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.


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 any of you  
>>>> worked with Airshow or Plangent? If so, what has been  
>>>> yourexperience?