[net.audio] A-B CD comments

jj@alice.UUCP (04/16/85)

Well, I haven't been reading this part of nutnews for a while,
but since I've been getting mail about the A-B test that involved
my CD player (gasp, yes, JJ has one of those heathen devices),
I figured that I should at least read the comments on the test.

	I've seen several humorous comments (why is it that some
people can't recognize humor when they see it?  Kudos to the
Bavarian Beagle for making the humor clear.. or will someone
take THAT seriously, too?) and two comments about
the speakers that were used.  Neither of the speaker commentators
bothered to notice that headphones were also used, and both
saw fit to behave as though they were the one and only guardians of
the truth.  Nobody in the review claimed that the test was conclusive,
in fact, the conditions were carefully explained so that people
could draw their own conclusions, and get some idea of the minimum
sensitivity necessary to hear a difference.  (Face it, the system
described is't audiophile, but it's much, much better than 98% (or more)
of systems "installed", so there IS useful information contained.)
(No, I don't own Bose speakers.)

	Hedley... Your comments seem to indiciate that your
speakers are good enough for the test.  Care to explain why?
(Or were you really being sarcastic?  If so, it seems to me that
the sarcasm was not obvious enough, given the attitudes in 
nut.audio, where superstition masquerades as fact, and physical
fact as superstition, experience only counts if you don't have
an education in acoustics, and being a researcher in the field of
audio means that you are automatically wrong.)

	That's why I don't contribute to nut.audio anymore.

'nuff said?
-- 
TEDDY BEARS NEED SECURITY BLANKETS, WRAP YOURS TODAY!

"I think I'm going to regret this!"
ihnp4!icarus!jj

herbie@watdcsu.UUCP (Herb Chong [DCS]) (04/17/85)

In article <3583@alice.UUCP> jj@alice.UUCP writes:
>Neither of the speaker commentators
>bothered to notice that headphones were also used, and both
>saw fit to behave as though they were the one and only guardians of
>the truth.

i don't remember the type of headphones being posted in the original
article.  about the only pair of headphones that i am sure almost no-one
will dispute as a reference set are stax pro's.  having the good fortune
to know someone who owns a pair, i use them when i can.

Herb Chong...

I'm user-friendly -- I don't byte, I nybble....

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peters@cubsvax.UUCP (Peter S. Shenkin) (04/19/85)

In article <> jj@alice.UUCP writes:
>
	(a modicum of stuff)
>
Wait till I tell the folks:  jj was back, if only for a visit!  

I hope it's for longer... life has been too dull for too long around 
this here newsgroup.  

"If ya can't stand the fire, don't walk in the flame."
(or however it goes....)

caf@omen.UUCP (Chuck Forsberg WA7KGX) (04/19/85)

)i don't remember the type of headphones being posted in the original
)article.  about the only pair of headphones that i am sure almost no-one
)will dispute as a reference set are stax pro's.  having the good fortune
)to know someone who owns a pair, i use them when i can.
)
)Herb Chong...

They were comparing CD players, not speakers or phones!  Unless both the
speakers and phones used block out the same portions of the audio spectrum,
the DIFFERENCES should have still been audible unless all the listeners
were total tin ears (seems unlikely) or the cat was meowing too loudly.

I'd like to hear the results of a similar CD A-B test with the Sony
CDP-200 and the Pioneer 900 videodisc/CD player.

I would also like to know about any headphones with great sound, reasonable
price and 50 to 60 db attenuation of ambient sound.  I have a pair of
Sony MDR-CD5 that sound great and give maybe 10-30 db attenuation
(vs Sen's which have almost NO ambient attenuation) but would like to
have more isolation, the better to enjoy CD's in my computer room.
-- 
Chuck Forsberg WA7KGX	..!tektronix!reed!omen!caf
Omen Technology Inc 17505-V NW Sauvie IS RD Portland OR 97231
Voice: 503-621-3406	Modem: 503-621-3746

ben@moncol.UUCP (Bennett Broder) (04/22/85)

>)i don't remember the type of headphones being posted in the original
>)article.  about the only pair of headphones that i am sure almost no-one
>)will dispute as a reference set are stax pro's.  having the good fortune
>)to know someone who owns a pair, i use them when i can.
>)
>)Herb Chong...
>
>They were comparing CD players, not speakers or phones!  Unless both the
>speakers and phones used block out the same portions of the audio spectrum,
>the DIFFERENCES should have still been audible unless all the listeners
>were total tin ears (seems unlikely) or the cat was meowing too loudly.

