This is all good information, thanks!
I've wondered about the usefulness of a 2-head stack for playback transfers of full-track tapes.
Head #1 would be a 4-track quarter-inch head with tracks 1 and 4 connected to electronics that
connect to a scope. Head #2 (in the primary playback can, with the primary playback idlers and/or
guidance around it) would be the audio head for transfer purposes. The head would be to monitor
azimuth on the scope and tweak if things get very badly out of whack, using ear as the final judge.
The tweaks would have to be suble and suple to be inaudible to most people. If not doing this on the
fly, the scope-connected head is still useful to make notes if you are transferring spliced-together
Finally, as much as I don't like too many "standards" (because they quickly become impractical and
unenforcable), I think Ampex and the few other professional tape machine makers should have gotten
together at the dawn of tape recording and agreed upon a standard fixed azimuth, baked into all tape
recorders. Theoretically, guidance and tape slitting would still effect the outcome, but I think
there would be much less varience than we see out in the field today. The first few 8-track 1-inch
machines from Ampex had fixed azimuth for all heads. I don't know if anyone experimented with
playing tapes made on Les Paul's machine on the machine at Atlantic Studios. Maybe they did, and
decided azimuth has to be user-adjustable?
-- Tom Fine
----- Original Message -----
From: "Richard L. Hess" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, September 10, 2014 10:25 AM
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.
> 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
>>> with machines that have been "banged up", may be recorded with azimuth
>>> is slightly off. Therefore, the higher frequencies may be lost or
>>> diminished if playback is not adjusted to the exact azimuth of the
>>> 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
>>>>> 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
>>>> 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
>>>> 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
>>>> if the transfer captures them they can later be used to improve the
>>>> 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
> Quality tape transfers -- even from hard-to-play tapes.