Hi Ellis:

I didn't say that as a statement of my belief. I said it was long-time thinking in audio circles,
meaning professional audio. I actually like an extended top end as long as it's not noise and
ringing and other junk. My point was, what you find out at those frequencies on old tapes is mostly
noise and ringing and other junk. This was backed up by John Chester's statements, based on his
spectrum analysis of information recovered by the Plangent head, which extends out to bias
frequencies.

-- Tom Fine

----- Original Message -----
From: "Ellis Burman" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, March 26, 2014 8:48 PM
Subject: Re: [ARSCLIST] Fwd: [ARSCLIST] "Why Vinyl Is the Only Worthwhile Way to Own Music"


> Hi Tom. I don't agree with your statement "frequencies over 20k are
> mostly trouble and should thus be filtered (which is the long-time thinking
> in most audio circles)" At least not from an equipment manufacturer's
> standpoint. I suppose you are speaking about if from a mastering
> perspective. But from an equipment standpoint, good high frequency
> bandwidth, and the lower phase shift that accompanies it, has been a virtue
> as long as I can remember (API, Neve, De Medio in the pro realm, and Harman
> Kardon (Ultrawidebandwith) in the consumer realm. Those guys clearly
> believed that there was a sonic benefit to preserving frequencies above 20
> kHz.
>
> I remember when CDs came out and one of the claimed benefits was wider
> frequency response. My Pioneer RT-707 1/4" deck went out to 28kHz, so I
> knew that claim was false. I recently re-built some Ampex 440s and ran
> them on an Audio Precision and was surprised how far they extended (past
> 30K if I recall) when they are properly tweaked and with modern tape
> formulations. And many phono cartridges go way beyond 20K - I seem to
> remember some going out to maybe 40K in order to reproduce the 30 kHz high
> frequency subcarrier for the CD-4 quadraphonic decoder.
>
> And also this statement "input and output transformers acted essentially as
> band-pass filters, unable to pass ultra-sonic frequencies." There are
> plenty of good transformerful (as opposed to transformerless) mic pres that
> go out to 80 or 100K. The 440s had transformers in them too. I think
> "unable to pass ultrasonic frequencies" is a bit of an exaggeration. A
> good audio transformer can definitely pass ultrasonic frequencies. With
> early digital I think it was more about the brickwall cutoff slope (and the
> horrendous phase shift that accompanies it, especially using the multi-pole
> analog filters of the day). Analog equipment (and transducers - such as
> phono cartridges and tape heads, which are also really transformers) tend
> to roll off more gently.
>
> As far as musical instruments not producing frequencies above 20K, that is
> patently false. It doesn't even make sense from a logical standpoint. Why
> would a physical object stop vibrating above 20 kHz just because our
> hearing cuts off there? The highest frequency emanated by an object is
> defined purely by physics, and there is no magical 20 kHz limit. Hit a
> triangle and put a good mic and mic pre on it and look at it on a spectrum
> analyzer. The harmonics go on practically forever - they just decrease in
> amplitude until they're down in the noise floor, way up in the ultrasonic
> range. Same for cymbals and muted trumpets.
>
> As to whether any of this stuff is directly audible, that is up for debate
> I suppose, though there seems to be plenty of anecdotal evidence to lead me
> to believe that we don't completely understand the ear-brain mechanism.
> I'm not sure the Geoff Emerick example is a good one though - true, an
> unterminated output transformer will ring at ultrasonic frequencies, but
> the Q may be wide enough for there to be significant HF boost and phase
> shift well within the accepted audible range.
>
> Ellis
>
>