Audio Research SP-11 MK2 ...

I owned an SP-11 mk II for a number of years. In its time it was one of the best preamplifiers available, and it gave me a lot of pleasure. It is still good, but I believe it to be surpassed by the better preamps out there now (I replaced it around 1990 with a Jadis JPL/Vendetta SCP-2B combination, as the tubed JPL was more to my liking and the Vendetta was a quieter and better phono stage than the ARC's). It is not really as liquid or dimensional as a great tube preamplifier, and its solid state circuitry is not as good as more recent mainly solid state preamplifiers I have heard, like the Lamm L2 (the tube in that unit is in the power supply) and Boulder units. It's very good as far as vintage equipment goes, as Elizabeth says, and it does have some very useful features that you don't find in modern units (especially for listening to vinyl, including a mono switch and a knob in the front for some cartridge loading). I have found it interesting that it does not seem as prized in the used market as the SP-10 that it replaced in the ARC line.

I recall the ARC SP-10 having legend status back in the 80s. That probably carries down through the years.

Minorl's SP-11 now sits in my system deep behind the Orange Curtain (South Orange County, CA) and I remember listening to his system a few years back when he was kind enough to do an A/B session to help me in my decision making process. The SP-11 held up very well against his Ref 3.

I use the SP-11 quite extensively now, but I do prefer my SP-10 mki for analog playback (60% of the time) and the SP-11 for digital playback (remaining 40%). But then I get my jollies moving power sources and front ends around every 3-4 months (not!). If there was a way to extract the best of both preamps and cram it into one, I'd be in audio heaven...

Elizabeth's adventure with her SP-15 is intriguing and I have never had the oppportunity to audition one. That would be a fun listening session, an SP-10, SP-11 and SP-15 shootout.

I've worked on both the SP-11 and the SP-10 extensively. The SP-11 is probably a bit quieter in the phono stage then the SP-10. Both are marvelous preamps. Both bench test very well. Before comparing a new preamp with a rather old preamp one would have to recap the old preamp. That way you are comparing apples to apples. After 15-20 yrs, both preamps should be recapped before any serious listening comparisons take place.

The SP-10 was the last full-on tube preamp ARC made and was the zenith
of its 'old' sound. I owned one for many years, and its phono section was
glorious for the time period. A good clean example that has been brought
up to spec is probably fine, but it will be noisy as a phono preamp. I had a
devil of a time, back in the day, finding tubes that were not microphonic.
It was, and still is, a classic, much like the original SP 3 (which I also
owned, way back in the day). By today's standards, both are old school and
the SP3 would probably be considered very colored (it's been a long time
since I heard one), but in its time, it was a revelation, compared to
everything else.
But... since you asked about the SP-11, at the time, lot's of folks upgraded
from the 10 to the 11. The 11 was probably far quieter, but lacked the
warmth and rounded 'old school' tube sound of the 10. I think that this
actually stimulated the market for the SP-10 (at least the mkii, I never heard
a mk i). The 10 is a classic, in large part because of the sound it
represented. ARC seemed to go for a more modern, less 'tubular' sound
after that. Interestingly, the 'Ref' level stuff that ARC makes, in the form of
separate line stage and phono stages, seems to have gone back to tube
rectification and/or regulation. I just took a quick look on the ARC site, and
the preamps with integral phono stages all seem to be hybrids, following in
the path of the
SP-11, rather than the 10.
A low output MC would be a beeyoch on the SP-10. (Believe me, I tried
and
when I finally switched to horns, I had to get rid of it, it was just too noisy).
But, with low efficiency speakers and a higher output cartridge, my money
would probably be on the 10 (and i think they command a premium
compared to the 11, although I'm guessing- haven't looked at market prices
for these in a long while).