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
martykl
3,578 posts
 
To rephrase my post:

The OP may or may not have several issues with his system. However, if he's trying to feed a single ended signal into an ARC amp designed for balanced inputs he WILL have an issue very much like the one he describes. Per ARC, he should not drive his amp with anything but a balanced signal.

As a less technical type, I can only gather that the ARC design is unusual. However, I can assure everyone that the relevant ARC amps do, in fact, behave in precisely this fashion.
jtimothya
612 posts
 
I didna read the entire thread but any chance the cable could be wired wrong? RalphK once warned me certain XLR/RCA adaptors are wired incorrectly, eg Cardas leave pin 3 floating.
pakwong OP
38 posts
 
Thanks Al for the insight of single ended and balanced design. I'm sure learn a lot from you. What you've mentioned about substituted amp I used was correct. It was a pair of VTL MB125 which rated 55-watts and 100-watts into 5Ω in triode and tetrode modes respectively. It do sounded louder with the Maggie at lower volume in comparison with the Ref 150 but have the same distortion perhaps due to clipping as you suggested.

For your information I've wrote to ARC, Jensen and SMc. We'll see what the answer's like.

Regards
pakwong OP
38 posts
 
Czarivey, My XV-1S is zero hour brand new cartridge. It has just been about 50 hours now. Yes, I have the same problem with my previous XX2 cartridge.

Regards
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.
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