ARC Ref 75 vs. Ref 75 SE

Bifwayne wrote....Have tubes arced and taken out bias resisters?? Yes!! But how often?? Maybe once or twice a year. And since I've been using KT-120 and KT-150 power tubes, tube arcing has been a very rare occurrence.

Once or twice a year?? You call that not too often. I call it unacceptable. Audio Research are not exactly new to the game.

Brf ... tubes arc. It's what they do. The problem isn't with the amp ... it's about the nature of tubes. The only fair push back point is that ARC doesn't use circuit breakers. I can't answer that question because I'm not an electrical engineer. All I can do is pass along what ARC told me. Take it FWIW.

Bifwynne, having an ARC repair tech nearby does make ownership of their power amps more reasonable. Imagine having to ship a heavy power amp to Minnesota every time a tube blows! In his writings on amp design and building-in reliability, Roger Modjeski made an analogy something like this: What if a car maker designed and made his vehicles such that when a tire blew (which is likely to happen) the suspension was sacrificed? And that this design choice was made because to prevent damage to the suspension in the event of a tire blowing, the suspension's performance was deemed to have to be slightly compromised. A fair and reasonable trade-off? That's for consumers to decide. Roger claims (of course) that his design protects the amp from damage by tubes without compromising it's sound quality. He states that the idea of using the circuit parts themselves to protect the rest of the amp from damage by it's tubes is just plain, bad engineering. Inelegant, at least!

Tom pointed out something else in the ARC amps---the burn marks on the circuit board, around the tube sockets. Mounting power amp output tube sockets on a circuit board = a very bad idea. In the mid-80's I went to hear Bill Johnson talk when he came to a local dealer. He mentioned that the ARC products were built with a projected lifespan of twenty years. At the time that seemed like an eternity---it doesn't now.

Of course, if you own ARC power amps and haven't had any problems, non of this matters. My history with ARC began in '72 with me turning on my brand new SP-3 pre-amp, fresh out of it's shipping carton. It immediately made a POP! sound, and I had my first smell of a fried resistor. Welcome to ARC ownership!

Bdp24 ... I respectfully disagree with your views about modern ARC amps. I think your car analogy is ridiculous and simply not fair.

As to the mysterious Mr. Tom's comment, I don't recall ever seeing burn marks on the circuit boards of any of my ARC amps. Nor do I understand Mr. Tom's comment that mounting power tubes on the circuit board is a bad idea. Where else should they be mounted? Btw, is Mr. Tom an electrical engineer. Does he design and manufacture Class A electronics??

Just an fyi, ARC has been in business for over 40 years. That stands for something to me.

Your mid-1980s Bill Johnson story is not relevant. ARC gear has come a long way since 1985. And your anecdotal comments about the SP-3 are similarly not relevant nor persuasive. The SP-3 was first introduced in 1972 and was later modified several times in the 1970s.

Nowhere do you mention that you actually listened to modern ARC gear. So I'll ask you now. Have you ever seriously auditioned a current ARC Reference amp such as the Ref 75 or Ref 150, or the Ref 5 SE linestage?

Finally, I will conclude by saying that at some point, our hobby comes down to very subjective tastes. If you seriously listened to modern ARC gear and walked away underwhelmed, I would respect your opinion. However, bashing ARC for its design choices concerning bias resisters is just a bit over the top for me.

Cheers,

BIF

Bifwynne, Do you check the bias of your tubes regularly and replace them after about 2500 hours or so? The reason I ask is that seems awfully frequent to have problems.

I have owned ARC gear since the late 1980s. Everything from a D70 to my current Ref 110. In that time I have had a tube take out a resistor twice. And then once in the early 1990s I had to send my Sp9 to ARC because it would not come out of mute. That is it, no other problems. But I check my bias about once a month or so to make sure everything is fine. Tubes can drift, especially when the tubes are new.

Having a problem twice a year seems way to frequent.