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

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Since these threads live online for all eternity, I thought I’d post an update on the KT150/SE issue.
 I contacted ARC yesterday via their website and they responded very quickly and courteously. ARC say the stock Ref 110 can run KT150’s without the need for any modifications. I know this conflicts with at least one statement in this thread. [@docknow]So there is no official Ref 110 SE and apparently no need for one. Obviously my next move is to decide what to do about my interaction with this particular dealer, who upsold this unit over a stock Ref110 on the basis of mine being a modified SE version and thus a “better deal”.
They also stated that “the SE upgrade was done in-house”, further confirming their narrative that this unit was modified from stock.
For the record, this really is a great sounding unit, and, when I’ve optimized the cabling, will work very well in my system, should I choose to hang on to it. Frankly, it’s tainted my experience somewhat, knowing that I was misled, so I will have to see if that passes, or not.

I run a small review website at www.AudioResurgence.com and will post additional information on that website as I untangle my interaction with the local ARC dealer.

Thanks for all of the helpful input. I’m still interested in power amp recommendations from ARC, if you have them.

Rooze
Your Thor amps are just wonderful.  A couple of internal upgrades and they would give you exactly what you want. Do you need more power? Love those Thor mono-block amps. Very musical with that rich and full tube sound. 
Well if this ARC dealer ends up taking the unit back and refunding your money because he flatly mislead you (I would make sure ARC knows all about it), then the Ref 150SE becomes possible - its a great amp.  If you can get by with less power a used Ref 75SE is awesome.  If you're considering the Ref 150 you might also consider what I'm running right now and enjoying tremendously - a GS150.  My only regret is that I didn't try ARC tubes earlier.  I'm fairly certain my next temptation will be to replace my Aesthetix Janus with an ARC Ref 6 preamp but not quite ready at the moment to make that particular expensive jump especially when I consider the fact that I'll need a new phono stage as well.
One thing to take into account as you sort this out is that some unapproved "mod" by the dealer (if in fact the dealer did anything and isn't just blowing smoke) may render whatever factory warranty you otherwise have invalid. One possible approach is to ask ARC to investigate this since it is their "franchise" at stake. In the old days, ARC was pretty intolerant of shoddy dealers. Ultimately, it may require ARC to open up the amp and inspect it for themselves to see what was done to the amp. That means you'll be out of an amp while that process is going on- perhaps ARC can arrange a relationship with another dealer or accommodate you directly through the factory while they address this. 

First, I'm pretty certain that the factory warranty for REF 110 amps is long past. 

Second, this is a clear example of us needing to do our homework before purchasing.  a quick initial inquiry to Audio Research before purchasing would tell one whether a REF 110 amp was offered as an SE model.  It also would address the use of KT150 tubes.

Third, most Audio Research amps were not designed to accommodate KT150 Tubes.  This has absolutely nothing to do with allowing customers to tube roll.  It had to do with some pretty extensive modifications to equipment to allow for the extra power handling capabilities of KT150 tubes.  Transformer upgrades are one thing that the REF250 amps required among other things.

Since KT150 tubes didn't exist at the time the original amp was designed/built, it is hard to blame Engineers for not allowing for the amp to be used with KT150 tubes.  You design around certain parameters. It can't be open ended designs.

The REF 110 amp in and of itself is a very nice amp, even to today's standards.  If Audio Research tells you that it is okay to use KT150 tubes in it, that is great.  However, I do have an issue with the "dealer" telling you that it was upgraded to SE status.  Since upgrading to SE status for most Audio Research Amps took way more than just changing tubes.

Enjoy