pn_day Posted March 27, 2012 Share Posted March 27, 2012 Hi all, I've been a lurker on here and TB for years, and have enjoyed learning from the collective wisdom (despite my GAS being encouraged!) I have a pedal board that is now giving mains hum when listening through headphones (in ears in church, and for testing I've been using my earwig headphone amp). On diagnosing the fault I seem to have had 2 supplies both start humming - one for a DHA VT1 drive pedal (12V, 1250 mA), and the other from effectspowersupply for running tuner (ST200) and chorus (CE-2B). I also have a Carl Martin comp/limiter which runs off AC, and a an old silver Qtron+ which runs off its own 24V supply, both of which are still noise free. All supplies have been plugged into a 4 way extension at the top of the board. I'm not aware of any power fluctuations, drinks spollages or problems that could have caused this, so wondered if anyone wiser than me could think of a possible reason? All pedals run hum free when tested individually with a Uniross regulated supply. I've separated signal and power lines. I'm seriously having to consider dropping the VT1 and chorus at the moment just to get noise free. Chorus I can live without, but the VT1 is really nice for some subtle valve breakup. If anyone has any thoughts or things to try I'd be most grateful, particularly if they don't involve spending 100s in new power options! Thanks Phil Quote Link to comment Share on other sites More sharing options...
pn_day Posted March 27, 2012 Author Share Posted March 27, 2012 Oops! Should probably have said I'm running a Clement bass through the pedals. Hum exists in both active and passive modes for the magnetic pickups, and also when using the piezo pickups. Quote Link to comment Share on other sites More sharing options...
simwells Posted March 27, 2012 Share Posted March 27, 2012 When you say it is now giving hum was it previously not? Also is the PSU for the DHA the originally supplied one? Quote Link to comment Share on other sites More sharing options...
pn_day Posted March 27, 2012 Author Share Posted March 27, 2012 Thanks for the reply. Hum is now obvious as we're using in ears after a few months back on wedges. Hum was not noticeable when on IEMs before. The DHA supply is the original one. Quote Link to comment Share on other sites More sharing options...
tayste_2000 Posted March 27, 2012 Share Posted March 27, 2012 Check your instrument leads and patch leads, work it 1 cable at a time. Quote Link to comment Share on other sites More sharing options...
pn_day Posted March 27, 2012 Author Share Posted March 27, 2012 [quote name='tayste_2000' timestamp='1332867233' post='1594202'] Check your instrument leads and patch leads, work it 1 cable at a time. [/quote] Thanks for the help. I've tried this. Hum only exists when PSUs mentioned above are applied to the pedal. Quote Link to comment Share on other sites More sharing options...
phil.i.stein Posted March 27, 2012 Share Posted March 27, 2012 quick experiment : if possible, plug the two into seperate sockets (i.e. try not running them off the same 4-way). any difference ? Quote Link to comment Share on other sites More sharing options...
pn_day Posted March 27, 2012 Author Share Posted March 27, 2012 [quote name='phil.i.stein' timestamp='1332871146' post='1594268'] quick experiment : if possible, plug the two into seperate sockets (i.e. try not running them off the same 4-way). any difference ? [/quote] Good idea. Alas, no difference. Swapping out either of the PSUs for an old Uniross one makes the hum go away. Time to spend some money on new power options methinks. Quote Link to comment Share on other sites More sharing options...
jwood662 Posted March 27, 2012 Share Posted March 27, 2012 I had a couple of cheap power supplies that caused hum when chaining more than a couple pedals. Filtering on the £18 ones you can get is toilet, went and bought a Diago power station, sorted that problem out. 50 odd quid but worth it! Quote Link to comment Share on other sites More sharing options...
Ant Posted March 29, 2012 Share Posted March 29, 2012 Just to echo what tayste said about leads! I had some awful noise in my setup which was caused by one dodgy lead! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.