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From: ccicpg!keith@uunet.UU.NET (Keith McIntyre)
Newsgroups: rec.audio.high-end
Subject: Re: Amps, preamps, CD players, etc.
Message-ID: <8550@uwm.edu>
Date: 26 Dec 90 13:55:11 GMT
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Approved: tjk@csd4.csd.uwm.edu
Originator: tjk@csd4.csd.uwm.edu



This is a marvelous and essentially free improvement for your stereo system.
Please read on even if you don't own the same components that are mentioned
in this posting. My system has a Threshold 400A power amp that has been 
upgraded to Stasis technology. In the course of listening to my new Martin
Logan Sequel II speakers, I found that if the power amp was left on and 
allowed to warm up, the sound improved noticeably. 

Finally I called Threshold and found out that this is indeed the case and
got more exact figures from them on the warm up periods required. There are
at least three warm up periods for a Threshold Stasis amp. I include my own
observations for the curious.

Initial warm up: Threshold's time period: 45 minutes - my estimate: 1 hour
Prolonged warm up: Threshold's time period: 2 hours - my estimate: 2 to 3 hours
Extended warm up: Threshold's time period: 10 hours - my estimate: 12 hours

What are the differences in sound? Imaging is the easiest to describe. Prior
to 45 minutes the sound stage is very small left to right, front to back and
vertically as well. After the 45 minute warm up, the stereo will begin to
image instruments and voices beyond the right hand side of the right speaker
and beyond the left hand side of the left speaker. Front to back imaging or
depth becomes a little better. 

After two hours about half of my recordings begin to image out past the
outside edges of the speakers. Vertical imaging starts showing up on some
recordings as well. Depth becomes pronounced, going back several feet even on
many pop recordings.

The extended warm-up of 10 hours can reasonably be accomplished only by never 
turning the power amp off - which is in fact Threshold's actual recommenation. 
Leave the amp on all the time, it causes less stress in the electronics and
gives the best sound. The result is that imaging goes out past the outside 
edges of the speakers on almost all the recordings I have whether they are 
pop, jazz, classical or even Christmas music. This is rock solid imaging, 
not fuzzy or vague sound placement. Depth is astounding on even pop 
recordings. It easily goes back 7 feet or more at a minimum. Vertical imaging 
suddenly is evident on recordings that never gave any hint of up and down 
sound source placement.  Transparency and midrange detail are also enhanced 
dramatically. Even bass response improved.

Once the amp was warmed up, I quickly found out that my CD player also 
benefitted from a warm up period. The "glassy" or "hard" sound many people
associate with CD players disappears after several hours of warm up. What is
left is a clear, clean, "analytical" type of sound. 

Audiophiles love to A/B stereo components. Due to the warm up times involved, 
many of us have probably been listening to cold electronics that overwhelm the 
differences in components that we have been evaluating. Especially in the area 
of speaker wire, component interconnect cables, and other extraneous items. 
I would say that any evaluations done with my system on a cold power amp are 
practically useless.

					   Happy listening to everyone!
                           -Keith McIntyre