Wrong.  The problem with using the BOSE speakers is not one of
frequency response.  In fact, it would be foolish to compare CD
players on the basis of frequency response because they are all so
good in this regard.  The primary differences in the sonic performance
between various models is caused by phase anomolies introduced when
filtering out aliases and smoothing the signal.  Less successful
designs manifest themselves in a couple of ways:
  1. A harshness or hardness to the trebles, particularly noticable on
      female vocals and violin strings.
  2. A loss of precise and stable instrument positions in the stereo
     image.

The BOSE tends to be very forgiving of suboptimal sources, and might
lack the resolution to differentiate between the players. More importantly,
the quality of the stereo image cannot be judged with any pair of
headphones, and is all but impossible to judge with a direct
reflecting loudpeaker like the BOSE 901.  

Of course, the original poster of the comparison did not claim to be
providing a definitive review of the players, rather to report the
results of an informal comparison.  Readers with top quality
audiophile equipment might prefer to perform the comparison themselves
or to rely on a review done by a professional reviewer using reference
quality components.

                                Ben Broder
                                ..ihnp4!princeton!moncol!ben
                                ..vax135!petsd!moncol!ben
                                ..pesnta!moncol!ben

ark@alice.UUCP (Andrew Koenig) (04/22/85)

> The BOSE tends to be very forgiving of suboptimal sources, and might
> lack the resolution to differentiate between the players.

I would like to see your evidence for this claim.

herbie@watdcsu.UUCP (Herb Chong [DCS]) (04/22/85)

In article <3612@alice.UUCP> ark@alice.UUCP (Andrew Koenig) writes:
>> The BOSE tends to be very forgiving of suboptimal sources, and might
>> lack the resolution to differentiate between the players.
>
>I would like to see your evidence for this claim.

for starters, by its very design, the Bose 901's are nonlinear phase
transducers.  the primary sound is from the rear speakers which reflect
off of the walls and back into the listening area.  great cancellations
occur between the back sound wave and the one from the front speaker.
there are 8 drivers in the back.  even if each were an ideal point
source, the combined is anything but, and after reflecting off of
uncontrolled wall surfaces with absorption curves that can be wildly
different between setups, flat freqency response can't be guaranteed
even with equalization.  which brings up another point, the supplied
equalizer.  the drivers in the 901's are 5 inches nominal diameter.
equalization must be supplied to bring up the low end and the high end
to get flat response.  this also means that the 5" drivers are being used
well above 10K.  yes, plenty of boost will even allow a 10" woofer
to play a 15K tone decently, but how much power do you have to supply
when the natural roll-off of the driver is 6dB/octave above 5K?  so you put
high power voice-coils in, as Bose did, which increases mass, which 
decreases the natural roll-off frequency.  fortunately, he uses a sophisticated
ducting system to achieve decent low frequency response without equalization,
but then massive phase shifts are produced, and the air from the ducts
are such high velocity that you can sometimes hear them whistling (depends
upon how much other frequencies are being reproduced at the same time).

the direct/reflecting principle is very interesting and has some theoretical
advantages, but they are hardly ever realized in practice.  the equalizer
removes some of the variables, but using electrostatic elements and
properly designed conventional woofer would have been better from the
point of view of reduced driver mass and little or no equalization
in the high frequencies.  of course, electrostatic elements have a whole
set of problems of their own, but they are more appropriate for another
discussion.  the type of drivers that Omar Bose should have used given
his design requirements were horrendously expensive back when he started
and notoriously unreliable.  quads were about the only option.

Herb Chong...

I'm user-friendly -- I don't byte, I nybble....

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mohler@druxu.UUCP (MohlerDS) (04/22/85)

There is overwhelming evidence that the Bose speaker design is highly
flawed for critical monitoring! That doesn't mean that some people 
that like them can't hear, sound after all is subjective (beauty in
ear of listener). The Bose 901 series (any) is virtually worth-less
for critical monitoring (see my previous comments on the net in Re:
A-B CD). 

Phase and frequency response as well as speed of the transducers
are much too flawed, to not be the weak and masking link in the comparison.
Dispersion and delta directionality with respect to frequency are also
very poor (yes even with the direct-reflecting idea). If the Bose were
perfect in the previously mentioned areas (which it is far from) it 
would still be poor for critical monitoring because of the multiple
driver effect on phase and dispersion as well as the direct-reflecting
design pulling the other weak link (the room) into the comparison much
more than most speakers.

