New TMB w/reverb Build

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foreverstrung
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Re: New TMB w/reverb Build

Post by foreverstrung »

I've built many speaker cabinets for amp heads with tolex and grill cloth. I am a carpenter and have been for over 40 years. I can certainly make cabinet for this amp, it's just finding the time. I own and run a construction company AND I'm raising my 3 grandchildren solo. Age 10, 8 and 7.....Time is what I don't have. What little I have, I choose "hopefully" wisely. After this discussion tho, I do believe I'll consider building one.

Any thoughts on this reverb issue? I played today and noticed that even at 2-3 on the knob, I can hear the reverb underneath the harshness. Turn it all the way to 9 and I hear only reverb, but it's not a good reverb. Light high pitch hiss when turning the knob too. On the PCB board I followed the line from the cap to the tube socket. Caps and resistors are as they should be. Has anyone else experienced this?
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Re: New TMB w/reverb Build

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foreverstrung wrote:
Mon 12/12/22 1:25 pm
I've built many speaker cabinets for amp heads with tolex and grill cloth. I am a carpenter and have been for over 40 years. I can certainly make cabinet for this amp, it's just finding the time. I own and run a construction company AND I'm raising my 3 grandchildren solo. Age 10, 8 and 7.....Time is what I don't have. What little I have, I choose "hopefully" wisely. After this discussion tho, I do believe I'll consider building one.

Any thoughts on this reverb issue? I played today and noticed that even at 2-3 on the knob, I can hear the reverb underneath the harshness. Turn it all the way to 9 and I hear only reverb, but it's not a good reverb. Light high pitch hiss when turning the knob too. On the PCB board I followed the line from the cap to the tube socket. Caps and resistors are as they should be. Has anyone else experienced this?
Did you already try swapping the rca cable connectors between the jack inputs?
The schematic says in and out, but in means the return from the tank output and out is to the tank input. In colors, your red tulip should go in the 'in' on the amp.. that will go to the grid of the recovery circuit (pin 7)
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Re: New TMB w/reverb Build

Post by foreverstrung »

Did you already try swapping the rca cable connectors between the jack inputs?
The schematic says in and out, but in means the return from the tank output and out is to the tank input. In colors, your red tulip should go in the 'in' on the amp.. that will go to the grid of the recovery circuit (pin 7)
Yes. Reversing the RCA cables was the first thing I did. When I swapped them, there was no response from the Reverb pot at all. 1-10, no change whatsoever in the sound.
The other way, as I described, is harsh with reverb barely audible in the background until the pot is all the way up and then it's straight reverb, but not a sweet, wet reverb. Not a "good" reverb
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Re: New TMB w/reverb Build

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foreverstrung wrote:
Mon 12/12/22 4:47 pm
Did you already try swapping the rca cable connectors between the jack inputs?
The schematic says in and out, but in means the return from the tank output and out is to the tank input. In colors, your red tulip should go in the 'in' on the amp.. that will go to the grid of the recovery circuit (pin 7)
Yes. Reversing the RCA cables was the first thing I did. When I swapped them, there was no response from the Reverb pot at all. 1-10, no change whatsoever in the sound.
The other way, as I described, is harsh with reverb barely audible in the background until the pot is all the way up and then it's straight reverb, but not a sweet, wet reverb. Not a "good" reverb
What pan do you have connected to the amp?
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Re: New TMB w/reverb Build

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What pan do you have connected to the amp?
By pan, do you mean my actual reverb spring ensemble? It's the one that came with the original components. After playing the amp more and kinda breaking it in, with the reverb now, 1-3 sounds good and 9-10. 4-8 is no bueno. Might be this reverb unit itself.

On another note, this cabinet I got from Tube Depot I can make work if I could just get the mirror image of this chassis plate. Any suggestions? If I could get the writing on the back side of the plate, it would be fine. The pots should be left to right, but I could make right to left work. Assuming the writing can get flipped. The way it's laid out, I don't think I can really get it into any combo amp. I could make this chassis work for a head, but not a combo. Any combo, the writing is still upside down and left to right pots.
Unless I'm missing something.
I'm not totally opposed to a head.
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Re: New TMB w/reverb Build

Post by JMPGuitars »

The reverb problem could be a parasitic oscillation causing that issue. Post a demo of what it sounds in each volume range.

Your scope might come in handy if that's the case.

I just checked, I only have head faceplates right now. Unfortunately, my laser isn't big enough to make you one (it would be in two pieces, which is kinda weird). I can order the combo version of the faceplate, but one-offs are expensive. I was planning on ordering a few faceplates soon, so if you're not in a rush, that would work out better.

