NAD 1966 Ampeg Gemini Ii

Discussion in 'Amps' started by jimytheassassin, Mar 10, 2017.

  1. jimytheassassin

    jimytheassassin Well-Known Member

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    So I've been on a bit of a tear lately with gear deals. Why break the good luck?! I saw this amp posted for a about 6 weeks and suddenly I noticed that the price dropped in half. It took about 10 minutes before I messaged the seller and started a conversation. Less than 48 hours I have it at home. I have a weakness for old Ampeg amps. I considered this one a rescue. It needs some tlc and a nice home. I just sold a guitar Also so this basically paid for the amp. I spent two whole minutes looking at it before I was certain my hunch was correct.

    Brief summary.
    All original electronic components, transformers etc. original speaker. Likely the Original grill cloth in great shape. Possibly some original tubes (7591 and 6cg7. The ones not original are !!! 3 Amperex Bugle Boy made in holland 12ax7 tubes and a Sylvania 7199(possibly OEM?). Basically about $320 in old tubes if they're still functioning in top form. Whoop whoop!

    Missing ; the handle. One knob. 2 cabinet corners. 4 feet And most of the original blue diamond tolex. Someone put green alligator on it and then later painted it black. Weird!

    SOUND: haven't plugged it in. Pictures show why I won't. Besides having 50 year old capacitors, the cap can is hanging out of the chassis with wires making contact and one cap shows a bulge. Seller said it works (and I have reason to believe him to have been honest) but I am not chancing it until it's looked over good. I may variac it but component changes are a must.


    Let the show begin.


    7a4bb568e28e4ee93efa2b2ff2ec1157.jpg
    More coming in a minute
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    15 INCH SPEAKER! Nice.
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    Last edited: Mar 10, 2017
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  2. jimytheassassin

    jimytheassassin Well-Known Member

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    So there you have it! I'll put up larger photos of the inside when I pull the chassis. No plans for that yet because I will need to raise funds for the component changes. Upcoming gear sales may take care of that shortly. I will probably screw the cap can back up and try to variac it slowly in the meantime.


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    Last edited: Mar 11, 2017
  3. Manodano

    Manodano Well-Known Member Supporting Member

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    Killer. Don't get near the top side of that cap can, though. You just need a can capacitor mounting ring.
    [​IMG] [​IMG]
     
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  4. jimytheassassin

    jimytheassassin Well-Known Member

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    The pictures don't show it well but there is a ring present. Fortunately I know not to touch anywhere near that thing! I also was smart enough to look before plugging in and turning it on. my band mates think I'm crazy when I talk about stuff like this. But then that's why I'm the one buying these amps in the first place . It's a good crazy


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  5. Manodano

    Manodano Well-Known Member Supporting Member

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    Those are some great pictures. What fine wiring.
     
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  6. devdem

    devdem Well-Known Member

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    Man am I jealous!! That's awesome. Post more when the project moves along.
     
  7. idiotsdelight

    idiotsdelight Well-Known Member

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    Especially this one.
    image.jpg
    Congrats on the find.
     
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  8. tonebender

    tonebender Well-Known Member

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    I got mine from OMB and they do sound dreamy. I am a sucker for Ampeg as well.

    Congrats on a killer amp.
     
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  9. jimytheassassin

    jimytheassassin Well-Known Member

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    Hah. I didn't mean to take a selfie but had to post it. Damnit though. Should have smiled . I figured this would take the place of a AGF signature foot shot


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  10. jimytheassassin

    jimytheassassin Well-Known Member

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    WILL DO! I have actually already done a simple continuity test to see that the Power Transformer Primary winding is still intact. Using a meter I'm going to check this thing slowly just as in the video i'm linking here, and then move on to more thorough testing as I proceed. It's a good watch IMO, if you have a vintage amp that needs some investigation. I don't usually subscribe to just any "Joe Shmoe" tube jockey unless they seem to have old school knowledge and can explain it very thoroughly. This guy may seem boring, but he's got it going on!
     
  11. andrewsrea

    andrewsrea Well-Known Member

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    A 1966 Gemini 2!!

    So these were Ampegs answer to Fender's Tweed deluxe, when they were still located in New Jersey. A little more head room than the Fenders and really nice amps. That is a great speaker as well.

    Mojotone has your handle and tolex if you are ever interested in making it look right.
     
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  12. mozz

    mozz Well-Known Member Supporting Member

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    I once read that the concert series speakers were replacements when the factory speaker blew under warranty. They were a better speaker and the chances of a warranty return were knocked way down due to the speaker blowing again. I don't know if that's true for Ampeg but it was for a few other manufacturers. Does anyone know if Jensen speaker warranty was paid for by Jensen or the manufactuer? I have some amp here that has a concert series (not original) and the date code is very close to the original date codes. Bring that beauty back to life.
     
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  13. idiotsdelight

    idiotsdelight Well-Known Member

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    Love his videos. I don't find him boring at all.

    He reminds me of Mutual Of Omaha's Wild Kingdoms narrator.
     
