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Regarding Richard's Comment:
"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."

During my mastering years, transport guides and tape slit error can produce
dynamic azimuth problems that are difficult to solve:  thatís because the
tape to playback azimuth relationship can change over time - depending on
how the tape edge follows the guides on the tape path.  If you've tried to
do sum/difference nulls to optimize azimuth correction, and found that it
would change over the duration of the tape, you might have this issue.  On
bad examples, I would have change the tape path guide to use the top of the
tape rather than the bottom - and often produce a more stable azimuth
correction for the length of the recording.

What's worse are compilation tapes or dubs of a comp'd tape where spliced
portions exhibit completely separate azimuth relationships - because each
recording was from a different tape.  IN some cases different mixes
performed on different days are spliced together.  A spliced master could be
corrected but a dub of a comp'd tape not very well.

Richard's other comment about 1" 2-track brought back some interesting
long-forgotten memories too.  From time-to-time I had to recreate new
1/4masters from a 1" 1/4 track, low-speed "running master" used for cassette
duplication.  Gap scatter and slitting errors become a *MUCH* bigger issue
at low speeds and on wide tape formats...   not a pleasant task I can tell
you.

Cheers!

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Rob Poretti - Sales Engineer - Archiving
Cube-Tec North America LLC
Vox.905.827.0741† Fax.905.901.9996† Cel.905.510.6785 
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-----Original Message-----
From: Association for Recorded Sound Discussion List
[mailto:[log in to unmask]] On Behalf Of Richard L. Hess
Sent: September 10, 2014 10:26 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] AZIMUTH (was recording "cleanup" plugins and 192/24)

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.
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]>
> To: <[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]> 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]>
>>>> To: <[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]
Aurora, Ontario, Canada                             647 479 2800
http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.