TMB tremolo part deux

[Bieworm]

Well after being unable to find the part that made my new build sound like winds going through my amp I solved that in a very radical way ... one must know I have been searching and soldering for over 2 weeks to solve the problem.. fruitless. I was very angry on the crap turrets whom were very hard to let solder stick to it. I was suspicious about just every component that was soldered to a turret being way overheated. I was also suspicious about every tube socket because it was very easy to put in a tube the wrong way, meaning sometimes a pin goes next to the grabber...making bad connection.

The radical solution:

Replaced the entire turretboard + all components
Replaced all tube sockets with Beltons
Replaced all wiring between the tubes and from sockets to turretboard.
Along the way I was very careful and clean on EVERY aspect.
See the result:

20200419_153437.jpg

[Bieworm]

Josh, after following the new layout I was unable to make the tremolo operate. There was a terrible buzz when I engaged the switch, as if it wasn't grounded...
So I started the highlighting and I found a flaw in the layout, that appears correct in the schematic. The juice for the tremolo on the layout comes from the last terminal from voltage D. But in fact that juice should be tapped after the 100k resistor that goes to V1 pin 6. So the buzz I got was an overpowering voltage. Now it's back in business!!!

[JMPGuitars]

Your skill has much improved! You've really come a long way in a short period. That build looks much better and cleaner than the previous. I'm impressed.

I'm also proud that I've got you reading and understanding schematics better.

Great catch on that error, the docs have been updated. Thank you! (side note: not really a new node of B+, just sharing part of D)

It looks great...but everybody wants to know how it SOUNDS.

Thanks,
Josh

[Bieworm]

Your skill has much improved! You've really come a long way in a short period. That build looks much better and cleaner than the previous. I'm impressed.

I'm also proud that I've got you reading and understanding schematics better.

Great catch on that error, the docs have been updated. Thank you! (side note: not really a new node of B+, just sharing part of D)

It looks great...but everybody wants to know how it SOUNDS.

Thanks,
Josh

Thanks Josh! This means a lot to me..coming from you.
All I learned is thanks to you. You have a kind way of pointing things out that need to be changed. You are a library of knowledge and always have pointed me in the right direction.
I am the proud owner of the first TMB tremolo.. The prototype. It was an exciting and very learningful journey. Thanks man.
Now there is only the PR mod left. You can see on my board I have saved the necessary room for the mod.
Here's a quick clip with a vintage 70's G12H30. Wow!!!
https://www.dropbox.com/s/28gizwdzbqvdn ... 1.m4a?dl=0

[JMPGuitars]

That sounds fantastic!

I didn't hear any weird crossover distortion yet, so you might not need the ruby mod. It doesn't hurt to do it though. You'd have to crank the gains and let a chord ring out or something like that to test. Or see how it responds to your booster pedal.

[Bieworm]

It's there, but way less. I cranked it earlier. PR is still required I think...
Will do tomorrow..the clip

BTW... The 100k resistors at the PI...why do you mark them otherways? Are they a specific type of resistor and why?
I use the same as all. I have no idea if they are CC , MF , CF...only that they are all 2W , except the ones marked as 3W or 5W.
The rectifier resistor is a 150R / 25W in my amp. The type with aluminium housing as heat sink. Happy with that one.. it gets pretty hot.

[Bieworm]

BTW
This is my build on layout:

TMB tremolo execution.pdf

[Daviedawg]

Super job B. You must be very satisfied. Great to hear the prototype running.

Dd

[Bieworm]

Super job B. You must be very satisfied. Great to hear the prototype running.

Dd

Thanks Dd!
You have to know that this amp was the initial goal on building an 18W. I had some raw designs on a TMB with added tremolo. I was asking around here on the viability of the design..that's when Josh pointed out that it wouldn't work like that (design). But he thought it was a great idea of creating a TMB with tremolo and he would design it when he would have some spare time. I was too anxious at that time to start building and couldn't wait. So I took an existing classic 18W layout and started building that. The big joke was that somewhere halfway the build Josh posted a TMB tremolo design.. I was like: ah crap!!!
Bottom line: built the classic 18W (see my avatar pic) and as an extra I built the TMB tremolo too. Now I have two 18 watts. I felt I kind of owed it to Josh, him going trough all the effort... + I wanted one. Well he designed a really great amp. I can hardly imagine me playing the classic when I had to choose. But have both, so why choose?
Building the combo now. But the TMB tremolo will have to live in the first combo since it's a combo chassis. The classic is a head chassis, so now the tubes point to the front in the 'old' combo. So the classic is going to fit in a new combo, mounted to the top board a la matchless (or JMP)
I painted the wood black yesterday. Did the cut outs for the 2x10 speakers first. Wil do the grill cloth tonight. NOT looking forward to that...I find it the hardest part of cab building.

20200414_205227.jpg

[JMPGuitars]

BTW
This is my build on layout:TMB tremolo execution.pdf

Ditch the dummy jack and make a proper ground connection with a lock washer. If that jack comes loose at all, you lose all your input and preamp grounds. That would be bad.

If you have a 3 position switch for the output, you should connect all 3. What if your speaker blows and only an 8ohm cab is available?

For anybody that wants to do the drive mod, I would recommend a 47K or 56K as the minimum value resistor until further testing is done (replace the 10K connected to the 250K drive pot). I will eventually release a doc including this mod.

