touching plates also?  Thanks.

I just inspected the tube socket connections using a flashlight and a magnifying glass.  I can confirm that there are no stray strands connecting the heaters to the plates.

I am going to bypass the OD and FX portions by going from the wiper of the level pot to PI input cap C26 and I will report back.

SLW

[SLW]

I removed all connections to / from the relay board.  I ran a jumper from the level pot wiper to the PI input cap C26.  The buzz was gone.  I have to turn the volume and level pots up pretty far(Level at 3 o'clock and volume at noon) to hear any noise.  With a guitar(epi les paul) plugged in the noise gets a lot louder.  My shop area is only lit with florescent bulbs and one is three feet above the open amp. 

For fun I patched in the OD portion by running a jumper form the junction of C7 and the level pot to R15/C13.  I connected a jumper form the wiper of the OD level pot to the PI input cap.  This buzz was still gone but there was more noise.  The amp would give me a ringing squeal if the drive was turned up past 10 or 11 o'clock.

I went ahead and patched in the FX portion by changing the jumper from the wiper of the OD level pot to C20 at the start of the FX loop and I put another jumper from C24/R26 to C26 at the PI.  The buzz was still gone but the noise was even greater.  The amp would make a funny squeak/squeal that died off a second or two after the note was struck.   The only way to make it stop was to turn down the send/return pots to zero. 

I put the amp back to just coming out of the level pot and going into the PI input cap.  This is the same as the first test in this post. 

I take this to mean that there is a problem with my 5VDC/ switching setup.  Let me know what you guys think.  I will proceed from there.

[sluckey]

I removed all connections to / from the relay board.  I ran a jumper from the level pot wiper to the PI input cap C26.  The buzz was gone.

OK, that's progress. Now we know the problem lies with the bells and whistles or the wiring to/from the main amp. Let's continue dividing and conquering. Add one section at a time.

I would like you to wire in ONLY the OD section and K1. Put a jumper between K1 and C26 as shown by the red line in the attached pic. Do you have buzz again?

I'll tell you my concerns about your 5v power supply, but do the above test first. 5VAC is really lean to drive a 5V regulator chip. 5VAC_RMS is only 7VAC_peak and that may not be enough headroom for your regulator to make clean 5VDC. It may be producing a lot of 120hz switching noise. Check the DC voltage output of the regulator and then switch your meter to measure AC ripple at the output of the regulator. We want that ac ripple to be very, very low. A scope would be very helpful with this check. Even if everything looks OK, try another input source for your bridge. If you have a 12VAC transformer use that. Or you can connect a 6V lantern battery to the bridge AC inputs (polarity doesn't matter). Does any of this cure your buzz?

[sluckey]

I'd be interested in seeing you wire it like this bypassing the relay and FX only.

Tubenit, he wired it exactly as per your drawing and the buzz was gone.

For fun I patched in the OD portion by running a jumper form the junction of C7 and the level pot to R15/C13.  I connected a jumper form the wiper of the OD level pot to the PI input cap.  This buzz was still gone but there was more noise. 

[sluckey]

For fun I patched in the OD portion by running a jumper form the junction of C7 and the level pot to R15/C13.  I connected a jumper form the wiper of the OD level pot to the PI input cap.  This buzz was still gone but there was more noise.  The amp would give me a ringing squeal if the drive was turned up past 10 or 11 o'clock.

I went ahead and patched in the FX portion by changing the jumper from the wiper of the OD level pot to C20 at the start of the FX loop and I put another jumper from C24/R26 to C26 at the PI.  The buzz was still gone but the noise was even greater.  The amp would make a funny squeak/squeal that died off a second or two after the note was struck.   The only way to make it stop was to turn down the send/return pots to zero.

That's a lot of gain stages strung together! It's gonna want to squeal and be noisy. Lead dress and layout are gonna be critical. And you will probably need to decrease the gain of some stages to tame that. But the good news is the buzz is gone. That points toward the relay board or 5v power supply, or a miswired relay. Fix the buzz then tackle the noise/squeal.

[tubenit]

Sluckey,

Sorry about that ............. I was trying to follow what you were saying as I am very interested in his build being a success!
I just wasn't comprehending what was unfolding.  Please accept my apology.

For my own clarity ............... is the schematic you drew with the red line, the same idea as this schematic?  Is that what you're saying he needs to do to pinpoint this as a relay/5v issue?

The only way to make it stop was to turn down the send/return pots to zero.

What send/return pots are you referring to?  Do you mean master volume and/or the OD pots?  Typically, I think of send/return pots as in an active FX loop?

with respect, Tubenit

[sluckey]

No need for apologies. The disappearing message made me pause for a minute though. By the time I responded, the message was gone.  

is the schematic you drew with the red line, the same idea as this schematic?  Is that what you're saying he needs to do to pinpoint this as a relay/5v issue?

