Tube Amps / Music Electronics
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|7/8/2000 12:56 AM|
||Warming up a Reverberocket reissue|
A friend of mine just bought an ampeg reverberocket
head and matching cabinet. He's into vintage Ampeg's
so he thought maybe this would sound somewhat similar but it turns out it sounds like a Marshall!
It's a screaming lead amp but he can't get any warmth out of it. It has way too much gain for the sound that he wants. It uses 3 12AX7's and two EL34 output tubes. My question is,
Would lower gain preamp tubes help this situation? I told him maybe 12AY7 or 5751 might help but I'm not sure. Any suggestions would be greatly appreciated.
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|7/9/2000 4:38 PM|
Get rid of the EL-34s. This amp was designed for use with 7591s or 6V6 tubes depending on the year and sometimes depending on whatever they had available at the factory. The power tranny in these amps, unless it has been changed, will not survive very long running EL-34s due to the extra current draw. Ususally these amps have a schematic posted inside the cabinet. Often the schematic won't be very accurate since Ampeg was notorious(in the early days especially) for making on the fly production changes depending on what they had in their junk box that day. The schematic is usefull to some degree though for determining what the original circuit was like. Try to determine if any other changes were made when they did the EL-34 conversion and put the amp back to stock. Obviously someone wanted a Marshall so they made some changes to the amp. You can pretty much tell by looking at the circuit board if they monkeyed with the original circuit. Most important of all though......get those EL-34s out of there. Also check the cathode resistor to see what the value is. For 7591s they used a 140ohm....for 6V6s it should be a 250ohm. Good luck.
|7/9/2000 11:27 PM|
Dave, I just noticed you were talking about a reissue...
When I bought my Reverberocket II (modified quite a bit, btw) I could also try the new model RI (combo too), and they don't sound the same.
Not better or worse, just plain different.
I even believe the circuit is not the same at all.
'My' RR is quite modified, so I should better shut up, but the guy at the shop told me they were definetely different.
I think it shouldn't scream as you point, the stock I tryed didn't... One tube for the reverb, one for the phase inverter, leaves just one for the preamp...
I have nos ecc81 in the preamp socket and the phase inverter, and I like it.
|7/10/2000 1:57 AM|
Yeah, his amp is a reissue. He's an ampeg head with a '65 Gemini, a '61 B12X and a '63B12XY so he though he was getting something that would sound as sweet as those but ended up with something that sounds like a modern day Marhall in a blue tolex box.
I have a B15 reissue that sounds nice so when he heard that he figured he'd try the RR but was disappointed when he tried his Harmony Rocket guitar through it. It has the stock sovtek 12ax7's and GT EL34's which I guess are original. It has tone that is unbecoming for someone who is into vintage ampeg tone so I told him maybe some lower gain triodes would help it out.
It's kind of funny though, I have an uncle that plays harp in a blues band. He plays through a RR reissue combo amp with a single 12 and gets nice vintage Chicago blues tones out of it.
|7/10/2000 5:32 PM|
I have not seen the insides of these "reissues" but from what I understand they have nothing to do with Ampegs from the 50s-70s besides the logo and blue tolex any similarity ends there. Stick with the originals if you are looking for a vintage sound as I do not believe any small company makes a clone of any of the old Ampegs and certainly Ampeg has not choosen to.
|7/10/2000 8:50 PM|
ooops, guess I didnt read that carefully enough. The reissue Ampegs are a completely different story. They are actually Crate amps with Ampeg cosmetics. I would try selecting different tubes and maybe you can get a sweeter tone. Also try adjusting the bias. Htis amp will never sound anything like an Ampeg though, because it Ampeg in name only. SLM (Crate) bought the Ampeg name, but they are not building Ampegs the way Ampeg or Magnovox built them, they are a whole different amp.
|7/10/2000 10:23 PM|
Do you have any suggestions on which preamp or output tube substitutions might give a sweeter more vintage tone?
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