# First build: TW Express (having low muffled output issues)



## warplanegrey (Jan 3, 2007)

Howdy gang.

I recently completed my first amp build (a TW Express circuit). Everything fires up, and I'm getting signal through my speakers, though it's very VERY quiet (as in, with the volume on 10, I'm only as loud as someone talking loudly). It's also very muffled. I currently have a full compliment of EL34's and 12AX7's known to be good loaded in there.

I've gone through the amp to make sure no connections are shoddy or missing, and I can't find anything.

and before anyone offers insight about lead dress or component placement, I know. Ken Fisher did it better. My goal is to have an amp that fires up and makes the right amount of volumes. I’ll worry about stability and noise once the volume issue is sorted.

I've attached my voltage chart to the post As well as some photos. 


Note: the heater voltages were measured at each pin, so I'm really getting 5.6vac to the heaters.

I’ve done a pop test (checking voltage at the plates to see when the sound from touching the probe drops) and V1 is noticeably quieter than all others.

I’ve checked the impedance on both sides of my OT primary, and it’s good.

I've also confirmed my input jack is wired correctly.


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## Paul Running (Apr 12, 2020)

Check your heater supply, all the heater voltages are very low.


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## Mark Brown (Jan 4, 2022)

Paul Running said:


> Check your heater supply, all the heater voltages are very low.


What might cause them to be less than half of expected voltage?


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## WCGill (Mar 27, 2009)

Do you have one leg of the 6.3v heater supply and centre tap mixed up? I'm assuming the PT has a heater CT. Those voltages are suspect.


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## warplanegrey (Jan 3, 2007)

WCGill said:


> Do you have one leg of the 6.3v heater supply and centre tap mixed up? I'm assuming the PT has a heater CT. Those voltages are suspect.


howdy. I don’t think so! The 6.3 windings are green and it’s centre tap is white (which is have going to ground). Each 6.3 lead is green and going to the right pins.


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## Always12AM (Sep 2, 2018)

warplanegrey said:


> Howdy gang.
> 
> I recently completed my first amp build (a TW Express circuit). Everything fires up, and I'm getting signal through my speakers, though it's very VERY quiet (as in, with the volume on 10, I'm only as loud as someone talking loudly). It's also very muffled. I currently have a full compliment of EL34's and 12AX7's known to be good loaded in there.
> 
> ...


Looks fantastic, especially for a maiden voyage.

Make sure you are measuring the heaters with both meter nipples on either side of the V1 heater supply and not one to ground. I say this as I’ve done that and gotten the same readings.

Check that the V1A cathode resistor and (cap) are secure and of the right value etc.


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## Always12AM (Sep 2, 2018)

Mark Brown said:


> What might cause them to be less than half of expected voltage?


measuring one side at a time in my case lol.


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## Mark Brown (Jan 4, 2022)

Always12AM said:


> measuring one side at a time in my case lol.


I like when other people fail because then I can learn before it is my turn.

Thanks buddy!


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## warplanegrey (Jan 3, 2007)

Always12AM said:


> Looks fantastic, especially for a maiden voyage.
> 
> Make sure you are measuring the heaters with both meter nipples on either side of the V1 heater supply and not one to ground. I say this as I’ve done that and gotten the same readings.
> 
> Check that the V1A cathode resistor and (cap) are secure and of the right value etc.


yeah those readings were definitely per pin, other lead to ground. I’ll get some updated readings once the kids go to bed


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## warplanegrey (Jan 3, 2007)

warplanegrey said:


> yeah those readings were definitely per pin, other lead to ground. I’ll get some updated readings once the kids go to bed


heater voltage actually reading 6.7vac


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## Always12AM (Sep 2, 2018)

Remove the heat shrink from the bypass cap of V1 and reapply some more solder to it.

or you can maybe gator clip another cap of the same value right on the existing one just to see if that’s haunting your gain.

If you have chop sticks, turn that puppy on with the speaker connected and turn the volume up and literally tap each pin on each tube socket and see if you hear a crackle or a big volume jump. If nothing happens, follow each wire and lead pressing and moving the wires all the way to their destination seeing if this doesn’t create any obvious crackles etc. ONE HAND IN YOUR POCKET.

