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
bifwynne
2,206 posts
 
Thanks Al. I take your point about using a transformer to connect an SE output to an XLR input. As I have admitted many times, I am not a EE-type, so the theory and application is way north of my pay grade. I suppose I am just biased (pun) about inserting artifacts into the signal path.

You may properly ask why, if I really feel that way, did I insert a DEQX digital time and EQ correction device in between my linestage and amp? My response: perceived sonic cost versus perceived sonic benefit. So far, I believe the latter significantly outweighs the former, ... I hope and think?????

Thanks for the electronics lesson. :)
onhwy61's avatar
onhwy61
5,218 posts
 
Almarg, we will have to disagree about how appropriate, or more importantly, how helpful someone's recent comments on this thread have been. So many people have offered advice and guidance trying to solve the OP's situation. I didn't see the point of chiding or berating him. When I did the same thing to that poster, not surprisingly he didn't like it. Was what I did petty? Borderline. However,
This is an open forum and I'm contributing my .02.
pakwong OP
38 posts
 
I admit that I didn't do enough research before buying a balanced only amp for my single ended only preamp. So I'm the one that should be blame. However, it's a rare case when an adapter cable couldn't solve the connection problem. Anyway, I hope the negative comments on ARC shall end now.

Al, I didn't have the chance to audition the JL5 with my system. But I have friend whom I can trust to build confidence on the CAT amp. I only have moderate size room(10'x14x'17') and didn't go for high SPL while listening, so I think the 100 watts JL5 is good enough. I'll still keep the Ref 150 for comparison. If the Ref 150 is superior to the JL5, I don't worry about selling it as I bought with good price and there are plenty of CAT's fan down here. Perhaps I have same "problem" as Bifwynne, just don't feel comfortable with something else in the signal path!

Best regards,
Pakwong
almarg's avatar
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almarg
9,670 posts
 
Thanks for the update, Pakwong. Sounds like a good plan, which will greatly reduce the risk I had been envisioning if the CAT doesn't work out.

BTW, although I could be wrong, I had been interpreting Knghifi's comment about doing homework before purchasing to be in reference to the CAT purchase, not to the ARC purchase. As you said, it's very unusual for a balanced amp to not be able to work in a reasonable manner when provided with an unbalanced input, so that "oversight" is certainly understandable. And since you have a fallback strategy which minimizes the risk I and perhaps he were envisioning regarding the CAT purchase, it seems like all the bases are covered (to use a baseball analogy).

Continued good luck as you proceed. Regards,
-- Al
knghifi
1,668 posts
 
Almarg, until Minorl post, I felt tone of the thread was blaming and questioning ARC design which was unfair IMO.

So I want to make a GENERAL SUGGESTION best do pre-purchase homework to avoid compatibility issues post purchase so I guess it applies to both Pakwong ARC and CAT experiences.
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