New tremolo TMB build in progress

[Bieworm]

Done!...
Well.. get the voltages more on spec first. PI is nearly to spec but the 2 first preamp tubes are a little high. Reverb too, but not that high.
Power tubes cathodes 10.53V... and now here it comes: when trying to measure the plate voltages my DMM probe sparked!!! Result.. my DMM is ruined. Smell and all.
I got a very faint sound... very very faint and all distorted. Turned out to be the black comm wire from the OT wasn't soldered well. The heatshrink was melted inside the solder. So it didn't connect to ground properly. When I redid that the tremolo TMB tone was all there in all its glory!!!
But when I dial the reverb past 10 O'clock it fizzes on the notes. Those wires are soooo sensitive. But I'll have to buy a new DMM and get the voltages more to spec before I start tweaking the reverb, because maybe my power stage might not be on par.
I'm wondering something... I couldn't get a .001uf cap so I put in a 1000pf silver mica in there. Could that be the issue here?
Here's hhe voltage chart of voltages I remember

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[Bieworm]

Problem solved. I've put an 8k2 grid stopper on V4 pin 7 after the .1uf cap ...
Man..Josh!!! Very nice reverb!!! I'm filled with awe on that design. Crazy good reverb!!!

[JMPGuitars]

Problem solved. I've put an 8k2 grid stopper on V4 pin 7 after the .1uf cap ...
Man..Josh!!! Very nice reverb!!! I'm filled with awe on that design. Crazy good reverb!!!

Sweet! I look forward to seeing the latest voltages, and hearing a demo. Congrats!

Thanks,
Josh

[Bieworm]

I'm glad my work on having good and tight connections has paid off. Apart from the OT common wire's heatshrink being pushed into the solder joint and the overly pushed reverb tube I had zero issues. Really proud of myself and the progress I've made in the past year and being able to solve the problems myself. This feels good

This design is a worthy competitor for all "low" wattage amps on the market and offers great versatility for the modern demanding players out there. Hats off for JMPGuitars!!!

I really hope this amp will find its way to lots of players. I will not stop promiting the tremolo TMB. Good luck on retailing them kits when you putthem out there. That board looks cool too.

Btw.. I don't know if the latest layout corresponds with the schematic, but terminals Y and Z are different from schematic to layout. Might be confusing for future builders...

[JMPGuitars]

Btw.. I don't know if the latest layout corresponds with the schematic, but terminals Y and Z are different from schematic to layout. Might be confusing for future builders...

Huh? Z isn't on the schematic, and Y is the same on both. X is the only one that's different. On the schematic it's before the .022µF, and the layout has it after. I should probably make that match, but it's placement was arbitrary. You can send the X point to reverb from anywhere in the preamp and experiment with it if you're bored.

EDIT: Now it matches.

[Bieworm]

Voltage chart...

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[JMPGuitars]

Voltage chart...

Very nice! Your dissipation puts you at 9.1W per tube. You made an ACTUAL 18watter!

How does it sound?
Where's our demo???????????????????????????????????????

[Bieworm]

I know.. i was happy with the voltages after I went from 2k2 to 4k4 resistor after the 2nd filter cap. Played with the CR too, but found the 180R to be the best value.

I'll demo it when I put it in the combo. I'm testing on crappy 2x10 jensens. But I need to buy other M6 bolts first.

There are some things bothering me though..
1. The volume pot is scratchy. A low pitch whoosh. I don't see anything wrong with the ground connections. Maybe DC finds its way into the pot? Or maybe a lead dress issue at the pots? I'll start there..
2. Reverb hum increases with the dial of the reverb pot
3. The reverb is still pushing the PI into clipping harshly when hitting the strings harder. It's solved when I put a 12at7 in the PI socket. But I wonder if upping the grid stopper on PI pin 7 will take care of that? Or do I rather lower the input signal earlier ( a .47uf or .22uf cap between the reverb pot and V4 pin 7 perhaps?)

The riddle is: what do I address first? Volume or reverb? I'll disconnect the reverb pan and tube first to check if it's all related. If the volume pot is still scratchy then it's not related...