If nothing happens, pull V1 and the power tubes and look in the holes to make sure that solder didn’t drip down into them messing with a pin placement etc.

If still stuck, start going through the amp using this



https://www.digikey.ca/en/resources/conversion-calculators/conversion-calculator-resistor-color-code



Just to confirm you have the right resistors in the right places (emphasis on input jack, anything leading to or coming from volume or V1.

Hope something yields some insight.

The exact same thing happened to me this morning. I went over my connections and two of my heater solders were not fully coated and connected. Found em, fixed em, fixed the issue.

Look for grey solder joints and add some new solder to it. Remove the grey solder if possible. One piece of feedback for future, heat shrink can melt and mess with connection points. Especially on a tag strip build. I try to keep the heat shrink for really tight, really high traffic overlapping areas. And when I do. It’s literally just a small piece that is covering where it may contact another wire. It gets in the way otherwise. Especially when trying to use a heat sink to protect or remove a cap or resistor, which is important when trouble shooting etc.


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## Paul Running (Apr 12, 2020)

warplanegrey said:


> TW Express circuit


What Express version did you build to?


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## Latole (Aug 11, 2020)

5.6 ac heater voltage ; something wrong. You should never go lower than 6 ac
Possible cause ; To low Power Transformer , wiring issue
Low tubes heater voltage = low output

The path of your wire will have to be redone
It must be very short and not too high but along the frame,
Now your amp will be very very noisy, unusable.
Heater wiring is right.

Wrong wire dress ; 












Right wire dress ;


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## warplanegrey (Jan 3, 2007)

Always12AM said:


> Remove the heat shrink from the bypass cap of V1 and reapply some more solder to it.
> 
> or you can maybe gator clip another cap of the same value right on the existing one just to see if that’s haunting your gain.
> 
> ...


thank you for the tip! I’ll give this a shot today!


Paul Running said:


> What Express version did you build to?


this one:



http://imgur.com/6VqIq33




Latole said:


> 5.6 ac heater voltage ; something wrong. You should never go lower than 6 ac


as mentioned earlier, my heater voltage is actually 6.7VAC. I was measuring it wrong.



Latole said:


> The path of your wire will have to be redone
> It must be very short and not too high but along the frame,
> Now your amp will be very very noisy, unusable.
> Heater wiring is right.
> ...


Thanks for your input. As mentioned in my original post, my priority at this point is to have an amp that makes guitar sounds at the right volume:



> and before anyone offers insight about lead dress or component placement, I know. Ken Fisher did it better. My goal is to have an amp that fires up and makes the right amount of volumes. I’ll worry about stability and noise once the volume issue is sorted.


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## Latole (Aug 11, 2020)

As a first amp you are brave to have started with such a difficult amp.
I built several amps and not kits

Another thing, the 5 filter capacitors should not be simply glued to the chassis. It won't last for years and it's not safe. Strong fasteners are needed.


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## warplanegrey (Jan 3, 2007)

Latole said:


> As a first amp you are brave to have started with such a difficult amp.
> I built several amps and not kits
> 
> Another thing, the 5 filter capacitors should not be simply glued to the chassis. It won't last for years and it's not safe. Strong fasteners are needed.


In that regard, I followed KF’s technique and siliconed them together and to the chassis. If I notice they start to come loose, I’ll fasten them another way.

A benefit to this being built in a Traynor chassis is that the components can’t fall, as they’re already mounted to where gravity is pulling them.


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## Latole (Aug 11, 2020)

Gravity is not enough to keep them solid, neither silicone.
What is KF's technique ? Any link ? 

I built all my amp as Leo Fender built them. Or Vintage Marshall or Traynor.


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## RBlakeney (Mar 12, 2017)

Latole said:


> Gravity is not enough to keep them solid, neither silicone.
> What is KF's technique ? Any link ?
> 
> I built all my amp as Leo Fender built them. Or Vintage Marshall or Traynor.








