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
 
Zd,

Some confusion here, no Wadia components in my house. I never sold the ARC amp either. In fact, I still use the ARC LS 25/VT 130 SE with Verity Parsifal Encore speakers and a Qsonix front end (which, come to think of it, does utilize a Wadia digital section).

I also kept the Joule preamp paired with Cary 300b mono sig amps and Merlin VSM SE speakers. Analog only from an Oracle/Graham/Graham front end. I still really like all of this gear and have been using every piece mentioned here IIRC for over a decade.

Most of my listening time is now spent in front of an Ohm (sometimes Magnepan) and Rythmik based system with an Onkyo pre-pro and rotating power amplification. Digital sources continue to vary but the analog front end is Acoustic Solid/Rega/Lyra.

Variety being the spice of life and all....
zd542
5,339 posts
 
I didn't realize you didn't have the Wadia in your house. I was just going by this:

"Last night I did a final test by listening again to digital sources from a Wadia 381i CD player connected to line stage of the CAT SL1. To my surprise, the same distortion also happens on the digital source which I thought didn't exist! I'm not a big fan of digital hence very seldom listen to it. The last time I listened to it were kind of background listening with lower volume. This time I crank up the volume control to about the same level while listening to LPs and the same distortion shows off immediately!"

That's why I thought you had one. Also, I didn't think you sold your 150, it just looked like you may do so. I was just saying to give it a chance before you did sell it. Its a very nice amp. I also didn't realize you had an LS25. I'm sure there's no distortion when use that with you 150. Either way, its good that you were able to figure out what the problem was.
almarg's avatar
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almarg
9,670 posts
 
ZD, the comment you were responding to was from the OP, Pakwong, not from Martykl (who is not the OP).

Best regards,
-- Al
martykl
3,578 posts
 
My bad, I should have seen that ZD had confused me for the OP. To the best of my knowledge Pakwong's ARC adventure is still unfolding and we'll all have to wait to see how it plays out.
pakwong OP
38 posts
 
ZD, your suggestion has save me from selling an excellent amp. Today I loan a XLR cable form the Maggie dealer to try a direct connection from the Wadia which have balanced output and volume control to drive the Ref 150. Guess what? Not only the distortion has disappeared even at maximum volume, the sound it produced was something I never heard in my system!

First thing which I immediately aware of was the dead silence background and powerful bass with very good authority and definition. I never realized low frequency from Maggies can be that great!

Such experiment has confirmed that the ARC do need balanced only signal and that you guys has proved your points to be very true.

Right now, what was left is to find a way to change the CAT output signal to balanced. Al, please forgive my ignorant. Can you explain to a guy like me with almost zero electronic knowledge about how the transformer from Jensen or SMc can actually convert unbalanced signal to true balanced signal?
My Maggie dealer also talked about something like pin 1 or pin 2 "hot" in the RCA to XLR cable and he suspected that the termination of my RCA to XLR cable was not done correctly hence the distortion. How true is it?

Thanks in advance.

Best regards
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