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I think I've made up my mind

After having auditioned the following :

1. Avantgarde Uno G2 + Audio Note SET amp/Pathos Twin Towers integrated amp
2. Magico V2 + Soulution 720 pre + 710 power amps
3. Sonus Faber Elipsa/Wilson Sasha + ARC Ref 3 + Ref 110
4. Thiel CS3.7 + Parasound JC1 pre + JC2 power amps

...and after weighing all factors like room interaction, degree of difficulty of setting-up, value for money, magazine reviews, and comments posted here and AVguide.com....

...the winner is: Thiel CS3.7 + Parasound JC1/JC2!

Now for the cables. MF and JA of Stereophile noted that the specs of Parasound show ultra-wide bandwidth and high-current capability which reminds me of Spectral amps. Therefore, would MIT Magnum MA speaker cables and interconnects be a good match? Anyone has any other suggestion? Thanks.
jtein

Showing 6 responses by tvad

tvad
9,467 posts
 
I agree with Madfloyd. When I owned the REF3, and used it with Pass Labs XA-60.5 amplifiers, the resulting sound was bland, bland, bland.

The REF3 did not come close to meeting my expectations based on all the fawning reviews.
tvad
9,467 posts
 
04-09-10: Jon2020
...if it sounds bland or dull, it is quite likely the impedance mismatch with your amps, as suggested by Pubul.
I used the REF3 with Pass Labs XA-60.5 running balanced. The input impedance of the XA-60.5 in balanced mode is 30K ohms. The REF3's output impedance is 600 ohms in balanced mode. Even allowing for high output impedance spikes from the REF3, the impedance match was well within range.
tvad
9,467 posts
 
The match may be within range but 30K ohm is still towards the low end of the SS amp input impedance range from what I've seen, which seems to be around 10K ohm.
Mapman (System | Reviews | Threads | Answers)
I don't understand this comment. In the case of the Pass XA-60.5, which is the only observation I am making in this thread, 30K ohms is well above the minimum required to match a preamp with an output impedance of 600 ohms.

John Atkinson's test measurements of the XA-30.5, which correlates to the 60.5, stated:
The input impedance of the balanced XLR jacks was 29k ohms, close to the specified 30k ohms; the input impedance of the single-ended RCA jacks was higher than specified, at 20k ohms. Both figures were constant across the audioband.
The important statement being "both figures were constant across the audioband".

Therefore, the 10K ohm input impedance figure you mentioned in your post is not applicable to my observation of the REF3/XA-60.5 impedance match.
tvad
9,467 posts
 
Mapman, what I have posted here are specifically the impedance numbers for the REF3 and XA-60.5, including test measurements from John Atkinson for the XA-30.5, which correlates to the XA-60.5 (comparing the specs on the Pass Labs website).

Atkinson measured an output impedance spike from the REF3 at of 1437 ohms at 20Hz in balanced mode. That spec still provides at 20:1 ratio into 30K ohms.

These numbers are well within the generally accepted range for impedance matching.

Nevertheless, if you have specific numbers that would suggest a non-optimal match, then I'd be interested in seeing them and learning more.

Certainly, my experience with the REF3/XA-60.5 match was that the sonic results were not the best I had heard.
tvad
9,467 posts
 
an amp with 60K, 100K, or 200K input impedance would probably sound different and might sound better than one with 30K input impedance, all other factors aside.
Mapman (System | Reviews | Threads | Answers)
It might. Not having heard a match with those specs, I can't say for certain.

The numbers of the REF3/XA-60.5 combination suggest there should not have been any mismatch whatsoever if one agrees with the thorough contributions of member Almarg (and others) on this topic.

Anyway, the horse is dead.
tvad
9,467 posts
 
Plus also, who's to say how accurate published specs are or that specific units operate to spec?
Mapman (System | Reviews | Threads | Answers)
For components that make it into Stereophile reviews, John Atkinson's test measurements are invaluable for verifying manufacturer specs. In fact, this is the most valuable part of a Stereophile review, IMO.

For the components that haven't been measured by Atkinson, it's a crap shoot.
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