Trainwreck Pages


The Trainwreck Pages by Ken Fischer



robrobinette.com




this will probably have most things you need to know


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## Paul Running (Apr 12, 2020)

warplanegrey said:


> this one:


That wiring diagram shows version 1.8 however, the schematics that I have, use a different revision scheme. There are 14 versions to the Train Wreck Express.


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## Latole (Aug 11, 2020)

RBlakeney said:


> Trainwreck Pages
> 
> 
> The Trainwreck Pages by Ken Fischer
> ...


I know Ken Fisher . I have difficulty with abbreviations


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## WCGill (Mar 27, 2009)

There's really only one Express, but many hobbyist variations exist as the above schematics show. It's a great circuit but very sensitive to layout and lead dress, incredibly daunting for a first-time build. I expect your troubleshooting skills will be tested mightily. I have done several, some true to schematic, others modified, none had the classic layout.


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## Paul Running (Apr 12, 2020)

WCGill said:


> There's really only one Express


And from what I read, Mr. Fischer modified the original several times...I believe that no amp is truly finalized...not with a tweaker on-board.


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## Latole (Aug 11, 2020)

Paul Running said:


> That wiring diagram shows version 1.8 however, the schematics that I have, use a different revision scheme. There are 14 versions to the Train Wreck Express.


I have all of these great schematics.


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## Always12AM (Sep 2, 2018)

Just to clarify what I was saying earlier and what other have mentioned.

In terms of heat shrink and lead dress. It’s not about looks, it’s that for example, when I solder I like to stick a gator clip or heat sink on the end of a capacitor to protect it from the outrageously over powered iron that I use.

I also like to do the same thing when I remove or revise something. The heat shrink won’t allow for a metal on metal connection etc.

I am also willing to bet that the culprit is that on one connection or a couple, the plastic from the heat shrink or the PVC coating from the wire has found it’s way into one of the posts or mounting places. Preventing a metal (mechanical) connection.

I originally thought that the coating of a wire needed to cover all bare wire to protect it from signal. This is not true unless it’s shielded wire. Worst case scenario, you may have to re do leads. And this time making sure that there is a solid 1-2 cm of bare wire to feed the connections.

This is why many people choose the cloth push back wire. It’s more expensive by far. But it is really easy to push back or prep the wires etc.

As others have said, this is a brave first build. I think it’s great all things considered. But there are certain habits and mistakes that we all make and something really simple like a champ can even create problems. But re doing it is what enhances your skills. Unfortunately it can come at a cost of time and money replacing and waiting for a small component at times.

If you know how to drain the filter caps, which you should definitely do before touching things after a fire up.. you could go through the amp and make sure that you can pull PVC and heat shrink plastic back a bit from connections to make sure that none have melted into the joint.

This kind of activity is like sex. We watch guys do it on the internet and think “that looks very fun and very easy” but it turns out that we have to do it a bunch of times before we get good at it. And quite frankly, it can cost money to find a really attractive set of midget twins who will dress up as hobbits and chase you around with water guns full of chocolate syrup.


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## warplanegrey (Jan 3, 2007)

Always12AM said:


> Just to clarify what I was saying earlier and what other have mentioned.
> 
> In terms of heat shrink and lead dress. It’s not about looks, it’s that for example, when I solder I like to stick a gator clip or heat sink on the end of a capacitor to protect it from the outrageously over powered iron that I use.
> 
> ...


Great post.
Went through all of the connections where heat shrink looked like it was getting close to the terminal, solder braided it clean, pulled the heat shrink back, redid it.
But with this in mind, I might take a look at how the wires are connected and pull back the sleeve


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## warplanegrey (Jan 3, 2007)

to rule it out, I redid all connections that had a sleeve close to infringing, and had no change in effect.


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## greco (Jul 15, 2007)

GOOD LUCK with your troubleshooting. Please keep us updated.
Following with interest.


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## epis (Feb 25, 2012)

Most of new builders ignore importance of proper layout.
Your pictures show clearly output transformer primary wires too close to input circuitry. 
Most likely this is causing unwanted feedback.
Cheers, Damir.


