Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jerrydyer on November 20, 2013, 07:48:32 pm
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ive got this older 50 watter (60 watter) and the clean channel is now hot and overdriven with a lot less volume. Swapped out some 4558's, some J175's that were attached to the switching etc. no luck. lead and crunch on this amp are very good. BUT the guy wants it for its loud clean tone.
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which carvin is it
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thats kinda important . man im slippin. X60.. very early model but someone brought it up to current specs.
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well probably not any help but here's a combo schem for a few of their amps in that range.
http://www.carvinmuseum.com/pdf/amps/s24104N_X100B_schematic.pdf (http://www.carvinmuseum.com/pdf/amps/s24104N_X100B_schematic.pdf)
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again probably no help but the manual says "the 2 triode stages of v1 are preamp stages for rhythm and lead channels.the lead channel uses a cathode bypass for max gain and the rhythm uses none for max clean headroom.selection of a tube for v1 with low noise and low microphonics is crucial".
have you tried both inputs with different tubes in v1?you know the easy stuff lol?any chance you can find out who brought it to current spec and talk to them about the clean channel issue?what does their work look like in the amp and have you checked it for mistakes?are you sure the older x60 is compatible to be brought upto current specs?I would be looking in the v1b section of the schem i guess but after verifying from carvin that the circuit board didn't change throughout versions of the x60.
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I'd probably gut it, build a whole new board and make it into a loud clean amp.
OR ......... if he doesn't like that idea ......... try some 12AY7's, 12AT7 in LTPI and reduce value of preamp coupling caps to 2.2uf.
With respect, Tubenit
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but the lead and crunch sound so good.... its one of the best X amps Ive heard. voltages are good. I see that the 2N5550 is tied into the switching and its the only one I have not swapped out. local store said they are obsolete. said it was the same as a J175.. I say it is not. I ordered one easily on ebay so I will try that as soon as it gets. All 4558 's are new All J175's are new.
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from the manual"fet switch q1 mutes the lead signal whenever the lead channel is not selected in order to prevent distortion products from leaking into the clean channel".
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I had a Carvin X100-B head. People always rave about the clean channel and it is quite nice. I was very surprised to find out that the clean channel is largely solid state. The overdrive channel on mine was nothing special but the clean tones were good and it took pedals well. I think the first stage was a tube.
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I changed Q1. ( J 175 ) the best way to describe the prob is to say it sounds like a boogie clean channel when you engage the "push" feature. It breaks up not terribly bad but all the headroom is gone and its flubby. not sure if im getting lead or crunch signal in there or if its some other issue.