Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #80881  by oldjoebones
 Sun May 30, 2010 5:08 pm
Thinking about picking this up......for a starting point on the "tone" this a good amp as is or do any mods need to be done to it? Possibly put a JBL K120 instead of its current 12". Obviously this is before any pedals or effects are added.
 #80885  by raisingfreen
 Sun May 30, 2010 5:31 pm
What about a 79 Silverface with a K120? I have one listed in the Garage Sale section for sale on here that is in very nice condition. Sorry if this is not a appropriate place to mention it. Used Reissues seem to go anywhere from $550-$750 and you really cant mod them them other than a speaker swap and tubes (as far as I know). If you were planning on buying a new one why at least take a look at a used Silverface Deluxe. Handwired no circuit boards and ready for Jerry mods. Brad had mentioned some great ones on here before as well specifically aimed at this amp.
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 #80891  by oldjoebones
 Sun May 30, 2010 6:19 pm
While im sure your amp is fine I would prefer to go with something more in the line of less of a worry of something going wrong with it. So back to my original question.........would this amp be good to use with a speaker mod or any other mods that would make it suitable.
 #80897  by raisingfreen
 Sun May 30, 2010 6:50 pm
I would email Brad Sarno or Waldo and ask them their opinion on the mods. Waldo had sent me some great mods to make this even more Jerry sounding. Below is part of what Waldo had mentioned about the mods.
"getting a solid state rectifier in a tube socket and swapping out the tube rectifier in it presently. you can also use 6l6's power tubes in there but will need the tech to rebias for them. the sockets will fit them. another thing to consider is recapping the electrolytics in there, and use some good atom spragues. and lastly if your after that jerry chime, have the tech throw in some rn65 100k plate resistors"
I would say it is pretty much there already. It has been recapped, replaced reverb pot, re-biased for new JJ power tubes and a few other maintenance items. It is all extremely well done and the wiring inside is tight and done right. Very unlike many silverfaces I have seen. No need to use the volume boost knob at all just leave it alone. It can be converted to a mid boost however. I had considered that as well. The buyer does not have to take the JBL either. I can sell that separately. I had just assumed that it would be wanted. Very good condition/sounding K120.
 #80899  by SarnoMusicSolutions
 Sun May 30, 2010 7:11 pm
Abso-Freakin-Lutely consider that '79 with a K120. I honestly have a fairly strong distaste for the reissues when you can have a "real" Fender instead. Even a late '70s Fender is very much a killer REAL Fender amp. The reissues are based on the right circuit, but the build quality and method makes them very undesirable in comparison. A real Fender like that '79 mentioned would be a dream to own and extremely friendly for upgrades and modifications. Good luck with a reissue when it comes to longevity and servicing. The transformer in the '79 is gonna sound better too.

It appears that the seller may accept an offer of $1200. In my mind, that's a steal. And this amp is mint. Seriously. It doesn't get better than a real Fender Deluxe Reverb with a K120. The silverface prices are rising rapidly as the blackface amps did in recent years.

And I promise I don't even know who the seller is. I have no bias here other than my deep love and strong recommendation for a real Fender Deluxe Reverb with a K120 in it. It really is a holy grail of guitar amplifiers. No question about it.

 #80905  by JonnyBoy
 Sun May 30, 2010 8:27 pm
If mods are in the future for the amp the Part to Part older construction is easier to fiddle with. I know the pre printed boards aren't the same thing but they allow for a much more organized layout for me to do work on. I have never tested to see if the gold pcb leads are superior or inferior to regular wiring, but it keeps all the parts snug on the board, a little more sturdy and cleaner working surface for me.

I have to agree the tone is classic and worthwhile on the P2P amps versus the reissues, but a dude used a DR tonight and it was awesome, nothing done to it. he ran a tube screamer and nothing else. He played Delta blues, and was nailing a true blues tone, I was envious.

I had to do a lot of mods and work on my reissue (twin Reverb) to get it to a more classic sound,The tone stack, filter caps, plate resistors and next the transformer, but they were well worth it and fun to do! Brad helps numerous pros develop a Jerry tone for stage use, his free advice is worth taking, That one with the k120 already in it? That's a god send for you... your so close with that! plus like tonight it can be mic'd and played LOUD at a show. Thank's Brad for helping everyone like you do! My Speaker set up is what I want now.
 #80906  by Grateful.Ed
 Sun May 30, 2010 8:29 pm
I've been f'ing around with my DRRI for a while...trying to get a mini-twin thing, kinda, basically more headroom/later breakup. After doing a bit of research here and there I found a few things that may help you.