Yes, that schematic is the same except I wanted the relay K1 wired in also, rather than hard wiring the OD section. This schematic is the same as the one you posted earlier with the blue jumpers. He's already wired it exactly like that and there was no buzz. Now I'm wanting him to add in the K1 relay to begin checking for the return of the buzz (sounds like a Star Wars episode!)

What send/return pots are you referring to?  Do you mean master volume and/or the OD pots?  Typically, I think of send/return pots as in an active FX loop?

You'll have to look at his original schematic to see the send/return pots in the FX loop. I've purposely omitted the FX loop from my partial schematics for the time being just to keep it simple.

[DummyLoad]

in your video, that sounds like 120Hz buzz from PS. relay board PS is mis-wired and/or needs to be grounded and/or the footswitch jack needs to be an isolated type. IMO, 470uF is too small a filter for that PS. in similar applications, i like to use as much filter as i can stuff  into the space allotted. use coax for signal connections to and from the relay board.

post the artwork of the relay board and the model/mfg. of the relays, if you care to share; sometimes another pair of eyes can help.

you can confirm that the relay board /relay PS is not the issue with a 6V battery and a pair of clip leads. 6V won't damage the relays, however, if you're still concerned about it, use a series dropping resistor in the + path. BTW: if you can't find a 6V lantern battery, 4 D cells in a radio shabby battery holder would work.

slucky has you going down right path. i'm stepping out of the way now, i just wanted to share my thoughts and limited experience.

respectfully,

--DL

[SLW]

I would like you to wire in ONLY the OD section and K1. Put a jumper between K1 and C26 as shown by the red line in the attached pic. Do you have buzz again?

I'll tell you my concerns about your 5v power supply, but do the above test first. 5VAC is really lean to drive a 5V regulator chip. 5VAC_RMS is only 7VAC_peak and that may not be enough headroom for your regulator to make clean 5VDC. It may be producing a lot of 120hz switching noise. Check the DC voltage output of the regulator and then switch your meter to measure AC ripple at the output of the regulator. We want that ac ripple to be very, very low. A scope would be very helpful with this check. Even if everything looks OK, try another input source for your bridge. If you have a 12VAC transformer use that. Or you can connect a 6V lantern battery to the bridge AC inputs (polarity doesn't matter). Does any of this cure your buzz?

The buzz returns. 

I measured the 5VDC power supply and it is puny.  I am getting 4.3VDC and 135mVAC of noise just measuring with my Fluke.  I should have hooked it up to the 6.3VAC winding.  Oh well... 

At this point I am thinking about pulling the switching board and hooking it back up with simple DPDT switches.  I think I can focus on getting the amp to run its best that way.   Once we have it running well I can put the fancy switching back into the amp.

My little buddy is asking me to make a "steam shovel" with him.  He is standing here with wood and a saw in his hands.    After that I have a delay pedal that I want to finish up so it will be a couple of days before there is any progress. 

I am grateful for all of the help and encouragement you guys have been willing to give me.

Thanks
SLW

[tubenit]

At this point I am thinking about pulling the switching board and hooking it back up with simple DPDT switches.  I think I can focus on getting the amp to run its best that way.   Once we have it running well I can put the fancy switching back into the amp.

That sounds reasonable to me.  Reality is I am flipping a switch between clean and OD when I play at home anyway. Only hook up the foot pedal playing live.

PLEASE do NOT give up!  These are really sweet sounding amps and are worth the effort, IMO.

We'll be looking for to your updates and progress.

with respect, Tubenit

[DummyLoad]

I measured the 5VDC power supply and it is puny.  I am getting 4.3VDC and 135mVAC of noise just measuring with my Fluke.  I should have hooked it up to the 6.3VAC winding.  Oh well... 


what is the ACV measurement @ the + terminal of the bridge recto? remove/clip the V reg out of the ckt. before you measure - if it's less than 7VAC you're going to have problems unless you're using a Low Drop Out (LDO) regulator.

agree, 6.3AVC taps would have been the way to go with "conventional" 78xx type regulator.

--DL

[sluckey]

The buzz returns.  

I measured the 5VDC power supply and it is puny.  I am getting 4.3VDC and 135mVAC of noise just measuring with my Fluke.  I should have hooked it up to the 6.3VAC winding.  Oh well...  

Disconnect the 5vac PT winding from the relay board and connect a lantern battery to the bridge. Heck, even a 9V battery will power K1 long enough to know if the buzz will go away.

And here's a cheap alternative... You really don't need a regulated supply for those relay coils and LEDs. Just pull the VR chip and the 47µF cap. Replace the 470µF cap with a 2200 or 4700µF and finally put a jumper strap where the VR in and out pins were connected. Bet that will cure the buzz. As DL said earlier, you may have to ground the negative rail of the 5v power supply to chassis. Or maybe not.

