New TMB w/reverb Build

[JMPGuitars]

It's 48.18k

47K = 47,000. 47K + 820 = 47,820 ohms. The resistors are 1%. So you should be within 1% of 47.82Kohms. 48.18 Kohms = fine. 48.18 ohms = not fine.

That's the math: resistors in series are added together. 1 + 1 = 2.

Thx for this. I did not understand the measurements correctly or the math.
I understand now.
It is 48.18 kiloohms. Grount to cathode. V4, Pin 3 and 8

Good, and that makes sense anyway considering your cathode voltage is pretty close. Nothing needs to be exact, but you want things close.

Back to searching for soldering issues.

Also, test your plate resistor value at the PI. My guess is they're fine, but check anyway if you haven't yet.

Thanks,
Josh

[foreverstrung]

Back to searching for soldering issues.

What would you recommend I do, that I haven't already done, (some a few times), to check soldering issues? I've rewired nearly everything and I've gone over the PCB multiple times as well. What's left? What am I missing?

The poor output sound is the same now, after everything I've done, as it was the 1st time I plugged in. No change

[Bieworm]

Back to searching for soldering issues.

What would you recommend I do, that I haven't already done, (some a few times), to check soldering issues? I've rewired nearly everything and I've gone over the PCB multiple times as well. What's left? What am I missing?

The poor output sound is the same now, after everything I've done, as it was the 1st time I plugged in. No change

A scope would be convenient

How do you run the output to a speaker? Is it a speaker cable and is it in good condition?

[foreverstrung]

A scope would be convenient

I was just looking at these. There not that expensive.
I don't know how to use them, but You've gotta start somewhere, right?
What should I look at picking up? Suggestions?
Simple as possible and best for this stuff?
Thx

[Bieworm]

A scope would be convenient

I was just looking at these. There not that expensive.
I don't know how to use them, but You've gotta start somewhere, right?
What should I look at picking up? Suggestions?
Simple as possible and best for this stuff?
Thx

A good budget scope is the Siglent SDS 1102CML. That's the one recommended to me, which I bought back then

[JMPGuitars]

I'm a fan of the Siglent scopes. Which you get depends on your budget. Bieworm's is good at that price point, or if you want to spend a little more, the SDS1104X-E is really good too. That's what I used before I won a nicer one.

There's a TON of videos on using a scope for general use and guitar amp stuff on youtube.

A good / quick info page on how to use it is here: http://www.r-type.org/articles/art-125.htm

To answer your other question, if we assume for a second that there's definitely nothing wrong with your solder joints, nothing wrong with the wires, or speakers, perfect tubes, and all resistors are correct and in spec, then we would want to look at your coupling capacitors.

Or you might need to chopstick the wires, because a wire being out of place could cause a parasitic oscillation that could destroy your sound entirely.

Chopsticking the wires means moving them carefully with a single wooden chopstick while the amp is on (keep your other arm behind your back or in your pocket). You would need to have some sound input to the amp (looper pedal or tone generator) to be able to hear the difference.

Chopsticking the wires is the easier choice, so start there.

Thanks,
Josh

[foreverstrung]

then we would want to look at your coupling capacitors.

What is this? Coupling caps?

You would need to have some sound input to the amp (looper pedal or tone generator) to be able to hear the difference.

If I plug a looper pedal into this, I assume I'll have a rhythm playing, yes? Some continuous sound, correct?

Also, for some reason that I'm unaware of, does it have to be a chopstick? I've got a nice soft plastic probe stick I use when I'm getting into a live amp. This should be fine for the tap test, yes?
Thx

[JMPGuitars]

What is this? Coupling caps?

The yellow ones. Some of them are for tone, some of them couple one section to another. If you look at the schematic, section by section, you might notice which caps are joining one stage to another, or which are attached to tone knobs.

If I plug a looper pedal into this, I assume I'll have a rhythm playing, yes? Some continuous sound, correct?

Also, for some reason that I'm unaware of, does it have to be a chopstick? I've got a nice soft plastic probe stick I use when I'm getting into a live amp. This should be fine for the tap test, yes?
Thx

Yes, continuous sound.

