At some stage we need to give this 'expectation bias' mantra a break - otherwise we might as well all just listen to midfi - and be content ...
That's it, maybe it was the mid fi coming thru ....
Why not clue us in on the rest of the system , what amp type was he running, was the phenom noticed on one disc or all disc, did you compare to see if first track sounds different to last , tracking error..?
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Sy,
Having never thought about what Richard brought up about polycarbonate that made me wonder, are they using some form of UV protection that keeps the poly from yellowing? I have never seen this happen to a disk, perhaps because we usually, at least I do keep our cd's in a cover or case? Even if they did yellow a bit it would seem that the laser would still be reading the same pits and lands.
On your tonearm explanation what are you proposing, a tungsten wire internal to the tone arm or some distributed tungsten weights on the outside of the tube?
Frank,
Still can't understand how you make these statements when it has to do with your own personal system unless you have finally gotten some decent speakers besides the PC speakers you have that would ever resolve any high frequencies in the least. Perhaps on someone else system with a decent playback system but never your own.
Having never thought about what Richard brought up about polycarbonate that made me wonder, are they using some form of UV protection that keeps the poly from yellowing? I have never seen this happen to a disk, perhaps because we usually, at least I do keep our cd's in a cover or case? Even if they did yellow a bit it would seem that the laser would still be reading the same pits and lands.
On your tonearm explanation what are you proposing, a tungsten wire internal to the tone arm or some distributed tungsten weights on the outside of the tube?
Frank,
Still can't understand how you make these statements when it has to do with your own personal system unless you have finally gotten some decent speakers besides the PC speakers you have that would ever resolve any high frequencies in the least. Perhaps on someone else system with a decent playback system but never your own.
Yes a.wayne,
With Franks reference system I expect no useful answers, just a pc based sound card system running on cheap JBL pc speakers. I only expect lots of prose and not any real answers, haven't seen more than a couple of good references he sites but never a real measurable answer to any of his comments. Lots of expectation bias towards his posts that is for sure!
With Franks reference system I expect no useful answers, just a pc based sound card system running on cheap JBL pc speakers. I only expect lots of prose and not any real answers, haven't seen more than a couple of good references he sites but never a real measurable answer to any of his comments. Lots of expectation bias towards his posts that is for sure!
Well, that's a journey of discovery for others to make - that the speaker drivers aren't a limitation in the way most people see them. Because cheap speakers are always, always combined with cheap power supplies and minimal engineering in consumer electronics they always sound cheap, normally. I've heard ultra expensive speakers output totally crap bilge far too often, and I've heard magic from cheap and nasty, nothing drivers - so, yes, I'm just a touch prejudiced about this ...
You may not believe it, but a small, cheap full range driver can punch your head with the blast of a full throttle trumpet just as well as the real thing, if driven properly - something I've experienced countless times.
You may not believe it, but a small, cheap full range driver can punch your head with the blast of a full throttle trumpet just as well as the real thing, if driven properly - something I've experienced countless times.
Yes, expectation bias, here. You expect this to not be able to sound good, therefore it never can. Others, wet their paints with excitement seeing expensive speakers, and then have to deal with the fact that what they actually hear is rather mediocre ...
Sorry, I missed the question .. he's a nice chap, I'll check first that he's OK with my mentioning fine details here - tomorrow.
In the meantime ... plenty of amplifier power, full active, microphone EQ'ed ...
No Frank,
I work with speakers and I know that often retail cost has nothing to do with whether a speaker is a quality reproducer or not. Most of the time you are getting nothing special except for a fancy box and marketing bull. There really are few quality speaker manufacturers out there, most things are just repackaged commodity speakers at best, so my expectations of speakers based on price alone are just not there. I am hard to impress so name branding just won't do that.
At the same time I don't expect a 50 cent speaker to blow my mind, or produce a lifelike sound, just not going to happen with a cheap full range driver. The notion of a full range speaker getting from a modest low of let's say 60hz to 20Khz is just silly, the physics just doesn't compute, you have to give up something somewhere, you can't have your cake and eat it to.This doesn't mean you can't have a pleasant sounding background speaker but I have never heard a full ranger that I would say is truly high fidelity across the entire frequency range.
I work with speakers and I know that often retail cost has nothing to do with whether a speaker is a quality reproducer or not. Most of the time you are getting nothing special except for a fancy box and marketing bull. There really are few quality speaker manufacturers out there, most things are just repackaged commodity speakers at best, so my expectations of speakers based on price alone are just not there. I am hard to impress so name branding just won't do that.
At the same time I don't expect a 50 cent speaker to blow my mind, or produce a lifelike sound, just not going to happen with a cheap full range driver. The notion of a full range speaker getting from a modest low of let's say 60hz to 20Khz is just silly, the physics just doesn't compute, you have to give up something somewhere, you can't have your cake and eat it to.This doesn't mean you can't have a pleasant sounding background speaker but I have never heard a full ranger that I would say is truly high fidelity across the entire frequency range.