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## warplanegrey (Jan 3, 2007)

epis said:


> Most of new builders ignore importance of proper layout.
> Your pictures show clearly output transformer primary wires too close to input circuitry.
> Most likely this is causing unwanted feedback.
> Cheers, Damir.


helpful!


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## Mark Brown (Jan 4, 2022)

warplanegrey said:


> helpful!


And they wonder why no one wants to build amps or learn anything hey??

Stick it out man, there are very helpful people that will offer advice when and where they can. As I am sure you know it is not an easy thing to figure out what is "the" problem. I'm hung up on an amp I am working on right now, I promise it is something stupid just like you, but I can also guarantee it isn't because your output transformer primary wires are anywhere near your anything


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## warplanegrey (Jan 3, 2007)

Mark Brown said:


> And they wonder why no one wants to build amps or learn anything hey??
> 
> Stick it out man, there are very helpful people that will offer advice when and where they can. As I am sure you know it is not an easy thing to figure out what is "the" problem. I'm hung up on an amp I am working on right now, I promise it is something stupid just like you, but I can also guarantee it isn't because your output transformer primary wires are anywhere near your anything


yeah there’s always a few people on every board who just want to jump in and say “bUt YoUr LeAd DrEsS iS wRoNg” but there have been a bunch of super helpful people out there too.

I traced the signal to the ins and outs of V1 and I’ll focus in on those components and joints and see if I’ve botched anything


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## keto (May 23, 2006)

You may be misinterpreting? I have seen @epis be very helpful, to both myself and others many times in build threads.


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## Paul Running (Apr 12, 2020)

warplanegrey said:


> I'm getting signal through my speakers, though it's very VERY quiet (as in, with the volume on 10, I'm only as loud as someone talking loudly).


Speakers okay with another amp?


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## warplanegrey (Jan 3, 2007)

keto said:


> You may be misinterpreting? I have seen @epis be very helpful, to both myself and others many times in build threads.


¯\_(ツ)_/¯ I thought my ask for help to get the amp’s volume issue fixed and I’ll sort out the instability issues later was pretty clear?

I guess I don’t see the value in coming into a thread that outlines a specific issue (low output) and then dropping this nugget of wisdom:



> Most of new builders ignore importance of proper layout.
> Your pictures show clearly output transformer primary wires too close to input circuitry.


I get the OT primaries are in a spot that may cause noise, but not the issue I’m describing.

Personally, if it were me, I’d rather save a few minutes and just skip the thread?


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## warplanegrey (Jan 3, 2007)

Paul Running said:


> Speakers okay with another amp?


Yep! I thought about that too and tried a different cab, speaker cable, etc


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## Alan Small (Dec 30, 2019)

In the same spirit, and almost all of us has discovered and corrected for, ...
a. Different tubes(new tubes can be faulty)
b. Check value of the pots(a supplier can mislabel a pkg 1M when it is a 10K)
c. The resistor to ground at input wants to be 1M


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## Latole (Aug 11, 2020)

To come back to the initial problem, there is a very big chance to have made a mistake in the assembly.
As if a part of the sound would go to ground.
This as well as a defective soldering are the most common errors on circuit building.

I would go over everything, part by part

With a quick look, the voltage seems good. The problem seems to be in the signal/sound path. This one is attenuated without doubt by an error of assembly. Assuming that all lamps are good.

Do you have an oscilloscope?


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## Latole (Aug 11, 2020)

What is you cathode curent at each Power Tube ?

Show the amp's schematic you build, there are many versions; 2 of them :


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## warplanegrey (Jan 3, 2007)

Alan Small said:


> In the same spirit, and almost all of us has discovered and corrected for, ...
> a. Different tubes(new tubes can be faulty)
> b. Check value of the pots(a supplier can mislabel a pkg 1M when it is a 10K)
> c. The resistor to ground at input wants to be 1M


I have now tried three sets of EL34’s (one used but operational, one NOS, one brand new - same result). Also cycled 6 different preamp tubes through with no change.


