CD transports and resonance
 

On Sat, 06 Nov 2004 14:29:18 +0000, Andy Evans wrote:

Don't feel bad about this, Andy. I think I can safely say that we have
*all* gone through this. It appears that human hearing is easily fooled by
psychological factors

Hello Mick - I'm a psychologist specialising in music and musicians, as it
turns out, so I'm not unfamiliar with psychological factors! Anyway, to

grin

start from the beginning - I sought to replicate the CD transport of
Japanese designer Junji Kimura, who worked for Pioneer, Trio and Kyocera.
He uses a thick aluminium slab to support the transport. See
http://www.soundstage.com/revequip/4...rogression.htm I talked

That's one interesting-looking setup...

to this guy at the London HiFi Show. He is quite eccentric, but
definitely recommended mounting the transport on an alu slab. I was
using a CD-ROM at home which was rather 'shouty'. I changed the
switchmode PSU for a normal toroid, which helped a bit, then mounted the

Now that I can understand. The psu may be letting noise through to the DAC.

unit on an alu slab, which helped more, particularly smoothing out
highly modulated pasages. If you pick up a CD-ROM while it's playing you

That's the bit that makes me a bit sceptical - I'm not denying that you
may be right. Its just that without *measurements* you are unlikely to
convince many people.

can feel the vibrations quite clearly, so we know that there is
vibration present. Now, to my ears there was a significant change in the

I agree about the vibration. I would suspect that the system would have
been designed to handle it in the first place though.

sound, not just a slight change which I would - just as you say - be
sceptical about and attribute to 'causes unknown'. I posted this in case

I don't have access to large lumps of ali, but I may be able to get a lump
of 6mm steel plate to try something similar. It should give a suitable bit
of inertia to the system...

it was of some use to other ng members - its useful to hear about
various tweaks even if they might not be relevant or replicable in one's
own system. Fine. But I also asked if anyone else had an explanation or
empirical evidence of the effects of damping on CD mechanisms. I've had
various responses, none of which are based on empirical evidence of
exactly that. So if this is outside the experience of those posting, It
would be honest and simple to say "Sorry, Andy, I don't have any
experience of this". Since I would be interested in some empirical

Fine! "Sorry, Andy, I don't have any experience of this". I might give it
a go though! After all, I have an old CDR drive and it wouldn't be all
that hard to rig it up with and without a lump of steel plate to add mass.

knowledge, I'll post this on other forums and ask some of my friends in
the audio industry. As I said at the start, this is based on an actual
product, the designer of which clearly does have empirical knowledge.


I'm afraid that I'm a bit sceptical about some of the product designers
- especially those who produce "new wave art" appearance equipment at
high prices. I have this horrible suspicion that they may well be selling
brand X snake oil... Sometimes I'm wrong. The Michell Gyrodeck is really
excellent and that is rather odball in appearance!

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info

CD transports and resonance
 

I'm afraid that I'm a bit sceptical about some of the product designers (mick)

I don't think it's the product designers so much as the tweakers. I'm sceptical
myself - it seems paradoxical that resonance can effect binary code.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

CD transports and resonance
 

mick wrote:

I don't have access to large lumps of ali, but I may be able to get a
lump of 6mm steel plate to try something similar. It should give a
suitable bit of inertia to the system...

If my fag-packet spreadsheet calculations are correct, Andy's lump of
aluminium weighs about 1kg, and a piece of 6mm steel of the same area is
about 1.8kg. (I converted his inch dimensions to 165x240mm.)


--
Wally
www.artbywally.com
www.wally.myby.co.uk

CD transports and resonance
 

mick wrote:

Thats wrong, however IIRC there is less error correction *data* on the CDs
themselves for redbook audio than an ISO9660 disc.

Cheers, Ian. I wasn't sure - it was a while ago that I read the item &
I've no idea where I saw it. My memory is c**p... ;-)

Glad to be of help.

CD transports and resonance
 

Andy Evans wrote:
I could tell you how to easily do a representative set of measurements(AK)

But evidently you can't explain an obviously audible phenomenon.

Can I ask you a question?

Do you believe that if on two successive runs, if a CD transport
recovers the same bit pattern, the resultant sound will be the same?

If so then your simple test would be to compare the bitpatterns on two
runs, one silent output, the other cranked to the max, and if they are
the same, you must agree there is no effect to observe.

If they differ, you have a defective CD transport.

CD transports and resonance
 

Andy Evans wrote:

Apart from the fact that I can hear it. There's no assurance that you have any
technical knowledge that can explain it. I don't mind the fact that you can't
explain it - our knowledge always has limitations.

Your ear is a transducer - pressure to electrical impulses.

we have mics available that can hear stuff humans cant (demonstrably -
animals can hear the difference in the recordings where humans cant)

therefore the tool to measure your claimed effect is available.

either prove it or **** off.

CD transports and resonance
 

Andy Evans wrote:

If you pick
up a CD-ROM while it's playing you can feel the vibrations quite clearly, so we
know that there is vibration present. Now, to my ears there was a significant
change in the sound,

Guys I figured it out... when he picks it up it pulls the phonos out ;-)

CD transports and resonance
 

On 06 Nov 2004 12:34:08 GMT, ohawker (Andy
Evans) wrote:

there's no assurance that there is in fact an audible phenomenon.

Apart from the fact that I can hear it. There's no assurance that you have any
technical knowledge that can explain it. I don't mind the fact that you can't
explain it - our knowledge always has limitations.

But knowing about auditory illusions is not one of them! :-)
--

Stewart Pinkerton | Music is Art - Audio is Engineering

CD transports and resonance
 

On 06 Nov 2004 15:15:40 GMT, ohawker (Andy
Evans) wrote:

To resolve, employ suitable measurements. Otherwise we (including you) have no
real idea if the effects you describe have anything to do with the 'causes' you
assume.

Hello Jim - I'm open minded - my assumption is that it's to do with resonance,
I suppose, but I've been very clear in saying I don't understand how this
happens. I'm not in a position to measure, so my next step is to find others
who have observed similar things and others who can offer some kind of
explanation based on their own empirical knowledge. Andy

Actually, your assumption is that there *is* a real effect.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

CD transports and resonance
 

On 06 Nov 2004 11:27:16 GMT, ohawker (Andy
Evans) wrote:

I have no wish to 'endow' (DP) anything. I'm reporting less distortion in
highly modulated passages when a transport is damped.

No, you're reporting that you *think* something is happening. You have
as yet shown no indication that anything *real* is occuring.
--

Stewart Pinkerton | Music is Art - Audio is Engineering