If there's nothing conductive on the plastic probe, that should be fine. I like sushi, I have an abundance of wooden chopsticks.

Keep in mind you're not just tapping things, you need to physically reroute wires sometimes. If you look at my build photo, you'll see all my wires are color coded. Red is anode (plate) wires, closest to the chassis, and kept away from blue or purple grid wires (never parallel). Black are cathode wires. They all have specific routes to avoid issues.

Having an oscilloscope can help isolate parasitics and help kill them.

Thanks,
Josh

[foreverstrung]

The yellow ones. Some of them are for tone, some of them couple one section to another. If you look at the schematic, section by section, you might notice which caps are joining one stage to another, or which are attached to tone knobs

So, if i'm understanding correctly, I want to concentrate on the yellow caps separating sections/stages. yes?
Not so much coming off the pots.
Also, what am I checking? Resistance?
Any advice on how I go about checking them if diff from resistors?
Thx

[JMPGuitars]

The yellow ones. Some of them are for tone, some of them couple one section to another. If you look at the schematic, section by section, you might notice which caps are joining one stage to another, or which are attached to tone knobs

So, if i'm understanding correctly, I want to concentrate on the yellow caps separating sections/stages. yes?
Not so much coming off the pots.
Also, what am I checking? Resistance?
Any advice on how I go about checking them if diff from resistors?
Thx

You would want to test capacitors for capacitance. You already tested them for whatever resistance they see (which they are not responsible for). You could also just replace them one at a time and see if anything happens.

I would also try your knobs in different positions while you have a loop going to see what the amp sound like. Put all the tone knobs at 50% and adjust from there to see if anything mysterious happens. If the issue was just that the tone knobs were down the whole time, then make something else up when you report back.

Another possible test is to insert sound at different points in the circuit, but that requires the right tools, and careful practice with the amp off prior to connecting anything anywhere. Ignore this last bit for now.

Thanks,
Josh

[foreverstrung]

I would also try your knobs in different positions while you have a loop going to see what the amp sound like. Put all the tone knobs at 50% and adjust from there to see if anything mysterious happens. If the issue was just that the tone knobs were down the whole time, then make something else up when you report back.

That's funny. I'm not that proud. I'll cop to whatever the problem is when we get to it. I did however think of the knobs 1/2 way-ish. It did change the sound, for the better, but still breaking up harshly.

I did find a couple things. When I was checking/moving wires with the looper pedal. 1st, with the pedal, the sound was much better than straight guitar. (I have been switching with a few diff guitars and cables to make sure it's not the guitar), tho it still had that harshness over the top when I turned it way up.
The other thing is that when moving wires, the blue wire from the OT to pin 7 of V5, changed the sound when I moved it. I thought it might be a cold connection at the tube socket, (tho I replaced all of the tube sockets trying to chase down this problem) so I let it cool down, disconnected the wire, cleaned it up and resoldered.....Same sound produced.
And still, there is change in sound when I move it. Not big sound, but still, significant that there's any at all I'm sure.....Possible the wire connection at the OT.....Might be one of those parasites you spoke of.

[Bieworm]

And still, there is change in sound when I move it. Not big sound, but still, significant that there's any at all I'm sure.....Possible the wire connection at the OT.....Might be one of those parasites you spoke of.

Those wires should never be twisted. Twisting those can have a bad influence on tone.
I don't remember you did this or not...
But here's a long shot: in an amp with a NFB circuit you sometimes have to swap the blue and brown wires from tube socket to eliminate oscillation. This is an easy fix. I suggest you try doing that swap anyway, even though you don't have a NFB circuit.

[JMPGuitars]

I did find a couple things. When I was checking/moving wires with the looper pedal. 1st, with the pedal, the sound was much better than straight guitar. (I have been switching with a few diff guitars and cables to make sure it's not the guitar), tho it still had that harshness over the top when I turned it way up.
The other thing is that when moving wires, the blue wire from the OT to pin 7 of V5, changed the sound when I moved it. I thought it might be a cold connection at the tube socket, (tho I replaced all of the tube sockets trying to chase down this problem) so I let it cool down, disconnected the wire, cleaned it up and resoldered.....Same sound produced.
And still, there is change in sound when I move it. Not big sound, but still, significant that there's any at all I'm sure.....Possible the wire connection at the OT.....Might be one of those parasites you spoke of.

