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From: ross@raster.UUCP
Newsgroups: rec.audio,sci.electronics
Subject: Re: Re: INTERCONNECTS
Message-ID: <199@raster.UUCP>
Date: Thu, 30-Apr-87 17:28:42 EDT
Article-I.D.: raster.199
Posted: Thu Apr 30 17:28:42 1987
Date-Received: Sat, 2-May-87 01:51:41 EDT
References: <18511@ucbvax.BERKELEY.EDU> <196@raster.UUCP> <1770@mtx5a.UUCP>
Reply-To: ross@raster.UUCP (Ross Werner)
Organization: Raster Technologies, Westford, MA
Lines: 43
Xref: utgpu rec.audio:1243 sci.electronics:576

In article <1770@mtx5a.UUCP> mat@mtx5a.UUCP (m.terribile) writes:
>> I did some playing around with trying to measure differences between cables.
>> Using a function generator, a 'scope, and an HP gain-phase meter (shows
>> amplitude and phase differences between the two inputs), I connected the
>> function generator to one input of the HP, and the cable under test between
>> both inputs.   [ ... ]
>> 
>> The results?  NO MEASURABLE DIFFERENCES FROM DC TO 250K Hz.  [more]

>
>1) Have you tried it with a 60K source and 40K load?

No.  I was attempting to simulate the pre-amp to amp interconnection.  My
pre-amp (PS Audio 4.5) has a class A buffer amp (i.e. low output impedance)
in the high-level mode that drives the outputs.  In "straightwire" mode,
the buffer amp is switched out and so the outputs are driven essentially
by a voltage divider (the volume control) and the output impedance would
vary with the position of the volume control.  (I haven't been able to
notice a difference in sound between the two modes, though).

I didn't try to simulate the cartidge/cable interactions since it is 
obvious that there will be a difference - the loading has a very
noticeable effect on cartidges.

>2) What happens when you put 120 pf in parallel with the load?

Have to try this.  But I would expect that there would be a roll
off due to the cap, not the cable.  Hmm....

>3) What functions did you drive the thing with, and can the PGM pick
>   up phase lag/lead at different frequencies?

Sine, square, triangle waves.  The HP has several frequency ranges - 
1 Hz to 1K Hz, 10 to 10K, 100 to 100K, etc. up to the many MHz.  It
automatically displays the gain from A to B in db and the phase shift
from A to B in degrees.

>	from Mole End			Mark Terribile

Thanks for the comments.  I'll let you know when I have a chance to
play some more.

Ross