Thanks,
Josh
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Re: New TMB w/reverb Build

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I just checked, I only have head faceplates right now. Unfortunately, my laser isn't big enough to make you one (it would be in two pieces, which is kinda weird). I can order the combo version of the faceplate, but one-offs are expensive. I was planning on ordering a few faceplates soon, so if you're not in a rush, that would work out better.
That would be great josh. No rush
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Re: New TMB w/reverb Build

Post by JMPGuitars »

foreverstrung wrote:
Mon 12/12/22 8:52 pm
That would be great josh. No rush
BTW- if you decide you would be okay with making a head version instead, I use their "Tall 20" British style head, but same thing, 10" depth for an 8" chassis.
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Re: New TMB w/reverb Build

Post by foreverstrung »

Update.
Still haven't taken care of the reverb issue. I'll upload a sound demo of it later today. Put the scope on it soon.
I've been fooling around with this amp all week and I'm very very happy with the sound. Very much looking fwd to adding the reverb.
I'm going to go ahead and build a head cabinet. Lots of great videos out there. I pulled out a couple old speaker cabinets I built about 6-7 years ago. They work, but man, my grill cloth work is awful. Tolex not bad. All of it has lots of room for improvement. My memory of these is twisted. LOL. I thought they were much nicer.
So I'll keep this thread updated with these items, but I'm also looking at my next project. Just throwing around some ideas. I really am being drawn to just something like an original 18w. On the download page, there's a few. I don't want all the bells and whistles. Just a vintage scheme that's relatively quiet.
As always, appreciate you alls thoughts
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Re: New TMB w/reverb Build

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Not an 18w, but a 6G3 is a really great amp for overdrive. It was so much fun I even built a 35W 6L6 version of it.
The recent 18W Tremolo TMB I built has also reverb. I’m not a fan of the 1tube reverb. I won’t build it in an amp anymore. I’m glad I added the fx loop to use my reverb tanks with this otherwise great amp. But it’s personal preference.
I can’t seem to get it (1tube reverb) noise free either… in any amp I built. There’s always some low pitch noise when mix pot is past 50%.. like white noise, but darker in tone
FWIW all my blackface type reverbs are absolutely noise free
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Re: New TMB w/reverb Build

Post by JMPGuitars »

foreverstrung wrote:
Wed 12/21/22 11:31 am
I really am being drawn to just something like an original 18w. On the download page, there's a few. I don't want all the bells and whistles. Just a vintage scheme that's relatively quiet.
As always, appreciate you alls thoughts
If you want a basic (but better) 18W, look at the 18W Modern Classics in the downloads section.
Bieworm wrote:
Wed 12/21/22 11:48 am
I can’t seem to get it (1tube reverb) noise free either… in any amp I built. There’s always some low pitch noise when mix pot is past 50%.. like white noise, but darker in tone
FWIW all my blackface type reverbs are absolutely noise free
I've never had an amp that had 100% noiseless reverb (fender, marshall, mesa, etc...). The 1 tube reverb isn't noiseless, but I haven't found it to be that noisy either.

Here's some of my earlier amps with reverb / gain cranked:

https://www.youtube.com/watch?v=EB0gux3Wrdk
https://www.youtube.com/watch?v=c2kVir5erwM

Both of those are cranked, and one is an EF86 preamp before I redesigned that preamp for lower noise/better gain.

Here's one of my most recent builds, a Tremolo TMB Reverb: https://www.youtube.com/watch?v=7NLzAzifDKg

I wouldn't accuse that of being noisy either. 😉

Thanks,
Josh
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Re: New TMB w/reverb Build

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You know, the noise isn’t that bad. In a band situation it’s not a bothering thing. And at home I don’t turn the reverb up to that level. It’s just not my cup of tea… I’m probably pickier than most when it comes to reverb.
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Re: New TMB w/reverb Build

Post by JMPGuitars »

Bieworm wrote:
Wed 12/21/22 12:37 pm
You know, the noise isn’t that bad. In a band situation it’s not a bothering thing. And at home I don’t turn the reverb up to that level. It’s just not my cup of tea… I’m probably pickier than most when it comes to reverb.
That's fair. So here's your challenge then: make a standard 2-valve reverb in a Tremolo TMB. I was planning to eventually, but won't likely any time soon.
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Re: New TMB w/reverb Build

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JMPGuitars wrote:
Wed 12/21/22 1:08 pm
Bieworm wrote:
Wed 12/21/22 12:37 pm
You know, the noise isn’t that bad. In a band situation it’s not a bothering thing. And at home I don’t turn the reverb up to that level. It’s just not my cup of tea… I’m probably pickier than most when it comes to reverb.
That's fair. So here's your challenge then: make a standard 2-valve reverb in a Tremolo TMB. I was planning to eventually, but won't likely any time soon.
Planning that… but I will first look at this one. Maybe I will add a tube or maybe I will do the recovery with mosfets
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Re: New TMB w/reverb Build

Post by foreverstrung »

https://youtu.be/50sEk-FK4l4
You can hear the reverb channel sounds like crap. Noisey. Little to no actual "reverb".
Like I said, I haven't spent a lot of time chasing this down. I've swapped out the RCA cables. And then back. Changed out the 12AX7. I did flip it over and stare at it for a while. LOL. Looking for the obvious.
Besides the reverb, this amp is quiet quiet.
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