[JMPGuitars]

Address the reverb last. Leave it muted / volume off all the way.

It sounds like you probably have an oscillation in there.

Your thoughts on testing are fine. Pull the reverb tube, and fix the other problems. Highlighter test, check solder connections, etc... You have a lot of questionable looking soldering in there.

I can't see from the photo what's going on with your pot grounds. It should be exactly like the layout.

The reverb part is super sensitive to lead dress and solder quality. Once you get the rest of the amp sorted out, you will need to turn turn up the reverb and chopstick the wires until it's super quiet. This is not a simple build, and it requires a lot of attention to detail.

BTW- I fixed the schematic, download it again before highlighting. The X/Y letters didn't make sense with the reverb. They weren't for the reverb in this build, they were for the FX loop. The reason they got carried over is because my reverb circuit was using them in another build without an FX loop and I wasn't gonna share it, so it didn't matter. Anyway, it's clearer now.

Thanks,
Josh

[Bieworm]

I went over it again and again. Chopsticked everything and tweaked all wires. With the reverb down it's totally gone. Tried many tubes.. some better than others, but still there. With z 12at7 in the PI it's the best result. I think its PI or PT related. But the voltages are fine.. except xuth the 12at7 it's different of course.
Tried a 10nf cap to pin7 V4.. no difference. 100k grid stopper there too, no difference.
It wouldn't have anything to do with the reverb grounding? It's all star grounded on a dedicated lug right next to the rca connections .
One thing suspect too is the distance from the board to the chassis. I used 10mm studs .. maybe it's too close to the rca connectors.. i bent them though.. but still.

[JMPGuitars]

I went over it again and again. Chopsticked everything and tweaked all wires. With the reverb down it's totally gone. Tried many tubes.. some better than others, but still there. With z 12at7 in the PI it's the best result. I think its PI or PT related. But the voltages are fine.. except xuth the 12at7 it's different of course.
Tried a 10nf cap to pin7 V4.. no difference. 100k grid stopper there too, no difference.
It wouldn't have anything to do with the reverb grounding? It's all star grounded on a dedicated lug right next to the rca connections .
One thing suspect too is the distance from the board to the chassis. I used 10mm studs .. maybe it's too close to the rca connectors.. i bent them though.. but still.

Follow the grounding exactly as the layout/modern ground scheme. Not following that will give you noise.

10mm is definitely too short. I used 20mm.

You can't cut corners with a sensitive design like this. Go compare your solder joints to Coolidge's in that other thread. Smooth and shiny wins the race.

You need to correct your ground scheme, raise the board, check your solder joints (that's my nice way of saying FIX them ), and chopstick the wires to avoid noise.

Highlighter check everything again too after fixing the grounds.

Thanks,
Josh

[Bieworm]

Where do yo mean that my grounding isn't following the layout? But "extacly" is impossible. The line up from the pots is different between layout and faceplate. I like the layout in the faceplate better the way it is
I did daisy chain connect all pots on the lugs that should be grounded. I crossed from that daisy chain to the ground buss at the connection where the last filter cap is grounded...

So you're saying I have to connect the 3rd lug from the reverb pot to the daisy chain ground wire. I could swear your pot is wired to the rca's dedicated grounding lug...

[Daviedawg]

Have you considered external influences? By that I mean while testing, where your tank is in relation to other equipment, the amp itself, etc. I have a stand alone reverb unit which picked up noise when in certain positions in relation to the amplifying portion of the circuit or the amp I was using.

It was a harsh hum not like mains.

Dd

[Bieworm]

Have you considered external influences? By that I mean while testing, where your tank is in relation to other equipment, the amp itself, etc. I have a stand alone reverb unit which picked up noise when in certain positions in relation to the amplifying portion of the circuit or the amp I was using.

It was a harsh hum not like mains.

This is like mains hum. Doesn't increase with the vol pot. Increases with reverb level. The tank is 50cm away.

