Old Gibson amp fun

mad dog

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Hey all:

Someone local expressed interest in my '58 GA40, said he'd be willing to trade his '61 GA77RV for it. Tantalizing. Seriously tempting. The GA77 is the other Gibson I've always been most curious about; this transitional model is tweed, very narrow panel, but with reverb and no trem. 15" speaker. Capn'Juan was kind enough to give me some background on this model, told me enough to know it was worth checking for sure. (Thank you John as always for your advice!)

So I spent hours last night in Brooklyn doing a side by side. Bottom line: His GA77RV is one of the coolest amps I've heard yet. But to get it, I'd have to trade another of the coolest amps ever. Just couldn't do it. The GA40 is much louder than stock with the CRex in there now, can get wild and raunchy or soft and sweet. Ungodly tasty sounds. Bouncy and responsive feel. Fat, dark and hot OD tones from the 6v6s. Magic with strats, teles and P-90 guitars. Does a rich clean at low and medium volumes.

The GA77 is more spare sounding. Fixed bias, 6L6. A different clean, and more of it. (As pretty a clean as I've heard.) He has a Legend 151 in there, and old 6L6WGB power tubes. A precise clean up to pretty loud, then drives so smooth as you turn it up further. It's a parallel universe tweed pro, but with an unmistakeably Gibson slant. In a word, refined. Loves P-90s. I found myself telling this guy "Don't let this one go. It's too good to do without."

I want both, but I can't have both. If you ever get the chance to hear these fine amps, it's well worth it.
MD
 

capnjuan

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mad dog said:
... It's a parallel universe tweed pro, but with an unmistakeably Gibson slant. In a word, refined.
Hi Michael; Wally Marx' book covered Gibson's struggles to compete in the amp market with Fender. What gets lost is the fact that, irrespective of sales success, Gibson still produced some fine amplifiers. Offered as an audio-to-visual comparison; if that's a Fender tweed Pro on the left, then that's the Gibson GA77RV on the right:

twocars.jpg



That 'Fender' on the left was originally sold with a 383cid engine (hp ??) and the 'Gibson' on the right with a Chevy-licensed 327cid engine ....... and a Judson supercharger together pumping out 425 hp. Both of these offer extraordinary rides ... and the fact that the Studebaker - commercially - competed poorly with Chrysler says nothing about whether the Studebaker was a great car.

I can understand your reluctance to let go of the GA40 for the reasons I suggested. The only other amp that might give you more headroom but hang onto the tone is the Victoria Electro King which is <gulp> not an inexpensive amp :shock:
 

mad dog

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So right John. I've seen forum threads on the Fender vs. Gibson amp thing, where otherwise sane people claim that the Gibsons were mostly dogs ... they failed for good reasons ... and that longterm market preference proved it. I'm sure there are those who say similar things about Ampegs, about Magnatones or whatever.

Which is pretty funny. Fender has somehow become the revisionist icon of "back in the day" ampdom. Much as I love Fenders, there were so many other fascinating makers and models. An open mind works wonders in this department.

MD
 

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What's the saying, "the winner writes history"? If Vox 100 watters didn't have a tendency to burst into flames, Marshall might not be the giant that it is now. If Premier had stuck reverb into it's amps from the beginning, Fender might be a niche manufacturer. :roll:

There were a lot of great amps out there. Still are.
 
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One of my favorite things about this forum is that its amps section isn't all Fender. Fender made fantastic amps, but when I go to a show and see two guitar players playing out of two silverface Twins, I wonder why they don't want to diversify their sound a bit more.

A few months ago, I caught a performance by the up-and-coming band Deertick (they're the alterna-band Rolling Stone has picked out of the ether for whatever reason), and the two guitar players were both playing Jaguars out of Hot Rod Devilles. My girlfriend assuaged my bafflement by explaining that most people don't put as much thought and research into things as I do.

I would have loved to see one old Gibson up there instead. Those are underrated amps.
 

capnjuan

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Hi Caleb: I personally don't think Fender is the only amp worth owning any more than I think Martin is the only guitar worth owning. If that were true, then we'd all be wasting our time here celebrating Guild guitars. Michael's right; there are any number of good-sounding makes of vintage amps out there including Fender ... what's tiring is Fenderista 'There Is Only One True Amp' dogma ... it just isn't true.
 
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The GA77 is the other Gibson I've always been most curious about

My Gibson "White Whale" is the GA-79RVT--the one with reverb and trem. The stereo options of this amp fascinate me to no end because I often play out of two amps for dry/wet reasons. It would be cool to have that out of one combo, and I understand the amp(s?) itself sound pretty great. I also find EL84s great tubes for roots/R&R and don't see them as much in vintage American amps. My main amp, a boutique "Verellen" handmade in Seattle by a fellow I quite like runs EL84s into Fender-esque tremolo and spring reverb. It's a unique amp. No tolex and it's open at the back, so it is very "woody".

