want 2 Rok JM signature tone board layout

[M Fowler]

Reviewed the early schematic version with last version (page 3) and only slight differences.

The PS is drawn and labelled differently but electronically is the same, no change.

1. MV was corrected
2. Reverb driver V3 a/b cathode 2k2 original schematic changed to 1k.
3. V2b cathode 1k original schematic changed to 1k5.
4. 4b has a 108k connected to anode original schematic changed to 205k.
5. 4b cathode 1k8 original schematic changed to 1k5.

For now I'm not changing any values. So to keep people straight I used the original schematic aaron drew but corrected master volume wiring.

Mark

[Aaron]

Nice build Mark!

The first schematic I drew I guessed some values from squinting at the picture. The latest one has different values that were suggested by some people who had built it.
Did you stick with the 108k in the mixer section. AFAIR Mhartman built one but used a 205k to get the right blend. What reverb trans and tank did you use?

[M Fowler]

Aaron thank you for putting the schematic together and posting and to the other guys.

I went entirely on the first schematic posted but corrected the MV.

I used 108k in the mixer and tested with Super Reverb tank, I need to look up the numbers if needed. Currently I have the short tank 8AB2A1B in the head cab for testing but will be using a 17" tank eventually. Probably in 4AB family. Used MC Twin Reverb transformer set (PT, OT, choke, driver).

Had question? Why does the 68k go to ground V1b ,02uf/68k ground/1m to mixer.

[mauiboy81]

Hey mark, looks great! It looks to me like the 68k to ground should come after the 1M forming a voltage divider. .02/1M to mixer/68k to ground

Nick

[M Fowler]

Hey mark, looks great! It looks to me like the 68k to ground should come after the 1M forming a voltage divider. .02/1M to mixer/68k to ground

Nick

Guess what this was corrected in updated schematic just as you stated, now I have to execute a perfect change on my board. Crap that's going to be fun.

[Aaron]

Hi Mark,

Can't you just shift the white wire to the other end of the 68k and put an earth wire in.

Aaron

[M Fowler]

Yeah it looks like an easy fix I just had to stir up some drama.

[mauiboy81]

So how is it sounding mark?

[M Fowler]

Wonderful, I really enjoy this amp. I don't get to play it often but when I do it's an adventure. Trying to get JM's Gravity song down.

I'm more of an aggressive blues rocker player.

[mauiboy81]

Super! You have switches on any of the various LNFB loops?

[M Fowler]

Super! You have switches on any of the various LNFB loops?

Yes on V1 LNFB there is a switch on back panel see photo.

[rogb]

A really interesting build Mark, thanks for sharing. I'd like to hear some Gravity licks on it sometime

[M Fowler]

Thanks Roger and for the first request for Gravity by M. F. oh what a treat that would be.

[sunny]

Which schematic and layout did you use for your amp?

Paul

[M Fowler]

Paul I would use this one https://tubeamparchive.com/download/file.php?id=30389

Also, the honeymoon with this amp is still on, I'm getting exhausted thought

Seriously good amp can't wait to gig with it, so I better build a new cab for it and I seriously need to measure controls for a faceplate too. Maybe Taylor will send me one.

Also, I have not changed my amp to updated schematic specs yet mainly because it works so well now.

Mark