The oscillation/ high freq distortion is reverb related. Without reverb everything is perfect. The oscillation occurs only when turning up the reverb pot past 50%. So it's amount of signal related I guess... I'm going to try some stuff. Maybe grid stoppers on the reverb tube grids? But first going to put the reverb pot ground to the daisy chain ground of the rest of the pots. I think I misinterpreted Josh’s photos. There's a connection between the input rca and the switchable pot that I took for a ground connection. So taking that wire for THE ground connection of the reverb pot might cause the oscillation in that very sensitive part of the circuit...

I already lifted the turretboard from 10 to 17mm to rule out the proximity of the components to the rca inputs...

[JMPGuitars]

This is like mains hum. Doesn't increase with the vol pot. Increases with reverb level. The tank is 50cm away.

The oscillation/ high freq distortion is reverb related. Without reverb everything is perfect. The oscillation occurs only when turning up the reverb pot past 50%. So it's amount of signal related I guess... I'm going to try some stuff. Maybe grid stoppers on the reverb tube grids? But first going to put the reverb pot ground to the daisy chain ground of the rest of the pots. I think I misinterpreted Josh’s photos. There's a connection between the input rca and the switchable pot that I took for a ground connection. So taking that wire for THE ground connection of the reverb pot might cause the oscillation in that very sensitive part of the circuit...

I already lifted the turretboard from 10 to 17mm to rule out the proximity of the components to the rca inputs...

Don't build from my photos, build from my layout. Not everything in my photos is in the docs. My photos were not taken as a guide. Having the pot ground in the wrong place can definitely cause issues.

How is the tank oriented? The red Out jack on the tank can't be anywhere near the OT.

It's also possible you might need to reorient your reverb transformer.

[Bieworm]

This is like mains hum. Doesn't increase with the vol pot. Increases with reverb level. The tank is 50cm away.

The oscillation/ high freq distortion is reverb related. Without reverb everything is perfect. The oscillation occurs only when turning up the reverb pot past 50%. So it's amount of signal related I guess... I'm going to try some stuff. Maybe grid stoppers on the reverb tube grids? But first going to put the reverb pot ground to the daisy chain ground of the rest of the pots. I think I misinterpreted Josh’s photos. There's a connection between the input rca and the switchable pot that I took for a ground connection. So taking that wire for THE ground connection of the reverb pot might cause the oscillation in that very sensitive part of the circuit...

I already lifted the turretboard from 10 to 17mm to rule out the proximity of the components to the rca inputs...

Don't build from my photos, build from my layout. Not everything in my photos is in the docs. My photos were not taken as a guide. Having the pot ground in the wrong place can definitely cause issues.

How is the tank oriented? The red Out jack on the tank can't be anywhere near the OT.

It's also possible you might need to reorient your reverb transformer.

The tank is momentarily on the bench, 50cm away from the amp.. and 80cm from the OT, so that would be very unlikely a cause for hum..
I put my reverb transformer on the same place as yours.. I hope that isn't the issue, because I'd have to remove the entire turretboard for that.

[JMPGuitars]

The tank is momentarily on the bench, 50cm away from the amp.. and 80cm from the OT, so that would be very unlikely a cause for hum..
I put my reverb transformer on the same place as yours.. I hope that isn't the issue, because I'd have to remove the entire turretboard for that.

All of those suggestions are to be considered only after fixing your grounding, lead dress, solder joints, etc...

[Bieworm]

Did the ground wire like I told before . It's better.. but not yet superb.. but hey, I wanted to hear it in its shell.. so here it izzz

https://www.dropbox.com/s/fatxajs1b6l2u ... 5.m4a?dl=0

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[JMPGuitars]

Sounds great! You're definitely making progress. Be patient, and work through the issues and you're obviously going to love the final result.

[Bieworm]

Sounds great! You're definitely making progress. Be patient, and work through the issues and you're obviously going to love the final result.

I'm happy how it's turning out. There are some issues with the reverb but i will solve it.
The rest is very ok.
That creamback is nice too.
To be honest.. I'm not disappointed there are issues. It's part of the learning process for me... Will get there even more satisfied