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andy
 
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Default What happened to perpetual technologies?

I cannot locate their web site, I am just re-directed to the av123
site which sells the units.
Are they out of business? What about the room correction SW which P1A
users are waiting for?

What about active lodspeaker-toom correction? It is all silent and no
appearent interest in the audio communicty, which seems to continue to
tweak the system using cables while missing the big point )the room)

Thanks

marco stanzani
  #4   Report Post  
andy
 
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Default What happened to perpetual technologies?


OK, some of us knew that. OTOH, answers to the other questions would
be more interesting and useful.

Kal

Thanks Kal

did somebody experienced the DeQX devices? Is SigTech still opearting
with new prodocts (I still see Copyright 1996-2000 Cambridge Signal
Technologies on their URL) Is TacT available with some more affordable
products?
Is Perp. tech providing the room correction services )this was their
claim in Y2K but nothing happened so far (and AFAIK)

Overall the BOM cost of digital correction systems is VERY low, so we
are going to pay for the IP (which is OK). Still I feel very promising
for the medium- to low-end system the technologt fallout in the near
future. Still it does not seem to happen so near ..

Thanks
  #6   Report Post  
Andre Yew
 
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Default What happened to perpetual technologies?

(andy) wrote in message ...
did somebody experienced the DeQX devices?


Yes. I heard some DeQX-corrected NHT Pro A-20s at CES a couple of
years ago, when they were still known as ClarityEQ. Very interesting
comparison as the uncorrected system had a larger and more enveloping
soundstage, while with correction on, the sound got tighter and more
focused, but at the expense of the soundstage. I'd say it's not a
clear choice which one is better.

Overall the BOM cost of digital correction systems is VERY low, so we
are going to pay for the IP (which is OK). Still I feel very promising
for the medium- to low-end system the technologt fallout in the near
future. Still it does not seem to happen so near ..


I disgree about the cost of room correction systems. Research seems
to indicate that at least 1 second of room correction (or 1 Hz
correction resolution) is desirable. At 44.1 kHz, and done with FIR
filters, this amounts to about 44.1k*44.1k = 1.9 billion multiply and
additions (MACs) per second, and over 8 billion MACs per second for 96
kHz processing, a sample rate at which many receivers and surround
prepros are operating at today. That is well beyond affordable, and
even achievable. Top-of-the-line Pentiums and Athlons can barely
achieve Dhyrstone MIPS at half these numbers, and those numbers are
unrealistic and inflated anyway, given that Dhrystone isn't a
realistic, or even meaningful benchmark.

If you want less latency than 1 second (and that is desirable for
systems that have to deal with video), then the computational
requirements go up even more. People have had success at running bass
correction at lower sampling rates (like 1 kHz), and lowering
computational costs greatly, but this requires some non-trivial amount
of technical know-how as well as good taste in audio to judge the
different tradeoffs. Unfortunately in the audio world, good audio
taste and technical know-how seem to be contradictory traits.

And that's just for the implementation of the correction playback
side. The measurement side that determines what needs to be corrected
has its own set of challenges, which include a simple enough user
interface so that typical receiver owners can use it effectively, and
having enough smarts to correct the right things, and leave other
things alone, and do it all fast enough (less than 1 minute is
desirable) for a casual user. Many correction systems have
measurements that don't correspond at all to human hearing, but rather
are convenient mathematical computations. Taste, experience, and
technical know-how again are required here.

--Andre
  #7   Report Post  
Denis Sbragion
 
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Default What happened to perpetual technologies?

Hello Andre,

(Andre Yew) wrote in
:

...
I disgree about the cost of room correction systems. Research seems
to indicate that at least 1 second of room correction (or 1 Hz
correction resolution) is desirable. At 44.1 kHz, and done with FIR
filters, this amounts to about 44.1k*44.1k = 1.9 billion multiply and
additions (MACs) per second, and over 8 billion MACs per second for 96
kHz processing, a sample rate at which many receivers and surround
prepros are operating at today. That is well beyond affordable, and
even achievable. Top-of-the-line Pentiums and Athlons can barely
achieve Dhyrstone MIPS at half these numbers, and those numbers are
unrealistic and inflated anyway, given that Dhrystone isn't a
realistic, or even meaningful benchmark.

...

