Supratek Owners Thread

Thanks @jslateiv for your feedback. Indeed the electrolytic caps are not on the sound path as they are coming from the 5V DC regulator. These are the Panasonic 10000uf. My guess is they are used for smoothing the DC from regulator. Nonetheless I replaced them with similar equivalent.

Very interesting that you tried different set of transformers. What did you try and was it a drop in replacementm? I might try a set of Hashimoto with similar ratio.

DC after the reg is already smooth. (that's what the reg does, ;-)) those 10Kuf help knock the ripple down before the reg so it doesn't work as hard and produce as much heat.   Again,.  I suspect it is tied into the supplemental V circuit used to boost the cathode V,.   Anywho,  sounds like you got it sorted and working.

I try all kinds of different configs, including messing with and adjusting the feedback..  can't help myself.   Lundhal,  Jensen, some hammond are what I've tried,  some with air gaps, and some without (purpose built for parafeed).   4:1 and 8:1 ratios are what you need to look for. I  prefer the 8:1 as the circuit already has alot of gain.   Keep in mind that these are configured as parafeed (no DC current) so you don't have to worry about any dc current spec on the tranx.   Unfortunately don't have any of the really nice trans like hashimoto, tango, etc..  laying around to try.  Honestly though i doubt I would like them enough more to justify the cost but ya never really know till ya try,.  plus most of those are all big units with air gaps which are not needed..   Anywho,.  feel free to PM if you have any specific questions about the circuit,  I'll try to help the best I can.  Don't want to continue to junk up this thread with repair related posts..  Best,

Thanks @jslateiv. This indeed matches my guess. Let's talk separately with mod ideas. :)

Well Mick sent me a new power supply and it still hums. I tried without umbilical cord and a new tube and it still hums. I am so disappointed because I love the sound of the preamp but the hum is driving me crazy. I can hear it in the speakers and I hear it if real close to the power supply. Any suggestions what I should do?

couger4u
Try disconnecting one component at a time from the pre amp. First the TT then turn everything on. If it still hums reconnect the TT and this time disconnect the DAC then turn everything back on. If it still hums your now down to the amp and pre as the suspects. You could have a ground loop hum. For about a $100 on amazon you can buy the iFi GND Defender, first try it on your amp then next the pre. If that does not get rid of the hum i'm not sure what the issue could be. Good luck.