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
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almarg
8,673 posts
 
Gentlemen, keep in mind that the problem at hand is simply that the amp has broken down.

Also keep in mind that Pakwong was quite happy with the sound he was getting using the Jensen transformer, prior to the recent breakdown of the amp. And some other highly experienced A'goners having very high quality systems have reported in the past being similarly pleased, using the same Jensen transformer.

I have no doubt that Ralph's/Atmasphere's statements about the compromises the transformer introduces are correct, but it seems based on these anecdotal reports that the degree of those compromises is small enough that for many users it would not warrant replacement of either the amp or the preamp.

Best regards,
-- Al
dbarger
179 posts
 
Atmasphere mentioned using only a balanced source. This I assume is only referring to the preamp. It is very possible to use single-ended sources into a balanced ARC preamp, going into a Ref150. They work great, it is only the preamp which needs to be balanced. ARC even makes a few of the single ended sources...
atmasphere's avatar
atmasphere
7,068 posts
 
Davef, this quote is incorrect:

single ended gear sounds better than balanced gear; IMO,unless one is using their gear in a VERY highly corrupted noise environment or with VERY long runs of cable, balanced is nothing but a joke in high-end.

If you have ever heard a difference in audio interconnect cables, then you now know why balanced lines are not a joke- because they solve that problem if used properly! Further, it does not matter the length, 6 inches is easily enough to hear a difference, especially if there is a noisy environment. Further, the proper use of balanced lines and balanced operation offers lower distortion.

Tubes are often docked for having that ever-lovin 2nd harmonic, which is nice and rich sounding, but not neutral as it is distortion. That can be eliminated by employing balanced operation, resulting in more transparency and no loss of smoothness.

By running balanced lines, I can put my amps much closer to my speakers, allowing me to run shorter (thus better sounding) speaker cables, plus I can put my front end where I want it, rather than in between the speakers. The first thing I noticed in doing this was greater ability to make out vocals. It was not subtle.

Al, what I was describing in my post above is not a malfunction. The OP did have a malfunction, but it was coincidental and unrelated to the basic problem: distortion when driven by the CAT directly.
daveyf's avatar
daveyf
1,174 posts
 
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.
atmasphere's avatar
atmasphere
7,068 posts
 
Dbarger, I spoke to both Kalvin and Warren at ARC and they told me the same thing: if the amp is used with a single-ended source it will have lower output power and will make distortion.

This is because the drive to the power tubes will become unbalanced. IOW, the amplifier is not compatible with single-ended sources and if one is employed, a transformer should be used to balance the input to the amp.
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