2. amps-preamps
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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
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almarg
9,670 posts
 
As might be inferred from this post I made two days ago, I am in essential agreement with Minorl's comments. And especially with:
My reading of the posts, indicates that the OP used the Jensen transformer and the resulting sound is wonderful. Problem solved.
The old saying "if it ain't broke, don't fix it" comes to mind. (In this case, of course, the amp is broken and in need of repair, but that is unrelated to the question of whether or not to replace it). Certainly the JL5 will be a good match with Pakwong's preamp. But can anyone say with a high degree of confidence that it will be a better sonic match for the Maggie 3.7 speakers than the combination of the ARC amp and the Jensen transformer? Or that its 100 watt power capability will be adequate, considering that a VTL amp rated at 50W triode mode/100W tetrode mode into 5 ohms is not?

Pakwong, hopefully you can audition the JL5 in your system prior to committing to a purchase. Otherwise, it seems to me that you would be bringing significant risks into play, in an effort to eliminate what may be from a subjective standpoint (as opposed to a theoretical standpoint) a non-issue.

Good luck. Regards,
-- Al
zd542
5,339 posts
 
"10-01-14: Daveyf
So Zd542, you want to expand on why you believe what i posted is incorrect.
I am all ears."

No. It was my post that was incorrect. My post was meant as a humorous comment for someone else in an entirely different thread. How I managed to put it here, I have no idea. Sometimes I'm amazed that I don't kill myself just getting out of bed in the morning. Sorry.
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daveyf
2,926 posts
 
Zd542, Thank you for your retraction. All good.
knghifi
1,668 posts
 
Minorl +1
pakwong OP
38 posts
 
The fact is, though having trouble with the Ref 150, I'd still recognized it as a great amp after solving the matching problem with the CAT preamp. But as recommended by some of you here, I feels that the Ref 150 would be better matched with a true balanced preamp as the design concept suggested, in order to achieve the amp's full potential. If the new ARC preamp has build in phono stage like the good old days, I would have gone the ARC path!

Regards,
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