Are we foolin' ourselves...

[formica]

That's not consistent with my understanding of
how the RIAA compensation works. Could you elaborate or provide a
reference?

In theory, it's a "cut off shelf" at 50Hz ... http://www.euronet.nl/~mgw/background/riaa/uk_riaa_background_1.html

[ByteWrangler]

"When

storing audio at, say 44.1 kHz, it is not really possible for the

electronics to differentiate between a sine or square wave at above 10

kHz."

I think what this means is the format only offers sine waves for the high frequencies, the harmonic detail is lost...

The quote is correct. The second statement, while technically correct, misses an important point.

In a system limited to a maximum of 20 kHz there are no

harmonics of fundamentals above 10 kHz. Period. The second harmonic

of 10 kHz is 20 kHz (there are no lower harmonics). In other

words, 10 kHz+ square waves become sine waves in any signal (digital or analog) that is

low-pass filtered to 20 kHz (actually, for square waves, the third harmonic is the lowest present, so this is true for square waves above 6.666... kHz). Frequencies between 10 kHz and 20 kHz can

be distinguished if sampled at 44 kHz, however. For instance, the

sixth, seventh, eighth, ninth and tenth harmonics of 1760 Hz ('A' 2

octaves above middle 'A') all fall in this band and can all be recorded

and distinguished, as can the fifth through ninth harmonics of, say, 2000 Hz

- and all at the same time. The harmonics of fundamentals in the range of actual music and voice are not lost; the ones lost are outside the range of hearing (or at least outside what is considered the "audio band").

Frequencies above 22 kHz cannot be

correctly represented in a digital signal sampled at 44 kHz. Even worse than

simply disappearing, if present in the signal being sampled, they

appear, all right, but at the wrong frequency! They "go by a different name" (in other words, an alias). Once the input frequency (Fi) goes above the Nyquist frequency (Fn = half the sampling frequency) - the "aliased" recorded

frequency (Fr) decreases as Fi increases until Fi reaches the sampling freq (Fs = twice Fn) - where the recorded alias becomes zero freq, or DC.

Above Fs, the recorded alias frequency increases from zero again until Fi reaches 3Fn (1.5 Fs) and the recorded alias is Fn,

then down again until Fi reaches 2Fs and the alias is again zero, then up, and so on, in a phenomenon called

"folding".

So, for Fi <= Fn: Fr = Fi (input freq below or equal Nyquist freq: recorded frequency = input frequency... not aliased - this is good)

For Fn <= Fi <= 2Fn: Fr = 2Fn - Fi (input above Nyquist, below twice Nyquist: recorded alias not equal input frequency... not good)

For 2Fn <= Fi <= 3Fn: Fr = Fi - 2Fn (... and so on)

For 3Fn <= Fi <= 4Fn: Fr = 2Fn - Fi (... and on)

This is the same effect you see in old Western movies when

the spokes on stagecoach wheels appear to speed up as the stagecoach goes

faster, then get blurry, then turn the opposite way, slow and stop, then turn forward again. Because of this, when making digital recordings, it is absolutely imperative that everything above the Nyquist frequency for the sampling rate used be completely eliminated (or at least hammered waaayyy down) before sampling.

[jacksonbart]

8 posts wow!

The 44.1 kHz sampling rate of the CD format, in theory, restricts CDs' information losses to above the theoretical upper-frequency limit of human hearing of approximately 20 kHz (see Nyquist limit)(note - sampling rate and frequency range are two different things. It is doubted that human can hear over 20khz, yes, but the 44.1kHz refers to the sampling rate of the music - it means the sound is sampled at a rate of 44.1 thousand times per second.). It should be noted that typical audiophiles are in their thirties or older [3] and highly unlikely to be able to hear beyond 18 kHz. Some critics argue that there are still deleterious effects on the sound quality at this sampling rate. Newer formats such as DVD-Audio and Super Audio Compact Disc (SACD) with sampling rates of 96 kHz or higher have been developed in an attempt to address this criticism.

[ben.]

That's not consistent with my understanding of how the RIAA compensation works. Could you elaborate or provide a reference?

In theory, it's a "cut off shelf" at 50Hz ... http://www.euronet.nl/~mgw/background/riaa/uk_riaa_background_1.html

OK, none of that or jacksonbart's cut/paste is inconsistent with my previous understanding of the topic - though more detailed. I skimmed it and still see nothing that limits the LF bandwidth upon playback.

[jacksonbart]

That's not consistent with my understanding of how the RIAA compensation works. Could you elaborate or provide a reference?

