Thiel CS3.7

EBIT -- Sun, 10/26/2008 - 03:45

Anthony Cordesman

I enjoyed your review of the CS3.7's, having had a little experience with earlier models.

You mentioned ".... you will hear the hardness and excessive upper-octave energy that is actually present on far too many classical recordings ..... and .... the bad moments of tenor and, particularly, soprano voice."

Can you please confirm a couple of things for me about your reviewing practices (and other reviewers too, if you know):

1. As you reference equipment you use allows appropriate switching, do you experiment with absolute polarity settings for each of the recordings that show the adverse sound quality tendencies you describe above?

2. Additionally, if it is vinyl do you experiment with VTA through finite arm height adjustments to ensure inaccurate settings are not the cause of the unsatisfactory sound quality?

Many thanks
Frank

Bob Stern -- Sun, 10/26/2008 - 04:13

Frank, it would be informative for you to share your experiences regarding the two parameters you mentioned, i.e., polarity and VTA. I'll share mine regarding polarity in the hopes of initiating a discussion.

My experience with absolute phase is that it never affects "hardness and excessive upper-octave energy". Instead, inverted phase can produce a recessed character and lack of dynamic impact.

In my experience, both of these effects are quite subtle on most CD's. Even on CD's in which absolute phase is most apparent, the effect is never what I'd consider pronounced enough to affect one's overall assessment of the performance of a loudspeaker.

(My experiences are based on Thiel 3.7's used with a Lavry DA-10 DAC that has a phase reversal switch. My system is listed at:) http://www.audioasylum.com/cgi/m.mpl?forum=speakers&n=259489&review=1

EBIT -- Tue, 10/28/2008 - 00:48

Bob

I was really trying to get an indication whether reviewers treated Absolute Polarity and VTA with any care during the review process. I come from the perspective that a reviewer should avoid any possibility that such potential SQ distortions could cloud review conclusions.

I would rather the above focus than a general discussion on AP & VTA.

However, my experimentation with both goes back well over 20 years. I was directly responsible for polarity switches being added to early Plinius preamp designs. I also set up my turntable for accurate VTA settings for every record - with the resulting curse that you become more sensitive to these distortions with "practice"

I owned Swann Speakers (D'appolito design) that were phase coherent & time aligned (with an excellent all positive step response). My understanding is the Thiels excel in these performance areas and would be much better at highlighting the benefits of correct absolute polarity and VTA settings. As a result, the Thiels might also emphasise incorrect settings.

I am puzzled that your switching polarity doesn't affect hardness or upper octave energy in your system. I always found that on top of the recessed character, lack of dynamic impact, softening bass, loss of transparency and air (insertion of haze instead), there was a tendency to emphasise sibilance on voices, harmonic accuracy on violins (steeliness), and splashiness on cymbals. The later I clearly perceive as excess upper octave energy/noise. Most of these distortions, while not as prominent as with VTA, can be very similar to those from incorrect VTA.

There is one area you may be able to answer regarding implementation of the absolute polarity/phase switching in the Lavry DA-10. Do you know if the design "truly balanced"? Not all XLRs are truly balanced with separate amplification stages for each pin connection.

In the original Plinius Preamps the was an extra line amp stage for each channel to achieve truly balanced operation. This was also required for true absolute polarity switching and best results! Any simplification of that approach has the potential to mask the outcome.

Is there a way for you to compare? Say, set up for your most desirable records for best sound and switch the polarity of the speaker cables on both Thiels instead of the DAC to see if that creates a bigger difference?

Cheers
Frank

Bob Stern -- Tue, 10/28/2008 - 01:30

Frank, in response to your question, the Lavry DA-10 DAC is inherently balanced rather than having an extra phase inversion stage.

I'm sorry that I don't have time in the near future to compare reversing the speaker cables with the Lavry's phase switch.