[DummyLoad]

for your consideration should you wish to continue using a Vreg. otherwise, omit and use a series dropping resistor for relays - you should "tune" series drop R for 4.5-5VDC with all 3 relays + LED on.

--DL

[sluckey]

Any progress?

[tubenit]

Got any update for us?

With respect, Tubenit

[SLW]

It has been a very busy few days in my house and at work.  I have only mounted the DPDT's.  I hope to get to it some more this weekend.  I am going to redo some of the signal wires since they are looking a little beat from all the prior trouble shooting.  I used shielded wire for any run that was longer than 4" or so.  Should I consider using shielded for the ones that I am redoing?

SLW

[SLW]

I spent the some time with the amp this weekend.  I pulled the 5V supply and switching board.  I replaced the relays with two simple DPDT switches.  I hooked it up with shielded wire except for a couple of short lengths.  I reconnected the VVR.

I am happy to report it works.  I played it for about a half an hour.  The clean and OD channel work with no buzzing or other noises.  I have a homemade tweed Princeton and the noise level seems about the same to me.   I have not tried the effects loop at this time. 

I am going to put the cover on and play it for a few days.  The speaker in my cab is new and need to break in.

I eventually need to redo the relays and indicator lights.  I think my issue with the last switching setup was using the 5VAC to power it.  I will use the 6.3VAC to power it this time.  I am open to more suggestions on channel switching from the forum. 

Thanks for all the help with everything.  I will report back after I live with it for a while.

Shawn

[tubenit]

Wonderful news!   THANK you for reporting on the progress!

I am going to send you a PM.

With respect, Tubenit

[kagliostro]

Here is some documentation from Doug, about relay supply and montage

http://www.el34world.com/projects/relay_switch.htm

Kagliostro

[Willabe]

I am happy to report it works.  I played it for about a half an hour.  The clean and OD channel work with no buzzing or other noises.

All right Shawn! Nice job!    

I'm sure you'll get relays and FX loop working too.


             Brad        

[shortfuse]

Man that's great I can only imagine the amount of time you spent taking things apart to find it.  Congrats.

[kagliostro]

Hi SLW

where did you buy the relays board ?



Many Thanks

Kagliostro

[SLW]

It is one that I had made.  When I have prototype pcb's for pedals made I have to pay for a minimum amount of board space whether I use it all or not.  I will put small things like this on it so I don't waste space(and money).  My mistake with it was using 5VAC to power it.  I am pretty certain that it would have worked well if I had used the 6.3VAC to power it.  I already have something new for the next attempt with the switching relays.   

SLW

[kagliostro]

If you still have the draw of that PCB can you post it ?

Thanks

Kagliostro

EDIT: this days I started learning Eagle, I've find a PCB Layout that I can modify for this use

[SLW]

I wanted to give a little update now that I have played the amp for a few hours. 

Clean Channel – I like it the way it is.  It sounds good with my strat.  The tone control has a nice range.  Perhaps a little more “sparkle” with my strat would be nice but I don’t want to try to change it at this time.

Overdrive channel is not offensive.  I am still getting to know it.  Need more time with it.  I do like it in general.

I am not feeling any love for the VVR.  It doesn’t seem do a lot until I have the knob at 9:00 or so.  I am not in a hurry to change it.
 
The effects loop needs a little work.   It changes the tone a little.  I expected this.  There is a hum present when you engage the loop.  I did not expect that.  Perhaps the PS  node needs another level of filtering.    The big issue(to me) is a strange oscillation or something that dies away with the note.  For lack of a better description, it sounds a little like a cricket.  It happens when the guitar (and amp) is louder.  It does not happen when I play softly or have the volume on the guitar turned down.    I want to tackle this first.  Is this a problem of too much gain in the FX loop?

SLW

[tubenit]

When I build my FX-Reverb unit, I discovered that I liked a 12AU7 the best in the FX.  I think I liked a 12AU7 best on the on board FX I built also, but can't remember for sure?   

Is the hum there with an effects pedal in the loop?   

And yes, I discovered I needed more fitering also then I would have anticipated.  Not sure why the hum is there though?

with respect, Tubenit

[tubenit]

I am not feeling any love for the VVR.  It doesn’t seem do a lot until I have the knob at 9:00 or so.  I am not in a hurry to change it.

 

If you are referring to 9:00 as being like 9 o'clock, ..... then I agree.  I've done a few of the Dana Hall VVR's and anything under "4" (1-10) sounded kind of anemic to me.  I typically would have the VVR dialed in between 5-7 (90%) of the time.

After you get used to your overdrive, please give us an update.  And I'd be happy to offer any suggestions if you can describe how you would want the OD to sound differently.

With respect, Tubenit

[SLW]

Yes, I do mean 9 o'clock.  I am thinking about pulling it out and reworking the power supply in a more normal way.  Perhaps with a couple of nodes in front of the the FX loop node the hum will go away.  I will try another tube in the loop.  I think I have a 12AU7 but not sure.

SLW