I think you should take a look at this site:

http://www.ludd.luth.se/~torger/brutefir.html

Realtime FIR filtering with better than 1 Hz resolution at audio sampling
rates is available since at least 5-8 years. A top-of-the-line processor
should be able to run at least 30 channels at 96 Khz using a program like
that. The main problem is that this convolution method is patented by
Lake Audio, so it cannot be used outside free programs like the one
above, but AFAIK the patent is going to expire within few months.
If you use the program above with the following one:

http://freshmeat.net/projects/drc/

(incidentally developed by me you can build a good quality room
correction system almost for free. You can see some example results
achieved with the program above, along with traditional room treatment,
at the following URL:

http://www.avsforum.com/avs-vb/showthread.php?s=
24df513b860d46cb4eb85577a6528c9a&threadid=283878&p erpage=20&pagenumber=16

And that's just for the implementation of the correction playback
side. The measurement side that determines what needs to be corrected
has its own set of challenges, which include a simple enough user

...

I agree, making a good quality RCS is difficult, making it easy to use is
near to impossible (DRC is definitely difficult to use).

Bye,

--
Denis Sbragion
InfoTecna
Tel: +39 0362 805396, Fax: +39 0362 805404
URL: http://www.infotecna.it

  #8   Report Post  
Rusty Boudreaux
 
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Default What happened to perpetual technologies?

"Andre Yew" wrote in message
...
I disgree about the cost of room correction systems. Research

seems
to indicate that at least 1 second of room correction (or 1 Hz
correction resolution) is desirable. At 44.1 kHz, and done

with FIR
filters, this amounts to about 44.1k*44.1k = 1.9 billion

multiply and
additions (MACs) per second, and over 8 billion MACs per second

for 96
kHz processing, a sample rate at which many receivers and

surround
prepros are operating at today. That is well beyond

affordable, and
even achievable. Top-of-the-line Pentiums and Athlons can

barely
achieve Dhyrstone MIPS at half these numbers, and those numbers

are
unrealistic and inflated anyway, given that Dhrystone isn't a
realistic, or even meaningful benchmark.


I agree that it's not as cheap as the previous poster was
claiming. However, your argument using general processors is not
valid. In the realm of DSPs and ASICs this level of processing
power is certainly achievable at modest cost.

  #10   Report Post  
Rusty Boudreaux
 
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Default What happened to perpetual technologies?

"normanstrong" wrote in message
news:Gbtub.181649$ao4.610833@attbi_s51...
That's a strange name for an audio company. Was it supposed to

be
"perceptual"?


Nope, it was Perpetual. Run by a guy Mark Shifter (sp?) who
harks back to Audio Alchemy. Snake oil is probably a tad harsh
for AA...but there was some debates about their claims and
products (DAC-in-a-box for one).

Perpetual Technologies/AV123 on the other hand is supposed to
have some good stuff. Their Rocket line of speakers enjoys a
large internet following and review very well. They also have a
high end reference series and some smaller HTiB systems.
Designed here in the states and manufactured in China they are
supposed to be very high quality for the buck. A "perpetual"
comment is the Rockets hold their own both cosmetically and
performance wise with speakers several times their price. The
crossovers (patent pending) and drivers were designed by none
other than Dick Pierce who is without reproach. As his client it
appears Mark actually listening to what Dick said and got a good
product as a result.



  #12   Report Post  
Rusty Boudreaux
 
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Default What happened to perpetual technologies?

"Mkuller" wrote in message
news:58Pub.246217$HS4.2182771@attbi_s01...
Snake oil is more than a "tad" harsh to call AA. Mark owned

the company and
had a very talented designer in the days when digital was

evolving. They
produced excellent products at great prices and their DTI

jitter buster was a
breakthrough product that is still in use today by people using

separates.

That may be true but I still think they weren't totally honest
with some of their products. There should be no need for jitter
correction in CD audio as has been pointed out by Dick Pierce and
others that CD's can't have jitter. If a jitter buster helps
then something is wrong with the CD player.

Another example is a quote by Tom Nousaine in this newsgroup a
few weeks ago:

"I'm guessing that my experience with an Audio Alchemy outboard
DAC might be
illustrative. Using that device for a level matched test I
discovered that the
output of the AA was +10 dB compared to the analog output of a
Marantz CD-63
player.

Inside the case there was a jumper with 0 dB and +10 dB settings.
Moving the
jumper to the 0 dB position and, guess what, the output was still
+4 dB. So to
an end-user the device always delivered a higher output level.

I'm guessing that this kind of level de-match accounts for
practically all, if
not exactly all, of the reported cd-player sound differences."

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