Conference cookie::notes$archive:cd_v1

                           
    These must be just like them tipytoe thingys for your speakers, and
    them record clamps for warped records, and that there record cleaner
    stuff tries to actually cleans records, and that there anti-static gun
    that can't possibly work, and of course the biggest of all, the tweak
    and cramolin goop that actually tries to improve the conductivity of
    metal surfaces!  Ha what a farce. 
    
    Boy oh Boy, my Soundesign all-in-one dual cassette eight track with
    3 speed turntable with ceramic cartridge sounds sooo good.
    
    						.dave.
    
    
    
    Oh course everything mentioned so far actually works, it's just
    that most people refuse to believe the truth because it will mean
    that they have to admit that they could possibly be mistaken (or
    that their ears cannot hear it, therefore it cannot work). Kinda
    like saying that when the sun goes down it also shuts off.

    Bad news skeptics!!! These damping pads can work to improve sound.
    
    Yes, the info is digital, but it is not immune to problems. Vibrations
    cause mistracking (either position or focus) and that results in
    read errors. Some minor ones can be corrected accurately with ECC,
    other more serious errors are guessed at and still more severe simply
    carry over the last good data (so you dont hear a hole in the sound).
    
    
    As .0 points out, there is a sucker born every minute. I happen
    to believe the biggest suckers are the ones who think this generation
    of CD (recording technology included) is perfect and have not only
    done an intelectual shutdown but also forgot to shut-their-mouth
    lest they insert-their-foot.
    
    Walt (couldnt resist shooting at the shooter) 

    Does placing a second disk on top do same thing?

    Now I am refering to my experience with vinyl records. Vibration
    and damping techniques should be transportable between the two even 
    though one is digital and the other analog. 
    
    Adding additional mass to a CD (such as one would do with a second
    CD on top) without extremely close physical coupling would not change
    the resonances or vibrations in the disc much. It would change the
    type of vibration coupled into the disk however. The added weight
    on a spindle bearing may either reduce bearing noise (if inadequate
    preload was applied to the bearing or the disc wobbled on the spindle
    due to inadequate disc-spindle clamping) or increase it (if bearing 
    contact surfaces are uneven). Since the spinning mass is higher, the 
    rotational stability would probably be improved (assuming the motor 
    could bring both up to speed). As I understand it, this is not as 
    critical as in analog. So if increased clamping and added rotational 
    stability is needed then a second disc might do the job. Adding
    a second disc would at least tell you whether one of the commercial
    pads would hurt or not.
    
    Probably the most effective system of addon improvement would be
    to provide damping of the disc with minimum added weight. A Sorbothane
    pad the size of the disc would couple very closely to the disc which
    should damp out any vibrations within the disc. The thickness of
    the pad would probably increase the clamping force applied to the
    disc on the spindle in a manner similar to a second disc. The pad
    would be similar in weight to a disc and would similarly either
    improve or agravate bearing noise.

    Walt
    

    Re: .3  yes.

    Okay. You redeemed yourselves.  I darned near put my head through
    my VT as visions of more endless religious disussions danced through
    it.  Please!  Information, yes.  Religous ranting, no.  One needs
    to be wary of new products for the CD market.  The industry is riddled
    with misinformation and is ripe for ripoffs.  So, thanks to all
    who provide information on new products.  Though not all of us may
    agree on the value of a certain product, we need to be aware of
    whether or not these products can indeed be harmful to our hard
    earned players and collections.  If a product causes no harm and
    indeed may benefit some ears, then it is a viable product.
    
    Removing serious face, and stepping out of pulpit,
    Gary

    In an earlier reply I mentioned an increase in clamping force
    of the disc by adding a pad or second disc.  I have become aware
    since then that Philips and some Sony products use a magnetic
    clamping system instead of spring forces. In this case, an additional
    disc or pad which moves the clamp further from the spindle would
    actually decrease the clamp force (sort of inverse of what would
    happen with a spring clamp) and could lead to more slippage or
    vibrations between the spindle and the disc. Whether the additional
    weight of the second/pad offsets this or not is anyones guess. 
    
    Based on this, I would think that one would want a pad with a spindle
    hole larger than the clamp diameter, at least if your unit uses
    magnetic clamping. This way you get the benefits of both damping/
    mass of the pad and the clamping force in the magnetic clamp is
    not reduced.  This raises a question in my mind. How does one center the
    pad on the spindle, and if it is off center how does this affect
    performance ?  
    
    Finally, if this conference designs the ideal pad, does DEC get the
    profits ?  ;^)
    
    Walt

    
    The Mark Kaepplein CD liquidation sale got me a Mod Squad damper
    for my Maggie.  The hole for the damper is larger than the 'regular'
    CD hole, and uses a stick on centering ring to center the damper
    onto the CD.  Tonight I shall get a chance to see if it will improve
    the bass of the Pink Floyd I just got from Glenn Davison (in comparison
    to the MFSL version).  
    
    Also, perhaps after I get Marks manuals I will let you know the
    spindle spec for maggies...
    
    						.dave.
    
    Unless he remmebers of the top of his head.

    What's  MFSL?

    Why Mobile Fidelity Sound Labs, of course.  They're in the business
    of releasing sonically enhanced versions of classic (not classical)
    recordings.

    
    Alright, who is going to be the first person to conduct an experiment?
    Somewhere in the middle of your CD player I would imagine you would
    find a pin that went high (or low) when interpolation was going
    on.  Monitor that sucker.
    
    Now, play a CD with and without pad.  Does it make any difference
    in percentage that the player is interpolating?
    
		    						-mr. bill

In addition to the plastic pad, I've now seen aluminum (heavy) and brass 
(wicked heavy) damping pads...although, the brass one warns you that your 
player may not be able to cope with the weight.

						     
							- JP

    RE: .12
    
    I understand they give you some lapping compound with the brass
    one  :^)
    
    Walt

    
    re .11
    
    	Ok I will..  Once I get the manuals for my CD player from Mark,
    and figure out where that bit is, I'll stick a LED or something
    on it.  (it's been so long since I actually did EE work I'll probably
    blow the machine up)
    
    Anybody wanna show me how to hook a LED into that pin? (assuming
    its a pin).  I can't believe I don't remember any of that stuff,
    time to drag the old EE books out...
    
    						.dave.
    
    bad thing is, their only three years old...

    RE: .11,.14
    
    What you need is a counter.  I put a scope probe on the signal,
    but my eyes wern't quick enough to count the times it went high.
    Rapping on the player, though, made errors easy to see.
    
    I was going to build a counter with led display, but never got around
    to it...

	Nahhhhh, what ya really want to do is hang a Tek DAS 9400 logic
analyser in there.  Then you could really see whats going on!

	Re: .15

        Would you need another display, or could you connect the added
        counter to the existing display logic used to show time/track
        information? 

    
    ok, everyone send me 10$ and I will go out and buy another Maggie,
    rip it to shreds and see if I can rig up a counter to see if the
    10$ piece of plastic actually helps reduce the error rate due to
    an unbalanced cd.
    
    Seriously, when I get the manuals, I'll take a counter home and
    see what I can come up with.
    
    						.dave.

    Get a Cray-1 and do some real-time sampling, then produce reams
    of reports.  Make sure you use the vector instructions, for snob
    appeal.
    
    

   
   Well, so far I can say this much for the CD Damper, it makes the
   Maggie work better.  On several occasions the player was incapable
   of skipping to the 9th track from the 4th or 5th, and couldn't go
   from 9 to 8 either.  But with the damper I have had no problems going
   from any track to any track.  At least that much is better.
   
   I also think that the bass is a little less muddy.  
   
   						.dave.