Hi,

I was just looking at some of the Panasonic home theather specs to see
in terms of the amp power and speakers themsevles.

The THD is 10%!!!! Isnt that pretty crap ?????? I know of amps with 1%
(admittedly hi-fi amps, not home theatre) - but wouldnt they have WAY
better sound quality output than the panasonic h.t. ones ?

Next question...speakers. The frequency range spec quotes that for the
range it is, 75Hz-50kHz, it is -16 dB! Isnt that very very poor too
???? I have read that +/- 3dB is considered good, so -16 must be
attrocious ?

Last thing, for speakers in general - what is an average sound pressure
level ???? The pana's one is 84dB ..... is this average? Would 90dB be
considered good??


Thanks,,
Andrew

"andrew_h" wrote ...
I was just looking at some of the Panasonic home theather specs to see
in terms of the amp power and speakers themsevles.

The THD is 10%!!!! Isnt that pretty crap ?????? I know of amps with 1%
(admittedly hi-fi amps, not home theatre) - but wouldnt they have WAY
better sound quality output than the panasonic h.t. ones ?

Next question...speakers. The frequency range spec quotes that for the
range it is, 75Hz-50kHz, it is -16 dB! Isnt that very very poor too
???? I have read that +/- 3dB is considered good, so -16 must be
attrocious ?

Rule of thumb about published "specs": You can safely assume
that the actual performance is even worst than the numbers
indicate. What is a "Panasonic home theatre"? Some kind of
amp with a bunch of channels in the same cardboard box with
a bunch of cheap speakers? Yuck.

I wouldn't recommend buying by the numbers. Chances are
I wouldn't recommend some plastic home-theatre kit (just
add water?) with or without the numbers.

Sorry, this page:
http://panasonic.com.au/products/cat...fm?objectID=66 - I was
looking at those models?

It is not cheap though ($1200)... so thats why I was looking at the
specs though, to see how it compared to others...

"andrew_h" wrote in message
ups.com...
Sorry, this page:
http://panasonic.com.au/products/cat...fm?objectID=66 - I was
looking at those models?

It is not cheap though ($1200)... so thats why I was looking at the
specs though, to see how it compared to others...


Certainly at this price level you can go with separates. DVD players die
like flies compared to your other components. At least get a system with a
separate DVD player. Pioneer DVD players have been the most reliable on
average the past several years. I recommend receivers by Yamaha, Denon,
Onkyo, or Sony, having had experience on many types of home theater
receivers.

Mark Z.

"andrew_h" wrote in message
ups.com...
Hi,

I was just looking at some of the Panasonic home theather specs to see
in terms of the amp power and speakers themsevles.

The THD is 10%!!!! Isnt that pretty crap ?????? I know of amps with 1%
(admittedly hi-fi amps, not home theatre) - but wouldnt they have WAY
better sound quality output than the panasonic h.t. ones ?

Next question...speakers. The frequency range spec quotes that for the
range it is, 75Hz-50kHz, it is -16 dB! Isnt that very very poor too
???? I have read that +/- 3dB is considered good, so -16 must be
attrocious ?

Last thing, for speakers in general - what is an average sound pressure
level ???? The pana's one is 84dB ..... is this average? Would 90dB be
considered good??


Thanks,,
Andrew

10% with modern amps?
Think about it, it doesn't make sense. Escpecially knowing Panasonic which
is a reasonalbly serious company, not an obscure company that doens't have
to care about its reputation.
Unless it is sold for a few dollards, no modern amp produce such high level
distorsion except when output start clipping beyond maximum rated power.

Dan

"andrew_h" wrote in message
ups.com
Hi,

I was just looking at some of the Panasonic home theather
specs to see in terms of the amp power and speakers
themsevles.

The THD is 10%!!!! Isnt that pretty crap ??????

This is mostly a way to inflate the power rating of the power amp. It's also
a matter of conforming to how specs for certain classes of audio gear are
specified.

IOW, the same power amp might put out 30 watts at 0.1% THD, 35 watts at 1%
THD and 45 watts at 10% THD. It is traditional to rate mid-fi hi fi gear
for power at 1% or 0.1% THD. It is traditional to rate portable or low cost
hi fi gear at 10% THD.

