Print

Print


 Is the only tool available our ears listening as we manually
adjust the azimuth?

IASA-TC04...5.4.12.2... Additionally or alternatively, a software programme providing a real time-spectrogram function can be used. Azimuth adjustment should be a routine part of all magnetic tape transfers.

Wavelab's Spectrometer has helped me.  Also their spectrum view, while not real-time, can offer a quick comparison of separate recordings of the same bit of content, same with iZotope RX's detailed spectrum viewer.  I've used the spectrometer in a Waves meter package I had, though the detail seemed lacking.  Other spectrometer suggestions?

For those of us who have taught ourselves how to adjust azimuth by ear (sort of the same thing as focusing a camera lens in many ways), we do not need crutches, but I have come to realize that using a two-track head for "factory workers" might be beneficial.

I hear the azimuth/camera lens analogy quite a bit.  Our film scanner (through its associated software) provides a focus-assist feature - a tool that seems to be fairly widespread in video.  This also seems to frequently be labelled a "crutch" by folks who have been in the industry a long time.  I understand this criticism in terms of videographers framing up a shot, but focusing for the transfer of an old film is entirely less subjective.  Using software to find the point at which all possible detail from the original shot can be recovered - where a mm one way or the other would reveal less detail - makes sense to me.
This also makes sense to me in terms of azimuth adjustment - using a scope/software/spectrometer for help with an adjustment that is seeking a definitive point of detail doesn't seem like a crutch to me, considering how perceptions can change throughout the day.   Please let me know if I've missed something.

Neal Warner
Walter J. Brown Media Archives and Peabody Awards Collection
University of Georgia Special Collections Library
300 S Hull St
Athens, GA 30602
706.542.4391
[log in to unmask]<mailto:[log in to unmask]>


On Sep 10, 2014, at 11:47 AM, Jamie Howarth wrote:

Playing the mono tapes on a multitrack head and bias tracking the tracks and pulling them together would have solved the Sun Records azimuth problem.

Please pardon the misspellings and occassional insane word substitution I'm on an iPhone

On Sep 10, 2014, at 10:25 AM, "Richard L. Hess" <[log in to unmask]<mailto:[log in to unmask]>> wrote:

Hi, Andrew and Tom,

I am (very) slowly working towards a paper on azimuth.

The full-track mono tape is, of course, the hardest to play from an azimuth perspective (of the common formats)--I hate to think about the 1-inch two-track!

Transport guidance is a huge issue and I have found that the Studer A80 is magical in that regard--and the Studer A810, not so much. The Sony APR-5000 is between the two.

For those of us who have taught ourselves how to adjust azimuth by ear (sort of the same thing as focusing a camera lens in many ways), we do not need crutches, but I have come to realize that using a two-track head for "factory workers" might be beneficial.

For one project I proposed (but we chose not to implement) a wide/narrow head for full track mono. We batted around a few different configurations--including a long discussion with Greg Orton. I was thinking of something like 0.120 and 0.04. The nice thing is even if things go south, you still have a good percentage of the highs on the 0.04 track, albeit noisy.

With that said, for oral history cassettes, I use, in addition to manual azimuth adjustment, the azimuth compensation feature of www.stereotool.com<http://www.stereotool.com>. This allows excellent channel summing for improved noise, assuming both channels were recorded.

There is a similar feature in iZotope RX Advanced.

Cheers,

Richard



On 2014-09-10 7:51 AM, Tom Fine wrote:
Hi Andrew:

It's interestng you bring up this topic. I was just reading the book
that comes with the new Beatles In Mono LP box and they talk
specifically about azimuth on the full-track tapes. Despite the fact
that these mono masters were made in-house at Abbey Road, most of them
on the same machines, the mastering engineer said he had to adjust
azimuth on the fly as records were being cut, especially with the later
albums where mono mixes were done days or months apart. His point was,
azimuth was specific to each track on some albums. He had made notes and
used a gauge-based azimuth adjustment on his Studer A80 playback deck,
so he was able to make precise tweaks as the tape rolled between cuts,
according to the book text.

I was taught, with full-track azimuth, that you really have to adjust to
ear, how the top end sounds best. Keep in mind that time-damaged tapes
and poorly slit tapes will likely "country lane" through the transport
and wreak havoc with azimuth. Adjusting tones at the head of the
full-track tape (when they exist) is somewhat helpful, but ears need to
be the final judge.

