Re: arsclist Arhoolie Foundation - Digitizing Project

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

Date sent:      	Fri, 16 Feb 2001 13:17:10 -0800
From:           	Tom Diamant <tom@xxxxxxxxxxxx>
Send reply to:  	tom@xxxxxxxxxxxx
Organization:   	Arhoolie Records
To:             	ARSCLIST@xxxxxxxxxxxxxxxxxxxxxxxx
Subject:        	arsclist Arhoolie Foundation - Digitizing Project

Tom, you are connected to a very interesting project!

I have a few comments to some of your points, and I will quote a minimun of text form your mail.


> The first part of the project, the 78s, comprises about 80,000 minutes of
> music (about 26,000 78 RPM sides).

All transfer uses up a multiple of real time. In 78s you must calculate at least 10x recorded time, unless you really want to do a "quick-and-dirty", as we used to call ill-prepared on-line literature searches. Remember the steps of cleaning, determining speed, determining stylus dimension, determining maximum recorded level.

Sadly, sadly, 24 bit is not 24 useful bits at all. You cannot record 8 bit below maximum level (ca. 46 dB below) which would get you 16 bit - these 16 bits amplified would not get you 16 bit which are as good as 16 bit A/D conversion from a proper 16 bit A/D converter! If you don't believe me, try to examine the throughput specs from Agilent (formerly Hewlett-Packard) for their various digital voltmeters. These people have stable and linear converters which would perform as I indicated above. All audio 24 bits is just a fad to enable the sale of more storage space per minute. A number of operations on the digital datastream do provide more pleasant- sounding audio, but it is not linear and it is not identical from one session to the next.

You may want just to clean the records and then to do a "quick- and-dirty". But in this case, if you want to provide to the end user an approximation to the functionality of having the original disc in the hand - and good replay facilities as well, then you must use suitable calibration. Either you must calibrate your equipment and make a precise logging of the various adjustments: speed, pickup, equalisation, are the most important. Or else you may want to use a special calibration record which provides a groove on a record containing a suitable signal. The replay conditions for your collection record and for the special calibration disc must be the same, and you make a recording of both records - the signal from the special calibration disc will give information on all the three replay parameters mentioned (could be considered metadata in audio format!), and obviously you also have a signal representation from your collection record. Such special calibration records do not exist this instant, but a working group under the Standards Committee of the Audio Engineering Society is currently constructing one (AES SC-03-02).

It goes without saying that no archival storage can be of noise- reduced signals - the technology improves all the time, and a "raw" signal is most useful long-term. In any transfer work, suitable headroom for correct representation of the noise must be made available - 10 dB below maximum level is good, 14 perhaps even better. The Technical Committee of IASA (International Association of Sound and Audiovisual Archives) is currently revising the recommendation called TC-03 and moving away from the previous recommendation: quarter-inch magnetic analog tape.

I am a member of both the IASA TC and the AES Working Group.


Now back to your questions:
>
> A. Capturing the analog sound.
> 1. What is a good currently manufactured turntable with variable speed
> that will play 78s?

I do not hesitate to recommend the  ELP Corporation LT series of Laser Turntables. They in one instrument combine a variable speed turntable and "one stylus plays all", i.e. there is a combination of laser beams which performs the reading of the groove without any mechanical contact. The reason for a range of stylii is usually that one may find one which rides above parts of the groove which are worn - this is obtained in the LT by adjusting the height of the reading head. The output is analog in a form which may be fed to a suitable preamplifier. This turntable will not play Edison Diamond Disc or Pathé Saphir types, because the laser reflection depends on some part of the groove having been generated with a cutting stylus which has a linear part. The two mentioned used a diminutive sharpened cylinder end. Also, the tracking is only from the edge and inwards. Check out the http://.www.elpj.com website for more information. The LT machines come with a kind of vacuum cleaner, because good reflection from the groove and not from dust particles is essential. The machine is hideously expensive, however technical support may be termed "archive responsible", i.e. long-term which is rare for analog equipment.

2. What is a good currently manufactured pre-amp,
> preferably one with various EQ curves?

I myself use the Elberg MD12 multicurve preamplifier which is a recent Danish product to international standards. Check it out at http://www.vadlyd.dk where you may also read good advice on transfers.

3. What is a good cartridge that
> accepts a currently made 78 stylus?

My preference (apart from the LT above!) is the Ortofon series which fits on the Concorde "headshell" or rather interface. I do not have the current designation for it handy. I have had special stylii fitted by Expert Stylus Company in England. They have a vast range, and will also provide to specification.

I would like to hear about your project from time to time!

Best regards,


George Brock-Nannestad
Preservation Tactics
Resedavej 40
DK-2820 Gentofte
Denmark

Phone: +45 21 67 77 12