My Mod800 (Modulus Amps) build

Fenderish

My first amp build courtesy of Modulus Amp. I had prior experience in servicing amps (mine and friends' not professionally) but I wanted to try my own this time and loved it.

Then after a while I added a bright  3-position switch and a cathode/clipper switch and reverted from PPIMV to the classic MV and switched tubes to TAD :

I especially love the cathode/clipper switch because it allows me to switch from a classic JCM800 clipping to a plexier clipping

It roars ! Love it a lot !

I'm a beginner so it's not as tidy as it could be, yet I have absolutely no hum or noise abnormal noise issue, i could even say it's less noisy than all my previous pcb based amps. I use it with a Marshall 4x12 1960AX (with greenbacks) and it's a killer halfstack

victorludorum

It looks like a great job to me. Somebody's shrunk your speaker cab though! ;-)

barneyd

Looks very nice!

Fenderish

victorludorum said:

It looks like a great job to me. Somebody's shrunk your speaker cab though! ;-)

yeah My 4x12 wasn't home the day I plugged it in, sadly

Sassafras

I'm more interested in how you've mounted four 12" speakers in that little cab. I suppose they're front, back and side mounted. Makes for a novel arrangement.

Fenderish

 

thermionic

Great work - very neat. Now I want to build another one myself, that looks considerably more complicated than the ones I've built.

clarkefan

Nice! Proper big transformers!

Curious why you binned the PPIMV? 

Fenderish

'cause I preferred classic MV + attenuator in the end, Also because the loss of high end with an attenuator can be compensated a bit with the presence whereas with the PPIMV, You lose less high ends but the presence control is so attenuated that you can't really use it.

Mark1960

Well done - looks like a really good job!

Fenderish

swapped the 2 sozo coupling caps from the first stages with orange drops as one sozo was leaking a bit of DC (the fact it was upside down on one of the earlier pictures came from an attempt to see if changing the direction of it would stop the leak. it didn't of course...)

Modulus_Amps

That's a great job for a first build, what coupling caps are on the effects board, 47n or 22n? glad to see you did not fit the bright cap on that board too.

If you want the presence control to be more effective you can lower the feedback resistor.

Also for a more more low end grunt and low mid thickness try a 33k resistor in the tone stack instead of the 56k, put it on a switch even.

Actually there are so many good mods for this amp and trying them all is part of the fun

Fenderish

I did just what you advised on the effects board (you provided the 47nF caps) and it works flawlessly So transparent it's very hard to notice when it's on or bypassed

For now I do not feel the need, but the lowering of the feedback resistor is already on my list of future potentiel mods too

I'll try your tonestack mod as i have 82k resistors i can piggyback on the 56k for a quick test

Fenderish

I tried the piggybacking and liked the 33k slope resistor better so just put this one. But I'll add a mod to have the choice to bypass completely the tonestack when using a full eq in the loop.

Modulus_Amps

Put in a mini toggle switch to go from 33k slope and 500pf treble cap (superlead 1968 onwards), to 56k and 250pf treble cap (JTM45 1967 era) I prefer the JTM45 values for clean settings and the superlead ones for more overdrive settings

Handsome_Chris

@Fenderish , please could you repost the pics for this thread?  I am mad keen to see what one of these beauties looks like.

FelineGuitars

Handsome_Chris said:

@Fenderish , please could you repost the pics for this thread?  I am mad keen to see what one of these beauties looks like.

+1