Supratek Owners Thread

Long time Supratek user here. I owned a Cabernet Single since 2010. When I got it it was used and already had several issues. I told myself it was just common with tube equipment and I would fix it one day.

After 10 years owning and comparing it to a high voltage output DAC without preamp, I finally put myself to face the fact: The supratek just doesn't sound as good as without a preamp. And I also looked into the issues the unit has for so many years.

Frankly I was disappointed when I opened the unit. The two silver cans are empty and just for show. The unit actually uses PCB power transformers as output transformers.

I investigated the many issues with an oscilloscope. The right channel always had noise that felt like ground loop. Turns out it was a loose ground wire of the XLR connector to the center tap of the output transformer, probably due to poor soldering.

The right channel always felt louder to me, regardless how I swap the tubes between channel. Surely this was verified with a voltmeter and oscilloscope. It turns out the DHT filament wires were soldered in the other way round!

I also found the input tube clips when volume knob is pass 10 o'clock, which is just one third of the maximum volume! Still after so much tuning the phase of the two channels are still a little off.

The summary: if you plan to own a supertek, be prepared for a very involved experience. Either communicating with Mick or do it yourself as a project.. 

@Alpha_lam 

I find it interesting that you have one post here on Audiogon, and it's a negative one. Not trying to pick a fight. Just find it interesting.

Also, I note that you bought your Supratek used. How can you be sure that the issues you found were due to the way the equipment was built originally? Might the previous owner modified it or had it worked on by a someone who didn't know what they were doing? Isn't that possible? 

The purpose of *this* post is simply to reinforce my satisfaction with my Supratek Cortese, which I have now owned for about two years. It sounds superb and I doubt that I will ever replace it. I'm *not* saying there aren't better alternatives out there. I simply don't think I could afford them. 

Best regards,
Markus

Hi Markus,

As this thread is titled the owner thread and I thought my experience would be interesting to someone who owns a Supratek or planning to get one.

Don't get me wrong, I still like the preamp and it is good looking. And frankly my hearing could only tell a small difference between having the preamp versus not. That's why I kept it and continued to use for more than 10 years.

My intention was to present facts about my experience, which is the workmanship left a lot to be desired. And that caused actual issues in the sound. Namely loose wire and switched polarity of the electrolytic capacitor. It would be quite unthinkable that the original owner decided to solder the wires in opposite polarity. I am trained as an electronic engineer and tell the unit was not modded.

Anyway take it anyway you want, I still plan to work on the unit to further improve it. I'm looking forward to connect with fellow owners and trade ideas about tube rolling and modifications.

Last night I fixed the incorrect polarity and it corrected the volume imbalance issue on the Cabernet preamp. I plan to replace the electrolytic capacitor for the DHT filament and adds a film capacitor in parallel. Also planning to replace the TJ 101D with a set of Linlai.

Update on my Supratek Cabernet pre, it is packed down, ready to being shipped back to Mick for warranty repair. Hopefully I will have it back soon in full working order.
Will keep you updated.

@alpha_lam  gotta disagree with you on the  'if you plan to own a supertek, be prepared for a very involved experience',..   you bought a used unit and have issues, you are in the minority of owners out there.  If owning a Supra was 'involved' Mick wouldn't have a business. Especially a biz with tons of units out in the field an such a loyal following.   Yes, stock units will present issues from time to time and yes when I have repaired,  I have found a bad solder joint here and there,  it is not the norm though and honestly they have been much older units that have had some very obvious use and been banged around a good bit.  His soldering is excellent and rarely do I ever find bad joints though on occasion I will.   Regardless,  it happens anywhere in this business and more importantly Mick covers any issue on stock units for their LIFETIME.  That's pretty amazing considering the size of his operation.    I'm not aware of him using electrolytics in the cathode of the DHT, much less anywhere in the circuit save for on PS regualtors or B+ filtering in early models.  I have worked on these units with models going all the way back to 2005,..  always film caps and always one on each side of the DHT filament above the center tap.  It sounds as if this unit was modded and someone didn't know what they are doing based on your description.  When I repair a unit,  you would be hard pressed to tell that the circuit (solder joints)  are not original and had been repaired.   It is entirely possible the unit was modded (which it sounds like from your description).   Not to mention that when that unit left Mick's shop,  I can almost guarantee that it did not have the issues you experience.  That type of imbalance would have been easily caught while Mick QC'd the unit.    Anything is possible so I'll stop short of saying it isn't possible,  but I do want to correct you on your idea that Supra's in general require effort to own.  That is just not true as they are created and made correctly 99% of the time.