mortn Posted May 28, 2013 Share Posted May 28, 2013 Hey Guys, while toying around with my new HD500, I noticed a high pitched squeal that seems to be emanating from inside the unit. It's continuous, has a steady pitch and seems to increase with higher dsp usage. In contrast, my old HD300 is dead quiet. Has anyone else experienced the same? Quote Link to comment Share on other sites More sharing options...
moondancer Posted May 28, 2013 Share Posted May 28, 2013 To get reasonable advice you should post all facts. What instrument your plugged in How is your input/output configuration How you connect your HD output (XLR, 1/4" Jack, SPDIF, USB) To what you connect? (mixer, amp, earphones) Have tried to connect to another device? You will have to give more input! Quote Link to comment Share on other sites More sharing options...
mortn Posted May 28, 2013 Author Share Posted May 28, 2013 Hi moondancer, Thanks for your reply. The noise I've described does not correlate with I/O configs and connections. In that regard the unit works fine so far. The squealing sound seems to originate from the circuit board itself and is clearly audible trough the metal chassis of the unit. Quote Link to comment Share on other sites More sharing options...
moondancer Posted May 28, 2013 Share Posted May 28, 2013 Oh I understand. This could come from some electronic components and I have heard high pitch noises sometimes from a capacitor or from tubes. If it is really considerably audible you should bring the HD to a service center to check the board before it fails in a live gig :( Quote Link to comment Share on other sites More sharing options...
mortn Posted May 28, 2013 Author Share Posted May 28, 2013 Yes, that would be my guess, too. :( Quote Link to comment Share on other sites More sharing options...
wildbillmojo Posted July 31, 2013 Share Posted July 31, 2013 As a one-time digital electronics engineer who's just bought an HD500 I can tell you what the noise is, it's the internal clock that synchronizes the digital electronics (CPU, DSP, RAM etc) and it's probably breaking through on the Ground (Earth for Europeans) side of the signal path; I'm getting it too on certain set-ups.I used to get the same thing on my 'old fashioned' pedal board from my EHX Cathedral pedal, which was digital. I fixed that by ensuring it had its own isolated power supply.I have noticed for example that it is a LOT worse when the HD500 is wired up to an amp using the 4CM AND the USB is plugged into a computer. If I unplug the computer its gets better but does not completely go away; if I wire directly to the front of the amp then it pretty much disappears except for very high gain amp models.All this suggests that it's an earth loop problem. I'm still experimenting with some solutions, but I can make some suggestions. Firstly try ensuring that the POD and Amp are not plugged into the same mains outlet. Obviously this is not always practical and doesn't always work anyway, as the outlets are often just connected together behind the wall. Next you could try an isolating mains filter for the POD PSU. Some mains boards come with them built in. You don't need to spend $$$hundreds but don't get the cheapest you can find. Note that just a filter (which filters noise) is no good; it has to state that it is fully isolating. The next option is much more of a pain so I'm not going there yet, but its build a fully isolating PSU filter yourself. I've done this but obviously you have to know how. Should cost < $80 depending on where in the world you live. Good luck and let us know. I'll do the same. Quote Link to comment Share on other sites More sharing options...
spaceatl Posted August 1, 2013 Share Posted August 1, 2013 While filtering is good to have, the only way I know to truly isolate AC is to use a transformer...I prefer to kill three birds with one shot and use an AVR...Voltage Regulation, Isolation and Filtration....I use a Tripp Lite LC1200... about $100...I got mine new for about $80 and there $20K of gear insurance on that also...never needed it...Oh yea, I have NEVER had a reset...If you perform using generator power without an AVR it is just a matter of time until your gear blows up...I have seen those never got over 90 volts...while the gear will run there...silicon regulators get pretty hot when they have to regulate that hard... Best to go 2 or 3:1 ratio since the current potential drops when the AVR steps up (if you need 300 watts, get a 600-1000 watt AVR)...I can't remember the last time I had a "ground voltage" causing noise...oh, that's because there is no voltage on my ground because it is isolated...I also use a XLR isolated splitter box for my direct and put the house on the isolated split...again, transformers are made to solve these issues... I shall step off the soapbox now... Here's a good little paper on the subject: http://www.jensen-transformers.com/an/generic%20seminar.pdf Quote Link to comment Share on other sites More sharing options...
wildbillmojo Posted August 1, 2013 Share Posted August 1, 2013 Yeah 'Guru', hence my use of the term fully isolating filter. 1 Quote Link to comment Share on other sites More sharing options...
spaceatl Posted August 1, 2013 Share Posted August 1, 2013 whatever noob... 1 Quote Link to comment Share on other sites More sharing options...
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