joeystrange Posted November 9, 2014 Share Posted November 9, 2014 I bought a Fender Super Bassman this summer and it has a problem... It regularly loses volume. It'll either drop really quiet or keep going between normal and quiet. Has anybody had this problem with an all valve amp before? The valves all look fine and I think I've figured out that it only happens when it's been on for a couple of hours and got pretty warm. The fan is working fine too. At first I thought it was the bass but I took it to bits and it seems fine. It appears to be ok through a different amp too. Thanks for any input. Quote Link to comment Share on other sites More sharing options...
basshead56 Posted November 9, 2014 Share Posted November 9, 2014 Preamp tubes perhaps? Do you sit the amp directly on top of a big cab? Quote Link to comment Share on other sites More sharing options...
gsgbass Posted November 10, 2014 Share Posted November 10, 2014 (edited) Check how the electrical power is, where you are playing. Is it possible you may have power fluctuations where you play? the Super Bassman may be draining power on it's own. Edited November 10, 2014 by gsgbass Quote Link to comment Share on other sites More sharing options...
Billy Apple Posted November 10, 2014 Share Posted November 10, 2014 I had this happen on my Matamp and the fault was the input jack. I had a similar thing on an SVT and it was a pre-amp valve. What I'm saying is get it looked at by a pro. Is it still under warranty? Quote Link to comment Share on other sites More sharing options...
joeystrange Posted November 10, 2014 Author Share Posted November 10, 2014 [quote name='basshead56' timestamp='1415568362' post='2601597'] Preamp tubes perhaps? Do you sit the amp directly on top of a big cab? [/quote] Possibly, but all of the valves look fine as far as I can see plus the amp has valve error lights, all of which read ok. The amp is currently on top of a 4x10. [quote name='gsgbass' timestamp='1415584990' post='2601774'] Check how the electrical power is, where you are playing. Is it possible you may have power fluctuations where you play? the Super Bassman may be draining power on it's own. [/quote] Again, it's possible but I've been rehearsing there for a while and never had a problem with any other amp. [quote name='Billy Apple' timestamp='1415603559' post='2601784'] I had this happen on my Matamp and the fault was the input jack. I had a similar thing on an SVT and it was a pre-amp valve. What I'm saying is get it looked at by a pro. Is it still under warranty? [/quote] It should be under warranty seeing as I've only had it since the summer. I'm in two minds whether to get it looked at or just ask for a replacement. I'll see what GAK suggest. Quote Link to comment Share on other sites More sharing options...
joeystrange Posted November 25, 2014 Author Share Posted November 25, 2014 Turns out its a problem with the auto biasing system. Should be an easy fix. I seem to remember someone on here saying that they had the same problem and its a common fault with these amps. Quote Link to comment Share on other sites More sharing options...
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