Latole said:


> To come back to the initial problem, there is a very big chance to have made a mistake in the assembly.
> As if a part of the sound would go to ground.
> This as well as a defective soldering are the most common errors on circuit building.
> 
> ...


I don’t have a scope right now, but I plan on acquiring one in a week or so.

From my pop test, I’ve localized the signal getting dumped between the input and v2.

I rewired all connections at v1, and resoldered all connections from the first bypass cap to the second bypass cap. I haven’t fired it up yet to see if this has made any difference.



Latole said:


> What is you cathode curent at each Power Tube ?
> 
> Show the amp's schematic you build, there are many versions; 2 of them :
> 
> ...


according to my bias king, I’ve got 33mA at each power tube.

the layout I used is based on the attached schematic


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## nonreverb (Sep 19, 2006)

I know this might sound simplistic but here goes. You might have one power tube that's not turning on (not getting signal). Try this...Remove one power tube at a time and play the amp. If the sound completely disappears with one removed, you know where the problem lies and can concentrate your efforts there.


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## warplanegrey (Jan 3, 2007)

nonreverb said:


> I know this might sound simplistic but here goes. You might have one power tube that's not turning on (not getting signal). Try this...Remove one power tube at a time and play the amp. If the sound completely disappears with one removed, you know where the problem lies and can concentrate your efforts there.


will try that as well 

for what it’s worth, when I check voltage at pin 5, I can hear it through the speakers, same effect when I check back at r16 and 17.

and the pops from checking plates on v2 and v3 come through the amp at the proper volume


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## Latole (Aug 11, 2020)

nonreverb said:


> I know this might sound simplistic but here goes. You might have one power tube that's not turning on (not getting signal). Try this...Remove one power tube at a time and play the amp. If the sound completely disappears with one removed, you know where the problem lies and can concentrate your efforts there.



Cathode current reading will tell if one or both tubes are good or no as I ask fews hours ago.
So easy to do.


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## Latole (Aug 11, 2020)

With a scope you also need a audio signal generator.
You can't play guitar and checking your scope in same time.


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## Latole (Aug 11, 2020)

warplanegrey said:


> will try that as well
> 
> for what it’s worth, when I check voltage at pin 5, I can hear it through the speakers, same effect when I check back at r16 and 17.
> 
> and the pops from checking plates on v2 and v3 come through the amp at the proper volume


Your issue is before,
You talk about that tubes ? Where do you read R16, R17 ?


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## Latole (Aug 11, 2020)

If I were in your shoes, I would, I repeat, I would go over it parts by parts following the schematic to make sure that the assembly is faithful to the schematic. 
That's probably where the mistake comes from

It will be faster than waiting to have a scope and a signal generator and then learning to use them.......


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## warplanegrey (Jan 3, 2007)

Latole said:


> Your issue is before,
> You talk about that tubes ? Where do you read R16, R17 ?
> 
> View attachment 455562


check out the layout diagram I posted on page 1


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## Latole (Aug 11, 2020)

warplanegrey said:


> check out the layout diagram I posted on page 1


Thank's 
It easy for you to check parts by parts


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## nonreverb (Sep 19, 2006)

Latole said:


> Cathode current reading will tell if one or both tubes are good or no as I ask fews hours ago.
> So easy to do.


As I stated in brackets, if the signal is missing, there won't be any sound....regardless whether the tube is conducting or not.


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## warplanegrey (Jan 3, 2007)

nonreverb said:


> As I stated in brackets, if the signal is missing, there won't be any sound....regardless whether the tube is conducting or not.


yeah and I definitely have signal. It’s just very attenuated.

For those just joining up here’s a so to recap:

Amp passes signal, but very quiet and muffled
voltages are good throughout
Ground contacts go to ground 
Several tubes known to be good have been tried
Components and chain have been checked and double checked
Shielded cable from input has been swapped for regular wire
Pop test nets a much quieter result at V1
All connections have been cleaned up and reflowed
Removing bright switch removes all signal
Bypassing tone stack removes signal 
All preamp tubes have been rewired
Different speaker and speaker cable combinations make no difference


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## nonreverb (Sep 19, 2006)

Looking at those pics again, I don't see a grid leak or grid stopper resistor(s) on the input of V1 from the jack. Are they hidden at the jack?


