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
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,
knghifi
1,668 posts
 
10-04-14: Pakwong
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!
You should do your homework before and NOT after the purchase.

CAT makes great amps so you will be happy but it doesn't sound like ARC. They are different and not superior to the other. GL!
onhwy61's avatar
onhwy61
5,256 posts
 
In a free society a person should be able to do his homework whenever he wants to and it's nobody's business but his own.

As others have pointed out, it's questionable why ARC makes amplifiers that cannot operate correctly with single-ended sources.
knghifi
1,668 posts
 
10-04-14: Onhwy61
In a free society a person should be able to do his homework whenever he wants to and it's nobody's business but his own.
Are you serious? You have issues with my suggestion?

I could care less what Pakwong does with his $$ and problems. This is an open forum and I'm contributing my .02.

As others have pointed out, it's questionable why ARC makes amplifiers that cannot operate correctly with single-ended sources.
Because it wants to?? In a free society a company should be able to produce whatever it wants. They stay in business if there are demands, otherwise bye bye.

Also in a free society a person can buy whatever they want. If they don't like ARC's approach, don't buy it. Again, if you do your homework pre-purchase, it will save some headaches.
bifwynne
2,206 posts
 
Just read the last 5 or 6 posts. I posted a few comments a while back. Two points.

First -- Yes ... it is true. The ARC Ref 150, and presumably Ref 250, are designed to accept only a balanced (XLR) inputs. Not an SE (RCA) type. If you can rig some contraption to somehow do an end-run ... all the power to you. I own an ARC Ref 150. The last thought that would come to my mind would be to jury-rig (sp?) that type (or any type) of similar gizmo.

Second -- I've said this before and I'll repeat it once again. Maggies are power hogs.

I think Maggie 3.7s deserve a lot more juice than the Ref 150 can deliver. I'm sure the Ref 150 can drive the Maggies to an "ok" SPL, but not to the point where the 3.7s will open up and sound their best. I seem to recall that many years back, I had a similar conversation with either Len or Kal at ARC. They expressed similar views.
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