Panny sa-xr45 and zero autoformers (long)

Prima Negev · « **on:** 12 Feb 2004, 07:00 pm »

Along with some of the fans here of the new darling the Panasonic sa-xr45, I too have noticed a little bit of "sizzle" and lower treble thinness in this remarkable receiver. In a previous post, I removed my past reference amp, an atmasphere s30 from my system and added the panny as my main amp. After the requisite 200 or so hours of break in, I continued to notice that the highs were still a "weakness" in this amp.

I have the amplifier connected to a pair of unmodded VMPS RM 40's. These as you may know dip to 3.2 ohms with a nominal 4 ohm impedance. As you well know panny is rated to 6 ohms.

Quite by accident I left my zero autoformers connected to the speakers while A/B testing my two amps as above.

The zero autoformers were wired to present a doubling of the impedance of the speaker to the amp it is connected to. That left me with an 8 ohm load at the terminals of the panny, rather than 4 ohms.

Was there an audible difference? YES.

The highs smoothed out, and the lower treble upper mids regained "bloom". The slight harshness reported by some of the contributors here was entirely gone.

I rewired the autoformers so that they presented a 1.3x load to the amp and I noticed a bit more of sparkle to the treble but some thinness presented as well. I settled on the 2x ( 8ohm) setting and left it there for now.

It seems that the sa-xr45 is quite sensitive to impedance. Possibly that explains the differing results people have been hearing and the disparate comments regarding the amp.

Your thoughts?

http://www.zeroimpedance.com/Zero-New.html

Newk · « **Reply #1 on:** 12 Feb 2004, 07:22 pm »

I think that you are definately on to something regarding impedance. I use the Carolina Audio JTM's with the Jordan 92s driver and they will really tell you what is going on upstream and I haven't experienced any brightness or thinness with the 45.

The JTM's are a very stable 6-8ohm load and work so beautifully with the 45 that I am astounded everytime I come home and cut some music on. Even when it'd turned down low all the bass an detail are still present.

My current set up with the Pioneer 563 to the XR45 driving the Carolina JTM's using the Carolina cables is such a great simple system and at one sixth the price of my previous setup it so handily outperforms it.

Thanks to those who got the word out on the 45... very much appreciated.

Paul Speltz · « **Reply #2 on:** 13 Feb 2004, 09:35 pm »

Yes, I see the Panasonic SA-XR45 is only rated down to 6 ohms. Even amplifiers that are rated down to 4 ohms or less sound better driving a higher impedance speaker load. With the 45, (and its minimum rating of 6 ohms), I bet the sweet spot (where it gives best sound) might even be as high as 12 ohms.

I have sold hundreds of pairs of my ZERO-Autoformers to guys that have put them behind everything from 3 watt SET tube amps to 350 watt Solid state amps. Bottom line... whatever abnormalities an amplifier produces when it is stressed (because of driving lots of current into a low impedance load) goes away when the ZERO-Autoformers are added to increase the speakers impedance. Higher impedance = less current demands = easier job for the amplifier = better sound.

The ZEROs come with a 30 day risk free trial period, so if they end up not being needed, send them back for a full refund.

Enjoy!

Paul

www.zeroimpedance.com

maxwalrath · « **Reply #3 on:** 13 Feb 2004, 10:06 pm »

they look really interesting. good product Paul.

Wayne1 · « **Reply #4 on:** 14 Feb 2004, 04:49 pm »

I do appreciate the information about your experience with autoformers with the SA-XR45, Prima Negev.

I have personally not found any trouble with the modded unit on RM-40s or Vandersteens. I have not tried it on every speaker ever made. For some, there may be a benefit with the transformeres.

I do not appreciate an ad from another manufacturer in my forum, Paul.

Please read the rules for manufacturers on this board

http://www.audiocircle.com/circles/faq.php#26

Dmason · « **Reply #5 on:** 14 Feb 2004, 07:08 pm »

I too have suspected impedance sensitivity issues for awhile with the Panny, its mid-treble-and-up sonic signature is quite different between two (very different designs,) but one with an extremely benign 8+Ohm impedance, the other with a gnarly "4" Ohm figure with a poor excuse for an impedance curve, to the extent that the 45 sounds like a different animal between the two; Guess which speaker does much better?

My thinking is that if you need to buy $300 autoformers for the $300 Panny, (what a deal,) why not go for the "real thing" in a ZR, ultra-high value digital, with high current capability, Tripath sonics, buckets of power, and total indifference to impedance moduli? If I were going to need autoformers, it would be because of OTL amps, etc. I see that as a decent fix, but ultra-lousy economics.....no need for OTL amps, IMHO, because of properly implemented digital amps, my view..

Prima Negev · « **Reply #6 on:** 15 Feb 2004, 08:55 am »

I too have thought about the the "ZR" series of carver amps. I was disuaded by your previous postings stating that the sa-xr45 was superior in sound to the ZR series. Thanks for your observations regarding the impedence curves, they match my own observations.

Brad · « **Reply #7 on:** 16 Feb 2004, 08:00 pm »

The Carver doesn't offer a direct digital in though.
Which to me is the best benefit of the Panasonic.

Just match the Panny with suitable speakers....

The Carver does offer a lot more power

azryan · « **Reply #8 on:** 17 Feb 2004, 07:26 pm »

What Brad said plus.... of analog input digital amp chips I don't think Tripath is the best.

Plus the Pannie is 5 powered channels (in modded form), eliminates the preamp and amp sections of a system and is a full HT processor (and a tuner which I never use).

There's no way you can say get the Carver instead of the Pannie. It's a totally diff. thing.

Dmason · « **Reply #9 on:** 17 Feb 2004, 07:41 pm »

I agree with azryan; My sentiment was as a suggestion for anyone not contemplating replacing speakers which were not suitable for the Panasonic.

The digital-direct implementation is the future, and is definitely the one for me. My original thoughts about getting the Panny and spending the rest on the very best, [efficient--8 Ohm--full range] speakers one can afford. If one did require a-more power, b-impedance indifference because of existing speakers they wanted to keep, the ZR is A way to go, and still be using a "digital" amp. It may be worth noting that Tripath has a digital direct board they have yet to release, in an effort to keep up with the Dow-Jones

of the industry. Both JVC and Denon have Tripath receivers similar in pricepoint only to the Panasonic, but with analogue inputs. These currently are available in Europe only.

azryan, are you using the Panasonic with the GR Alphas?