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Post subject: weird old reverb unit...?
Posted: Sat Jul 26, 2014 10:30 am
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Sorry about the off-topic post, but you guys know all this kind of stuff... When I first started playing in the mid '60's we all wanted cool Vibro-Champs or Princeton Reverbs, but we had to make do with what we could scrape together. Anyways, I remember one guy had a little wooden Silvertone or some kind of amp that I think originally went with a matching Chord Organ. Anyways, here's the weird part: I remember he also had a reverb unit, but it looked like a little amp with like maybe an 8" speaker and a tube driven reverb tank. If I remember the thing had a couple of alligator clips that hooked on to the main amp's speaker's + and - terminals. So, the straight sound would come out of the main amp's speaker, and the reverb sound came out of the little reverb unit's speaker. I've never seen such a thing since then, but (in spite of how odd it seems) I'm sure that's how it worked. Anyone know what this contraption was?


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Post subject: Re: weird old reverb unit...?
Posted: Sat Jul 26, 2014 11:40 am
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Redfarfisa wrote:
Sorry about the off-topic post, but you guys know all this kind of stuff... When I first started playing in the mid '60's we all wanted cool Vibro-Champs or Princeton Reverbs, but we had to make do with what we could scrape together. Anyways, I remember one guy had a little wooden Silvertone or some kind of amp that I think originally went with a matching Chord Organ. Anyways, here's the weird part: I remember he also had a reverb unit, but it looked like a little amp with like maybe an 8" speaker and a tube driven reverb tank. If I remember the thing had a couple of alligator clips that hooked on to the main amp's speaker's + and - terminals. So, the straight sound would come out of the main amp's speaker, and the reverb sound came out of the little reverb unit's speaker. I've never seen such a thing since then, but (in spite of how odd it seems) I'm sure that's how it worked. Anyone know what this contraption was?


Vaguely (and I mean *seriously* vaguely) familiar. I seem to recollect that Lafayette Radio Electronics had something like that listed in their mid '60s catalogs. And AFAIK it did operate in the manner you described.

Perhaps BMW2002ti may have more info......?

Arjay

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Post subject: Re: weird old reverb unit...?
Posted: Sat Jul 26, 2014 11:54 am
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Very interesting. However, I don't remember such an amp-reverb unit. I ran the question up a Vintage amp board flagpole. See if another salutes it, with an answer.



:mrgreen:


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Post subject: Re: weird old reverb unit...?
Posted: Sat Jul 26, 2014 6:13 pm
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From Vintage Amp Board:


" Gibson made a similar product during their tweed era, around 1960. It was a reverb amp with no drive circuit, just a return circuit with a power amp and small speaker. The input was a zip cord with two alligator clips, and derived the spring drive signal directly from the speaker of another amp (through a 47 ohm dropping resistor). It did have a 1/4" input to allow you to use it as a small amplifier as well. "

Now, to find the model number of that Gibson unit.


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Post subject: Re: weird old reverb unit...?
Posted: Sat Jul 26, 2014 6:53 pm
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BMW2002Ti wrote:
" Gibson made a similar product during their tweed era, around 1960. It was a reverb amp with no drive circuit, just a return circuit with a power amp and small speaker. The input was a zip cord with two alligator clips, and derived the spring drive signal directly from the speaker of another amp (through a 47 ohm dropping resistor). It did have a 1/4" input to allow you to use it as a small amplifier as well. "


That sounds about right -- both the descriptive and the era.

I'm betting that amplifier had two bottles at most......a triode for the gain stage and a single-ended 7199 or 6V6GT.

Arjay

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Post subject: Re: weird old reverb unit...?
Posted: Mon Jul 28, 2014 11:45 pm
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Here's the schematic for the Gibson GA-1RT-1 reverb-tremolo unit. The 6BM8 tube is similar to the 7199 (triode-pentode in one bottle). Serving as tremolo driver and output tube in this single-ended unit. Note how the tank connected to another amp's speakers? And how Inputs 1 & 2 (1/4-inch jack) could be used as guitar or pedal inputs, though the reverb would not work, as there would be nothing to drive the reverb tank.


-----

Image


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Post subject: Re: weird old reverb unit...?
Posted: Tue Jul 29, 2014 12:17 am
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Pretty ingenious for 1950's technology. Note the rudimentary "speed-adjustable only" tremolo oscillator and a .022ufd "death cap" tapped at the off/on switch.

Arjay

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Post subject: Re: weird old reverb unit...?
Posted: Tue Jul 29, 2014 11:46 am
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From Vintage Amp board:

" Not nearly as rich sounding as Fender's reverb. Also, not as clean. This circuit has more gain than Fender's, and can be overdriven easily. AFAIK, this was the first commercially available outboard reverb unit. "

-----

Poster owned one of these Gibson units. And a brownface era 6G15.


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Post subject: Re: weird old reverb unit...?
Posted: Mon Aug 04, 2014 1:39 pm
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This looks pretty much like I remember it - sloping back control panel with 2 knobs. I don't remember the tweed finish - more like grey Lafayette amp Tolex stuff, but that was a hellava long time ago. Well, I guess I didn't dream it... :)

http://www.radiomuseum.org/r/gibsonco_m ... guage_id=2


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Post subject: Re: weird old reverb unit...?
Posted: Mon Aug 04, 2014 2:22 pm
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Redfarfisa wrote:
I don't remember the tweed finish - more like grey Lafayette amp Tolex stuff, but that was a hellava long time ago.


+1

Which is why I thought I remembered it from the LRE catalog. However, Gibson used a number of different covering materials in the early days, including gray, so it prolly was their unit that I'd seen.

Arjay

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Post subject: Re: weird old reverb unit...?
Posted: Mon Aug 04, 2014 3:20 pm
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Redfarfisa wrote:
This looks pretty much like I remember it - sloping back control panel with 2 knobs. I don't remember the tweed finish - more like grey Lafayette amp Tolex stuff, but that was a hellava long time ago. Well, I guess I didn't dream it... :)

http://www.radiomuseum.org/r/gibsonco_m ... guage_id=2



Thanks! The Radio Museum is a nice site for these vintage units and lesser-known tubes. Rough translation of the German (at the bottom of the page):



The label "reverb" is actually inappropriate because the hall-like tone was delivered only for accessories (edit: another amp?). To activate, a second external amplifier is required. Gibson then brought out a similar device in the GA-1RVT. That drives the reverb system (see model reverb-echo GA-1RVT).

[This GA-1RVT does not need a second amp to drive the reverb tank].


http://elektrotanya.com/PREVIEWS/634632 ... .pdf_1.png


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