Interesting Test

[NoProRalph]

OOps!

You're right.
There was a little booklet with mine when I bought it but it's long lost. Best as I can rememnber it hyped the fact that there were only so many records pressed with one master etc. etc. but I don't recall any engineering details being set forth.
BTW at 70+, 15k IS the spectrum ;-}

Ralph

[Craig Maier]

Some time back, I did a little analysis of the theoretical frequency response of various record formats. You may find it of interest and it is at the following link:

http://www.diamondcut.com/vforum/sho...uency+response

[DJBohn]

Craig, I just looked at your link for the theoretical frequency response limits. Could I assume that a MicroLine stylus tip, being even smaller than a common eliptical could squeeze out a bit higher treble? I was just curious as I finally replaced my worn Ortofon Super OM-20 with a new high quality Audio-Technica that claims a response out to 50k with it's MicroLine tip.

Also, there are a few audiophile discs out there, which I have 2 or 3 of these, that are 12" in diameter recorded at 45 RPM. (one song each side) The sound quality of these discs is first rate. I've also noticed the cartridge output is higher than normal playing these special records.

I guess the limits of the test records available would not be able to show the high frequency losses in the very upper end. Looking at the theoretical response limits on your chart, I can see why consumers in the past had such horror stories with CD-4 Quadraphonic playback. The playback setup had to be absolutely perfect. Response requirements extended out to 35k or higher. The biggest complaint from users of these systems was after about 5 to 8 plays of the quad record, the extreme highs were already wiped away enough where the CD-4 "Radar" preamp wouldn't lock into Quad anymore.

I have an original CD-4 setup record that came with one of my decoders. It looks brand new as if it had never been played. I'm sure it has at least 1 or 2 plays on it, but looks good enough for me to try and record at 24/96. I would be curious to see if a 24/96 CD copy would activate the decoders "Radar" lock. But being as the CD-4 decoders are also a cartirdge preamps, I would have to modify the sound card output level, impedance, and capacitance loading to do this. (It sure would be nice if someone out there could modify CD-4 decoders to bypass the cartridge inputs and accept line level inputs instead - would make things much easier) Maybe when I have more time to play with this idea...

[Craig Maier]

Hi DJ,

Per the formulae that I had derived wherein F = top end frequency response capability:

F = (Pi x D x RPM) / (W x 120)

Meaning that the Quotient (F) is raised by larger values in the Numerator and/or Smaller values in the Denemonator.

So, that means that a smaller styli dimension (W) increases the frequency response. Also note that increasing the RPM (RPM) for a given Diameter disc also increases frequency response. So, the combination of a small styli with a faster speed should produce the best result with one caveat. That caveat is that the record would have had to have been cut with the smallest possible cutting stylus as well. If the groove is too wide for the playback stylus, then the stylus will not ride the groove, but will ride the trough of the groove which will contain more noise than signal. You really want a situation wherein the stylus is riding on the groove wall, not the bottom of the trough.

I hope that helps.