I heard Bill Frisell on my local NPR talking about guitars, and he said he has always been faithful to his wife, but when it comes to guitars, he is as bad as Wilt Chamberlain. I'm that way with amps, though I only have three (four if you count my Silvertone 1448 amp-in-case [which I do, Juan :lol:] ). My Verellen is about all I could hope for when it comes to gigging and reliability, but variety is the spice of life.

Have any of you played out of a GA-79RVT? They ones online are more than I'd care to spend, but I'll always be curious. And someday I'll stroll into a pawn shop and find one for $300, I'm sure.

Thanks for your story, Mad Dog.
 

mad dog

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Guild B:

I did plug into a GA-79RVT, long ago, and not for long. It was certainly unusual enough ... not quite the amp I'd go for, mainly 'cause I'm not partial to multi-10" speaker formats, and it seemed a bit fragile. I gravitate more to the single 12" or 15". Though that GA-30 with the 12" and 10" is sure interesting.

Speaking of using two amps: I have done this live with the GA40, running it with a BFDR (great sound), later with a Clark Tyger (bandmaster), which was even better. The other night I jumpered my Sewell Wampus cat together with the GA40. Even with reduced signal going to the Sewell, I can hear that this match will be the best yet. The Sewell is a gainy beast, yet not as mid rich as other tweed pro types. The two amp tones fit together perfectly. My new mission is to get an isolated switcher (to keep full signal and defeat ground hum), then get these amps on a stage somewhere.
MD
 

capnjuan

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Guild Beginner said:
... I only have three (four if you count my Silvertone 1448 amp-in-case [which I do, Juan :lol:]
No ... that goes in the count column ... table radios, 45rpm players, and movie projector sound support systems must be reviewed by default's committee first though to get 'credit' ... :wink: Your speaker is in the mail Friday earliest but probably no later than Monday. J
 

capnjuan

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Guild Beginner said:
The GA77 is the other Gibson I've always been most curious about
My Gibson "White Whale" is the GA-79RVT ...
Ahoy Captain Ahab ... a Gibson GA79 on eBay but mis-ID'd as GA78. Not the best pics and not the best example of the model. Seller says: "... NOT the supply transformer but it is a great transformer from the famous Watkins amps from the 60's. The Watkins amplifier powered 4 EL84 tubes and the transformer is wired for US current."

Some versions of the Watkins Dominator had two hv secondaries to support two separate amps ... but the rest smells like the fishes. Replacement knobs and new Weber speakers. Says stereo but to get stereo out, must have L and R signal sources in; otherwise it's dual mono ... same signal from both sides ... not that that's a bad thing ... it just isn't stereo in the conventional sense. But still ... the best examples of these are now in the mid-$2,000 range. :shock:


ga78.jpg
 
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Thanks, Captain. After thinking about these amps again, I actually spoke to my friend who makes really nice custom stuff (as well as his own line of amps) about cloning a GA-78RVT. He offered to do one for me for $1800, which to me seems like a pretty good deal if I wanted to go ahead with it at some point. It doubt it would be an exact clone (none are) because his amps have a particular 'feel' and I'd have to pay more for tweed, I'm sure. It was an interesting conversation at any rate, and I'll probably talk about it a bit more when I have him re-cap the Doric Thursday.

I though about the clone because I'm aware these things are fairly fragile, and after reading your restoration threads, CJ, I have a feeling an old Gibson might be a little hairy for the uninitiated to get in to. Plus, the stereo angle seems like it might be apt for even more issues. I don't know. A good condition one (I'm thinking the ebay one is just 'fair'), with even a few repairs needed I'm guessing, might be pretty pricey. Cool purple color on it anyway.
 
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Says stereo but to get stereo out, must have L and R signal sources in; otherwise it's dual mono

Is this the situation with all of them, or just this particular set-up? I've read "true stereo" in most of the tube amp books and forums where I've read about these. Thanks.
 

capnjuan

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Guild Beginner said:
Says stereo but to get stereo out, must have L and R signal sources in; otherwise it's dual mono
Is this the situation with all of them, or just this particular set-up? I've read "true stereo" in most of the tube amp books and forums where I've read about these. .
Hi Caleb; schematic of the GA79RVT below; to get stereo out, must have a stereo signal in; that is, independent L and R signal sources. Channel 1 in red, channel 2 in green, the stereo jack in the blue box and 'stereo' switch in the blue circle. Notice that the stereo jack is ... just that ... a stereo jack - has wiring leading to both channel's input stages. It helps to remember that back in the day, both Ted McCarty and Seth Lover were hi-fi guys. Anyway and unless guitar pickups are wired like some old Rickenbackers or in stereo, a guitar only produces a monophonic signal. Jacked into channel 1, the signal can be 'bridged' to the output of channel 2 by the 'stereo' switch ... but that isn't stereo ... it's dual mono; listening to the same signal from L and R. If you took, say, a stereo FM tuner; brought its L and R output to a 'Y' connector terminated with a stereo plug, you could plug into the stereo jack and have true stereo - L and R channels independently being pumped out of each side of the amp. Plugging a conventional guitar into the stereo jack will only drive one channel .. throwing the 'stereo' switch puts the signal in both channel's output sections.

