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Title: Channel 1 Gain Issues Post by: breakthastatic on May 03, 2009, 09:32:49 PM Hi All,
I am having problems with low gain on channel 1. I understand that channel 1 should be slightly quieter than channel 2, but I'm talking way quieter. Channel 1 isn't loud enough to play any type of club, or even a band practice. I've checked the plate voltages for the tubes and everything is in 5% tolerance of spec. I've checked the pots to make sure they are working properly. Both the 1.5 K resistor and the 220 K resistor are within tolerance. I've also replaced all the preamp tubes. I can't think of anything else, short of changes to component values to increase gain. Does anyone else have a severe gain difference between channels? Anyone have suggestions on what to change or test? The amp has a great sound, but at this volume is useless. Any help is appreciated. Thanks! Title: Re: Channel 1 Gain Issues Post by: hywelg on May 04, 2009, 08:32:49 PM My channels are fairly similar in volume. Did you build yours yourself or was it a complete amp from Nik? If it was from Nik email him and he'll talk you through the diagnosis. Check your FX loop wiring each channel has its own FX loop.
Is the volume the same for both inputs? Check your input jack wiring. Title: Re: Channel 1 Gain Issues Post by: breakthastatic on May 05, 2009, 03:44:24 PM well i was talking to nik, since all the voltages check out its probably not any of the resistors or caps. most likely a wiring issue. maybe a cold solder or a bad ground that's attenuating the signal. i'm in the process of re-dressing the amp anyway, so any wiring issues should get fixed. i built the amp 2 years ago and was new to the field. i've since learned a lot about tubes and wiring, so i figured this amp needs to get updated.
i suspected the volume pots could be acting up, but they checked out. i am replacing them anyway with PEC pots as part of the re-dress. i'm currently desoldering the amp right now. i'll keep you guys updated on what happens. thanks. |