New TMB w/reverb Build

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Re: New TMB w/reverb Build

Post by Bieworm »

All in all the sound is pretty neat!
Did you already try switching tremolo with a pedal?
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Re: New TMB w/reverb Build

Post by foreverstrung »

The noise you're getting is probably a ground loop caused by where/how you're muting the tremolo. You should install the switches.

How does the reverb sound? Have you tried connecting that yet?
All in all the sound is pretty neat!
Did you already try switching tremolo with a pedal?
I haven't hooked up any of the FX. Just got the sound basically right. I'll hook up the tremolo switches and reverb tonight. give it another check and then mount it in the cabinet.
I'll do another sound check then. Clean and then with Reverb and Tremolo.
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Re: New TMB w/reverb Build

Post by foreverstrung »

Well here's the new voltage chart. Everything looks much different. Better I'm sure, but I'm still too new at this to really make that call.
I wired up the toggle switches and the FX completely. I'm getting reverb, but I still need to dial it in. Tremolo too. Gives me something to do tomorrow. The reverb dial between 2-6is kinda harsh. After that, 7-10, it sounds great, but like the pot is not balancing it well. It's like all or nothing. It's getting late now and I'll work on that stuff tomorrow, but I've gotta say, after I wired up the toggle switches and pedal, when I turned on the amp, it was way way quiet. I had to turn it way up just to make sure I truly had a speaker load as it warmed up. The sound was sweet and clean. Extremely happy about that. I'll use this new scope to go thru everything.
I'd appreciate any feedback on Bias. I'm not sure if I'm too hot or not. I truly doubt I'm cold as the sound is very awesome.
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Re: New TMB w/reverb Build

Post by JMPGuitars »

Your voltages look great now. Your power tube dissipation can be calculated here: https://robrobinette.com/Tube_Bias_Calculator.htm

You put your plate to cathode voltage at the top (power tubes' pin 7 minus pin 3), click calculate, then scroll down to "Tube Dissipation Using Cathode Resistor Voltage Drop" then enter your values and click calculate again. You're at 90.8%, which is slightly hotter than the 85% I usually shoot for, but it's fine.

Demooo time. ;)
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Re: New TMB w/reverb Build

Post by foreverstrung »

So, it's not an audition, right? LOL. Real sloppy, but I was just trying to get relay the sounds. Recording with an Iphone 12 is tough to give you guys what I'm hearing. I've also been trying to find which guitar sounds best with it. The strat won out. I think it get's the amps sound across best, via crappy recording device. I did not use the tremolo, but it works and sounds great. I'm still having some bugs with the reverb tho.

Also, I'd be interested in suggestions for a cabinet for this chassis. When I started this project, I picked up from Tube Depot the combo cabinet for the 1974x like build. This amp does not work well with this. Appreciate suggestions here. I can build it, but I'm interested in what others have done. Any drawings, etc...

https://youtu.be/yydGkkuC5GY
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Re: New TMB w/reverb Build

Post by JMPGuitars »

I use top-mount 18W style cabinets, but you have to make it deeper than standard for that chassis. The chassis is 8 inches deep, so I usually have a 10 inch cabinet depth.

What issues are you having with the reverb?

You should play around with different guitars. The amp is touch sensitive. If you play with higher output pickups, you should hear more dirt. If you crank the output to get more dirt, then you can pick lighter, or roll off the guitar's volume to get clean tones...and if you want the dirt pick harder, or raise the guitar volume.
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Re: New TMB w/reverb Build

Post by foreverstrung »

The whole channel is acting up. Reverb that is. I'm getting reverb, but only with the knob past 8. It's like all or nothing. Between 1-7 it's like another gain knob, but not in a good way. It changes the sound, but it's not reverb. I really haven't tried chasing it down any yet.
I use top-mount 18W style cabinets, but you have to make it deeper than standard for that chassis. The chassis is 8 inches deep, so I usually have a 10 inch cabinet depth.
Is this cabinet the type
https://www.ebay.com/itm/293190720636?c ... Dimensions:

W 24” x H 20” x D 9”
Chassis Cut-Out 16 ½
Retro fit as needed?
I think it would fit into this one nicely





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Re: New TMB w/reverb Build

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If the chassis is 8" deep, then a 9" deep cab will not fit
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Re: New TMB w/reverb Build

Post by JMPGuitars »

Bieworm is correct, that's not deep enough.

I thought you were going to build one, but if you're going to spend that much you can just have mojotone.com make you a cabinet (probably for less, they often have free shipping for cabs). They've made lots of cabinets for me. Go on their website, and pick out the custom cosmetics you want, and let them know that you need a cabinet depth of 10" for an 8" deep chassis.

This is the basic version of the one I get: https://www.mojotone.com/Front-Mount-Br ... -Cabinet_3

If you want custom cosmetics, this is the link:
https://www.mojotone.com/Custom-Front-M ... er-Cabinet


Thanks,
Josh
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Re: New TMB w/reverb Build

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Djeez those prices make my head spin! Thank God I'm pretty blessed with my woodworking and tolexing skills. A cab costs me about 120 to 150€.
If/when you decide to make one yourself, I gotta tell ya.. the hardest part is the grill cloth thing. I mean, your first grill clothing attempt is usually pretty horrific, believe me...
I develloped a good technique for that though.
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Re: New TMB w/reverb Build

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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

Post by foreverstrung »

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

Post by foreverstrung »

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

Post by Bieworm »

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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