Question For Those In The Know About Audio Research Power Amps


I've flirted with ARC gear over the years, owning an LS5 preamp some years ago but never trying their power amps.

I've always had the idea that ARC tube power was a little lean and sterile and not in the Conrad Johnson style of presentation, with tube bloominess and that glorious CJ midrange.

Of course, I realize not all ARC amps sound the same and that some are warmer and more tube-like than others.

Anyway, I recently purchased an ARC Reference 110 SE, and really like a lot about what it does. Stage depth and imaging are excellent, it's detailed and dynamic. As if to reinforce the negative stereotype, it is a little on the lean side, but not horribly so. It's a musical amp overall, and that's what counts.

Questions -
1 - this was sold to me as a "SE" model, which I understood to mean that it was modified to allow the use of KT150's, which my amp has. Was this an 'official' factory modification, and if so, is the SE designation something which can be used when I try to resell the amp? I can't seem to find others running KT150's referring to their amp as the 'SE'. Or is the SE designation relating to a different upgrade altogether? 

2 - is this 'SE' amp backwards compatible with any other tube types?

2 - what's the next model up from the Ref 110 that might exhibit a little more tube bloom (warmth) than the  Ref 110? I wouldn't want to lose the wonderful transparency and soundstage ability of this unit, but if it could be fleshed out a little more then that would be a plus. The amp is only a couple weeks old, to me, so I'm still trying cables and supports etc, to see if there's more to be had, but I would say at this stage that this is a pretty amazing amp.

Any insights would be appreciated!

Thanks
Rooze

128x128rooze
Post removed 
I have owned ARC amps for fifteen years, first a NOS VS110 that some wealthy guy just kept in his closet for about ten years as a spare before selling it to me and then three years ago moving up to a Ref 150SE paired with a Ref 6.
My VS110 killed tubes semi-regularly. I bet I went through an octet of various KT88’s or 6550’s annually. I also blew the protective resistors two or three times-just one on whichever tube failed. At some point on the advice of a regular on this Board, I upgraded the coupling caps, and the difference was subtle.
I bought my Ref 150SE as a dealer demo with only 30 hours on it and yet ironically enough, it shipped with one bad KT150. I replaced it with a single KT150 from Upscale Audio after providing then with the readings I was getting on my Fluke from the other tubes so that they could provide me with a matching tube. This is not optimum, but I have had no problems since with almost 1000 hours of use.
Keep in mind that the VS110 provided for biasing each output tube. ARC went to slave biasing with the Ref 150SE-you can only adjust bias on four of the eight KT150’s and then just hope that the tube coupled to the one you are biasing falls into acceptable range.
I immediately searched out a new octet of KT150’s to have as a back-up when I bought the single tube from Upscale.
Over the years I have purchased tubes from many suppliers, all of them "established" in terms of reputation. Though I have never met him, I consider Jim McShane to be the elite among the elite of tube authorities. Jim has little to say that is positive about New Sensor’s QC with the Tung Sol KT150. He flat out refused to source me an octet saying that it was not worth the trouble to buy a huge batch and sort out the duds from the winners. I eventually sourced a back-up octet from Tyler of TCTubes who was willing to buy the huge batch and sort out the better tubes and then return the bad ones.
I believe that this, in part, explains ARC’s very high prices on the KT150’s that it sells.
Btw, when I needed a back up set of KT150’s I sent three emails to ARC and they never responded to a one of them. From my fifteen years of owning ARC I can tell you that they go in spurts of being responsive and non-responsive. Their new business model is to try to insist that you engage a dealer rather than bother them.
All of this drivel, and I have not discussed the sound of the Ref 150SE with Ref 6. I believe the choice of XLR cables is critical (and you do not want to compromise with a single ended-only preamp and the true balanced Ref 150SE). I am using Cardas Clear Beyond. ARC warns the user in their manual that running balanced and using the best XLR’s one can afford is critical. The sound is definitely not of the "melting midrange with one note bass and recessed highs" that is common with classic tubed gear. It is very close to sounding like the best solid state. My Ref 6 and Ref 150SE have been perfectly reliable-after the one dead tube described above. They are a joy to use. I do hate removing 16 or so tiny set screws to remove the amp cover to check and adjust bias. The contact points for the bias adjustment are awkward to reach-so that aspect of "joy to use" is not so joyful.
But that aside, they together seem to push the aspects of a somewhat artificially widened (but not deepened) soundstage, pin point imaging, great dynamics (but not micro-dynamics) and bass slam at the expense of liquidity, tone, and timbre. I am quite content with the gear all the while not being in love with ARC now that they have been acquired under the McIntosh Group umbrella. For example, the dealer I purchased my amp and preamp from are both no longer ARC dealers. So when ARC tries to hand me off to "my retailer", I find that problematic. Also, ARC bet the ranch so to speak on the KT150 and as I said above, for the last three years New Sensor has not been able to get it’s act together to insure quality control.
@riaa.......my only source is their website.  I thought models still listed in their product sections meant they are current models in production?


Nope. 150/250's haven't been made since last year. All their remaining inventory for those models was wholesaled out to various dealers who are now offering them for 50% off or more. I know Audio Salon in Florida has many of the 250SE and Paragon in Michigan has some 150's,
@fsonicsmith response it very telling.  ARC goes through many tubes in order to produce "matched" tubes.  they probably re-sell they non passing tubes to other's.  however, that says a lot about Audio Research and their level of expected excellence.

I made the mistake of purchasing tubes for my REF 250 amps from a "reputable" tube supplier in Southern California.  They claimed that the tubes were matched and to specifications for the REF 250 amps.  Not cheap, but much less than what Audio Research sells them for.

Well, approximately $3000 in repairs later, I learned my lesson.  Tubes failed after they were correctly biased.  I was sitting there and actually saw the tube go up spectacularly and the circuit board.  It took out other parts of the circuit, not just resistors.  It costs $3000 to repair. 

If I had purchased the tubes from Audio Research directly, they would have repaired the amp free of charge if their supplied tubes caused the failure.

The authorized Audio Research repair center that did the repair work, told me to never purchase tubes from that supplier as although they claim that they are matched and to specification, they are not.  They proceeded to test all the remaining tubes and showed me the readings vs Audio Research's standards for that amp.  These brand new tubes weren't even close.  They were way outside the acceptable range. Also, when the tubes arrived, they listed clearly on the labels what the specs were.  That is so wrong.

I never contacted that tube supplier, because, what is the point?  If anything they would have replaced that one tube.  But no way would they have repaired the amp.

When I repair solid state amps and I have to purchase transistors, I typically have to purchase many just to find matching ones and also ones to match the "good ones" still in the amp.  Often, I just replace all the transistors, just to be safe.

So, I can see why the costs of tubes from Audio Research is so much higher.

enjoy