2. amps-preamps
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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
pakwong OP
38 posts
 
Atmasphere, totally agree with your statement.

I would suggest all balanced amp should be more user friendly so people who has live with unbalanced equipment for a very long time could try their hand on balanced equipment which they are not familiar with and eventually discover the benefit balanced amps has to offer.
atmasphere's avatar
atmasphere
11,953 posts
 
Agreed! Our amps are also fully balanced and differential; we made sure that it was no worries or loss of performance to use them with a single-ended preamp or source.
daveyf's avatar
daveyf
2,932 posts
 
Ralph, that would seem to have been a smart thing to do. Pity other companies failed to see or take that path.
minorl
1,016 posts
 
I don't think the attacks on Audio Research are warranted.
My understanding of this conversation is that the OP used an RCA to XLR conversion cable and even Audio Research would tell him that that type of cable should not be used. The Audio Research equipment when used as directed is wonderful. As with any equipment, if you connect it in opposition to the way the manufacturer recommends, then it won't work correctly. The solution was simple after conversations with AR and other experts. 1) use a transformer set up like Jensen, 2) replace the AR amp with an amp that handles RCA only or 3) replace the pre-amp with a balanced pre-amp. My reading of the posts, indicates that the OP used the Jensen transformer and the resulting sound is wonderful. Problem solved. I'm not really defending AR, but the direction the posts were going were a direct attack on a company that really didn't do anything wrong and produces absolutely wonderful equipment. And since I can't think of one manufacturer that hasn't produced equipment that eventually failed or required upgrades or repairs, it is unfair to label this was as problematic. The way AR designs their products is the way AR designs their products. Same is true for all other manufacturers. They chose a design path and that is the way they went. I for one really like their equipment and if the funds were there would jump on the opportunity to own them. REF 5SE, REF 250 amps, oh yeah! I can say the same for many other manufacturers out there also. AR produces top-of-the-line products, but like all others, you have to use them per the manufacturer's recommendations.

Sorry for the long rant, but enough already with the AR bashing. In this case, it is totally unwarranted.

enjoy
almarg's avatar
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almarg
9,670 posts
 
As might be inferred from this post I made two days ago, I am in essential agreement with Minorl's comments. And especially with:
My reading of the posts, indicates that the OP used the Jensen transformer and the resulting sound is wonderful. Problem solved.
The old saying "if it ain't broke, don't fix it" comes to mind. (In this case, of course, the amp is broken and in need of repair, but that is unrelated to the question of whether or not to replace it). Certainly the JL5 will be a good match with Pakwong's preamp. But can anyone say with a high degree of confidence that it will be a better sonic match for the Maggie 3.7 speakers than the combination of the ARC amp and the Jensen transformer? Or that its 100 watt power capability will be adequate, considering that a VTL amp rated at 50W triode mode/100W tetrode mode into 5 ohms is not?

Pakwong, hopefully you can audition the JL5 in your system prior to committing to a purchase. Otherwise, it seems to me that you would be bringing significant risks into play, in an effort to eliminate what may be from a subjective standpoint (as opposed to a theoretical standpoint) a non-issue.

Good luck. Regards,
-- Al
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