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Valve Senior is in the HOUSE!


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Just unwrapped the Valve Senior Combo that Santa brung me, and have already been playing with the various settings. All I can say is




This thing sounds great. The suggested settings are pretty good, although with a little tweaking they can be truly outstanding. Lots of dynamic range and touch sensitivity here, highly adjustable gain, plenty of volume and a TON of great sounds inside this box. I have found a few downsides, some serious and some purely design issues:


(1) It has as much reverb as my 5E3, which is to say it is non-existant. Any word from Epiphone on recommended improvements? I had a Mesa Mark IIb with this issue and even the folks at Mesa said that was just the way it was.


(2) When I went to check the reverb tube (hey, maybe it was dead already) I discovered that the back panel was on so tight I literally could not get it open. Eventually, I was able to get the back panel off (hey it is a very good fit, if a wee bit tighter than I expected!) and I discovered that,


(3) While the power tubes are chassis mounted, the 12AX7's are mounted direct to the PCB. As it ages, the heat and vibration are likely to age it prematurely


(4) It was actually bigger and heavier than I expected. Not Fender Twin heavy, but I seemed to think it would be about 16"x16" and weigh about 30 lbs. It's acually 18"x18" and weighs about 40. Not a huge difference, but I was a bit surprised when I pulled it out of the box.


All in all, it is definitely a keeper, especially for the price!

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Congrats Dino, I'm keeping mine too.


1) I'm still hoping that someone at the Sewatt site will come up with a mod to the reverb circuit, it doesn't appear to be a problem with the tank itself.

2) Back panels are put on while the tolex glue is still drying, so it tends to weep out and glue the panel to the enclosure. Same problem on the other two Epi valve amps I've had.

3) Probably correct. These amps are not really intended as hard core touring amps.

4) Mostly the weight of the MDF enclosure.


Cheers, and enjoy...

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  • 2 weeks later...
  • 3 weeks later...


I've updated the schematic to adjust the values of C6/7 (150p) and C25 (22u). I checked the other components and are all ok.

Here's the schematic and component list checked one by one.



R1 1M 1/2W

R2 330K 1/2W

R3 68K 1/2W

R4 1K5 1/2W

R5 56K 1/2W

R6 4K7 1/2W

R7 470K 1/2W

R8 3M 1/2W

R9 1M 1/2W

R10 1M 1/2W

R11 1K2 1/2W

R12 33K 1/2W

R13 1K 5W

R14 10K 2W

R15 68K 1/2W

R16 4K7 1/2W

R17 91K 1/2W

R18 100K 1/2W

R19 1K 1/2W

R20 1K 1/2W

R21 1K 2W

R22 250O 10W

R23 1K 2W

R24 1M 1/2W

R25 1K5 1/2W

R26 1M 1/2W

R27 1K5 1/2W

R28 330K 1/2W

R29 10K 2W

R30 470K 2W

R31 470K 1/2W

R32 100K 1/2W


C1 C2 22n 400v

C3 C4 22n 400v

C5 C10 10n 400v

C6 C7 150p lentil

C11 C12 250p 500v

C13 C14 22n 400v

C15 C16 100n 400v

C17 C18 100n 400v

C19 C20 100n 400v

C21 C22 100n 400v

C23 C24 47p 500v

C27 C28 250p 500v

C30 C31 1n 400v

C35 C38 22n 400v

C39 ¿? 47n (what is it doing here?)

C40 C41 1n 400v


C8 +/- 22u 50v

C9 +/- 22u 50v

C25 +/- 22u 50v

C26 +/- 6u8 50v

C29 +/- 6u8 50v

C32 +/- 22u 450v

C33 +/- 22u 450v

C34 +/- 22u 450v

C36 +/- 22u 450v

C37 +/- 22u 450v


Gain 1M log

Treble 1M lin

Middle 25K lin

Bass 1M log

Presence 25K lin

Master 500K log (double)

Reverb 1M log

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  • 4 weeks later...

Hi J Ventura


I doubled checked my board and C25 is definitely 1uF/50V (branded Imagine like the rest) on my revision..so they might have changed that already?? - the last 4 digits of my serial are 0010. I will have to remove the board to check what value was in C6/7 - but could be a similar revision..it wouldn't make a huge difference - you can graph the difference in that tone stack program..


Thanks for checking it out [biggrin]


Re dwell control - it probably slots in where R31/R24 are. You could remove R24, then disconnect the end of R31 from pin 2 of the tube, then connect pin 3 of your 1M pot to R31, pot pin 2 to tube pin 2 and pot pin 3 to ground where R24 was..least i think that was it from memory :)..better go and check that too :)

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So it seems there are two versions. I'm sure my values are correct too. Specially C25, I know it well because it exploded two times because a deffective tube.

The idea about the dwell control looks interesting. I played with R31 value (put a 4M7 pot in parallel) and it did nothing, but now I guess changing both resistors for a pot as you suggest should work...

My 4 last digits: 0059.

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it might work..i might be imagining that tho ;) could be something around there ;)


next time it blows you could try a 1u cap then and see what happens..i might try a 22u and see :)


Well, I hope my new tubes are good and this never happens again. ;)

Maybe I try it one of these days.

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  • 2 weeks later...

Thanks Svet, I've been meaning to add a couple more demos with the LP '57 Jr. RI and the cigar box guitar. Might also help if I warmed up a little. Maybe I'll do it today, the wife's going out for a while...


PS, you live in New England area, right? There's a VINTAGE '66 tea burst Casino at the Natick, MA Guitar Center. Single P90, but it sure looks nice. Item no. 103383147, on sale for $1,995. Seems like a good price...


And to anyone in the NC area, there's a JL Revolution Casino at the Durham GC for $1,500, item no. 105077594.


Cheers, Brian

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  • 4 weeks later...

Hi bremzzi,

yes this is what i have in my amp except I changed R31 from 1M to 2M. I have R31 and R24 removed from the board and connected directly to the pot at the back of the amp (next to the speaker outs). So yes, sounds good and not just an idea :-k


I will send through a photo later [thumbup]



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  • 2 months later...

here are some pics..



when i am listening to this amp and not looking at it, it's fantastic..pitty about it being so bloody ugly haha...coz damn it sounds great..i am in two minds about keeping it given the number of amps i have..i can't keep all of them and it is damn ugly...the only reason it is still here is because it sounds amazing..but i only have room for so many....the dilemma!


oh..and from the outside, it looks like this...





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Jaydodgce many thanks for the piccs! They are extremely useful but I don't have the expertise and the tools for that...

I think it will cost me less to buy an Accutronics unit than having a tech do the Dwell mod. Somebody has succesfully replaced the original Ruby rev tank with an Accutronics R8DB2C1C:




But then I read:


I have replaced the reverb tank with a Accutronics. I do not hear any change. There must be a way to add a mini pot to control the dwell. ?


Tragic, can you tell us the exact Accutronics model you tried?

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  • 2 months later...

quick update..found some spare time to mod this again so i decided to add a triode mode switch on the back to reduce the output power from 20watts to something more bedroom friendly..definitely did the trick - plus it adds a bit more tonal variety.


it involves removing R21/R23, adding them to the bottom of a DPDT switch, joining them and running a single wire back to the B+ line for grid 2..with the two middle pins on the switch, you connect up wires back to where R21/R23 were (so one wire from pin 4 of each output tube)..then the top of the switch has a couple of 100ohm fusibles for protection with wires going back to the pin 3 of each output, making sure you follow the same pattern you used for the wiring of each pin 4..


very happy with the result.. :)



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