jmstone Posted January 13, 2012 Share Posted January 13, 2012 I just bought a b21u and have a problem with the sound crackling and distorting when it's plugged into the mains. The sound is a kind of high frequency fizz which occurs when I touch the strings and also if I touch metal components on the unit. If I hold onto the bridge or metal parts of the lead, the distortion goes. Also if I run the unit on batteries, there are no issues. I thought it may be an issue with the guitar, but having checked the connections and re soldered the connection to the bridge I am not so sure. The psu which came with out is rated at a higher current than suggested in the manual, but out seems odd that they would ship something that doesn't work properly. Is it a bad unit or something else? Thoughts would be gratefully received. Quote Link to comment Share on other sites More sharing options...
phil.i.stein Posted January 13, 2012 Share Posted January 13, 2012 (edited) [quote name='jmstone' timestamp='1326483632' post='1497952'] I just bought a b21u and have a problem with the sound crackling and distorting when it's plugged into the mains. The sound is a kind of high frequency fizz which occurs when I touch the strings and also if I touch metal components on the unit. If I hold onto the bridge or metal parts of the lead, the distortion goes. Also if I run the unit on batteries, there are no issues. I thought it may be an issue with the guitar, but having checked the connections and re soldered the connection to the bridge I am not so sure. The psu which came with out is rated at a higher current than suggested in the manual, but out seems odd that they would ship something that doesn't work properly. Is it a bad unit or something else? Thoughts would be gratefully received. [/quote] sounds like an earthing problem. try a different power supply perhaps. although before this, try plugging the power supply into a different wall socket, in case it's your mains that is at fault. Edited January 13, 2012 by phil.i.stein Quote Link to comment Share on other sites More sharing options...
jmstone Posted January 14, 2012 Author Share Posted January 14, 2012 Thanks. The crackling only occurred when I plugged headphones into the B2.1U. I think it is some anomaly with my house.. I tried my other pedal and it had the same issue when I plugged headphones into it, and the problem remained regardless of swapping pedals, guitars or PSUs, but plugging the pedal into my computer (and presumably an amp - although I haven't tried that yet) dissipates the noise. James Quote Link to comment Share on other sites More sharing options...
BassBus Posted January 14, 2012 Share Posted January 14, 2012 You say this happens when plugged into the mains. Does this happen when you're using battery power? Quote Link to comment Share on other sites More sharing options...
jmstone Posted January 14, 2012 Author Share Posted January 14, 2012 [quote name='BassBus' timestamp='1326537963' post='1498471'] You say this happens when plugged into the mains. Does this happen when you're using battery power? [/quote] No - it's fine on batteries, it's fine on mains if I plug the output into the computer soundcard, and monitor from that with headphones. The only problem is when I have the headphones plugged direct into the pedal, and I get what I can only describe as a slow build-up of static - with clicks and pops when I touch the strings or any metal bits of the pedal/plugs. As I said, I tried my other pedal with plugging the headphones straight into the output, and the same kind of distortion happened there.. really weird. Tried swapping out everything - guitar, headphones, plugs, PSU, but to no avail. Any idea what's going on here? Quote Link to comment Share on other sites More sharing options...
phil.i.stein Posted January 14, 2012 Share Posted January 14, 2012 (edited) [quote name='jmstone' timestamp='1326580779' post='1499232'] No - it's fine on batteries, it's fine on mains if I plug the output into the computer soundcard, and monitor from that with headphones. The only problem is when I have the headphones plugged direct into the pedal, and I get what I can only describe as a slow build-up of static - with clicks and pops when I touch the strings or any metal bits of the pedal/plugs. As I said, I tried my other pedal with plugging the headphones straight into the output, and the same kind of distortion happened there.. really weird. Tried swapping out everything - guitar, headphones, plugs, PSU, but to no avail. Any idea what's going on here? [/quote] same set of headphones ? otherwise running out of ideas based on your description, - maybe faulty headphone lead/jack plug - clutching at straws here. Edited January 14, 2012 by phil.i.stein Quote Link to comment Share on other sites More sharing options...
TimR Posted January 14, 2012 Share Posted January 14, 2012 Take it to someone else's house. It has to be mains interference. When you plug into your computer soundcard you are earthing the unit so the noise is eliminated. Alternatively turn off some appliances in the house. Try fridge/freezer, dimmable or fluorescent lights Quote Link to comment Share on other sites More sharing options...
jmstone Posted January 16, 2012 Author Share Posted January 16, 2012 (edited) Hi All, Thanks for your replies. I think we solved the mystery before the Zoom technical dept got back to me: "I suspect that there is no fault with the unit and that it is being employed with possibly a headphone for monitoring and has no effective ground circuit. The modern power adapters such as the AD-16F is of switch mode design without a ground / earth terminal. This type of supply suffers from common mode rejection which can manifest as hum or induced noise when any metal surface is touched. When the unit is connected to its sound system, a mixer or amp, the unit is grounded and the problem is negated. With the very high price of copper, older low impedance transformer type adapters are regrettably being phased out. Regards, Roy" Out of interest, does anyone know of an AC/DC 9v .3A adapter that would provide an effective ground circuit? Edited January 16, 2012 by jmstone Quote Link to comment Share on other sites More sharing options...
phil.i.stein Posted January 16, 2012 Share Posted January 16, 2012 [quote name='jmstone' timestamp='1326706996' post='1500613'] Hi All, Thanks for your replies. I think we solved the mystery before the Zoom technical dept got back to me: "I suspect that there is no fault with the unit and that it is being employed with possibly a headphone for monitoring and has no effective ground circuit. The modern power adapters such as the AD-16F is of switch mode design without a ground / earth terminal. This type of supply suffers from common mode rejection which can manifest as hum or induced noise when any metal surface is touched. When the unit is connected to its sound system, a mixer or amp, the unit is grounded and the problem is negated. With the very high price of copper, older low impedance transformer type adapters are regrettably being phased out. Regards, Roy" Out of interest, does anyone know of an AC/DC 9v .3A adapter that would provide an effective ground circuit? [/quote] i've had good results with these two companies. [url="http://www.effectpowersupplies.com/"]http://www.effectpowersupplies.com/[/url] [url="http://www.johnnyshredfreak.com/"]http://www.johnnyshredfreak.com/[/url] Quote Link to comment Share on other sites More sharing options...
jmstone Posted January 18, 2012 Author Share Posted January 18, 2012 [quote name='phil.i.stein' timestamp='1326733208' post='1501225'] i've had good results with these two companies. [url="http://www.effectpowersupplies.com/"]http://www.effectpowersupplies.com/[/url] [url="http://www.johnnyshredfreak.com/"]http://www.johnnyshredfreak.com/[/url] [/quote] Thanks! They look good. This is what the Zoom tech recommended: http://cpc.farnell.com/stontronics/spu15a-104-9/psu-smps-9v-1-67a/dp/PW01333?Ntt=pw-01333 Quote Link to comment Share on other sites More sharing options...
chrismuzz Posted January 18, 2012 Share Posted January 18, 2012 I use a johnny Shredfreak power supply and it's awesome! No noise whatsoever... Unless I have all my drive pedals cranked Quote Link to comment Share on other sites More sharing options...
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