Re: [ARSCLIST] ELP Turntable (was historical stylus rake angles)

[Eric Jacobs <ericj@xxxxxxxxxxxxxxxxxxx>]

Indeed, I am in the midst of testing the ELP laser turntable,
thanks to the very generous help of several ARSC members.  We
have completed compatibility tests during the months of October
and November using a large range of historical disc formats and
materials, and we will soon begin sonic testing.

The earliest laser turntables indeed had sound quality
limitations, but the unit we are testing was just returned
from Japan two weeks ago with an upgrade to the latest
electronics, which also include an improved audio section.  I
took the liberty to peek inside the laser turntable and compare
the original electronics to the newest upgrade, and I am happy
to report that there are significant changes for the better.

It will be interesting to see how these changes will affect the
sound, and how the sound will compare to stylus-based playback.

I am in full agreement with George that the entire playback
chain has a role in evaluating sonics.  For the purposes of
our sonic tests, the playback chain does have reasonably wide
bandwidth** as George recommends, including:

Transducers
   Lyra Helikon SL (LP) - 10 Hz - 50 kHz
   Ortofon SPU-GT (pre-LP) - 20 Hz - 25 kHz
   Shure M44-7 (pre-LP) - 20 - 17 kHz

Turntable / Tonearm
   Simon Yorke S7 mounted on atomic force microscope isolator
   with 0.5 Hz horizontal and 0.5 Hz vertical isolation
   SME 309 with damping trough and VTA adjustment screw
   Graham IC-70 silver phono cable with Neutrik gold XLR

Record cleaning
   Keith Monks Mark 4
   Disc Doctor cleaning and rinse pads
   Hunt and Audioquest dry brushes
   Various solutions: Tergitol S-series, Disc Doctor, and
   the Library of Congress formula

Electronics
   Boulder 1010 preamp (RIAA EQ) - 0.02 Hz - 250 kHz
   Millennia LPE-2 preamp (historical EQ) - 3 Hz - 200 kHz
   Cables - primarily low capacitance/resistance Mogami W2549
   with serve shield and Neutrik gold XLR connectors,
   all cable runs are kept as short and direct as possible.

Monitoring
   Threshold SA-1 monoblock amps - DC - 50 kHz
   Sennheiser HD-600 headphones - 12 Hz - 39 kHz
   Revel M20 speakers - 46 Hz - 20 kHz (+/-0.75 dB)
   Revel F30 speakers - 34 Hz - 20 kHz (+/-0.75 dB)
   Cables - 3-foot Kimber 8TC "shotgun" with WBT gold crimps

**NOTE: frequency response is +/-3 dB unless otherwise noted.

And as George has recommended, if anyone in the Bay Area has a
pair of Quads, Magneplanar, Martin Logan or Stax electrostatic
speakers that they would like to loan for the test, please
contact me!  <grin, no seriously!>

A-B comparison tests will be recorded to CD (44.1 kHz sample
rate) and to DVD-A (176.4 kHz sample rate) using a professional
studio ADC (Mytek Stereo 24/192 ADC), and can be made available
to anyone interested for a small fee to cover the cost of optical
media and postage.

The remaining tests may take 4-8 weeks.  With some luck, I may
have these done in time for the ARSC meeting in Austin.

Oh - and if anyone has information on historical SRA values,
please let me know.  Of course, I'll be looking forward to
George's presentation in Austin.

Eric Jacobs
The Audio Archive


-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:ARSCLIST@xxxxxxx]On Behalf Of George Brock-Nannestad
Sent: Saturday, January 08, 2005 12:09 AM
To: ARSCLIST@xxxxxxxxxxxx
Subject: Re: [ARSCLIST] ELP Turntable (was historical stylus rake
angles)


From: Patent Tactics, George Brock-Nannestad

Jeffrey Kane wrote

> My apologies, I should know to be more specific, especially with you lot.
:)
> By noise, I'm referring to pops and clicks seemingly caused by dust,
sediment
> and other contaminants. The player seems to be extremely sensitive.
Despite
> the noise blanking feature pops and clicks still seem amplified far more
than
> a conventional player, to the point of being intrusive. I don't find this
to
> be as much of an issue with 78s (perhaps due to the larger groove
> dimensions?), it's primarily an issue with "micro-grooved" material.
>

----- and several others have commented in a similar vein.

Now, the noise (impulse) signal we hear that originates from a groove
surface
has been severely processed by a) the preamplifier, b) the amplifier, c) the
output amplifier, and d) the loudspeakers. Any of those components may have
insufficient headroom and/or bandwidth for the task, because a minute
surface
imperfection reproduced by a velocity-sensitive system has a huge level and
a
very high frequency content - above 30 kHz is quite relevant. This means a
smearing in time of the noise pulse by any uncorrected band limiting, and
that makes it very audible. Michael Gerzon in SEVA's 38 kb mail of yesterday
has a few words on this. So, unless you have a very large gain-bandwidth
product, local feedback rather than global feedback, hence fast overload
recovery, then your noise will be audible, irrespective of stylus origin or
laser origin. Only with a stylus, in addition you have cantilever problems.

And the loudspeaker must be of similar high grade - Quad electrostatics or
Magneplanar (or more recently Bang & Olufsen BeoLab5000 that works on a
different principle, but which is impulse-repsonse corrected). I fully
expect
the tests on the ELP that are upcoming (and I gather will be reported by
Eric
Jacobs to ARSC) to take the amplifier-loudspeaker chain into consideration.

And if you cannot afford an ELP after having upgraded all the rest: even
your
stylus gramophone will sound better for it.

Kind regards,


George