Azimuth is a tricky thing and I'm still learning about it after 40 years
of playing tapes. What I have learned is that it's really critical to
solve the azimuth puzzle in the analog domain because problems can't be
satisfactorily fixed in the digital domain.

For old full-track tapes, I am curious about using the center two tracks
of a 4-track quarter-inch machine. I haven't done much with this, but
when there are tones on the tape, you can get a scientific azimuth
adjust with a scope. Many old tapes are edge-damaged and I wonder if
it's better not to play the outer edges of the tape. However, the
effects of country-laning may be even worse if you're grabbing two
narrow bands of signal and either combining them or not.

If you want to hear a prime example of azimuth issues, get a copy of the
"Sun Records Greatest Hits" LP that was sold on Record Store Day this
year. The tapes were clearly and audibly played back with a 2-track head
and either were in such poor shape that they couldn't go through the
transport correctly or the playback engineer was inept. In any case,
with many of the songs, if you combine them to mono, they flange, "phase
effect" and go in and out of treble cancellation, telltale signs of
being played out of azimuth. If you listen on a stereo cartridge and
don't combine to mono, it's not as bad, it just sounds like bad
edge-warp. I think it was inept playback all around, but I've never
handled the tapes. I do bet that they'd sound better if played back
either through a narrow-width single head capturing the middle 1/2 of
the tape height or with the middle two tracks of a 4-track quarter-inch
head with azimuth constantly monitored on a scope and tuned to ear.

By the way, even with the less than ideal playback and remastering, the
tunes on that Sun LP jump right out the speakers, still hot and rockin'
to this day.

-- Tom Fine

----- Original Message ----- From: "Andrew Dapuzzo" <[log in to unmask]<mailto:[log in to unmask]>>
To: <[log in to unmask]<mailto:[log in to unmask]>>
Sent: Wednesday, September 10, 2014 7:34 AM
Subject: Re: [ARSCLIST] recording "cleanup" plugins and 192/24


While I understand the importance of capturing output "above 20kHz" with
the aforementioned tools, are there any tools available to help with
azimuth adjustments?  Older recordings, especially those made in the
field
with machines that have been "banged up", may be recorded with azimuth
that
is slightly off.  Therefore, the higher frequencies may be lost or
diminished if playback is not adjusted to the exact azimuth of the
original
recording.  Is the only tool available our ears listening as we manually
adjust the azimuth?

On Fri, Aug 29, 2014 at 6:18 PM, John K. Chester <[log in to unmask]<mailto:[log in to unmask]>> wrote:

At 04:49 PM 8/29/2014, Tom Fine wrote:

John, is there a modification for to remove those noises? Do 3rd party
electronics also carry those noises or are they something with the
power
rails under the transport? Sorry if these are ignorant questions,
I'm not
that familiar with the innards of ATR's.

I suspect this is neither the list nor the proper subject heading for
discussing such a highly technical issue, but here's a brief answer:

I have never tried to clean up an ATR with stock electronics, although I
have a good idea of where to start.  I have no data on 3rd party
electronics other than Plangent's.  When I got the Plangent
electronics to
be clean enough for our purposes, I stopped worrying about the problem.
Plangent does use a preamp in the headblock with a cable running
directly
to our box, which helps keep things clean.

I do find it a bit odd that folks doing 192k transfers often don't
seem to
worry about how much signal gets from the tape to the tape machine
output
above 20 kHz, and how much noise in that region comes from the machine
rather than the tape.  There are useful signals up there, and we know
that
if the transfer captures them they can later be used to improve the
quality
of the audio below 20 kHz that we can actually hear.

-- John Chester



----- Original Message ----- From: "John K. Chester" <[log in to unmask]<mailto:[log in to unmask]>>
To: <[log in to unmask]<mailto:[log in to unmask]>>
Sent: Friday, August 29, 2014 4:33 PM
Subject: Re: [ARSCLIST] recording "cleanup" plugins and 192/24


At 05:06 PM 8/29/2014, Shai Drori wrote:

So if I turn the display off the 28.8 kHz goes away?

No, that noise on an ATR is actually coming from the reel motor
drivers.  The display generates other noise which starts somewhere
in the
mid-50's of kHz and has lots of harmonics.

Turning off the display removes a lot of the noise spikes in the audio
output but not all of them.

-- John Chester
--
Richard L. Hess                   email: [log in to unmask]<mailto:[log in to unmask]>
Aurora, Ontario, Canada                             647 479 2800
http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.