Audible Illusions Modulus 3 Audio Research SP-11

"bubbled edges"

To me that says you've got a microphonic tube, to do a simple test (without an oscilloscope on a test bench).

Take the lid off turn on the whole system. Turn the volume control up around loud level.

Get someone to listen close at the speakers left and right. While you flick each tube with you finger nail.

If they hear a 'bonk" out of your speaker/s then this tube is getting microphonic.

If it is really bad then it can in the worst case start a continuous feed back bong happening, and you may have to turn the volume down to stop it.

Cheers George

I've owned a Mod 3 and two different ARC preamps, tho neither was an SP-11. IMO, they fall at opposite ends of the spectrum. ARC gear can get a satisfying 3d presentation, but never gets tubey in a dark or romantic sounding way. Tonality stays neutral enough to feel very much like the best solid state gear.

My AI Mod 3 was darker, thicker thru the bass and lower mids, and all together a tubier sounding piece. It was definitely less neutral. I liked both, but the AI was IMO more personal taste/system defendant. I'd think that most folks would have no problem choosing one or the other.

Stefanovitch...so you saying that you currently own (4) ARC SP-11's? I find that kinda hard to believe?

Also ARC never made a SP-11MK3. They made a SP-11SE (Special Edition) out of the last 50 or so SP-11MK2 models, but never a MK3.

I am really confused by your initial post if you already have the ARC unit(s)? Not sure what your end game is here?

The Modwright LS100 blows the Modulas 3A away.
I owned for several years very unreliable and it
takes months to get back from repair.
Sound is adequate but no magic!

Elliotdrum it is possible the Modwright LS100 is a better
sounding unit compared to the the AI 3A but at a far
greater cost. I have an ARC SP11 MKII I purchased several
years ago and yes it is better sounding than the AI 3A but
try to find one under three thousand used. I would prefer
to say all the above mentioned preamps are great in their
own right but go about their business in different ways and
depending what your trying to match them up with, will
determine what you end up with.