1967 Ampeg Gemini V Amplifier, who knows them well?

[Ed_Chambley]

I cannot find a schematic for this amp.  This amp does not have the blue diamond Ampeg covering.

Photo attached.  It is a transitional amp with black tolex.  I know Ampeg started using PCB near this time, but I do not know if they were doing so with this amp.  I am not really that concerned with the old Ampeg PCB as they did use the same components and had very large traces.  It is simply a question for determining value.

I have been offered one, but the drive to get it is fairly long.  Just trying to determine if I should try to get it.  I have schematic for the IV Gemini and the VI which I know to be different.  I assume it is closer to the IV Gemini.  Seems like during the late 60's ampeg changed model numbers if they used a different brand of diodes.

I played one years ago, but I do not remember how they sound.  I assume clean with great tremolo and reverb.

Any and all comments are welcome.

[stratele52]

Gemmini V look to have a strange name on schematic V 5 ??


www.webphix.com/schematic%20heaven/www.schematicheaven.com/ampeg.html

[Ed_Chambley]

Gemmini V look to have a strange name on schematic V 5 ??


www.webphix.com/schematic%20heaven/www.schematicheaven.com/ampeg.html

Thanks, but not it.  The GEMIMI V amp has 2 power tubes, 7591's and a 7199 for a PI.  2, 12AX7's and one 6CG7 I think.  This is all he knew.  From what I have read it is around 35 watts.

[terminalgs]

Introduced in 1968, made for a year or so then the name was changed to the  "Gemini 15".  very similar to it's stablemate the  G-15 Gemini II,  both had 15" speakers. the "Gem V" had both tremolo and vibrato (either or either).   these also had ultra-hi ultra-lo switches I think.  It was known as a GV-15, so search for it that way too.    Ampegs  had nice speakers and nicer upgrades.

don't get hung up on 7591A vs 6L6GC's on schematics, or in the amp.  Its common to find a 7591A ampeg rewired for 6L6GCs (there were at least 20 years between the original tube discontinuation and the reissue).
 
Gemini's sounds great, PCB or pre-PCB. they found homes in lots of studios. sometimes difficult to source the opto-isolator modules, but they are out there.  the 7199s are a PITA b/c there aren't any goods ones out there. sovtek made some, but discontinued them.  the trick is to re-wire the socket for a 6U8A (plentiful).

[stratele52]

Thanks, but not it.  The GEMIMI V amp has 2 power tubes, 7591's and a 7199 for a PI.  2, 12AX7's and one 6CG7 I think.  This is all he knew.  From what I have read it is around 35 watts.

G15 use these tubes


www.webphix.com/schematic%20heaven/www.schematicheaven.com/ampeg.html

[RWood]

Ed,

I did fairly extensive repairs on one that has the exact same cosmetics as that one.....black tolex with piping and a 15.........but this one used 6L6s; it was a GS15R. Yes, It had the pcb and from what I saw online, it used the same pcb that the Gemini V used, even though this one was designated Gemini VI. Parts of the board were unused, maybe for an additional channel.

I rebuilt the power supply (including dealing with a too-big replacement PT), converted it from cathode bias back to its original grid bias (I added the balance circuit that I found here, the one in French), and returned it from the 6u8 driver/splitter back to a 7199. It took a while but all worked out fine.

Tonewise, I liked it a lot but it is really dependent on the 15 that is in there. I would not consider it for clean, really; it screams when it is opened up. Nice rock solo tone, especially with a fat humbucker.

Here are some 'before' pics and a schematic for the GS15R:









{EDIT: fixed image link syntax -- PRR}

.

[stratele52]

Ed,

 Here are some 'before' pics and a schematic for the GS15R:

   

Clear schematic are avalaible at the link I write before your post.

[Ed_Chambley]

Ed,

I did fairly extensive repairs on one that has the exact same cosmetics as that one.....black tolex with piping and a 15.........but this one used 6L6s; it was a GS15R. Yes, It had the pcb and from what I saw online, it used the same pcb that the Gemini V used, even though this one was designated Gemini VI. Parts of the board were unused, maybe for an additional channel.

I rebuilt the power supply (including dealing with a too-big replacement PT), converted it from cathode bias back to its original grid bias (I added the balance circuit that I found here, the one in French), and returned it from the 6u8 driver/splitter back to a 7199. It took a while but all worked out fine.

Tonewise, I liked it a lot but it is really dependent on the 15 that is in there. I would not consider it for clean, really; it screams when it is opened up. Nice rock solo tone, especially with a fat humbucker.

Here are some 'before' pics and a schematic for the GS15R:









{EDIT: fixed image link syntax -- PRR}

.

RWood, Thanks.  This is what I wanted to know.  man I do not envy the condition you got yours in.  Congrats on getting it back like it was.  7199's can be a problem, but I have a lifelong supply.  It is common to male them 6l6 amps from what I have read.

Now I will know what to look for.  I think I will make the trip this weekend as it is a unique amp and may be worth a dollar or 2 in the future.   I wish it were all handwired, but you cant have everything.