From enakamura@unam.mx Sun Apr 02 02:35:03 1995
Path: ashpoly!cascade!transat!eunet-fi!relcom!kiae!unam!enakamura
From: enakamura@unam.mx (Elaine Nakamura)
Newsgroups: comp.dsp
Subject: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Apr02.023503.7626@unam.mx>
Date: Sun, 02 Apr 1995 02:35:03 GMT
Organization: Universidad Nacional Autónoma de México (DGSCA)
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Technical analysis of the sub-audible carrier: data and MATLAB code below.

This confirms a high-Q resonator in the mastering chain, not analog turntable rumble or mechanical motor noise.
With a 12th-order Burg AR model, the pole is located at z = 0.9992 * exp(j * 2 * pi * 14.2 / Fs).

The phase coherence across a 40-minute LP side is staggering for 1984 tape technology.

-- 
=== Elaine Nakamura ===
Dept of Electrical Engineering, Universidad Nacional Autónoma de México (DGSCA)
"They will send a copy in my place."

From hgarcia@cmu.edu Mon Apr 03 13:50:03 1995
Path: ashpoly!cascade!transat!sunet!nordrelay!cmu!hgarcia
From: hgarcia@cmu.edu (Hana García)
Newsgroups: comp.dsp
Subject: Re: 14.2 Hz sub-carrier PSD estimation - Welch vs Burg periodogram
Message-ID: <1995Apr03.135003.6768@cmu.edu>
Date: Mon, 03 Apr 1995 13:50:03 GMT
References: <1995Apr02.023503.7626@unam.mx>
Organization: Carnegie Mellon University School of CS
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In article <1995Apr02.023503.7626@unam.mx>, enakamura@unam.mx (Elaine Nakamura) writes:
> Technical analysis of the sub-audible carrier: data and MATLAB code below.
> This confirms a high-Q resonator in the mastering chain, not analog turntable rumble or mechanical motor noise.

Have you checked your sound card's ADC clock? Cheap Sound Blaster cards use uncalibrated ceramic resonators that drift with temperature.

-- 
Hana García
Tape trading list upon request. SASE required for international mail.