60s Ampeg Gemini II Chassis

[olddawg]

Hi guys. I love this site. Listen, I just picked up an old Ampeg Gemini II chassis. It's pretty rough but it is all there I got it for dirt and it has the reverb tank with it. I've played this model before and found them extremely clean. It has a solid state rectifier, 12AX7 pres and two 6L6s. I was wondering that since I am going to be doing a lot of work on this amp if you guys have any suggestions on how I might mod at least one channel for more gain and an earlier breakup. Could I put EL34s in it? Could I make it more Plexieish? I want to keep the trem and the reverb. I guess I could just restore it stock and slam it with an OD pedal, but since it is just a rusty old chassis withoult a cab and not that desirable of a vintage amp it would be fun to hot rod it into a head.
Schematic: (I hear it has a couple of mistakes)
http://members.aol.com/portaflex/schems/g-15.gif
Any ideas?

[Rob Mercure]

OD,

While I'm far from a Marshall expert I know that the Ampeg's circuit topology is far from a Plexi and I'd suggest restoring it and valueing it for it's own unique sound. The EL34 won't make it any more Marshallish and won't break more easily unless you're playing at maximum volume - the Marshall breakup is primarily in the preamp circuitry which would require a major butchering of the Ampeg. Perhaps you could restore it and then sell it to acquire a Marshall or a kit or another amp easier to convert.

Yeah, I understand it's in bad shape but you're talking about a basic gut and stuff frankensteining. At least just restore and try the pedal first so you have some idea of the basic sound of this amp which will point you in specific mod directions.

Ya never know - there were/are a hell of a lot more Plexis made than these guys so you might just find some with a Plexi - mebbe one that needed a bit of TLC - who's looking for Gemini II.

Rob

[gmoon]

olddawg:

I've got a Gemini II -- the version with the 7591 power tubes (the schem is marked 9/66.) Maybe we can compare notes.

I've owned it since the late 70's, but haven't used it much in the last 10 or 12 yrs...I know it needs some work--removing the death cap, adding the 3 prong cord, etc. The reverb never did work. It also had the speaker replaced with a crappy one before I bought it, so I'm shopping for a 15 inch replacement.

[PurpleX13]

Speaker and Amp

I'm looking to get a replacement speaker for my Gemini II as well. I came across a website that stated that a Jensen C15N would be a good replacement, sold at guitar center for 114.99 as well as other places. My amp needed a lot of work but it sounds great now. I did put in a mod for channel switching and FX loop, speaker disconnect and removable 3 prong power cord (like that found on a computer) my amp is a head with a separate cabinet; I have not seen one like it. I got it broken at an auction for about 475 or so. I could post a pic so you can see how you might want to build a head case for your amp. I have the older schematics for the amp, mine is amp is dated 3-23-66. Hope this helps.

Chris

[olddawg]

I'm looking to get a replacement speaker for my Gemini II as well. I came across a website that stated that a Jensen C15N would be a good replacement, sold at guitar center for 114.99 as well as other places. My amp needed a lot of work but it sounds great now. I did put in a mod for channel switching and FX loop, speaker disconnect and removable 3 prong power cord (like that found on a computer) my amp is a head with a separate cabinet; I have not seen one like it. I got it broken at an auction for about 475 or so. I could post a pic so you can see how you might want to build a head case for your amp. I have the older schematics for the amp, mine is amp is dated 3-23-66. Hope this helps.

Chris

Thanks Chris and Rob. I ended up selling it for a profit deciding it was more trouble than it was worth. I'll pick up something else eventually.

Cheers,
RE

[gmoon]

I'm looking to get a replacement speaker for my Gemini II as well. I came across a website that stated that a Jensen C15N would be a good replacement, sold at guitar center for 114.99 as well as other places. My amp needed a lot of work but it sounds great now. I did put in a mod for channel switching and FX loop, speaker disconnect and removable 3 prong power cord (like that found on a computer) my amp is a head with a separate cabinet; I have not seen one like it. I got it broken at an auction for about 475 or so. I could post a pic so you can see how you might want to build a head case for your amp. I have the older schematics for the amp, mine is amp is dated 3-23-66. Hope this helps.

Chris

Thanks for the info, Chris. Did you buy the speaker?

I don't expect I'll mod mine into a head--it's not in great shape cosmetically, but it's very "restorable." I bought mine nearly 30 yrs ago for $60. It's one thing I didn't get rid of...

[PurpleX13]

Speaker

Went to guitar center today.. Out of stock. ordered one from tubedepot.com shoud be here thursday. I let you guys know how it sounds. That was a Jensen C15N, i think i got the SD green one. Special design nice green color. http://store.tubedepot.com/sp-jen-c15n.html

hope it gets here soon
Chris

[PurpleX13]

Speaker Jensen SD-C15N

Got my speaker, Sounds great... Better than expected. Very clean sounding nice highs and lows. I would say this sounds very much like the original speaker I had. My old 1966 square magnet speaker was manufactured by CTS I found out. I would hate to toss it, it still works. Would it be worth it to do a re-cone? For now it sits.
Info
http://users.aol.com/bluemuse/ampeg.html

Chris

[olddawg]

Got my speaker, Sounds great... Better than expected. Very clean sounding nice highs and lows. I would say this sounds very much like the original speaker I had. My old 1966 square magnet speaker was manufactured by CTS I found out. I would hate to toss it, it still works. Would it be worth it to do a re-cone? For now it sits.
Info
http://users.aol.com/bluemuse/ampeg.html

Chris

I have had very good results in reconing vintage speakers. Just make sure you use a good reconer, they are not all created equal. It might even be worth shipping it to Fliptops if there isn't a good service close to you. In any event, even the blown vintage CTS speaker has value. If you don't believe me just search on eBay for one.

I did a similar thing with my 1960 Ampeg Rocket. I put a new Eminence in it when I blew the original Jensen. Originally, it was going to be a temporary fix until I could get the Jensen reconed. I found that I liked the Eminence because it sounds ok and I can drive the sh..t out of it safely. The old Jensen is tucked away in the Eminence box. I'll get to it someday........

Cheers,
Olddawg

[PurpleX13]

Speaker

Thanks for the info. What is this Fliptops you speak of? Who are they and where are they? I would not trust myself with something like this. What would you think something like a re-cone would cost? Just looked on ebay and I think you are right.
BTW someone needs to help my with getting my tremolo to work. I have a thread up as of today with 2 pics of my amp.
http://music-electronics-forum.com/s...ead.php?t=9094

Thanks
Chris

[olddawg]

Thanks for the info. What is this Fliptops you speak of? Who are they and where are they? I would not trust myself with something like this. What would you think something like a re-cone would cost? Just looked on ebay and I think you are right.
BTW someone needs to help my with getting my tremolo to work. I have a thread up as of today with 2 pics of my amp.
http://music-electronics-forum.com/s...ead.php?t=9094

Thanks
Chris

http://www.fliptops.net/