FamSarley Posted February 7, 2017 Share Posted February 7, 2017 Hello all, Recently, I modified my turntable set up. I did the ever so encouraged removal of the internal preamp from AudioTechnica AT-LP120. I recently put it all back together, grounded my new Gram Amp 2 Communicator and hooked it all up. The only problem is that I now have a consistent humming throughout my speakers. Considering the hum was there even without my turntable turned on, I figured it had to be originating from the preamplifier. To remove the stock preamplifier, I followed this video's walkthrough. The actual work starts around 13:50. So, I was wondering if the hum would be originating potentially from where I soldered new wires back on, or else if I didn't have the preamplifier properly grounded. All help is greatly appreciated, thank you very much! Quote Link to comment Share on other sites More sharing options...
allenh Posted February 7, 2017 Share Posted February 7, 2017 You've either not grounded something properly (chassis or motor) or made a bad connection. Surprising though that it hums without the TT powered on so does it do it without the TT connected? if so the problems not in the TT Quote Link to comment Share on other sites More sharing options...
FamSarley Posted February 7, 2017 Author Share Posted February 7, 2017 4 hours ago, allenh said: You've either not grounded something properly (chassis or motor) or made a bad connection. Surprising though that it hums without the TT powered on so does it do it without the TT connected? if so the problems not in the TT Yeah, it does hum without the TT powered on, but if I disconnect the preamp from the TT then the hum goes away. If you have watched the video, I followed it and simply connected the ground wire to where the former preamp was grounded. The new wires I am using might be a different gauge, would that matter? Also, would it be bad practice to simply remove the current wires that I soldered in and see if the humming persists? Quote Link to comment Share on other sites More sharing options...
allenh Posted February 7, 2017 Share Posted February 7, 2017 (edited) Ground problems are always a sod to diagnose when it's not in front of you but to help diagnose where it is you can try touching things like the arm or platter or spindle etc and your body should ground it to a degree and make the hum less if it's not properly grounded. Obviously be careful though don't touch inside the unit as there's mains voltage in there and you don't want to shock yourself. Edited February 7, 2017 by allenh Quote Link to comment Share on other sites More sharing options...
FamSarley Posted February 7, 2017 Author Share Posted February 7, 2017 17 minutes ago, allenh said: Ground problems are always a sod to diagnose when it's not in front of you but to help diagnose where it is you can try touching things like the arm or platter or spindle etc and your body should ground it to a degree and make the hum less if it's not properly grounded. Obviously be careful though don't touch inside the unit as there's mains voltage in there and you don't want to shock yourself. Yeah, I can't seem to figure this one out. I messed around with the ground a bit (put it on the platter, touched it to myself, etc.) but the hum hardly decreased. I'm starting to wonder if it could potentially be related to the wiring at all. I haven't soldered much in the past, but my connections look pretty clean. Would the gauge of the wire affect anything? I also had to manually strip these (meaning I used a wire cutters and pocket knife very carefully), would that possibly mess with any internal resistances if I thought it was a clean cut and actually took out a wire? Quote Link to comment Share on other sites More sharing options...
allenh Posted February 7, 2017 Share Posted February 7, 2017 No the thickness shouldn't really matter but you have used the cables that came with it haven't you? I mean just removing the phono stage board and joining the arm wires to the outgoing wires? If you used different wire that isn't for audio signal i.e. properly screened then yes all you are doing is adding a big antenna to the back of your turntable. Provided your joint is both mechanical and electrical then it should be fine but if it's not then there will be a high resistance there or if any of the cables are snapped inside. A couple of photo's of what you have done might help. Quote Link to comment Share on other sites More sharing options...
FamSarley Posted February 13, 2017 Author Share Posted February 13, 2017 On 2/7/2017 at 3:45 PM, allenh said: No the thickness shouldn't really matter but you have used the cables that came with it haven't you? I mean just removing the phono stage board and joining the arm wires to the outgoing wires? If you used different wire that isn't for audio signal i.e. properly screened then yes all you are doing is adding a big antenna to the back of your turntable. Provided your joint is both mechanical and electrical then it should be fine but if it's not then there will be a high resistance there or if any of the cables are snapped inside. A couple of photo's of what you have done might help. Sorry it's been a while, but it seems to have all sorted out. I started some trial and error testing with all of it and decided to buy new wires anyways. I cleaned things up with my soldering and it turned out that one of the channels wasn't even transmitting a signal, so I figured new wires were in order anyways. Once I put everything back together the hum went away! I'm assuming it was a grounding problem with the wiring, but either way I'm quite content with the sound. The only problem I'm experiencing now is some static and popping, but it's currently been storming quite a bit and it's been incredibly dry with the PA winters, so I have a feeling that should go away in the next couple days. Thank you for all of your help! Quote Link to comment Share on other sites More sharing options...
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