Re: [ARSCLIST] oscilloscope

["Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>]

Chris,

If you misunderstood Goran and me, then perhaps others did. Please allow me to
claify.

First of all, talking geek to geek, I can't live without a scope.  But a scope
isn't calibrated in dB. It reads peak not rms/average.

Yes, of course, align your azimuth to MRL, check your equalization settings, and
then readjust your azimuth to the source tape.

The point is that the only adjustment you should be doing for every reel (as
opposed to once a day/week) is adjusting playback azimuth to the source tape.
You know  your gains/levels are correct.

A separate topic of conversation is how to run levels for a transfer. One safe
thing to do is to set 250nWb/m for -20dBFS -- and there are good reasons to do
that if you're using 24 bits. But, I wasn't referring to that.

Once I check my tape machines' meters against my Amber 3501 or HP AC Voltmeter,
I then use the tape machine's meters for the EQ alignment. I think a pointer
width is accurate enough considering everything else.

Anyway, we all have different ways of working.

I'm not saying "don't use the MRL."

In fact, when I did the 51 reels of the Mullin/Palmer collection I insisted when
no one could come up with an EQ standard that we use the standard 17.5µs curve
for 30 in/s. It sounded a bit bright, but at that time, no one presented a firm
understanding of what the EQ curve of Mullin's machines was. Tests on the unit
at the Pavek museum in Minneapolis indicated that I needed more HF output, so
we just said "NO!" and transferred at 17.5.

Now I find out that the EQ MAY (and I must repeat MAY) have been either 27 or 35
µs. If that is the case, we can calculate a rolloff differential and "fix it in
post." If I had used an arbitrary EQ for playback (that sounded "right") I
would not be able to aritmetically fix it in post.

I hope that clarifies my position.

Cheers,

Richard
--

Richard L. Hess
http://www.richardhess.com/tape/


Quoting chris2@xxxxxxxxxxxxxxxx:

> The value given to utilizing an oscilloscope and aligning to an MRL is far
> too
> little here.
>
> Firstly, aligning to an MRL ensures proper functioning of the playback device
> prior to performing a transfer. A very important thing indeed, particulary in
> the realm of preservation.
>
> Secondly, it provides a point of reference for documentation. If you have to
> apply an azimuth or level offset how else do you notate it in a meaningful
> way
> without aligning to an MRL? Noting a +3dB offset in reference to a 7.5 ips,
> 250
> nWb/m MRL gives information regarding the degree of the offset and a way of
> backtracking to the source from a digital file or repeating it if necessary.
> It's an industry standard reference. Without the reference any notation is
> arbitrary and meaningless.
>
> I would argue that
>
> 1. It is a must that you have an oscilloscope in your studio.
>
> 2. Get an outboard scope. Much finer detail and easier to read. I have a dual
> 2GHz machine and I still prefer the analog to the software. You can certainly
> get by with the software scope but my preference is to have an outboard
> analog
> scope.
>
>
> Best Regards,
>
> Chris
>
> Chris Lacinak
> Director of Operations
> VidiPax
> 450 West 31st St.
> 4th floor
> New York, NY 10001
> 212-563-1999 xt. 130
> chris@xxxxxxxxxxx
>
>
> -----Original Message-----
> From: Goran Finnberg [mailto:mastering@xxxxxxxxx]
> Sent: Thursday, April 01, 1999 4:33 PM
> To: ARSCLIST@xxxxxxxxxxxx
> Subject: Re: [ARSCLIST] oscilloscope
>
>
> Richard Hess:
>
> > One other thought--calibrating for azimuth off a test tape is pretty
> > useless in an archive situation with all the variations of azimuth in
> > the collection.
>
> Yes, a big knob sitting on top of the calibrate azimuth screw so you can
> twiddle
> it EVERY time ANY tape is played is a must.
>
> Anytime.
>
> Any calibration with a calibration tape is useless as the azimuth on the
> recorder can be anyplace.
>
> Also test tapes don´t agree as regards azimuth.
>
> --
> Best,
>
> Goran Finnberg
> The Mastering Room AB
> Goteborg
> Sweden
>
> E-mail: mastering@xxxxxxxxx
>
> Learn from the mistakes of others, you can never live long enough to
> make them all yourself.    -   John Luther
>
>
>
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