Thanks,
Josh

[Bieworm]

BTW
This is my build on layout:TMB tremolo execution.pdf

Ditch the dummy jack and make a proper ground connection with a lock washer. If that jack comes loose at all, you lose all your input and preamp grounds. That would be bad.
--> ay aye sir! It came to mind that this was the closest I could get to the used jack

If you have a 3 position switch for the output, you should connect all 3. What if your speaker blows and only an 8ohm cab is available?
--> I used 2 inputs, 1 for 4 Ohms, and the other for 16 Ohms... I will order a 3 pos switch next time I order and rewire.

For anybody that wants to do the drive mod, I would recommend a 47K or 56K as the minimum value resistor until further testing is done (replace the 10K connected to the 250K drive pot). I will eventually release a doc including this mod.
--> ay aye sir! but why that minimum of 47k? what's the theory behind it?

Thanks,
Josh

[JMPGuitars]

--> ay aye sir! It came to mind that this was the closest I could get to the used jack

You don't own a drill?

--> ay aye sir! but why that minimum of 47k? what's the theory behind it?

The theory is that the value of 47K or 56K will maintain a minimum of about 10% of the signal voltage. The way you have it now, the gain knob drops the signal voltage to about 2%. Either way is sorta fine, but I'd prefer the gain knob have a minimal clean point rather than dropping out the signal to almost being muted. Another benefit is that the sweep range of the pot becomes more useful if you're not starting from an area that doesn't sound great.

And you also have to consider what the min/max useful resistances are in that position. I'll eventually test with a 500K pot next month when I can build this. If, for example, the maximum useful value is 350K, and the minimum useful value is 100K, then a 250K pot plus a 100K resistor makes sense. Then you're in a useful range without losing anything. On the other hand, if 300K is the highest useful value, then the 47K plus 250K combination makes perfect sense. But again, that all requires further testing.

Here's a rough rundown:

470K/470K = ~50% attenuation
470K/350K = ~58% attenuation
470K/260K = ~65% attenuation (this is currently your maximum gain).

470K/47K = ~91% attenuation
470K/10K = ~98% attenuation (this is currently your minimum gain).

The truth is that this is likely overkill. A lot of gain knobs cut the signal to zero. If you want to be lazy you could throw in a 500K pot instead of either part and call it a day.

EDIT: I might change the 470K to a 330K to work with the 250K pot giving what I assume would be a simple solution, with a usable range. Honestly, this is just theoretical entertainment right now.

Thanks,
Josh

[Bieworm]

--> ay aye sir! It came to mind that this was the closest I could get to the used jack

You don't own a drill?

--> like you, I CAN be lazy too

--> ay aye sir! but why that minimum of 47k? what's the theory behind it?

The theory is that the value of 47K or 56K will maintain a minimum of about 10% of the signal voltage. The way you have it now, the gain knob drops the signal voltage to about 2%. Either way is sorta fine, but I'd prefer the gain knob have a minimal clean point rather than dropping out the signal to almost being muted. Another benefit is that the sweep range of the pot becomes more useful if you're not starting from an area that doesn't sound great.

And you also have to consider what the min/max useful resistances are in that position. I'll eventually test with a 500K pot next month when I can build this. If, for example, the maximum useful value is 350K, and the minimum useful value is 100K, then a 250K pot plus a 100K resistor makes sense. Then you're in a useful range without losing anything. On the other hand, if 300K is the highest useful value, then the 47K plus 250K combination makes perfect sense. But again, that all requires further testing.

Here's a rough rundown:

470K/470K = ~50% attenuation
470K/350K = ~58% attenuation
470K/260K = ~65% attenuation (this is currently your maximum gain).

470K/47K = ~91% attenuation
470K/10K = ~98% attenuation (this is currently your minimum gain).

The truth is that this is likely overkill. A lot of gain knobs cut the signal to zero. If you want to be lazy you could throw in a 500K pot instead of either part and call it a day.

EDIT: I might change the 470K to a 330K to work with the 250K pot giving what I assume would be a simple solution, with a usable range. Honestly, this is just theoretical entertainment right now.

--> I think I'll wait for your build and adapt then. Don't want to mess too much in my beautiful landscape of electronics. Just one more tweak...

Thanks,
Josh

I find the amp still too trebly at home volume. How do you feel about a parallel treble cap, which I can switch in the circuit when I have need for more treble? I use a 330pf cap right now. Was thinking about putting a 250pf parallel, but switchable. Or try other values doing alligator clipping... So, kind of a bright switch thing. Or is lifting the 330pf going to get me there?
It's because I play offsets 99% of the time. they're known for the extra treble having the 1M pots and all. I tend to turn up the treble at practices or gigs.. but at home, sitting in front of the amp it's ear piercing. I usually play louder at home than elsewhere

[JMPGuitars]

I would switch the treble cap to a 500pF. If you want to learn more about it, search this site for bright cap values or treble cap values.

[Bieworm]

TMB tremolo ready!!! Only the PR mod... still waiting for the 2nd zener diode. The bastards sent me only 1!!
So now back to the combo shell of the classic 18W.
Grill cloth is applied. The tolex is cut...

[Bieworm]

Classic 18

[Bieworm]

Josh

the matter of the FX loop...

Is this schematic correct? I adapted this from the EF86 Xtra.
I want to use a stereo cable for this. So on the pedalboard I will make a stereo jack plugin for the reverb and delay pedals...

[JMPGuitars]

Josh

the matter of the FX loop...

Is this schematic correct?

That's not correct. You're missing two resistors, and the jack won't work that way. You need the send and receive to connect to each other directly when nothing is plugged in so the 68K resistor is bypassed. There are stereo jacks where you can make that all happen, but not as you have it drawn.

[Bieworm]

The brothers...

[JMPGuitars]

Very nice...but where's the logo?