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
dbarger
215 posts
 
Yes Almarg, that was what I was trying to clarify in my post. Most people don't consider the preamp to be the "source".

Atmasphere, I have had the same conversation with Kalvin. He told me also that the preamp must be balanced with the Ref150. He did not use the word source, just preamp.
daveyf's avatar
daveyf
2,871 posts
 
So Zd542, you want to expand on why you believe what i posted is incorrect.
I am all ears.
pakwong OP
38 posts
 
Thanks all for good opinions and comments.

At the moment I'm still waiting for ARC to send me the resistor as my technician down here couldn't find resistor with such value. In the mean time, my ever faithful VTL MB125 monoblock continue to serve music with the CAT. They are both single ended so no distortion issue here. The sound with the Maggie is acceptable but there were some sort of distortion at higher volume/peak of music probably due to lack of driving power.

After having such bad experiences with the balance amp, I think it's better to stick to single ended. Moreover, my CAT has comes with decent phono stage so changing the power amp instead of the preamp might save me some money. While me and some of my audiophile friends has got very good offer from local CAT dealer, I've decided to grab a new Black Path JL 5 to end the misery!^^

Anyway, will keep you guys posted on the ARC issue.

Thanks again!
atmasphere's avatar
atmasphere
11,807 posts
 
Pakwong, I would not take this particular event as somehow being a problem with balanced operation. I've been working with balanced line equipment for decades; this sort of problem that you experienced says more about Audio Research than anything to do with balanced operation.

We've been building balanced line equipment for high end audio longer than anyone else- all I can tell you is this should not have been a problem and is something unique to ARC.
daveyf's avatar
daveyf
2,871 posts
 
Pakwong, Congrats on the JL5. I think it will put the ARC to shame.Great amp and a perfect match for the CAT preamp.
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