Upscale Audio -- Tubes and Reliability


Just wanted to get this out there for the benefit of A'gon members who own tube gear. All of my gear is ARC tube equipment.

I've been buying tubes from Kevin Deal - Upscale Audio for quite some time. Most recently, I bought a tube set for my amp. One of the KT-120 tubes didn't bias well. Kevin replaced the tube -- no questions asked!

In another case, the common carrier screwed up the delivery of a tube order. I left a VM for Kevin. He returned the call within 24 hours and made the situation right.

As an fyi, Upscale Audio burns in their tubes for 72 hours before testing and matching. Yes, there have been some glitches here and there, but so far Kevin has always come througth and made good.

Although I still buy some tubes from ARC, on rare occassion a few tubes blew shortly after purchase. Yes . . . ARC was 100% reliable in making good. Problem is ARC charges twice the price Upscale Audio charges.

Although I suppose one could argue that an advantage of buying from ARC is that if a tube goes bad and takes out some passives, ARC will pick up the tab. That may be true, but what good is that guarantee if you have to pack up your equipment and send it back to the factory.

In my case, I am fortunate because an ARC authorized tech lives near my house and makes house calls. True! As I reported before, one time a power tube blew and took out a bias resister. The tech came to my house and replaced the resister in about 45 minutes.

So for me, I guess the bottom line is this: if an UA tube goes bad and takes out some passives, is it worth the price savings to have the tech come out to fix the affected gear. So far, the price savings has justified the risk.

FWIW.
bifwynne
Bifwynne. Well obviously being someone who services ARC under warranty I'm a bit biased. Did I just say that? There are quite a few ARC amps that I don't recommend people re-tube and bias unless the bias voltage points are outside the amp away from high voltage traces. These amps run at around 400Vdc and pack quite a wallop as Steve found out! Imagine someone with a weak heart or an unsteady hand, or improper test probes attempting to set bias. All it takes is one slip, and a trace can blow right off the circuit board and leave a crater in the board just for starters. Is paying for a few hours of labor worth that kind of dangerous exposure? I leave it to each person to answer that.
conrad-johnson supplies an all plastic screwdriver (just a thin plastic rod with the ends flattened) to use in biasing its power tubes. Would something like this solve the problem?
If I recall, Keven said he would not sell tubes for VT100 Mk II amps because of the design. He did not specify electrical design or physical design. I have re-biased this amp and I understand the dangers. I trust myself to do it without shocking myself. Perhaps I need to talk to Kevin in more detail to find out what his actual concerns are.
Gary (Hifigeek) is right on as usual. I own an ARC VS-115 amp which has bias test jacks OUTSIDE the amp. The ARC supplied plastic screw-driver thingy is a very safe tool to use to access the bias pots. I bought the metal screen tube cage, but will NOT pull the top panel that covers the works in order to screw the cage on. I rest the cage on top without screwing it on just to protect the tubes from an accident. It's just too damn dangerous to expose the electronics!

I just re-tubed my Ref 5 and VS-115 using Kevin's tubes. The old tubes from the Ref 5 and VS-115 had over 3000 hours on them. Major, major improvement!!
Regarding using the KT120 tubes in VT 100 amp. As some of the responders of the OP will remember I have just changed over from 6550 to the KT120s. (check older posts from about a month ago). Got them from tube depot here in Canada, but they also ship to USA. They are indeed a heavier tube and overall more robust construction, but fit well in the amp with enough clearances all around and very easy to bias. After a few days burn in, they sound very nice and I'm pleased. The horizontal mounting issue may be valid but I don't think so really. The socket pins on this amp are TIGHT. Also, they seem to run a little cooler but that might just be my imagination....