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Audio Research PH5 Phono Preamplifier Input Clipping Problem

I have an ARC PH5 phono preamplifier and most of the time it sounds fine.  But on a few of my favorite LP's with wide dynamic range, it will clip and distort on loud sections, especially those with lots of bass content.  This only happens with use of a step-up transformer, without the SUT in line, there is no clipping. I do prefer to use the SUT, as without it I have to turn the volume setting on my ARC REF 3 preamp to a very high level.   I have to conclude that the PH5 is distorting because of high input signal levels, due to the gain of the SUT.   I have tried two SUT's, one with 13:1 and the other at 7:1, both exhibit the same problem (although the lower gain SUT is much better).  The cartridge is Ortofon A90 with .27 mv output.  Given this, would you expect clipping or do you think there is something wrong with the PH5?  I have talked to ARC about this issue, and they seem to think that there is a chance the PH5's maximum input of 70 mv is being reached on these loud sections.  Would appreciate opinions from those that have experience with a similar setup.  Thanks.
scottwsmith

Showing 6 responses by rauliruegas

rauliruegas
13,125 posts
 
Dear @scottwsmith : """   I know the SUT's historically have been used when you have a phono preamp which is designed for MM cartridges only. """

With all respect that statement is a misunderstood. In the old times active high gain phono stages designs were almost non-existent and almost all the phonolinepreamps were designed for LOMC cartridges using SUTs internally and the external SUT option were used with Phonolinepreamps or phono stages with no internal SUT.

A well designed today SS active high gain phono stage or phonolinepreamp performs with a higher quality that a phono stage with external SUT.

Normally all SUTs has " problems " at both frequencies range extremes. Has inherent limitations at low bass and high frequency against a well designed SS active high gain phono stage. 

Regards and enjoy the music,
R.








rauliruegas
13,125 posts
 
Dear @bobsdevices  :   """  That is why many manufacturers using SUTs in their phono preamps to accomodate MC cartridges. """

Not really and not exactly as you posted. Yes, S/N is higher in MC active high gain devices than the same S/N figure in MM mode but this is just a number and if we know " to read " those numbers then it does not matters and does not goes against a SS active high gain designs.

The phono stages/phonolinepreamps that needs and use SUTs are the all tube designs because tubes are " noisy ".

AR, Herron and other tube designers instead of SUTs use SS devices at the input gain stage trying to lower noise and distortion levels.

The other designers that use SUTs are not because SUTs are better than SS active high gain designs ( that are not. ) but because is a lot more easy to design that " elussive " active high gain knowledge levels to do it.

A good SS active high gain design always beats to a design using SUTs.

What makes the real differences?: knowledge and skills level of the designers, nothing else.

In the other side here are 3 precise examples ( there are many more. Name of the game is in the design and implementation of that design. ) of SS active high gain designs where you can't detect that difference in S/N ratio between MC stage and MM one or even if the phono stage does not handle MM cartridges the S/N is so low in the MC stage that's imposible to detect any sign of noise or distortion levels:

http://www.stereophile.com/content/bmc-phono-mcci-phono-preamplifier-specifications#TWPUCjhcM5muLLb2...

http://www.stereophile.com/content/liberty-audio-b2b-1-phono-preamplifier#zP3dCRyDuo1Zyzoi.97

http://www.stereophile.com/content/parasound-halo-jc-3-phono-preamplifier-measurements#sEEGXPqsWEtwr...

As I said there are many other SS designs that are less affordable $$$  for almost any one.


Regards and enjoy the music,
R.


rauliruegas
13,125 posts
 
Dear @scottwsmith : I owned the A-90 that's one of the finest ( still ) today cartridge performers and I can tell you that for the cartridge can shows at its best  it needs a very good matching tonearm and the finest phono stage/phonolinepreamp we can get and with all respect your PH5 can't do it.

The gentlemans that posted in your thread are not a little " concerned " on the  A-90 cartridge needs and IMHO this must be the first " parameter/premise " to judge what to do.

Regards and enjoy the music,
R.
rauliruegas
13,125 posts
 
Dear @bobsdevices : Well, I understand feelings when some person has no facts in a discussion. I posted facts that goes per se against your opinion and that’s all.

Maybe you think that in audio SUTs are a perfect device and I think diferent: that in audio nothing is perfect not even near the perfection, all in audio has its own trade offs.

Regards and enjoy the music,
R.
rauliruegas
13,125 posts
 
Dear @czarivey : I don't know @scottwsmith  thinking but if I own an Ortofon A-90 I will make my best effort for this little gem can shows at it best even if some one gave me the A-90 as a gift and if I can't because I don't know how to do it or have no money for make changes in my system then I will put the cartridge on sale for it can find out a better place to " sing ".


Regards and enjoy the music,
R.




rauliruegas
13,125 posts
 
Dear @oregonpapa : Did you listen in your system the Ortofon A-90 and then compared against the ART-9?

I did it vs ART 7 and 9 ( both from an audio friend. ) and even that the AT are very good performers IMHO the A-90 is better.

Now, if you did not listening yet the A-90 then make no sense to me your advise.

Anyway, the ball is in the OP field.

regards and enjoy the music,
R.
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