Distortion with ARC Ref 150 and Maggie 3.7


I have this problem that drive me nuts for quite a while. I purchased a like new fully balanced ARC Ref 150 tubes amp through Audiogon for my single ended only CAT SL1 Ultimate preamp and connected both with a RCA to XLR interconnect. It sounded okay with most recording but has awful distortion with certain recording specifically piano and vocal. Some of this recording happens almost on entire record but some only on certain musical passage. Most of the time with higher pitch or peak of music or higher volume.

For your information I listen to vinyl only most of the time and more on Jazz music. Other component listed as follow:

Turntable: Sota Nova, Tonearm: Origin Live Illustrious, Cartridge: Dynavector XV1-S, Step up transformer: Bob's Device CineMag 1131 (Blue) feeding directly to CAT's own phonostage, Speaker: Magneplanar Magnepan 3.7. Power cords, ICs, Speaker cable, Autoformer: Paul Speltz Anti-Cable.

Trouble shooting which has been done includes: checking preamp tubes condition and checking power amp bias. Since ARC claims their Ref 150 was design for balanced preamp only so I also tested by replacing it with single ended tubes amp but the distortion remain. As for the cartridge I believe I have done the alignment pretty accurate with the Mint's Best Tractor but not very sure with the azimuth.

While tested with my other 2 pair of speakers, one which has higher spec show the same problem while the lower spec one seems get rid of distortion. So I suspected the issue probably was with the new Maggie. Called the dealer and he performed a test with his transistor amp with no distortion at all. So he assumed my Maggie is okay. Is it true that the Maggie only good with transistor amps?

By now it leaves me with total confusion! Sincerely hope fellow audiophile here could give me some advice and save me from this endless misery !

Thanks very much in advance!
pakwong
It's pretty rare when a real problem like that faced by the OP is posted and a straight up creative solution is offered by an Audiogon respondent. Congrats, ZD, you found a high quality, zero cost solution to a thorny problem.
Id send the amp back to Audio Research for a look-see. I think thats where your problem is..
Stringreen, if you read through ALL of the above posts beginning with mine on 8-12-14, I think you'll conclude that there is nothing wrong with the amp.

Regards,
-- Al
Thanks Al for the detail explanation. Now I pretty much understand the fundamental of both signal type.

Can't wait to try the transformer with my CAT. Unfortunately I still did not received answer from either ARC, Jensen or SMc. Anyway my plan is try on a Jensen first.

Regards
If you plan on keeping the CAT SL1, buy the CAT JL5 amplifier. If you plan on keeping the ARC Ref 150, buy the ARC Ref5SE preamp.