In theory, it's a "cut off shelf" at 50Hz ... http://www.euronet.nl/~mgw/background/riaa/uk_riaa_background_1.html

OK, none of that or jacksonbart's cut/paste is inconsistent with my previous understanding of the topic - though more detailed. I skimmed it and still see nothing that limits the LF bandwidth upon playback.

To play back an honest to goodness 20hz on an LP is theoretically possible, but with many things that can go very wrong. Most likely nothing like the actual signal, lots of equalization/ampflication, groove wear and stylus errors that can occur in those grooves. Enough techincal talk, its all about the music. I love good music.

[ARTIELANGE]

i just saw chops lurking in the 2 channel forum

[oldbuckster]

Unless you are Superman, you don't hear above 20kHZ anyway.............Spend $40. or $40,000. for a CD player doesn't matter, what matters is what the owner thinks.....................We spend alot of time telling people what they should hear, what they should buy, how they should set it up, and in the end, what the owner hears, buys, or does is his/her choice.............The average Joe Consumer isn't going to spend thousands of dollars on a CD player, I don't care what some of you think, Joe Consumer controls the market place, not HIGH END AUDIO people, so, you have to produce good products for a reasonable price that the average person can afford.................Silversport brings up a good point, but when he was asking for information on CD players, he didn't get this much response.......................My wife has a $38. Wal-mart dvd player upstairs and she loves it, easy to use, not alot of gadgets on it, simple, inexpensive.....................I have a SONY DVD downstairs, much more money, she hates it....go figure........Question, "Are we fooling ourselves?"........................my answer...................YES we are......................

[oldbuckster]

double post...................oooops!!!!!!!

[mike stehr]

I just hooked up one of these Pioneer 6 disc CDP's into my system. It's a 1992 model # PD-M501.

These old Pioneer six disc cartridge CDP's seem to be rather reliable. This unit has real low use, and still looks new. The old thing sounds rather good really, not much worse than the Rega Planet to me.....even got 5 or six cartridges. Geez, maybe the ol' planet's done it's last orbit........

The only bummer is loading the CD's upside down, not too much of a big deal.....

The guts of the Pioneer are a decent looking build quality for the line these things fall in. The only surface mount parts I seen were on the laser assembly PCB, everything else is through-hole, with through-hole Op-amps, DAC, etc....

The guts of the two Sony units around the same era, have the main board behind the display and faceplate. The PS board and optical out/analog output are on the back panel, with wires jumpered to the main board and nothing but space between them. The two boards, and the transport. They could have made the CDP unit half the size. All the parts on the main PCB are surface mount. Op-amps as well.

The transports on the Sony players when in use are very, very, quiet. The Pioneer kinda clicks and clunks in comparision. I remember my Toshiba 3950 clicking while in use up two 2 feet away. You have to tear off the covers of the Sony's to hear the transport/laser click with one's ear next to it.

The Sony units don't sound bad, maybe a little more ratty sounding than the others. Who knows....

You can change the sound from good to bad by changing op-amps and other parts in the analog ouput stage after the DAC, or by-pass the op-amp stage and output right off the DAC with a cap, which is one of the 3950 mods, IIRC...

I think isolation serves a purpose if the CDP is near a subwoofer, or some major soundwave level to the point where the unit is getting blasted enough to skip or vibrate.

Feet effect the sound of a CDP, from my experiences......anymore I just want a good sounding CD player that lasts for years, not just two. When I see a minty vintage CDP that isn't too cheap a build in quality, I'll usually snag it....prefer free, but will go up to 20 bux.

I'm flamboozled.......................

[SilverSport]

"trust no one"...thanks "X Files Meagain"......Too True...thanks for watchin' my "6" OB...

Bill

[LarryC]

OK, none of that or jacksonbart's cut/paste is inconsistent with my previous understanding of the topic - though more detailed. I skimmed it and still see nothing that limits the LF bandwidth upon playback.

I agree. Isn't the RIAA playback curve, including the 50 Hz limit or "shelf." a mirror image of the recording curve? I.e, isn't the record is cut with a relative boost below 50 HZ? Discussions of the RIAA curve refer to the need to reduce rumble in players of the time. So, logically, those lows would be relatively boosted (reduced less) in cutting the LP and then, according to the curve, lowered (boosted less), along with rumble, in playback. I've never read anything about the playback curve not mirroring the recording curve in that respect.

Anyway, I don't think the net outcome is a cutoff below 50 Hz. Otherwise, LP bass wouldn't be as deep as a La Scala's, and I just don't think that's the case.

[LarryC]

Hey Mark,

You referenced Wadia. I looked at the 861.

Its component list is not all that different from some mass produced machines. It does offer three software algorithms which offer their own individual compromises as you deviate from the standard (including rolling off the highs so it should appeal to vintage tube lovers). But... and here's where the money is... "its chassis is massive, constructed of thick, silky, brushed-aluminum slabs"...

