Ampeg V4.com

forum

You are not logged in.

#1 2011-08-28 17:14:48

Liquids
Member
From: CT
Registered: 2010-08-01
Posts: 491

Reverberocket 2 Details / Versions

So I just scored a Reverberocket 2 - I did research on it before I bought it, but mostly I just liked how it sounded, and bought it.

As I've started cleaning and fixing the amp up, I started noticing that there's more than one version of this amp.   At least 2, and maybe 3 notable variations actually?

I had assumed I had a "7199 version," as I originally thought that may have been the only one....but when I pulled off the tube shields, I found two 1ax7s!  At first I just assumed that somehow it was working despite someone having shoved a 12ax7 in the 7199 socket!   But I looked at the schematic harder, and tube chart again - nope, 2x7591s, 12ax7, 6U10, 12ax7!

That said, the schematic in my amp doesn't match all of the factory scans I see on the web.  Mine uses 1/3 of the 6U10 as the cathodyne phase inverter, which is driven by a 12ax7 stage.

But there is another version of the schematic that looks very reasonably simiar, unless you look closer - the phase inverter is the other half of a 12ax7 (which has poor drive characteristics), is coupled directly off the plate of the previous 12ax7 stage, and the tube order is 2x7591s, 12ax7 12ax7 6U10...

Anyone ever  compare the two or note these differences?   Piazza drew the Reverberocket 2 with a 7199!  Does such an amp even exist?!?


Matthew

Offline

 

#2 2011-08-28 20:55:41

hangman
Banned
From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: Reverberocket 2 Details / Versions

I've never seen the reverberocket 2 with a 7199.  but it wouldn't surprise me if there were some out there.   the problem i have is that ALL  of the ampeg schematics i have ever seen and ALL of the reverberocket  2 amps i've seen are 12ax7.

tough call to make.   i generally tend to feel like piazza just makes mistakes all over the place though.

Offline

 

#3 2011-08-29 18:07:02

hangman
Banned
From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: Reverberocket 2 Details / Versions

Oddly enough,   the Ampeg book also says the reverberocket 2 used a 7199.

Offline

 

#4 2011-10-19 09:17:13

Liquids
Member
From: CT
Registered: 2010-08-01
Posts: 491

Re: Reverberocket 2 Details / Versions

Now that I've got this sweet amp made safe, and in clean working order, I'm looking more closely at the circuit.

I find I like the bass pot all the way up for some full lows - and it delivers - but if the treble pot is anywhere past 11 o'clock on the dial (where is where I mostly have it) it's a treble monster.

That said, I think the voicing of the amp is otherwise REALLY impressive.  I've never liked a little amp so much.

Looking at the schematic though, the very first amp stage has a 100n cathode bypass cap; then the second stage has a 470n bypass cap!  Whoa, that is a LOT of treble peaking!  No wonder I need to max the bass and dial back the treble to get it sounding round and even.  In fact, if looks like the major thing limiting the high frequency content is that 2.2M resistor between stage 2 and stage 3 on the straight signal that is acting more or less like a huge grid resistor.   

Other Gemini, Reverberocket, and B-25 Models utilize one such cathode bypass cap on the second stage (100n or 470n) but this is one of the few or only that seem to have one on both first and second stages.

Forgive my heresy, but I am one night's soldering away from putting that 1st stage cap on a switch to go between stock voicing or no bypass cap.   From my simualations it looks like it will have a dramatic effect on the high end above 1k.

I may also tinker with reducing the value of that 2.2MEG resistor either via another switch or the same switch. I don't use the 'echo' reverb because I don't particularly like it's sound compared to my rack delay, and it comes on too fast anyhow so that may be an area for tweaking as well.

The amp sounds REALLY great right now (especially after increasing the cathode resistance on the 7591s) both clean and cranked up, and everywhere in between for that matter.  That's a lot more than I'd say about just about any fender amp I can think of.

But some component tweaks available via switch may make it that much more versatile all within the general Ampeg and reverberocket vein.

Don't shoot me.


Matthew

Offline

 

Board footer

Powered by PunBB
© Copyright 2002–2005 Rickard Andersson