2. amps-preamps
  3. 1407646817

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
pakwong OP
38 posts
 
Jtimothya, I didn't use adapter. It's a specially build RCA to XLR interconnect soldered according to many cable manufacturer's standard for RCA to XLR connection. I've two different set/brand of such cable but posses the same problem.
pakwong OP
38 posts
 
Martykl, many thanks for your input. It sure help to further justified the issue with ARC amps. But you didn't mentioned how you finally addressed the issue. Did you changed to a balanced preamp or use a transformer?

Regards
pakwong OP
38 posts
 
Bifwynne，FYI after some serious listening, I do aware that the distortion were clearly less obvious bypassing the Zeros and used the 4 Ohm tap from the Ref 150 to drive the Maggie. Now the issue has narrowed down to the balanced and unbalanced interaction.

Regards
martykl
3,578 posts
 
Pakwong,

I switched out a Joule Electra preamp for an ARC LS 25 line stage. The sound was a little less romantic or "tubey", but the distortion disappeared. I'm not suggesting that you go this route (like all gear, the ARC stuff isn't for everyone), but a true balanced signal is a MUST for your amp.
zd542
5,339 posts
 
Thanks for the response Al. Your explanation was very good.

Martykl,

Did you happen to connect the Wadia directly to your amp? Doing so will allow you to get a feel for how well your ARC can drive the speakers. I suspect that once you get is set up properly with a balanced signal, it won't have any problems driving your speakers. Not only that, its just a very good sounding amp. If it were mine, I wouldn't be so fast to get rid of it.
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