Next question...speakers. The frequency range spec quotes
that for the range it is, 75Hz-50kHz, it is -16 dB! Isnt
that very very poor too ???? I have read that +/- 3dB is
considered good, so -16 must be attrocious ?

This more of the same philosophy I was talking about with the power amp.
First off loudspeaker frequency response specs are to be taken with a grain
of salt, sometimes a whole 5 pound bag!

Secondly the same speaker might be 150-10KHz +/- 3 dB, 100-15 KHz +/- 10 dB
or 75=50 KHz +/- 16 dB. The 150-10 KHz spec might look kinda dire, but a
speaker that sounds pretty good, admittedly a bit light on bass could fit
into this spec.

Last thing, for speakers in general - what is an average
sound pressure level ???? The pana's one is 84dB ..... is
this average? Would 90dB be considered good??

Usually speaker efficiency is given in terms of dB per watt, measured 1
meter away from the acoustical or geometric center of the speaker. Things
get vague fast because speaker efficiency varies strongly based on other
parameters that typically go unstated.

However, 90 dB/watt under *standard* conditions (whose standard???) is
considered to be on the high side of average efficiency. It turns out that
low efficiency can be a good thing because it might indicate that the
speaker has better-than-average bass response given its size.

All things considered, you might just want to buy the thing with an
iron-clad money back guarantee, and see how it works out for you in your
situation.

Very nicely explained. Though this wasn't my query, but did answered lots of
'might be' queries.

wrote in message
ups.com...

Richard Crowley wrote:
"andrew_h" wrote ...
I was just looking at some of the Panasonic home theather specs to see
in terms of the amp power and speakers themsevles.
Rule of thumb about published "specs": You can safely assume
that the actual performance is even worst than the numbers
indicate.

Actually, the opposite is generally true. Publishing specifications
actually has real legal implications: if the unit can be shown NOT
to meet the specifications, many jurisdictions provide for economic
and or legal recourse on the part of the purchaser, usually including
but not limited to full refund of the purshase price. Some
jurisdictions
allow for further penalties.

It is thus very much in the manufacturer's self-interest to publish
specifications which actual units sold to the end user stand a
pretty high chance of meeting with a reasonably adequate margin.

In looking at the specification, the 10% THD is most likely chosen
to get as high a number as possible for the power output. For
example:

Audio Power Output (front x2) Watts RMS 170
Front Reference Spec (1 kHz, 6 ohms 10%THD)

Does that mean the amplifier is ALWAYS producing 10%? Nope,
it is probable that to arrive at the 170 watts spec, they had to drive
the amplifier sufficiently into clipping to reach the 170 watt level.
In reality, it might well be below 0.1% at 150 watts and lower.

That being said, these days it is AWFULLY difficult to build
amplifiers that have 10% distortion over most of their power
range. Even using the cheapest possible components, i.e.,
mass-produced monolythic power amplifier modules, with
minimal external parts count, 0.1% is EASY to achieve at
levels below clipping.

So, what I suspect we see here is an attempt to platy one-
upsmanship on the power spec by loosening the limits
on THD, and that allows them to get 5-10% higher power
rating.

Is it wrong, evil, dishonest? Absolutely not: they are completely
upfront and all the information is there IF you know how to interpret
the numbers. But that's the key.

Is it overpriced junk? Well, one man's junk is another's ... To those
that are saying you can do better with separates, you're ignoring
the fact that it's a wireless system: to some people, that particular
function may be worth the price of admission. Given that, consider
how much it would cost to get the same level of functionality, i.e.
wireless speaker connections, with seperates. I'd bet you couldn't
get close.

Add to that a significant feature of such systems, which the wireless
part speaks to, is the convenience in setup and operation. To many,
that's worth paying for, and it's not anywhare as easy to obtain that
ease of intergration and deployment with cherry-picked separates.
You either wind up with a traffic jam of remotes on your coffee table
or a single "univeral" remote that has the easy user interface of
an ENIAC-I.