Linus27 Posted July 8, 2009 Share Posted July 8, 2009 I have an Ashdown ABM EVO III Rack Mounted head that seems to have a hum but only when I turn on the EQ. It also only does it when the guitar lead is plugged in despite no bass plugged in on the other end. If no lead is plugged in, then the amp is silent. I have tried about 5 different leads and they all do the same, including brand new ones from OBHM. It also hisses quite loud when I turn the treble up. The Input dial also makes a whooshing noise when I turn it from zero to half way. I did speak to the guy at Ashdown but he said the hissing is normal and was not really interested in the humming noise. Pretty dissapointed especially as its only 6 weeks old. Before I take a trip over to Ashdown, just wondering if anyone else has this head and finds it noisy. I want to sell it as I have just got a Shuttle 6 but don't want to pass it onto someone if its faulty. Quote Link to comment Share on other sites More sharing options...
obbm Posted July 8, 2009 Share Posted July 8, 2009 An unterminated instrument lead, i.e. no bass, acts like an aerial and will just pick-up noise and amplify it. That is not a realistic test. Either put a bass on the end or short circuit the connector. Quote Link to comment Share on other sites More sharing options...
Linus27 Posted July 8, 2009 Author Share Posted July 8, 2009 [quote name='obbm' post='535522' date='Jul 8 2009, 11:06 AM']An unterminated instrument lead, i.e. no bass, acts like an aerial and will just pick-up noise and amplify it. That is not a realistic test. Either put a bass on the end or short circuit the connector.[/quote] Thanks Dave. I will give it a test tonight. I think my thinking behind it was that it was noisy with the different basses plugged in so to eliminate something, I would try it without the basses plugged in and it was no different. However, I will double check tonight again. Quote Link to comment Share on other sites More sharing options...
obbm Posted July 8, 2009 Share Posted July 8, 2009 ideally you should terminate the amp input with a short circuit and then see what noise/hum is generated by the amp itself. If it's different when you plug different basses in then the extra is coming from the basses/cables. The amp is just making that noise louder. A pick-up coil is a very efficient aerial and will attract all sorts of interference. Check your doemstic environment for noise sources such as motors, lighting dimmers, fluorescent tubes, etc. try taking it to the bottom of the garden ad see what happens. Quote Link to comment Share on other sites More sharing options...
Linus27 Posted July 8, 2009 Author Share Posted July 8, 2009 [quote name='obbm' post='535534' date='Jul 8 2009, 11:20 AM']ideally you should terminate the amp input with a short circuit and then see what noise/hum is generated by the amp itself. If it's different when you plug different basses in then the extra is coming from the basses/cables. The amp is just making that noise louder. A pick-up coil is a very efficient aerial and will attract all sorts of interference. Check your doemstic environment for noise sources such as motors, lighting dimmers, fluorescent tubes, etc. try taking it to the bottom of the garden ad see what happens. [/quote] Not sure my back could cope lugging the amp and speaker to the end of the garden. After all the rain we have had, I have a feeling that the speaker may also sink into the garden due to its weight :) So far I tried turning all the lights etc off and no difference. The one thing I need to try is plugging into a different mains socket. Thanks again for the help. Quote Link to comment Share on other sites More sharing options...
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