ga79c.jpg
 

capnjuan

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The amp seller talks about limited power output. Back in the day, I used to have a pair of these: Dynaco Stereo 70s; EL34s, 35wpc (the one in the pic modified and upgraded). They had 'mono' switches and were bridgeable; could connect the 16 ohm output taps together, tie a speaker on, and throw the mono switch. I fed L to one ST70 and R to the other. They ran as monoblocks at 70 watts. I too would like to spend a little quality time with a GA79. If I had one that was a little beat up, I'd tie the 8 ohm outputs together, hang a 4 ohm speaker on it and listen to 30 watts of glorious Gibson EL84 power 8)

st70topview2.jpg
 
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http://cgi.ebay.com/63-Gibson-MAEST...in_0?hash=item35a32b5258&_trksid=p3286.c0.m14

Here's another one I hadn't come across before. Looks a little rough around the edges too, and I find it hard to believe it was "tested extensively" if the seller doesn't even go into the sound. Seems like the fragility of these makes a clone seem an alternative worth some thought. I've never played a straight "clone" (always a mish-mash), but a lot of amp makers have made a good business of very slight alterations to proven designs.
 

capnjuan

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Guild Beginner said:
Here's another one I hadn't come across before. Looks a little rough around the edges too, and I find it hard to believe it was "tested extensively" if the seller doesn't even go into the sound. Seems like the fragility of these makes a clone seem an alternative worth some thought. I've never played a straight "clone" (always a mish-mash), but a lot of amp makers have made a good business of very slight alterations to proven designs.
Hi Caleb; maybe 'tested extensively' means the seller and his friends spent an evening messing with it ... yeah, doesn't say a word about tone ... only that it works ... not exactly a resounding vote of confidence. Schematic here: GA78 Maestro not very different from the GA79RVT. At least in Gibson's 'tweed' era '69-'62, I don't think they had the same build standard as Fender amps; smaller OTs and some of the models had cheesier circuit board construction.

In pic below; circuit board from this auction amp on top and pic of circuit board from GA18 below; the components are cramped impeding heat dissipation, the board material is plastic that oxidizes and becomes brittle with age, and this type board relies on all the tiny yellow jumpers underneath that are unreachable without taking stuff out:

Slide1-3.jpg




Fender boards from the same era; phenolic with eyelets; Bassman top and Vibrolux on the bottom:

Slide2-4.jpg




... and, it wasn't like Gibson didn't know how to make a better-grade board; in the pic below, GA30RV on top and a GA20T on the bottom: Fender-style phenolic with eyelets:

Slide3-3.jpg



If you're interested in learning more about Gibson amps, Wally Marx' Gibson Amplifiers, 1933-2008 is pretty good reading. The discussion about the relationship between Ted McCarty and Seth Lover provides some insight into what they were trying to do and why Gibsons sound the way they do. Mr. Marx' survey of the Gibson amp product line especially in the tweed era does contain a number of mistakes and omissions but it is the most readable survey out there. If I had the money, this would be the Gibson clone I'd want to own: Victoria Electro King; Victoria Amp's re-make of the Gibson GA40 Les Paul but with 6L6s for a little more power and headroom ... and reverb. Just my $.02 but I think it's the 5879s in the GA40 preamp that gives it such a distinct tone ... and what Victoria is hoping to capitalize on it its re-issue.
 
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Cool comparison, and I'll definately check that book out. In the Guitar Amp Handbook, there is almost no detail about Gibson amps, though in the interviews at the back, about half the amp guys interviewed mention how poorly reperesented they are, and how many are actually great amps. Ironic.
 

capnjuan

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Guild Beginner said:
Cool comparison, and I'll definately check that book out. In the Guitar Amp Handbook, there is almost no detail about Gibson amps ...
You're right in the sense that the author didn't waste much ink on Gibson amps although the GA19RVT got sort of an honorable mention. But in the end ... literally ... his project amp in the back of the book ... it's modeled on the Gibson GA8 Gibsonette and its single-ended, paralleled 6V6s output design. The resurrection of my near-death GA8 threaded here.

The most important distinction between the stock GA8 and the Hunter design is having each output tube's cathode independently biased with a 500 ohm R / 25uf bypass C to ground instead of tied together and then grounded. Allows more flexibility ... besides parallel 6V6s, it can run a single 6K6, 6L6, EL34, or a KT66 ... nothing in the kingdom of commercial small amps can do that. Fenderistas disparage the GA8 ... adding the 2nd 6V6 to the GA5 design seen as a cheap marketing one-upsmanship by Gibson to displace their sacred Champ. But, Hunter picked the Gibsonette as the foundation for his project amp ... I think that says something about Gibson. :wink:
 
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