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
syntax's avatar
syntax
2,193 posts
 
If both KEF and Maggie suffer the same distortion from the Ref 150, and no sign of anomalies from other components, is it possible that I've purchased a defected Ref 150? Or simply because the Ref 150 did not match the Maggie perfectly?

I think you narrowed it to the Ref 150.
This problem has nothing to do with a "mismatch" with a speaker, when your Phono Input is ok and based on your own comparisons, the Ref 150 has a defect part inside.
mrderrick
292 posts
 
If the issue is related to driving the REF 150 SE instead of balanced, perhaps one of the early Audio Research single ended to balanced converters would solve the problem?
zd542
5,339 posts
 
If you don't have a pair, see if someone will lend you a fully balanced IC. Be careful not to get a SE cable terminated with xlr connectors. You need a cable that's really balanced. Use it to connect your Wadia directly to your amp. If you do that, the noise will probably go away. Also, you may have to go inside the Wadia and adjust the overall gain settings using the dip switches. If the gain is too high on the Wadia, that can also create some background noise.
mrderrick
292 posts
 
Referring to the Audio Research BL-1 and BL-2.
pakwong OP
38 posts
 
After many painful and time consuming experiments,I have to believe that single ended and balanced components does have mating problem. It seems like many balanced only component were designed to match with other similar or same manufacturer component only. Thus, I think I better trade in my preamp or power amp to set up a balanced or unbalanced only system.

The Maggie is something I cannot live without. So do the CAT SL1. And the Ref 150 seems doesn't up to the task to tamed the Maggie. So a more powerful single ended tubes or solid state amps would be a sensible replacement. Of course, before buying, I will have the dealer brings them to my house for audition to make sure there are no more distortion with the new set up.

Hopefully someone have good single ended amp in mind which could drive the Maggie efficiently and match well with the CAT can offer some suggestion.

BTW thanks Almarg, Syntax, MrDerrick, Zd542 and others for your kind assistant on this issue.
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