1. Can't use 6l6's unless you upgrade transformer, choke, etc.
2. You can tame reverb with a 12au7 in reverb driver V3.
3. You can get more headroom with a 5751 in V2.
4. You can get more headroom with a weber copper cap rectifier.

I haven't changed the speaker yet, it sounds pretty good to me. I may pick up a used weber california.

And, Clip the bright cap.

There are mods to jump the two channels in phase and one for a mid pot.....haven't tried them.

I found a nice overview of mods (circuit and components/tubes and speakers), here: ... ations.pdf

I'm running a Fulltone GT500 into it, using the boost and low distortion for a nice crunch when you dig in.

Overall, for smaller rooms, this amp does it. Ed.
 #80941  by raisingfreen
 Mon May 31, 2010 1:36 pm
Grateful.Ed wrote:3. You can get more headroom with a 5751 in V2.
I would have never guessed a 5751 in V2 would do that. I always assumed that a 5751 is the same as a 12AX7 which increases gain and lowers headroom. I use either 12AY7 or 12AT7 in V1-V2 and it really cleans it up great. Also if only using the reverb channel I just remove V1 altogether so the signal does not split between V1 and V2.

Quote from

"12AY7 or 12AT7 as preamp tube:
If you want a cleaner and spankier tone you can replace the V1/V2 12AX7 preamp tube with 12AT7 or 12AY7. These tubes have lower voltage gain and different frequency responses, particurlarly when distorting. 12AX7 tube has a voltage gain factor = 100, while 12AT7 = 60 and 12AY7 = 45. One could describe these tubes to have less harsh and buzzy distortion. This mod does not alter the tone significantly when amp is played clean’ish. You’ll have to increase the volume setting to achieve a similar volume as before. If you hit sweet spot at volume=4 with 12AX7 you may go as high as 6-7 before reaching it with 12AT7 or 12AY7."

The only way I new this info was semi accurate was to try it and it worked beautifully. I would like to hear the sound with the copper cap rectifier as well. I sometimes wonder what the amp it would sound like if I could deactivate Waldo's TPC1. Would the chime go away? Would the tone be darker? I forgot what the guitar sounds like without this.
 #80950  by Grateful.Ed
 Mon May 31, 2010 4:24 pm
The 5751 is about 70% the gain of're going to even lower gain with the 12ay7 (45%) and 12at7's (60%)....I've never tried those, but now I'm tempted.

DRRI's are cool for f'ing around with! :hail:

I just learned how to bias power tubes and the DRRI has the trim pot right next to the transformer so you don't need to take the chassis out of the cab.
 #80959  by raisingfreen
 Mon May 31, 2010 6:44 pm
Grateful.Ed wrote:The 5751 is about 70% the gain of're going to even lower gain with the 12ay7 (45%) and 12at7's (60%)....I've never tried those, but now I'm tempted.
Absolutely try a 12AY7 in V2. Actually, if you don't use the normal channel at all, remove V1 and you will get a slight boost as well. Easy mod worth trying. Allows the dial to be turned up even more before breakup with the AY7. The sound however will depend on the tube. I like EH for the expense and easy availability at local stores. I have used RCAs in that spot and they sound great but got microphonic quickly.

Another thing that sucks on DRs however is the stock speaker connection cables. Get a new one made thats rugged with good connections and you may notice a slight difference. I did and it was slight but noticeable. AO Guitars makes great ones and a very reasonable cost. The right length is nice as well. Nice and clean.
 #81171  by sants
 Thu Jun 03, 2010 6:30 am
The Reissue amp is decent. I have one with with a jbl e120 in it and I can get a good garcia tone. The Silverface k120 would get you an even better tone and if you can spring for it do it!. They are more organic sounding. The Deluxe reverb reissue has one of the best tones for a reissue but they a little sterile compared to the vintage amps. BTW, I have my reissue biased as hot as I can.