[Pointclear]

I bought a 2x10 1982 Fender Concert last year after playing a friend’s concert amp and then hearing a YouTube clip of one Joe at Shakedown amps modded.
When I received mine (eBay purchase) it was stiff, sterile, and muffled - not at all what I was hoping for!!! I knew the potential must be there, so I started systematically approaching it. First to go we’re the Jensen ceramic speakers - they were terribly harsh. In went and e-110 and a k-110 (I really like the mix of the two). Then a bunch of nos preamp tubes got rolled through in hopes of replacing the newer jj tubes. I settled on a ge in v1 that has really “big” 3-d sound, v2 is an rca 7025 with more articulation and an even response, and the phase inverter is a nos Jan ge 12at7. The rest of the new jj preamp tubes I left in place because it just sounded better with them left in those spots. Power tubes are now the new tad black plate 6l6gc.

I now moved on to modding the circuit. After reading through the huge gearpage threads about the amp my head was swimming and I tried a few of their mods and realized that many of those guys are after entirely different tones than I am, so I did my best as a noob to apply the twin mods known for Jerry tone after I finished with the very basic mods that are well known and agreed upon to open up the concert amp into more classic blackface territory: removing snubber caps off preamp tubes, removing resistors going into volumes and between tone pots, etc.
First big change was replacing plate resistors with these really big plastic-housed dale metal film resistors: huge difference!!! That change alone is the most critical voicing step in my opinion for this amp.
Next was the tantalums bypass caps, which honestly the verdict is still out on. They certainly can’t hurt.
The tone stacks were next and I moved both channels to standard Jerry .022, .022, and 250pf (225p orange drops and silver mica). I experimented with a couple of expensive Angela copper foil caps for the .022 spots and they were too smooth and transparent. I then went to the Sozo blue caps and they were terrible for Jerry tone: flat and dead sounding! Mellow - but too mellow. I upgraded a few other caps: changed the metalized Mylar xicon on the master volume to Sprague225p. I did a couple of more changes to 225p orange drops, but wasn’t happy with them in the phase inverter. The xicon caps stayed there and kick butt: 3-d, textured, and articulate. I replaced the phase inverter resistors with metal film (too sterile), then with hand selected carbon comp (too dull), and went back to the carbon film in the end.
I may still tweak this or that but I’m really happy with the sounds of both channels, but especially the second, higher gain channel. It is super easy to voice this to sound like early 80’s Jerry in an uncanny way.
I’ll put up some sound clips or a video soon enough, but I wanted to put this out there for anyone wondering about this amp design. It’s been my introduction into amp modding and I couldn’t be happier. The concert has been more successful at capturing “that” tone than modding my 100 watt Silverface twin, though it still sounds great with the Jerry mods.

[PurpleTrails]

Great rundown! I liked your explanations for why you made certain choices after what sounds like a lot of experimentation. You're a braver man than me doing that many mods without any previous experience doing amp work.

[Pointclear]

I liked your explanations for why you made certain choices after what sounds like a lot of experimentation. You're a braver man than me doing that many mods without any previous experience doing amp work.

Thanks man, it took the better part of a year of obsessive homework before I cracked open the chassis and dove in. Once you start it’s hard to stop. I’d really recommend getting an amp to experiment with. I’m a technically minded guy, but I’d never wrapped my head around electronics in any real way. It’s like a whole new world has opened!

[gdrfk1990]

I own the Concert head Joe set up your mods sound pretty close to what he told me he did... Down to the tubes hE has TADs and NOS ge and sylvania 7025s in there. He had a Telefunken ee83? in preamp 1 but wouldnt part with it so its a GE 7025 now.

removing snubber caps off preamp tubes .... this he didn't do and is not recommended for channel 2.. I am thinking about doing it to channel 1 though ? Should I ?

There is also a mod on another board for the Pedal... making it not only a normal pedal but changing the circuit so it's the same as pulling the knob

[Pointclear]

He had a Telefunken ee83? in preamp 1 but wouldnt part with it

Ha! I watched that video over and over, and decided I had to have the Telefunkan in v1. I finally found a friend with one. I tried it and ultimately went with the ge. The telefunken was as described: hi-fi, articulate, with a unique note decay. Ultimately, the big sound and three dimensionality of the choice ge won out.
I’m surprised that the snubber cabs didn’t come off. If you have any desire to try removing them I’d do it in a heart beat. You can just snip one leg and try it. I felt it was necessary, and though I do have more background noise now, the openness and clarity of the amp really is helped by removing them along with the resistors going into the volume pots.
Let me know if you try it, I was hoping others with the concert would chime into this thread. Are you happy with it otherwise? Joe mentioned he pushed the amp more toward the midrange - is he referring to the tone stack changes or a changed value somewhere else?

[gdrfk1990]

I think he changed the cap associated with the pull switch on channel 1. So when I pull the knob it gives the mid scoop. That's how I use the amp with the mid scoop activated ? sounds great nails the Jerry tone (to these ears at least to these ears). I have received many compliments on this amp.

It's a great alternative to a Twin both for size and volume . Most rooms I play are too small for a twin.

[Pointclear]

Interesting. That pull knob is normally the bright switch, which I haven’t messed with yet. With the lack of a mid-control on channel one it makes sense that you’d use that switch to affect the mids. I’m curious what the switch sounds like - post any clips if you hav e them.

I agree about volume control. The concert is more versatile than the twin in that way. I use channel two with the main volume dimed, gain around 4, and I adjust the master for volume. It’s a pretty nice Jerry tone for an early 80’s feel, though if I up the gain too much I get more tubes sustain than Jerry normally does.

[Jon S.]

I use to own a 1X12 Rivera Concert combo that I bought new c. '84. I chose one with the stock EV option (a decision I came to regret due to its weight). It sounded great. A cool "trick" with it was to run a straight cord out and into the tube-driven loop, thereby adding a gain stage capable of more volume and grit. I ended up selling it because of its weight which, with the EV, if memory is correct, was probably around that of a TR. I remember how, when I carted it to practices or gigs, after I put it down, the handle would literally leave an indentation in my hand afterwards, it was that heavy. Today, of course, I would simply replace the speaker with a neo one and love the amp.