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## Alan Small (Dec 30, 2019)

nonreverb said:


> Looking at those pics again, I don't see a grid leak or grid stopper resistor(s) on the input of V1 from the jack. Are they hidden at the jack?


Schematic shows no grid stopper...straight in design ala ken fisher... @warplanegrey is checking on 1M grid leak and value of treble pot(also to be 1M according to layout pic)

This op update clearly points us to the tone section and a pic of all those pots and wiring including the input jack may reveal all.
Kreskin


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## warplanegrey (Jan 3, 2007)

nonreverb said:


> Looking at those pics again, I don't see a grid leak or grid stopper resistor(s) on the input of V1 from the jack. Are they hidden at the jack?


yeah the 1M resistor is up at the jack


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## warplanegrey (Jan 3, 2007)

Alan Small said:


> Schematic shows no grid stopper...straight in design ala ken fisher... @warplanegrey is checking on 1M grid leak and value of treble pot(also to be 1M according to layout pic)
> 
> This op update clearly points us to the tone section and a pic of all those pots and wiring including the input jack may reveal all.
> Kreskin


I’ll grab some photos of the pot wiring tonight


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## nonreverb (Sep 19, 2006)

Alan Small said:


> Schematic shows no grid stopper...straight in design ala ken fisher... @warplanegrey is checking on 1M grid leak and value of treble pot(also to be 1M according to layout pic)
> 
> This op update clearly points us to the tone section and a pic of all those pots and wiring including the input jack may reveal all.
> Kreskin


Yes, I see it that now. I was looking at the wiring diagram and it looked like there was one at the jack but upon closer inspection, it's just the positive blade.


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## Alan Small (Dec 30, 2019)

nonreverb said:


> Yes, I see it that now. I was looking at the wiring diagram and it looked like there was one at the jack but upon closer inspection, it's just the positive blade.


Some find it challenging to work from a picture or drawing of a layout and others, like me, prefer to use a schematic for clarity...
Hopefully all of us will sherlock holmes this unit to successful full operation.


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## Paul Running (Apr 12, 2020)

Wait for your scope to appear. You can use a 440Hz test signal (sine-wave) mp3 as an input. There are downloads on the web for any frequency at any amplitude...most mp3 players have the output impedance to drive an amp and more. Follow the signal from input to output, making sure that you know what to expect...gain can be easily calculated or use the datasheets for the tube types.


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## nonreverb (Sep 19, 2006)

Alan Small said:


> Some find it challenging to work from a picture or drawing of a layout and others, like me, prefer to use a schematic for clarity...
> Hopefully all of us will sherlock holmes this unit to successful full operation.


Meh...I was just being lazy.


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## nonreverb (Sep 19, 2006)

warplanegrey said:


> yeah and I definitely have signal. It’s just very attenuated.
> 
> For those just joining up here’s a so to recap:
> 
> ...


Looking at the schematic, removing the bright switch shouldn't block the signal as it's still going through the volume pot. Have you checked the pot to make sure it shorts when fully on or off?


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## warplanegrey (Jan 3, 2007)

nonreverb said:


> Looking at the schematic, removing the bright switch shouldn't block the signal as it's still going through the volume pot. Have you checked the pot to make sure it shorts when fully on or off?


Yeah it does. Wiper goes to ground when the pot is all the way down.


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## nonreverb (Sep 19, 2006)

warplanegrey said:


> Yeah it does. Wiper goes to ground when the pot is all the way down.


Does the centre leg short on the other leg when fully on? Also,check for 1 meg between the ground leg and the centre leg when fully on


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## warplanegrey (Jan 3, 2007)

nonreverb said:


> Does the centre leg short on the other leg when fully on? Also,check for 1 meg between the ground leg and the centre leg when fully on


I checked the volume pot (removed it from the circuit and confirmed it at 1M).
Here are some photos of each pot and how they’re wired:



http://imgur.com/a/tcg7nbH


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## nonreverb (Sep 19, 2006)

warplanegrey said:


> I checked the volume pot (removed it from the circuit and confirmed it at 1M).
> Here are some photos of each pot and how they’re wired:
> 
> 
> ...


