I reluctantly describe a process that weıve used on mono tapes
with country-laning. Itıs tedious and problematic, but it can
be better than aligning the azimuth just once at the beginning of
a tape. Weıve only resorted to this process a few times, itıs
hardly a ³production² process.
In essence:
1. We play the tape back with a stereo headblock that is fitted
with a precision vernier azimuth knob. The precision vernier
azimuth knob allows you to read the relative azimuth adjustment
that youıve made at any time. This is the actual headblock we
use to do this (a fantastic sounding headblock as well):
http://www.ataestuder.com/technical/shro-explained/
2. As the tape is playing we note the times and values for the
azimuth knob. This can be a very slow process since we need to
stop the tape to take the time and azimuth reading and write
it down. We also record how slowly or quickly we should change
the azimuth in seconds. Did I say ³tedious²? It really is.
3. We stuff the times and azimuth values into a spreadsheet to
calculate the relative azimuth changes. We use a spreadsheet
to calculate the changes because if you accidentally change
the azimuth in the wrong direction, you actually make things
worse.
4. Switch to a mono headblock that has an identical precision
vernier azimuth knob.
5. Play the tape and make the azimuth changes according to the
spreadsheet.
Iıll be the first to admit that there are all kinds of issues
with this process, just to name a few:
a. mechanical backlash in the azimuth adjuster
b. only works for gross changes in azimuth over the course of
playback
c. cannot deal with continuous real-time changes in azimuth
d. a mistake in calculating the relative azimuth is worse than
no azimuth adjustment at all
e. prone to human error during playback
f. requires great care and patience
g. effort is only justifiable on special/important recordings
Again, I mention this process as a method of problem solving, and
would never advocate this process as ³best practice².
Eric Jacobs
_________________________
Eric Jacobs
Principal
The Audio Archive, Inc.
1325 Howard Ave, #906
Burlingame, CA 94010
tel: 408-221-2128
[log in to unmask]
http://www.theaudioarchive.com/
Disc and Tape Audio Transfer Services and Preservation Consulting
Please consider the environment before printing this email.
On 9/10/14, 7:25 AM, "Richard L. Hess" <[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. 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.
>
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