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Please pardon the mispellings and occassional insane word substitution I'm on an iPhone

> On Feb 10, 2016, at 8:33 AM, John Chester <[log in to unmask]> wrote:
> 
>> On 2/9/16 7:36 PM, Tom Fine wrote:
>> Hi Dave:
>> 
>> There's no scientific or electronics design rule limiting a tape machine's frequency response to 10 octaves, that I know of. However, I will speculate that many antique designs may have indeed had about that limit in practice due to the fact that they used transformers in the circuits, although a good transformer should be able to pass more bandwidth than that (including good 1950's transformers). It could also have been a limit of tape-head designs of that time. I can tell you for a fact that the Plangent Process machine has way more than 10 octaves bandwidth, since the same heads that recover audio are also recovering bias (to a separate digital track). John Chester or Jamie Howarth will step in here, but I believe the pathway that reproduces the audio content on the tape may low-pass somewhere above 20khz so as to not recover ringing, RF or other detrimental noises that the original recording may have captured.
> 
> The bandwidth of the Plangent electronics is approximately 0.1 Hz to 500 kHz.  There are no analog filters in the audio path.  The low frequency limit of playback response depends on the width and profile of the head core, just like any playback machine.
> 
> Response of a record head and tape extends down to DC.  Thus, the low frequency limit of the signal recorded on tape is entirely determined by the record electronics and the signal fed to them.
> 
> The high frequency limit of the heads we use is well above the audio band.  A mastering grade A/D converter should be able to accurately capture any signal we can recover from tape, up to the limit of the converter's frequency response.
> 
> If necessary, non-audio signals above 20 kHz will be removed with digital filters -- but this is seldom required.
> 
> We try to accurately match the reproduce EQ standard used by the original recorder.  We do not attempt to replicate any deviations from this standard which were characteristic of a particular machine.  Our goal is to deliver audio which is as close to the input signal to the recorder as possible.
> 
> regards,
> John Chester