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
 
Ralph & Dbarger, you appear to be disagreeing simply because you are using the term "source" to mean different things. I believe that Ralph is referring to the "source" of the signals which are sent into the power amp, e.g., a preamp. Dbarger is referring to the "source component," e.g., a CD player.

As Dbarger appears to indicate, I would not expect there to be any problem if the power amp were driven by a balanced output of a preamp which in turn receives a single-ended input. Assuming, that is, that the preamp's output truly consists of a balanced pair of signals, rather than a single-ended signal provided on an XLR connector.

Regards,
-- Al
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atmasphere
11,807 posts
 
^^ This.
stickman451
553 posts
 
Guys, I read this entire thread and got lost a couple of times but here is my thought. The Ref 150 is NOT a good amp for any of the Maggies. Sell the 150 and try a pair of Carver Cherry 180's or even better a pair of his Black Beauty 305's. The Black Beauty's use six KT-120's per side and can drive anything. They sound fantastic on my 20.7's and I have tried many different amps.
stickman451
553 posts
 
BTW, both Dick Olsher and Jonathan Valin wrote reviews of the Carver amps and basically said that the Carvers were excellent matches for the Maggies. Read this:

http://www.enjoythemusic.com/superioraudio/equipment/0512/bob_carver_cherry_180_tube_monoblock_amplifier.htm

http://www.theabsolutesound.com/articles/carver-black-beauty-305-power-amplifier/
zd542
5,339 posts
 
"10-01-14: Daveyf
Ralph, IMO the loss potential generated by the additional electronics needed to go balanced in home electronics; is more of a problem than what one typically sees as noise infiltration into the system by outside sources. Unlike in the pro audio world, in home hi-fi, we're talking of cable runs of what...a few meters at most. In pro audio it may be 50-60'++ , then i can see the potential benefit. A cable that is effected by noise that is 6" in length must be a ****poor cable IMHO."

I can't help but think of that old saying "You know enough Karate to get your ass kicked.", when I read that post.
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