Post a video of your amp so we can hear the difference with the looper between lower and higher volume, and see where the knobs are. Start with the volume / gain knobs in the off position and turn up from there. Put the gain half way, then adjust the volume.

Thanks,
Josh

[foreverstrung]

https://youtu.be/qi_xuFk1LT4
I don't know if this video gets everything you wanted. I do believe it does NOT catch the subtle sound when moving the blue wire from the OT. It's there, but the video doesn't get it.
We def can hear the harshness with the guitar. Loop pedal too when the volume is elevated. Remember, I've swapped out guitars. Always with the same result.
Thx

[JMPGuitars]

https://youtu.be/qi_xuFk1LT4
I don't know if this video gets everything you wanted. I do believe it does NOT catch the subtle sound when moving the blue wire from the OT. It's there, but the video doesn't get it.
We def can hear the harshness with the guitar. Loop pedal too when the volume is elevated. Remember, I've swapped out guitars. Always with the same result.
Thx

Well, that does sound like dookie. For future testing, keep the TMB knobs at 50%. Then you might adjust 1 of them to 100% to see what effect is has. But if you're having sound issues, and keep the knobs too low, you're killing the tone curve, and possibly making your issue sound different than what it is...if that makes any sense.

When you did your highlighter testing, did you test the component values? For example, it says 100K on the schematic, then you test the resistor and see if your meter says ~100K.

Thanks,
Josh

[foreverstrung]

When you did your highlighter testing, did you test the component values? For example, it says 100K on the schematic, then you test the resistor and see if your meter says ~100K.

I went thru, (a few times), checking the values at the pads, I did confirm that they were the correct values.
I am going to go thru it all again. The marker check. It's gotta be here someplace. I'm close

[foreverstrung]

Question.
Attached is a photo of the layout in the background and a cap in my hand. (cap for fx). The cap has a black sharpie mark around one end. All my yellow caps have this black sharpie mark. This is how they were shipped to me. The layout shows all the yellow caps with a dark edge.
Impling that there is a direction for these caps to be installed.
Is this true?
If so, I've got half of my yellow caps installed backwards.
If it is true, how does one determine the direction of this capacitance?
Thx

[Bieworm]

Question.
Attached is a photo of the layout in the background and a cap in my hand. (cap for fx). The cap has a black sharpie mark around one end. All my yellow caps have this black sharpie mark. This is how they were shipped to me. The layout shows all the yellow caps with a dark edge.
Impling that there is a direction for these caps to be installed.
Is this true?
If so, I've got half of my yellow caps installed backwards.
If it is true, how does one determine the direction of this capacitance?
Thx

It's only for noise reasons.. dont worry

[JMPGuitars]

Question.
Attached is a photo of the layout in the background and a cap in my hand. (cap for fx). The cap has a black sharpie mark around one end. All my yellow caps have this black sharpie mark. This is how they were shipped to me. The layout shows all the yellow caps with a dark edge.
Impling that there is a direction for these caps to be installed.
Is this true?
If so, I've got half of my yellow caps installed backwards.
If it is true, how does one determine the direction of this capacitance?
Thx

Yes, that is to show the direction of the foil. Following the layout guidelines for the marked edges helps reduce unwanted noise.

It's not essential, but can be helpful.

Thanks,
Josh

[foreverstrung]

I need to order new caps. I did damage 1, (.022), trying to flip it around from the topside.
Can I get any helpful ordering info on ordering the correct caps? I don't want to waste more time trying to figure out what's needed. The details needed thru mouser are many.
I'll probably just swap them all out, so I'd like to order all new.
Piece by piece I'll replace if needed. The problem has gotta be here somewhere. I'm not sure what else to do. I got a new OT too. I'm waiting before throwing it in. Replace the caps first