ARC Quality Issues Ref75 Ref5SE Ref10

Decibell ... of course I can't dispute your sad tale. If it happened ... it happened.

For the record, all of my electronic gear is ARC. Never had a problem, save for an occasional and very rare pesky blown bias resister.

As I am sure other owners of ARC would attest, every ARC unit comes with a QC card that shows all the QC checks that every unit undergoes. Even Bill Gehl, ARC's official listener, performs a listening test before any unit leaves the factory. And this applies to new units that come off the production line as well as units that go in for repair.

Sorry to read about your troubles. But for the benefit of other readers, Decibell's ARC troubles are a rare anomaly. I hope ARC puts everything in proper order for Decibell.

Who jinxed me? I just blew a bias resister. :(

The ARC tech is coming out on Tuesday.

@Jasper ... let me try to translate your "high-English" vernacular into American. As a general matter, ARC says the "slave tube" bias spec should be between 57 and 73 mV assuming the "set" tube bias is set at 65 mV. If you have a tube that is presenting a bias of 5 mV, probably a blown bias resister. I assume your talking about a "slave" tube.

Do I understand your post correctly that you bought a GS-150? If so, I anxiously await your comments ... after break-in.

Meanwhile, I anxiously await for my local ARC service tech to make a house call tomorrow to replace a blown bias resister. Bummer ... no music for 2 days.

@Smoffatt ... very troubling news about Terry Dorn. As an ARC "oldhead," I recall the great customer service from the folks you mentioned in your post, especially Len. Not sure what to say. I am greatly troubled to learn that ARC "may" be shipping shoddy product. I hope your experience is that one in ten thousand case.

Jasper ... my local ARC just left my house. My Ref 150 sounds great!!! Two bias resisters on the same tube blew. No surprise really. The tubes have almost 2000 hours of use on them and they are ready for a replacement. Maybe KT-150s if this stupid KT-120/KT-150 enigma is "officially" resolved.

Your solution is NOT about using more "robust" bias resisters. The problem has to do with arcing inside the tube itself. Although new tubes can arc, older tubes are more susceptible because of the natural process of heating (expansion) and cooling (contraction) that occurs when the unit is turned on and off.

I am dubious that an authorized ARC repair tech will replace a burned/open bias resister with anything other than original ARC spec. It may seem crude, but one of the functions of a bias resister IS to open if the tube arcs. It protects the amp like a fuse.

Tsushima1 ... your point is beyond my technical pay grade. Maybe Gary (Hifigeek1), Al (Almarg) or Ralph (Atmasphere) can explain why ARC uses bias resisters that handle only the rated wattage so chosen.

Again, from a non-techie perspective, I surmise that ARC is using low wattage bias resisters as a fuse and wants a quick "blo" to protect the rest of the circuitry if a tube arcs.

If I knew what I was doing with a soldering iron, I would do the repair myself. It's actually quite simple and low tech. Just clip out the burned resister, but leave a little stub sticking out if the board. Then soldier in the new resister to the stub of the old resister. Took the tech about 20 minutes start to finish.

The ARC tech also checked the other passives in the tube pair to make sure they were still in spec --- they were.

Tsushima1 ... this is NOT a big deal. You wanna own a tube amp ... it goes with the territory.

Btw, I understand from older threads that the reason ARC doesn't use circuit breaker type devices in the bias circuit is to limit the number of artifacts. Even still ... hard to believe that a fuse or circuit breaker in the bias circuit would make much of a difference in sound quality. But as I said ... this is above my technical pay grade.

Thanks Ralph .... sure wish ARC would get where you are.

Pushing a button or replacing a fuse makes a lot more sense to me than calling my local ARC tech. I am dubious that if ARC did blind testing on a "with and without" basis, that Bill Gehl, ARC's official listener, could tell the difference.

Oh well ... in the meantime, just glad the ARC repair guy is a short drive away.

Ralph ... my bad. Thanks for the name correction.

Knghifi ... agree too. Trying to figure out what the story is with the new GS-150 amp. On paper, except for using KT-150s, it specs identically to the Ref 150. Check out the ARC web site. Oh ... it also has a new skin.

Anyone have any idea what else changed. One item may be that the GS-150 uses a two tap output tranny: 4 and 8 ohms. The Ref 150 has three taps: 4, 8 and 16 ohms. I patiently await the revival of 16 ohm speakers.

So maybe the GS-150 changed out its output trannies??? Anyone have any other info to share about the GS-150??

Happy New Year!

BIF