Hi all, Here's a problem I've been encountering over the last couple of days. The text below is taken from an e-mail that I sent to a load of suppliers of tonearm bits, and the post was originally posted on other forums. I couldn't be tatted to type it all out again, so here they are.... E-mail: Hello there, I have just failed an attempt at rewiring my Rega RB250 tonearm DIY style. Everything was soldered into place, and after all my hardship I am faced with a loud 'HUMMMM' over the music through both channels. I have changed the wire to an Incognito style design, with two 0.33mm uninterrupted SPOFC wires from headshell to phono plugs at the amp end for either channel. The cable outside of the arm is unscreened, not being coaxial. This brings me to a previous problem I encountered. I decided to experiment with my SME III by changing the supplied (screened) phono leads to a pair of Ixos leads, which are of the same configuration as my new DIY arm wires/leads, without screening. They hummed loudly, so I switched them back to the supplied leads, and the problem disappeared. I suppose this was to do with RFI(?). I noted that the SME leads had the screens gronded at the amp. So, what I am thinking is that if I were to screen my DIY cables and then ground the screening, would my problem disappear? Any advice would be greatly received. Best regards Forum post: Right then, here I go... I've spent the last 2 nights up until 2am, trying to diy re-wire my RB250. I ran 0.33mm FEP insulated silver plated wire from the cartridge tags straight through to the phono plugs at the amp. I then proceeded to solder in the earth wire, and this 'grounds' at the amp. Last night I finished, Today I remounted the tonearm to the TT, stuck the cartridge back on, and set the lot up. Plugged all in, switched amp on and HUUUUUUUUUUUUUUUMMMMMMMMMMMMMMMMMMM THROUGH BOTH CHANNELS!!!! I really don't understand what the problem is though. I'm pretty sure all the wires are ok, the earth is now via a seperate cable and not through the signal wire ground. This situation takes me back to my old SME series 3 arm. I thought that the SME leads weren't really up to much, so I swapped them for a pair of Ixos gamma cables instead. These cables were in perfect condition with no dodgy connections or anything, though they caused a hum. The Ixos cables were not 'coaxial', but instead are the same as my newly constructed arm leads, with a single wire for signal, and a single wire for earth for either channel. Note that when I swapped the SME arm leads back, the hum disappeared This brings me to ask 'is the problem due to the way the cable is constructed'? -Not being coaxial, Or is it something else. I think I've tried everything aside from borrowing a multimeter from work and testing for any continuity between the tonearm earthing and the signal wires. I can still hear music playing, but there is just a damn loud HUUUMMMMM in the way!!!! HELP!!!!! And: I think that I made the cables a'la the Incognito design, but I'm not totally sure about this. Could it be that there is no shielding so to speak of, as the wires run through PTFE tubes encased in heatshrink. Or is the Incognito design made with coaxial cable??? AAGGGGGGGGHHHHH!!!!!!!! Sorry if this doesn't make sense, I really haven't a clue. I'm in a world of my own at the mo and I really need some sleep! BTW, I'm pretty sure that there are no shorts along the signal wires etc. Cheers, Danza
