Speaker for Gibson/Maestro GA45

Discussion in 'Amps and Cabs' started by AndreasG, Jan 31, 2015.

  1. AndreasG

    AndreasG Member

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    I have this nice amp which is basically a Gibson GA40 but with treble and bass control and originally a 4x8" speaker configuration.
    I have a Celestion G12H30 Annyversary in it and it sounds nice but it's very dark sounding so I generally have the bass at 0 and treble at 10 but it's still too dark and bassy....any recomandation for a bright 12" speaker? I thought about the Jensen Neodymiums or Celestion Century....Greenback, Vintage 30...,
     
  2. DaveKS

    DaveKS Member

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    I'd go back to the 4x8, fill it with a mix jupiter 8" ceramic and tone tubby low watt alnicos.
     
  3. AndreasG

    AndreasG Member

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    Thought about the 4x8 too....but is a bt of a hassle in this amp.would prefer a 12" speaker. I heard the jensen tornado is kinda bright
     
  4. mad dog

    mad dog Silver Supporting Member

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    The WGS 50 blackhawk was certainly loud in my old GA40. A bit on the bright side too. It matched up well with the amp. I also really liked the Crex and weber cali ceramic in there. The Crex always gets tagged "dark, smokey," that kind of thing. Or "blanket over the amp." None of which I've ever heard. It's a loud one too, with a beautiful, smooth sound, especially high up. If anything, a bit on the bright side. Sounded perfect in the GA40. The Weber cali gets tagged as JBL like, but I actually hear a much warmer sound out of it. Even so, the cali was not too warm for the GA40.

    Not sure how your amps preamp is. Mine had octal tubes, added to the unusual sound.
    MD
     
  5. AndreasG

    AndreasG Member

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    Thanks for the great inputs...mine has the strange 5781 (??) preamp tubes that sound very THICK, therefore I would like a brighter speaker as there is always enough bass in the amp. No experience with Neodymium speakers?
     
  6. DaveKS

    DaveKS Member

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    Well I looked up that amp, a 5879 is the preamp tube and as far as I can see there is no other substitute available for that preamp circuit unless somebody has modded input to somehow to accept something else. It's a pentode not a triode, closest living relative would be ef86 but even that is not a plug n' switch.

    Have you had that tube tested, could be that it's half dead and not sounding anything like it's meant to sound, same goes for the power amp section. If you haven't had it done, get a knowledgable vintage amp tech give it a once over and make sure the everything is running in spec.

    Everything, especially with a Celestion as speaker , I would not think this amp should every be dark. It should be extra easy to push into a bright grinding OD with its preamp section and 6v6 power section. There's something else going on with this amp if it's dark and bass heavy. Old caps, resistors needing replaced by a qualified tech or near dead tubes.
     
  7. AndreasG

    AndreasG Member

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    Thanks for the input. Might consider also a tube swap etc. to see if it helps. But really those ams have a reputation of beeing thick and warm sounding. They might seem like a variant of a Deluxe but sonically don't have nothing in common. As is the amp is perfect for old style blues and slode playing. In fact I normally used it with my Reso.
     
  8. DaveKS

    DaveKS Member

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    Well I've never heard one of those but have played a GA-30, so have a idea on the way Gibson's sound. Thick crunchy sludge is best way I can describe it.

    And I will say again what your fighting against is probably why they originally went with 8" speakers in that amp to begin with, tighter more focused 8" but in a 4x8 array to give it some girth. Maybe even do something like the GA-30, put a tone tubby 8" alnico with a TT 10" ceramic even though ga-30 did have a 8/12 array. You'll probably a lot closer to the sound your looking for. Probably any 12" speaker is going to be to "Fat" for you. Get you a adapter ring and move down to a 10" even.
     
  9. jumping@shadows

    jumping@shadows Supporting Member

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    I have the exact same amp and you need to bypass/reduce the giant input resistors (commonly referred to as the 'AC10 input mod), as they really muddy up the channels. Here's a quick demo switching between the original dark/muffled input and the reduced/modded one:
    https://www.youtube.com/watch?v=3OijRpLLl0E
    With this mod and a quad of Weber ceramics it's my favourite amp of all time out of various '50s tweed and '60s Brown/Blackface Fenders, Magnatone etc :)
     
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  10. AndreasG

    AndreasG Member

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    Thanks to all...really you convinced me to go to the 4x8" configuration...but for now I stick to Celestion Eights...over here in Italy others are hard to come by and extremely expensive. I thought that I have my Marshalls with 12" speakers, my Super Reverb with 10" and now something different...4x8"... Kinda lile a mini-bassman!
     
  11. AndreasG

    AndreasG Member

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    Thanks for the info on the mod. Sounds great, but are these the resistors or the capacitors to change? Is there a schematic somewhere?
    Thanks a lot
     
  12. AndreasG

    AndreasG Member

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    Just finished putting in 4 Celestion Eights...did the Webers fit the original baffle? The Celestions are too big in diameter...but I managed to make them fit in some way. Doesn't look good but sounds really better and more open than with zhe 12" speaker
     
  13. Scott Woodruff

    Scott Woodruff Member

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    I just purchased a 1955-56 GA45. It comes with an Altec Lansing 417-8C. Well see if its a good fit. Sounds like you really dig the four 8" speaker configuration. In researching I came across your posting about the the 'ac10 Input' mod. Are you speaking about changing out the two 470 K resistor on channel 2 and two 220K resistors on channel one before they hits the 5879 tubes? Do you remove them completely or substitute a different resistor? What resistor would you put in? or is it best without-a complete bypass?
     
  14. bullet6759

    bullet6759 Silver Supporting Member

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    I would not mess around with the circuit it is a unique tone that makes these amps differnt. If you want bright check all your caps and resistors and make sure that they are spec to the schematic and that the tubes are strong.The only thing I changed in mine were the speakers that made a huge difference and now it's one of my favorites .
     
  15. Rockinrob86

    Rockinrob86 Supporting Member

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    I just got a pretty beat up one of these. Restored it electronically and it sounds killer! It didn't come with any speakers, but I have the original baffle.

    I was thinking about 1x15 since the cabinet is so big, but 2x10 could be interesting too. Also, how are the 4x8 for guitar? I would think that could sound a bit thin - I'm going to be playing mostly cranked up rock music a la neil young on this, so I would like it to sound enormous!
     
  16. bullet6759

    bullet6759 Silver Supporting Member

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    I have one with the original gold Jensen 4x8 sounds like a mini Bassman to me killer.
     
  17. Rockinrob86

    Rockinrob86 Supporting Member

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    are those p8r's? I guess it is hard to imagine 8's not sounding like a champ with guitar.

    I like the champ tone, but I'm wanting HUGE with this amp. It does sound killer through a weber silver bell in a different cab I was testing it out with...
     
  18. bullet6759

    bullet6759 Silver Supporting Member

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    Think of it this way 4x8 = 2x16s
     
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  19. Rockinrob86

    Rockinrob86 Supporting Member

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    I ended up looking around and I found a quad of 60’s c8r jensens for $46.58 on ebay!

    Worked out well, all are good, although one cone’s surround was a bit iffy. May end up gooping that one a bit.

    Otherwise, they sound fantastic! This amp is very loud, and is probably the rawest, most aggressive midrange amp I have. The bass is a bit thin, but really this is just the perfect raw, trashy, neil young sounding rig.

    The 4x8 configuration works greta for guitar, and it does not have a champ vibe at all. In fact, I think this rig may sound bigger than my 2x12!
     
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