Something is amiss in that part of the circuit if removing the bright switch kills the signal.


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## Alan Small (Dec 30, 2019)




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## Latole (Aug 11, 2020)

nonreverb said:


> As I stated in brackets, if the signal is missing, there won't be any sound....regardless whether the tube is conducting or not.


If power tubes are weak or bias is to cold sound will be low or muffled.
Grid bias at -33vd do not mean tube bias is the right one for the tubes you put in

If KF use and bias NOS RCA or EH tubes and, let say, you put JJ's, bias may be the wrong one.
For one tube;
EL34 power ; 25 watts
Plate voltage ; 383 volts
25/383 = 65 ma cathode current
Good bais ; 60% = 39 ma

You must adjust the -33 volts to reach the good bias. 
A cathode current lower than, let say,10 ma = low sound.
If you can't reach 39 ma. tube may be bad or circuit issue

Put 1 ohms resistor ( any watts ) between one EL34 cathode and ground
Read millivolts .
On 1 ohms resistor millivolts and milli amp are same;

Report


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## Latole (Aug 11, 2020)

Alan Small said:


> Some find it challenging to work from a picture or drawing of a layout and others, like me, prefer to use a schematic for clarity...


100% right. 

The right way to work / trouble shooting and the easiest way is with the schematic.
Beginner don't know how to read or to use them


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## Paul Running (Apr 12, 2020)

I believe that it is much easier to follow a schematic drawing than a wiring diagram when trying to understand the cause of a fault...that holds true for any technology; schematics were developed to help with the frustration that you are encountering. If you plan on scratch building, I recommend that you begin to learn how to read schematics.
Reading a foreign language is useless unless you recognize and understand what's written.


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## Latole (Aug 11, 2020)

Paul Running said:


> I believe that it is much easier to follow a schematic drawing than a wiring diagram when trying to understand the cause of a fault...that holds true for any technology; schematics were developed to help with the frustration that you are encountering. If you plan on scratch building, I recommend that you begin to learn how to read schematics.
> Reading a foreign language is useless unless you recognize and understand what's written.


1000 % right!

Without using schematic it may take 100 more time and more to repair


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## warplanegrey (Jan 3, 2007)

Alan Small said:


> View attachment 455659


I've confirmed that this is how I have my bright switch wired.



Latole said:


> If power tubes are weak or bias is to cold sound will be low or muffled.
> Grid bias at -33vd do not mean tube bias is the right one for the tubes you put in
> 
> If KF use and bias NOS RCA or EH tubes and, let say, you put JJ's, bias may be the wrong one.
> ...


I've biased all three sets of power tubes (a set of used but working Svetlana's, NOS Mullard XF2's, and a set of new JJ E34L's) using my Bias King meter (set them to roughly 34mA-39mA). No change to the sound.

I'll do the 1 ohm from cathode to ground this week and see if I get different readings.



Paul Running said:


> I believe that it is much easier to follow a schematic drawing than a wiring diagram when trying to understand the cause of a fault...that holds true for any technology; schematics were developed to help with the frustration that you are encountering. If you plan on scratch building, I recommend that you begin to learn how to read schematics.
> Reading a foreign language is useless unless you recognize and understand what's written.


For the most part, I can read and follow a schematic. I find following a layout easier (because everyone's brain works differently, I guess). I've followed the schematic in relation to the layout I've used, and I can't seem to find where any discrepancies lie.


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## Latole (Aug 11, 2020)

You do a good job !


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## nonreverb (Sep 19, 2006)

Latole said:


> If power tubes are weak or bias is to cold sound will be low or muffled.
> Grid bias at -33vd do not mean tube bias is the right one for the tubes you put in
> 
> If KF use and bias NOS RCA or EH tubes and, let say, you put JJ's, bias may be the wrong one.
> ...