If anyone still needs evidence of the flaws of this design send me mail,
there is tons of documentation on this speaker.
Most headphones have similar problems.

                 David S. Mohler
                 AT&T-ISL @ Denver
                 DRUXU!MOHLER

rfg@hound.UUCP (R.GRANTGES) (04/23/85)

[]
Considering the alleged "tons of documentation" available, it seems
strange you are unable to cite even one when challenged twice.
I am not a partisan of the Bose 901. Neither do I believe in
your brand of sweeping denunciation backed only by hot air.
At least you didn't start talking about Consumers Research. Thanks
for that.

-- 

"It's the thought, if any, that counts!"  Dick Grantges  hound!rfg

ark@alice.UUCP (Andrew Koenig) (04/23/85)

> There is overwhelming evidence that the Bose speaker design is highly
> flawed for critical monitoring!

Let's see it.

ben@moncol.UUCP (Bennett Broder) (04/23/85)

>> The BOSE tends to be very forgiving of suboptimal sources, and might
>> lack the resolution to differentiate between the players.
>
>I would like to see your evidence for this claim.



The BOSE 901 is used in many commercial applications in our area:
bars, nightclubs, etc.  As such,  I have had many opportunities to
compare its sound to friends B&Ws, Theils, Celestions as well as to my
own ProAcs.  First, I think the fact that professionals have chosen
the speaker for sound reinforcement is a clear indicator of the
speaker's strengths:  It has great power handling capability, and puts
out reasonably good sound, despite mishandled records played on
turntables designed for durability rather than sonic excellence.
Second, to my ears, they fall far short of any of the above speakers
in terms of imaging, depth, dimensionality, and transient response.
Third, the critics have had little good to say about this speaker the
last five years.  The Absolute Sound has joked about the speaker, and
even the mainstream pulications like High Fidelity seemed more
impressed that BOSE has been able to update the speaker and keep it
a major force in the marketplace than they were about its
reproduction.

Don't get me wrong, I don't dislike the BOSE 901.  What is does, it
does well.  It is still a reasonable alternative for someone who likes
to listen to rock music at high volumes, or for whom the ability to
achieve a reasonable stereo image from almost any place in the room
is important, or who just like the sound of the speaker.  BOSE has
sold an awful lot of these speakers, people do like the sound of them.
But I don't think you would find any professional who would claim that
the speaker is state of the art in upper mid-range and treble detail,
or in imaging properties.  And these properties, as I pointed out in
my previous article, are where the major differences in CD players
lie.

               Ben Broder
               {petsd,pesnta,princeton}!moncol!ben

karn@petrus.UUCP (04/24/85)

I submit that the discussion has gotten off track. The original purpose of
Andy Koenig's posting was to report some results of A/B CD player testing,
which of necessity involved a finite number of tests with a finite amount
of hardware. Instead of nitpicking his results, how about going out there
and re-running his experiments with different speakers and subjects?
The more tests that have been done, the larger the body of experience on
which to base conclusions.

It's easier to piss on a study than it is to do one. Give the guy a break.

Phil

rfg@hound.UUCP (R.GRANTGES) (04/24/85)

[]
But, Phil, if more tests were run they might show the same results shown in
the infamous Bose Experiment.  Now, while that wouldn't really <PROVE>
anything (because you can never prove that no one can hear a difference
under any conditions) it would sure put a crimp in the style of those who
want to believe there are differences.  It's much better to pursue a
red herring,especially if it allows one to defame another good product.
That's two good products one can defame (Bose and Sony). And it's a lot more
fun.
Now what I would like to hear is a no holds barred, flat out AB of a
Sony CDP-101 vs a Sony CDP-102.  This would pit a mfr against himself.
It would be 16 bit 41khz sampling vs 16 bit double sampling with low
phase shift filters. I'd like to hear this on a good system (but not
a Bose to spare us the same old flames).
I will volunteer the CDP-101 and a pretty fair system (*) if someone has
a CDP-102 in the area around Holmdel, N.J. and wants to AB.
(*) Pioneer 9800, AR-9's - a fair system but one which one golden ear
told me could "never give vinyl a chance." 
I would be delighted with either a positive or negative result.

-- 

"It's the thought, if any, that counts!"  Dick Grantges  hound!rfg