PC characteristics
Richard,
This does not happen, I assure you. The specific grade of PC is chosen (Sabic OQ1020 for example) for it's LACK of either scattering or absorptance at 500nM, both of which would reduce the s/n of the return beam. (the λ of the laser is 780nM in air, but 500nM in PC) I have run continuous tests to meet GPO purchasing specs using a Dr. Schenk Prometius substrate tester which uses a significantly larger amount of laser power. The results of these tests show zero change in the substrate characteristics after the initial 4-6 hour post-molding cool-down. There are discs which have been spinning in kiosks at airports, for instance, for years with multiple player replacements and they still play fine.
If there is a change after time with a CD playback system my money is on:
1) Thermal effects in the actual laser itself. They are servoed for current, and as they age they run hotter, which can cause the λ to increase (chip expansion). As the λ increases, the Airy pattern on the pit track also increases from it's nominal 1.7uM diameter. This change in λ has two effects: Less complete cancellation, since the 180° phase shift represented by the double-pass of light across the pit depth is designed for a 780nM laser, and increasing crosstalk as the Airy nulls fall off of the adjacent tracks. The increasing crosstalk and less cancellation cause a degradation in the s/n of the recovered light. This means the recovered EFM s/n is less, which can cause increasing amounts of E32s (uncorrectable errors), and resulting interpolation errors. I know you all know that interpolation errors are the main source of "sound difference" between players. As some may have noticed, I'm a broadcast engineer by hobby (there's no $$ in it...) and laser pickups in those CD players which are used 24/7 have only a year or two life before the pickup needs replacing. I've analyzed the failures of a few, and the s/n of the recovered EFM is significantly degraded, doubtlessly due to a combination of these factors.
2) Player circuitry drifting with thermal changes. Y'all know more about this than do I.
Howie
Howard Hoyt
ex- Dir. of Engineering
AMI, LLC
Burlington, NC
over 1B optical discs replicated since 1993
Richard,
This does not happen, I assure you. The specific grade of PC is chosen (Sabic OQ1020 for example) for it's LACK of either scattering or absorptance at 500nM, both of which would reduce the s/n of the return beam. (the λ of the laser is 780nM in air, but 500nM in PC) I have run continuous tests to meet GPO purchasing specs using a Dr. Schenk Prometius substrate tester which uses a significantly larger amount of laser power. The results of these tests show zero change in the substrate characteristics after the initial 4-6 hour post-molding cool-down. There are discs which have been spinning in kiosks at airports, for instance, for years with multiple player replacements and they still play fine.
If there is a change after time with a CD playback system my money is on:
1) Thermal effects in the actual laser itself. They are servoed for current, and as they age they run hotter, which can cause the λ to increase (chip expansion). As the λ increases, the Airy pattern on the pit track also increases from it's nominal 1.7uM diameter. This change in λ has two effects: Less complete cancellation, since the 180° phase shift represented by the double-pass of light across the pit depth is designed for a 780nM laser, and increasing crosstalk as the Airy nulls fall off of the adjacent tracks. The increasing crosstalk and less cancellation cause a degradation in the s/n of the recovered light. This means the recovered EFM s/n is less, which can cause increasing amounts of E32s (uncorrectable errors), and resulting interpolation errors. I know you all know that interpolation errors are the main source of "sound difference" between players. As some may have noticed, I'm a broadcast engineer by hobby (there's no $$ in it...) and laser pickups in those CD players which are used 24/7 have only a year or two life before the pickup needs replacing. I've analyzed the failures of a few, and the s/n of the recovered EFM is significantly degraded, doubtlessly due to a combination of these factors.
2) Player circuitry drifting with thermal changes. Y'all know more about this than do I.
Howie
Howard Hoyt
ex- Dir. of Engineering
AMI, LLC
Burlington, NC
over 1B optical discs replicated since 1993
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Thanks but the first quote was only $100 less than a new one, for that I would just buy a new one.
Plug the numbers in.
http://www.diyaudio.com/forums/analogue-source/35681-effective-mass-resonance-excel-sheet.html#post412760
http://www.luckydog.demon.co.uk/images/warpengine00.xls
Test against the results from the cartridge on a test disk (or empty groove).
Usually, the discrepancy with Denons is to be found at the cartridge compliance number copied from manuf data sheet (too low). Trust the experimental results on this.
After that, work on - the really important - damping the resonance. Using bluetak for distributing the mass helps with damping too.
Increasing the inertia at the horizontal plane is often neglected but is a key element soundwise.
Steel platter: DL-103 magnetic circuit pulls much stronger compared to DL-110.
George
Yes I've seen stories of folks with steel platters and thin felt pads have the cantilever crush itself on the first play (maybe urban legend).
Re: test disks - In my view this is a coupled resonator problem if the H and V frequencies are different. Add the out of round and non-flatness exciters, do the disks do a good job of separating the two?
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Howie,
Would this account for the difference in sound between tracks, first vs last for eg..
It is so.
Yet some people here (actually, the majority of the users here) don't get it and possibly never will.
In their (erroneous) view, if and when the subjective sound appreciation doesn't correlate with (the widely accepted) measurements results, 'there must be a psychological reason for it', like 'placebo effect', or any other imagined influence.
Probably, 'partially deaf ones' would never change this belief of theirs. 'What they don't hear doesn't exist' (in their minds). Hence, reasons are given to why the others must be deluded.
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