I think you need to take time when you read posts, Latole. Instead of wasting time posting things we already know, try to think outside the box....


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## nonreverb (Sep 19, 2006)

Alan Small said:


> View attachment 455659


Ok, based on that and what I saw on the schematic, removing the switch will not block the signal so that leaves two options. One the pot is bad or two something happened when the switch was removed from the circuit...maybe something shorted to ground? Either way, the signal loss at that point has to be further investigated


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## Latole (Aug 11, 2020)

English is not my language


nonreverb said:


> I think you need to take time when you read posts, Latole. Instead of wasting time posting things we already know, try to think outside the box....


English is not my first language.
I do what I can.
And rereading everything that has been written since my visit to the site before answering is often very long.

But you probably right when you say I waste my time.


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## nonreverb (Sep 19, 2006)

Latole said:


> English is not my language
> 
> 
> English is not my first language.
> ...


No, you don't waste your time. You know what? It's all cool. You have things to contribute and I should not try and derail that. My apologies.....carry on.


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## Latole (Aug 11, 2020)

Warplanegrey / Duncan

Good idea to ask this forum, they are really specialist in amps






First build: low and muffled output issues


Hoffman Amplifiers Tube Amp Forum, First build: low and muffled output issues



el34world.com


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## warplanegrey (Jan 3, 2007)

Latole said:


> Warplanegrey / Duncan
> 
> Good idea to ask this forum, they are really specialist in amps
> 
> ...


Thanks. Yeah I’ve asked on a few different forums to maximize my chances that someone knows exactly what is going on haha


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## Latole (Aug 11, 2020)

warplanegrey said:


> Thanks. Yeah I’ve asked on a few different forums to maximize my chances that someone knows exactly what is going on haha



Good thing to do , more amps experts there


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## warplanegrey (Jan 3, 2007)

ITS FIXED. 

I guess I wired the B+4 to the wrong side of a resistor. 

Holy hell I feel dumb. I greatly appreciate everyone’s input and help.


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## Latole (Aug 11, 2020)

Good news ! Congrat for you work.

A mistake in the wiring or bad solder ; it is always the case in a new amp building that does not work. You are not dumb.


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## Mark Brown (Jan 4, 2022)

warplanegrey said:


> ITS FIXED.
> 
> I guess I wired the B+4 to the wrong side of a resistor.
> 
> Holy hell I feel dumb. I greatly appreciate everyone’s input and help.


I wired two 220ohm resistors in place of 220k ohm. I even checked it no less than 4 times because I have a tendency to be an idiot. The only dumb thing you can do is quit buddy and you didn't so WINNING!


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## Latole (Aug 11, 2020)

The best way to learn is to make mistakes.
You don't learn anything if you turn the switch ON and everything works.


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## Mark Brown (Jan 4, 2022)

Latole said:


> The best way to learn is to make mistakes.
> You don't learn anything if you turn the switch ON and everything works.


Thats what I keep saying!

I also say it to myself every time I make one of those idiotic mistakes so I don't have a hissie fit and throw vacuum tubes all over my house in a rage 

Honestly though, I do learn more personally tracing the circuit path and running through all the possible scenarios that would cause failure than i do soldering the connections where they go.


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## Tone Chaser (Mar 2, 2014)

How does that amp sound?


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## warplanegrey (Jan 3, 2007)

Tone Chaser said:


> How does that amp sound?


ha well I figured out the issue while my daughter was sleeping, so I couldn’t turn it up. Hopefully tonight or tomorrow I’ll be able to sneak away


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## Latole (Aug 11, 2020)

warplanegrey said:


> ITS FIXED.
> 
> I guess I wired the B+4 to the wrong side of a resistor.
> 
> Holy hell I feel dumb. I greatly appreciate everyone’s input and help.


Is that the mistake you talking about ?


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## warplanegrey (Jan 3, 2007)

Latole said:


> Is that the mistake you talking about ?
> 
> View attachment 456341


Yep, that's the one.


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## Latole (Aug 11, 2020)

Tube may running hot !


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