Supratek Owners Thread

I just bought a used Chardonnay and got it running after a few hiccups like a stuck input selector and then getting a bit confused on using the correct input. But, all is well and this is one terrific preamp!!
A few things that were noticeable right away: 
1) detail retrieval is excellent 
2) this is the best representation, by far, of individual voices in a chorus 
3) voices and instruments are much more natural 
4) less glare/harshness and I’ll admit to having an asymmetrical room that needs lots of treatments  

The tubes I currently have are 
5U4C rectifier - Russian (green and white box)
6NS7                Tung-Sol 
6N3C                no brand visible

I’m quite open to tube rolling and an upgraded umbilical cord, maybe even a fuse upgrade. A couple of Agon members have been very helpful already and I much appreciate that. 

couger4u: if you turn down the gain and turn up volume, and reduces the hum and noise. That's probably because the hum is power supply related. My Cabernet has the same characteristic. I used to run the Cabernet 101D with lower gain with higher volume to minimize the noise and hum. The downside is higher level of distortion. You might like the result though. 

@couger4u    In regards to the gain control.  This is essentially a volume control placed at the end of the signal chain.  The main (front panel) volume knob is placed on the input, before the 1st tube stage.   If the 'gain' is engaged and the knob is fully counter-clockwise,. it is the same as not being in the signal.   As Alpha is saying,  if the noise is inherent in the circuit (and there's always some though typically very low),  the relationship between the noise and vol. controls (including gain control) will be the same.  ie,  lowering the gain will seemingly lower the noise but you would need to raise the main vol. back up (thus essentially increasing the noise) to make up for the lost gain.   One thing to keep in mind here,..   the pre's are very high gain to begin with.   It takes very little input to get a big/healthy output,  so the hotter the input signal from your source,  ie, 2+ Volts,   the less range you will get out of your vol. knob (regardless of using the gain control). This is also compounded by the amp sensitivity.  The gain control is useful in situations where the amp has a very high sensitivity and if the source has a hot output in the >+2v range..   You must be careful though to not reduce the gain so much that for a hot input/source you end up allowing too much signal (Vol. knob turned way up) into the 1st stage of the circuit.   This is when/where you will start to get some induced distortion as Alpha mentions.   If your curious as to test the inherent noise of the pre in relation to your amps sensitivity,..   turn the gain off,  if your pre has a gain switch in addition to the gain control knob, use the switch to completely remove the control knob from the circuit;  Once done,  select a input/source but do not 'play' anything.   Turn the volume control up until you start to hear the noise in the circuit.  Mark this spot on the volume knob.   Now,  turn the volume back down,  play something from the source that is selected and raise the volume knob back to the marked spot.  If the pre is functioning correctly and the noise is in the normal range (ie, no problems with the circuit) then the music should be extremely loud at this point and WAY over the noise you heard in the previous test.  As mentioned earlier this is VERY dependent upon the sensitivity of your amp.   If you have a solid state amp that has a very high sensitivity, ie, ~500mv   then   you will start to hear the pre's noise quicker within the volume range,  but the vol. control will also have less range unless the gain control is engaged a little.   A little gain reduction here could be useful but I would caution against using to much,  especially if the source has a very hot/high output.   For what its worth,  I have found that operating the Volume control in the 8-11am range is optimal,.  generally speaking of course).   Hope this helps a little.

My particular 101D Cabernet unit has not a small noise from the power supply. The HT lines had about 20mV p-p ripple and the DHT filament DC supplies had the same amount. It was a scary to work on the power supply so I decided to work on the main unit. Fortunately after removing the remote control PCB which I never use, it has space for me to put in a 5H choke and a 80uF film cap on each of the HT lines. I made use of the empty cans and put in a 18mH choke and 10000uF for the DC filament supplies. The circuit seems to be a constant current supply for filament with a LM317 which had about 20mVp-p ripple. After the mod which does not touch the signal circuit, I cannot measure the ripples with my equipment. The 2nd, 3rd, etc harmonics of the power supply noise are all gone. The SNR improved by 16dB and I cannot barely hear the annoying humming noise from the speakers. There's still a stubborn 60Hz noise from the FFT which I suspect is coming from the cathode which is from another DC regulator. But now I'm quite happy with the results.

Like @jslateiv said the sweet spot is around 8-10 o'clock of the volume knob to get minimal distortion, mostly consisting of 2nd harmonics. The gain I got was about -6dB to 0dB. 

Ok Guys, I spoke too soon about the hum being caused by the tubes. I bought a new set to tubes Tung Sol 6SN7GTB and hum is back. The previous tubes where all this started were Psvane 6SN7 Treasure MKII. Now the strange part is the 6SN7 tubes that Mick sent me do not hum. I have asked Mick if the preamp, he sent me, takes only one make and model of tubes. @jslateiv as you can see from my post I do not think its the gain issue. I could be wrong but lets see where this goes.