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  14. jimytheassassin

    jimytheassassin Well-Known Member

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    Thanks for the response! Ya i know Ampeg was trying to out do Fender, but didnt' realize this was an answer to the Tweed Deluxe. I wonder if there's volume interaction or anything now.. :D I am definitely feeling out restoration costs with original Blue Diamond Tolex, vs another color. I didnt' find any at Mojotone, but I have seen a select few places with remaining stock at $35 a yard.. yikes! But I need about 3 yards to wrap from bottom to top to bottom. The back panel is actually in mostly okay shape and still has the original covering so i'll probably leave that alone. Any other thoughts on where to get blue diamond. Antique electronics and most places i have looked are out. I'm wondering if $35 is the only deal left.
     
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  15. jimytheassassin

    jimytheassassin Well-Known Member

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    I've read a little on the history of Ampeg around the 1965 time frame.. I had a Rocket 2 amp that got me curious why there were 3 different schematics and variation in the speaker selections. Actually the Rocket 2 is an interesting departure in their lineup. From what I understand, they were changing factories at that time in NJ from linden to.. i forget where. or maybe it's the other way around. Anyways, they basically used what was on hand and available and modified designs to use up inventory and have less to move. This was my understanding.. Not sure if it's true but it makes sense. Speakers were the same deal in many cases, unless it was a requested upgrade to JBL or something. My Rocket has a alnico CTS 12" that's period correct in date. No bell was on it, and i've seen a lot like that over the years, but also those with Utah, and Rola. I would think they'd all been replaced because Jensen was the usual OEM, but there's far too many coincidences in that time period to be a fluke. Apparently it had one owner before me, and he told the store he was consigning it at that it was all original. Looks about right to me. Perhaps it was just a rough period of time for Ampeg, and other years were much smoother.

    FWIW, I've read about people saying that you should play an Ampeg Gemini II to find one that was "alive"! Perhaps this perception of one being more alive than another was just a symptom of Ampeg substituting what they had on hand when their typical spec'd parts ran out? I wonder if people with "good ones" ever checked them against the schematic and visa versa

    Now the Jensen Concert 15 in my Gemini is a 1966, 21st week. By serial number for 1966 which is between 20,000 and 40,000.. my amp is in the 35k range. I think the speaker was made before the amp. Hard to say if it was a replacement, but again.. Almost every Gemini II i've seen in this age range has these speakers (if it wasn't replaced with a modern one)
     
    Last edited: Mar 11, 2017
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  16. mozz

    mozz Well-Known Member Supporting Member

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    Good info. Look at the mounting screws and look for scratches on the unused mounting holes. It looks at least maybe the speaker was taken out and rotated? Many many many Ampegs, Gibsons, Premeirs, etc, do not match the schematics, they all used what was on hand or made continuing changes with never updating the schematics. Speakers were often lowest bidder items. Some Jensens were rated at only 15-20 watts, so a pair of 6v6's could blow that if a boost pedal was used. To me, period correct is close enough to factory original, unless you own a museum. That's a 15" in there? That speaker looks like a 56' or maybe 46', Jensen used EM to signify electro-magnet, which was the period right after field coil speakers.

    EDIT: I may be totally wrong, reverb is showing me 60's era.

    In 15's, there were (according to my 1966 Jensen 'instruction note' # 245): the EM-1500, EM1501, EM1502, EM1520, and EM1550 drivers. The last 2 models had an alnico-5 magnet
     
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  17. jimytheassassin

    jimytheassassin Well-Known Member

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    I can't agree more about speakers and museums. I get the "original" mystique but I also like to just play the damned things too :D . Ya it's a 15" in there. There are marks on the other screw hole areas.. and I wouldn't be surprised if this was unmounted and remounted during the Green Alligator Tolex disaster. That would indicate a 45 degree counter clock wise rotation, like in this example https://www.gregsguitars.net/1966-ampeg-gemini-ii-amplifier-for-sale.html The bell can't be rotated because it has a cutout for the speaker terminals. Thanks for getting me to look.. i hadn't even considered that it might have been turned.

    FOLLOWING YOUR EDIT @mozz : I pulled thne bell cover, which is a thin metal and light. Looks to me to be a ceramic type magnet underneath, and it also has the code you noted EM1501 on the frame. C7735 2. Cone code is B015B11W5

    12fd9d8ecada8b6a1abfd14d9872c1b5.jpg
     
    Last edited: Mar 11, 2017
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  18. jimytheassassin

    jimytheassassin Well-Known Member

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    This final image in my first post had me wondering. Looks like a dial "resistor"? I had read that this design of the Gemini II with 7591 (although probably not unique) had a fixed bias. Could this be part of that? curiously it looks like only one side is attached to anything. I will be looking closer when i pull the chassis
    [​IMG]
     
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  19. mozz

    mozz Well-Known Member Supporting Member

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    I'd say that is a replacement bias pot someone installed. I see a 15k pot on the schematic but i think it was replaced at one time. Those old style resistors are some sort of metal film, probably all within tolerance. Those yellow caps are probably still good, those green ones i have seen crack. I love old amps. You really couldn't have picked a more expensive amp to retube. Be very careful with 7591's and 7199's. I lost a 6eu7 and a 5y3 by rolling off the workbench and going smash on the floor.

    Somewhere i found a place selling lots of tolex, will have to see if i bookmarked it.
     
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  20. mozz

    mozz Well-Known Member Supporting Member

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