3Ch Rectifier FX Loop Tone suckage fix..

[mixn4him]

Have read all about the mods to change this to a simple serial loop and just couldn't bring myself to do it. So starting experimenting with tubes and sure enough I have found a solution!! Popped a Tung Sol 12Ax7 in there and boom NO tone suck or change at all. Now all I can figure is that since they are typically bright tubes ( in my experience ) that added brightness and gain of the Tung Sol balances out the dark tone of the loop. Have tried several pedals and FX units and seems to be cured. Really love that this works finally because I like the Loop Master volume and Solo boost, and switching the FX loop on/off from the foot switch is almost seamless..

Just wanted to pass along , good luck!

PS REALLY love this amp and don't run it in the normal fashion. I play a strat with Lollar PU's and really run the gains low; clean , raw and vintage modes only and tube rectifiers...spongy power I am not digging but the rectifiers give it a nice squish. Also run this thru a Marshall Greenback cab and an Electra Dyne 1x12 for smaller stuff...

 

[vick1000]

Well you will be replacing that puppy pretty often, they don't do well in a cathode follower spot. You want a non-spiral filament tube in those spots.

 

[mixn4him]

Its the loop driver tube not one of the cathode followers...

 

[vick1000]

V3 and V4 are cathose followers.

 

[TRENCHLORD]

I'm not sure about the older 3-channels with parallel-loop, but I know on my series2 single (parallel) I get a slightly thicker/louder/better tone by engaging the solo full-time and just leaving the solo knob off or very low. I don't use solo as it's intended anyways, and leaving it on seems to add just a little extra signal or something. Maybe a jumper cable in the loop would do the same thing, I'm not really sure.

 

[mixn4him]

V3 and V4 are cathose followers.

Wrongo:

V1 A= Input Stage all 3 Channels
V1 B= Clean Channel
V2 A= 2nd Input Stage all Channels
V2 B=Channels 2 & 3 Boost Stage
V3 A=Channels 2 & 3 Boost Stage
V3 B= Same as V3 A
V4 A= FX Send V4 B= FX Return
V5 A= V5 B=Phase Splitter /

 

[vick1000]

V3 and V4 are cathose followers.

Wrongo:

V1 A= Input Stage all 3 Channels
V1 B= Clean Channel
V2 A= 2nd Input Stage all Channels
V2 B=Channels 2 & 3 Boost Stage
V3 A=Channels 2 & 3 Boost Stage
V3 B= Same as V3 A
V4 A= FX Send V4 B= FX Return
V5 A= V5 B=Phase Splitter /

Do you even know what a cathode follower position is? It's a circuit design where the signal is taken off the cathode of the tube, amplifyng current, so a spiral filament 12AX7 tube can't handle the inreased current and will burn out faster.

Yes, the FX loop tube position is V4, a cathode follower, just as V3 is. It's how the tube is wired into the circuit, not it's function that determines if it is a cathode "follower" position.

http://www.valvewizard.co.uk/dccf.html

Notice in the schematic on that page where the output signal is coming from on the tube. Now compare and look at where it's coming off your V3b and V4a...