geilerbass Posted July 12, 2008 Share Posted July 12, 2008 My Trace Elliot AH350SMX has recently started adding a lot of noise to the signal that it outputs. I definitely appears to be with the amp, since it makes a hissing sound, regardless of whether my bass is plugged in or not. I'm also sure that the problem is at the output end of the amp's circuitry, since changing the gain, shape and eq settings do not seem to affect the level of the hum. Similarly the hum increases as the output level is increased, even if the gain is completely off. Adjusting the dual-band compressor knobs just boost/cut the noise at their respective frequency ranges. I also tried turning off the tweeter on my cab, but this just made the noise sound lower in pitch, obviously as it's higher frequencies are cut out. Apart from the noise, the sound quality is fine, but obviously this is an issue - I used it at a gig on Thursday and ended up having to use a DI box, because the sound man was getting too much noise through the balanced outputs on the back of my amp. Even with both the earth and ground lifts on. I'm pretty sure that I'm going to have take this in to get looked at, but does anyone have any immediate ideas about what the cause may be? Is it a write off? I have a pretty important gig coming up in less than two weeks, so I'll need someone to get it sorted asap. I was going to try one of the guys below, but does anyone have any other recommendations for amp techs in the central/north London area (I don't have a car, so will have to taxi it to whoever's going to fix it). John Kelly (Electronics) Ltd Brian Bond Ted Wood Many thanks in advance. Quote Link to comment Share on other sites More sharing options...
escholl Posted July 12, 2008 Share Posted July 12, 2008 what kind of noise is it? is it like a ground/mains hum, or a crackly noise, or more of a sort of white noise? are the any clicks/pops/etc? Quote Link to comment Share on other sites More sharing options...
geilerbass Posted July 12, 2008 Author Share Posted July 12, 2008 [quote name='escholl' post='237977' date='Jul 12 2008, 03:02 PM']what kind of noise is it? is it like a ground/mains hum, or a crackly noise, or more of a sort of white noise? are the any clicks/pops/etc?[/quote] It's a white noise kind of sound - not really a hum, more of a hiss. No snaps, crackles or pops either. Quote Link to comment Share on other sites More sharing options...
escholl Posted July 13, 2008 Share Posted July 13, 2008 well i have a couple theories, and i think it should be a fairly simple fix. definitely worth bringing it to a tech, any decent tech should be able to fix the problem fairly quick and simple. def not a write off, and shouldn't set you back too much, so no worries Quote Link to comment Share on other sites More sharing options...
geilerbass Posted July 13, 2008 Author Share Posted July 13, 2008 [quote name='escholl' post='238302' date='Jul 13 2008, 03:06 AM']well i have a couple theories, and i think it should be a fairly simple fix. definitely worth bringing it to a tech, any decent tech should be able to fix the problem fairly quick and simple. def not a write off, and shouldn't set you back too much, so no worries [/quote] Cool, thanks! Quote Link to comment Share on other sites More sharing options...
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