Re: arsclist ELT, more

["George Brock-Nannestad" <pattac@xxxxxxxx>]

From:           	"Art Shifrin" <goldens2@xxxxxxxxxxx>
To:             	<ARSCLIST@xxxxxxxxxxxxxxxx>
Subject:        	Re: arsclist ELT, more
Date sent:      	Thu, 7 Jun 2001 19:41:26 -0400
Send reply to:  	ARSCLIST@xxxxxxxxxxxxxxxx

> Hi George,
> 
> It'd be inrteresting to compare the unfiltered, identically equalized
> results of the same black, vertical cut side played on the ELT and a
> phonographic pickup with whatever the best size & shape stylus happens
> to play that side.

----- I agree, and I know a few archives who are working on doing 
this by storing an R-DAT (or hard disk) copy of LT output for later 
comparison with the same material leasurely elaborated on 
mechanical replay equipment. It is not ideal, because the 
subjectively optimal replay depth will be used (why do something 
worse), but if it were an actual A/B comparison, perhaps a mutual 
"agreement" between the two systems about the actual sound 
could be reached. However, any real "instant" A/B comparison 
would require identical records, and we almost never have that.

> 
> I disagree that the detection of the "vectors" is the same for both. 
> In the case of the stylus / cartridge pickup, the movement is directly
> cuased by the (nominally) vertical undulations. In the case of the ELT
> system, the laser does not directly read those up & down movements. 
> It in a sense, deduces them, but does not "see" them.

 ------- I must disagree here, because the very sense of 45/45 is 
that the two sets of coils are mainly sensitive in those two 
directions (any dissection of a pickup will show that). A purely 
vertical movement of the stylus because of the groove induces 
voltages in both sets of coils, as does a purely horizontal (lateral) 
movement, and only the adding of the contributions (one way or the 
other) will give the pure vertical or pure horizontal signal. If the sets 
of coils were mounted so that one set were parallel to the record 
surface and the other set one above the other, then we would have 
the situation you describe - Blumlein's 1934 setup, which is the 
only system actually reading the up-and down movements.
> 
> The might be case of (to paraphrase Groucho) are you going to believe
> theory or your ears?

----- If your ears tell you differences, then to some degree that may 
be because of the problems with a pick-up's channel separation 
between the two mono channels making up a stereo signal. Some 
of the purely left-channel hill-and-dale induces some voltage also in 
the right-channel coils and vice versa. When you do the adding 
(one way or the other) to obtain a vertical or a horizontal output, 
these errors add up so that e.g. a mono pickup (for lateral = 
horizontal) with good vertical compliance will sound better than a 
stereo pickup wired to be sensitive mainly in the horizontal 
direction.

> 
> I'm interested in knowing what yields the best result.  If I'm wrong,
> then I've learned something.  This wouldn't be the first time!
> 
> And then, it'd be interesting to try to play one of those brick red
> almost-hi-fi Western Electric vertical cut pressings from circa
> '34....let alone a stamper, or master, or uncoated aluminum, etc.....

----- Yes, this would be nice, however metal surfaces also do not 
work with the LT at present.


Best wishes,


George
Preservation Tactics