Dudgeman Posted April 18, 2011 Share Posted April 18, 2011 I use this amp along side a Marshall head to achieve a bi amp system. At rehearsal the other day turned on the amp and struggled to get any significant output volume. It was also distorting, sounded like a farty speaker (sorry but it is the best description I can think of) at certain frequencies..Ab and G specifically. I only use this for a warm clean bass sound running the graphic fairly flat..bass knob at about 1 o'clock..the rest at about 12 o'clock..Speakers are fine..definitely an amp problem.... Anyone got an ideas as to the cause of a significant drop in output volume? Just to save the questions..i have checked cables..volume control knob (Hasn't come loose) thought it might be my bass so checked on a different amp..no problem there.. Any help gratefully received. Thanks Quote Link to comment Share on other sites More sharing options...
Monckyman Posted April 19, 2011 Share Posted April 19, 2011 Hiya. How much Valve do you run? My ABM500 evo valve went recently and the vol dropped massively till I turned the drive right off, then the volume returned. Also, maybe check the amp via the D.I into another amp, see if the pre-amp section is ok, may be your output stage is kaput. MM Quote Link to comment Share on other sites More sharing options...
icastle Posted April 19, 2011 Share Posted April 19, 2011 [quote name='Dudgeman' post='1204320' date='Apr 19 2011, 12:25 AM']I use this amp along side a Marshall head to achieve a bi amp system. At rehearsal the other day turned on the amp and struggled to get any significant output volume. It was also distorting, sounded like a farty speaker (sorry but it is the best description I can think of) at certain frequencies..Ab and G specifically. I only use this for a warm clean bass sound running the graphic fairly flat..bass knob at about 1 o'clock..the rest at about 12 o'clock..Speakers are fine..definitely an amp problem.... Anyone got an ideas as to the cause of a significant drop in output volume? Just to save the questions..i have checked cables..volume control knob (Hasn't come loose) thought it might be my bass so checked on a different amp..no problem there.. Any help gratefully received. Thanks[/quote] As you're running a bi-amped setup, the first thing to do would be to isolate the two halves of the setup and see if the problem is still there. If you still get distortion then I'd take a look at the 'valve drive' controls and make sure they're not adding to or creating the problem. As far as I'm aware, if you have the 'valve drive' control set to 'out' then it makes no difference if the valves are shot or not. I have to say though, it is unusual to find a frequency selective amp problem and I'd be more inclined to look at the speakers again. HTH Quote Link to comment Share on other sites More sharing options...
Dudgeman Posted April 19, 2011 Author Share Posted April 19, 2011 [quote name='icastle' post='1204573' date='Apr 19 2011, 11:22 AM']As you're running a bi-amped setup, the first thing to do would be to isolate the two halves of the setup and see if the problem is still there. If you still get distortion then I'd take a look at the 'valve drive' controls and make sure they're not adding to or creating the problem. As far as I'm aware, if you have the 'valve drive' control set to 'out' then it makes no difference if the valves are shot or not. I have to say though, it is unusual to find a frequency selective amp problem and I'd be more inclined to look at the speakers again. HTH[/quote] Thanks for the info so far...this is what I have tried...I have tried sepereating the channels and there is still a problem..I am going to try a 4x10 cab that I have to double check that it is an amp problem..not a cab issue. I will take a look at the valve side and see if there is anything there that might be wrong. Obviously I have checked all leads etc to make sure that it isn't that simple.. Quote Link to comment Share on other sites More sharing options...
Dudgeman Posted April 19, 2011 Author Share Posted April 19, 2011 [quote name='Monckyman' post='1204499' date='Apr 19 2011, 10:03 AM']Hiya. How much Valve do you run? My ABM500 evo valve went recently and the vol dropped massively till I turned the drive right off, then the volume returned. Also, maybe check the amp via the D.I into another amp, see if the pre-amp section is ok, may be your output stage is kaput. MM[/quote] I don't run a lot of valve but will check out your ideas..much appreciated. Quote Link to comment Share on other sites More sharing options...
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