I just now saw this debate, thought I'd comment although the thread has moved on to other things. The Wadia 270se CD transport weighs 60 lbs. (up from a first-edition 53 lbs.), and the brass and aluminum disc clamping mechanism by itself weighs 30 lbs. as part of Wadia looking at vibration control. My experience is that a Townshend air-bladder isolation platform still reduced grit and grunge to some extent, so it seems to me that mechanical control of the disc and laser DO have a positive effect. I'm not so sure that these mechanical issues differ fundamentally from a TT, although opinion clearly varies.

Then, it has other hardware-software "refinements" -- the master clock is as close as possible to the DAC chips (supposedly less error in very high digital frequencies with such a short distance), and the 270 is meant to be "ClockLinked" to the transport to minimize timing errors (jitter) between the disc spinning and the DAC decoding. The digital and clocklinking signals are transmitted separately between the transport and the DAC by a pair of glass fiberoptic interconnects. Dithering is also added (8 bits out of the 24-bit signal to the DAC), which apparently provides a random-signal noise floor that is thought to have some similarity to a music signal, but at a level of resolution below lowest level available from a 16-bit signal. This supposedly avoids a sudden silence below 16 bits.

As you can see, it's a pretty elaborate transport, and I thought the info might be interesting to present. However, my vinyl still sounds better, more realistic and less digital than my CDs, but at least it's close enough that I don't mind switching between them.

[pauln]

The only reactions so far addressing my question about CDs only producing sine waves in the top octave of their frequency response was to be agreed with by one and called a troll a couple of times by another. I raised the question because in a discussion of variability in CD player quality it seems it should be a much more fundamental issue than player mass and construction, isolation, chip sets, advanced algorithyms, etc.

If you are foolin' yourselves, this more fundamental issue might be why...

[maxg]

"I'm not so sure that these mechanical issues differ fundamentally from a TT, although opinion clearly varies."

Nice one Larry - we are on the same page evben if most others here disagree with us.

PaulN,

I might agree if I understood the issue. I am sure there are many other variables in play than we have covered in this thread - and I am still not sure we (all of us) understand what they really are or their relative importance.

[PrestonTom]

I think the issue that there are no harmonics above 10k fundamental is a red herring.

This limitation is also true for analog as well and is a non-issue since our hearing (as well as the original recording) are both low-pass systems. There is certainly energy being reproduced up to about 20 kHz. That is plenty of bandwidth. The real issue on current CDs probably is due to the error correction (for big errors that cannot be corrected but need to be interpolated) and for the op-amps at the output stage. Currently the transports, clocking, DACs, and sampling are probably more similar than disimilar. Although there will still be a segment of the market that insists on bandpassing the signal and customizing the distortion with a tube output. But that difference is specific sort of choice.

-TOm

[ben.]

There's life above 20kHz! http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

[maxg]

"I'm not so sure that these mechanical issues differ fundamentally from a TT, although opinion clearly varies."

Didn't someone else say something like that? I think page 6 is definitely my favorite of this thread thus far.....

[]

[maxg]

I just realized I quoted Larry twice instead of quoting Tom the second time as I wanted to:

" The real issue on current CDs probably is due to the error correction (for big errors that cannot be corrected but need to be interpolated)"

Now that is definitely what I was talking about....I think.

[pauln]

I think the issue that there are no harmonics above 10k fundamental is a red herring.

This limitation is also true for analog as well and is a non-issue since our hearing (as well as the original recording) are both low-pass systems.-TOm

A red herring is something intended to divert attention from the real problem or matter at hand; a misleading clue. I'm suggesting that the limitation may be the fundamental problem.

The assertion that it is a non-issue is based on the incorrect assumption that the analog system has the same upper band limit as digital - in the case of the original recording that is just factually untrue. In the case of our hearing, the extension of the band limitation argument is invalid. The ear and your hearing do not work the way you think. The fastest firing neurons top out at about 1000/s because of depolorization recovery latency. All perceived frequencies above that pitch originate as derived neural signals whose frequencies do not correspond to that of the sound wave. Mid range and high frequency hearing is very complicated and cannot be lumped with audio hardware for comparative analysis.

[Mallette]

Amazing how opinions have changed! I was pretty much bslapped a couple of years back in the great "bits is bits" wars for suggesting that, well, bits is bits. No point in re-hashing as mdeneen and others have done an excellent job of making the point. While there remain definite and audible differences in various components of the audio chain, the bits sent to the DAC by a 5.00 CD transport in working order will not differ from those sent by a 5,000.00 transport. Everything else is up for debate...but not that.

Dave