The tape is what is biased, of course, through the heads.    It  
may be prohibitive to retrieve the signal, but if it never made it to  
the tape, then the tape wasn't biased.   The erase signal is much  
lower, at 144 kHz.  However, I see PP don't normally digitize higher  
than 192 kHz.    Even though the DSP operates at a very high F/s, far  
above that, doesn't the A/D converter performance force us to look at  
gremlins that are beneath 96 kHz?


Andrew




On Apr 29, 2010, at 9:31 AM, Shai Drori wrote:

> Hi Andrew
> I meant  that the recorded signal is so high that it is not present  
> on tape, I think that is the magic of it. It still biases the heads  
> but it's just too high for the tape itself. Don't forget that at  
> 15ips you're describing a theoretical 56kHz at 1 7/8 ips. It's just  
> not there. I love it. I like the way it sounds much better than the  
> reocridngs I made on otari or Studer, dare I mention tascam. I can  
> see the benefits of this system for film, but for nice audio tape  
> in good condition, an ATR recording will be hard to lock to. Did  
> they transfer any command recordings? I would love to hear the  
> Borelo!!! What a recording (I know I will now ge tons of emails  
> about my taste in music. In my defense, my wife would be on your  
> side and add her thoghts about my clothes as well).
> Shai
>
> On 4/29/2010 1:52 PM, Andrew Hamilton wrote:
>> Dear Shai,
>>      As I wrote in your quoted response, below, there are other  
>> signals besides bias that the PP can lock to.   They mention  
>> "logic control" signals.   I suspect there are other ghosts they  
>> could bust.
>>      The ATR is only bias-free while reproducing.   But when  
>> recording, it should be present, at 432 kHz - almost as high as  
>> the Dave Hill Aria bias.  Even if you recorded at 30 ips and then,  
>> on playback, select 3.75 ips and then also  vari-speed the  
>> oscillator to 50% of that, the 432 kHz bias signal would still be  
>> at 27 kHz.  Did you remember to digitize at 2x F/s?  Otherwise, it  
>> would have been filtered out by the ADC.
>>
>> Please audition the samples on the PP website.  They made a  
>> believer out of me.   There's a Waves plugin to inject wow and  
>> flutter into a digital recording.   The PP would not be able to  
>> undo this since it is simulated and does not contain a veiled clock.
>>
>>
>>
>>
>> Andrew
>>
>>
>>
>>
>> On Apr 29, 2010, at 5:53 AM, Shai Drori wrote:
>>
>>> I can see that working with 160 or even 200 (you can hear it if  
>>> you slow down the tape enough), but the ATR is bias free, at  
>>> least on tapes I made so far. The system is interesting though.  
>>> How does it monitor to see that the original bias did not drift  
>>> while recording? This would make you track the wrong frequency..
>>> Shai
>>>
>>> On 4/29/2010 10:24 AM, Andrew Hamilton wrote:
>>>> There are other forensic time stamp signals besides bias which  
>>>> would allow for an ATR-100-recorded tape to be de-fluttered by  
>>>> the PP DSP.   However, even though a tape may be played back by  
>>>> the Airshow ATR-100, it's entirely possible that the tape was  
>>>> recorded elsewhere by a different machine (having a much lower  
>>>> bias f).  I believe that Airshow are offering this service with  
>>>> PP for already-existing analog tapes, rather than for creative  
>>>> layback transfers.
>>>>
>>>> David Glasser is chief engineer at Airshow and he has mastered a  
>>>> huge amount of audiophile CDs, DVDs, and SACDs.   Great ear;  
>>>> great rooms; great gear.
>>>>
>>>>  From the PP website:
>>>>
>>>> "software algorithm, developed with researchers at Cambridge  
>>>> University in England, which identifies a steady-state  
>>>> ultrasonic reference tone (such as tape bias or logic control)  
>>>> embedded within the original analog signal and then performs  
>>>> continuous high-resolution pitch correction in order to keep the  
>>>> reference tone at a fixed frequency..."
>>>>
>>>>
>>>>
>>>> Andrew
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Apr 29, 2010, at 4:15 AM, Shai Drori wrote:
>>>>
>>>>> My experience with the ATR is just the opposite. I have tested  
>>>>> various transport and some tapes were handled only by the ATR.  
>>>>> Does the system figure out bias frequency automatically. What  
>>>>> does it do with tapes recorded on the atr where the frequency  
>>>>> is so high it doesn't show up on playback (400kHz+)?
>>>>> Shai
>>>>>
>>>>> On 4/29/2010 8:54 AM, Paul G Turney wrote:
>>>>>> Well they only use ATR 102 machines which are notoriously  
>>>>>> rough tape handlers....
>>>>>>
>>>>>> They use software to track and maintain a bias frequency so  
>>>>>> that any speed anomolies are and wow and flutter are reduced  
>>>>>> by maintaining perfect pitch with this tone.
>>>>>> Not worked with Airshow mastering.
>>>>>>
>>>>>> It appears to be a monopoly on the software so Airshow would  
>>>>>> be subbing the work out to PP.
>>>>>>
>>>>>> PT
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Chandra Lynn [mailto:[log in to unmask]]
>>>>>> Sent: Thursday, April 29, 2010 02:12 AM
>>>>>> To: [log in to unmask]
>>>>>> Subject: [ARSCLIST] Airshow Mastering&  Plangent Processes
>>>>>>
>>>>>> I noticed some earlier postings about Plangent Processes. It  
>>>>>> eliminates wow,flutter and speed aberrations from analog  
>>>>>> masters. They are now working withAirshow Mastering to offer  
>>>>>> optimized tape transfers. The announcement is onAirshow¹s site  
>>>>>> at http://www.airshowmastering.com/plangent.htmlHave any of  
>>>>>> you worked with Airshow or Plangent? If so, what has been  
>>>>>> yourexperience?
>>>>>>
>>>>>>
>>>>
>>