R/E/P > Fletcher

Mixing to 1/2" at 30ips or 15ips

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Jim Williams:
Run at +9 and you can improve the s/n ratio 6 db over standard + 3 operating levels. 30 IPS takes those levels twice as good as 15 IPS due to twice the magnetic particles to charge. THD is also lower at 30 IPS.

I always used 30 IPS back in the golden analog days, 1/2" and 2".

Loved the top end, hated the low end, or lack of. Fortunately, this was before 24" detuned kick drums and 5 string basses became popular.

Now days, the PCM4222 ADC is direct coupled so the low end goes to DC. Now I have the low end and the clear fast transients in the high end. I only miss the smell of tape now.

Geoff Emerick de Fake:
Jim Williams wrote on Tue, 15 February 2011 10:28
Run at +9 and you can improve the s/n ratio 6 db over standard + 3 operating levels.
Higher operating level => less headroom. Quote:
 30 IPS takes those levels twice as good as 15 IPS due to twice the magnetic particles to charge.

No. The length of tape in the record head gap is the same, whatever the speed. Quote:
 THD is also lower at 30 IPS.
You can't have it and eat it. More level or less distortion is your choice. That's the compromise. Be happy with the fact that you have only 3dB more noise and 6dB more level. Quote:
 I always used 30 IPS back in the golden analog days, 1/2" and 2".

Loved the top end, hated the low end, or lack of. Fortunately, this was before 24" detuned kick drums and 5 string basses became popular.
Low end can be equalized without adverse artefacts. High end that may be missing at 15" is difficult to recoup. Quote:
 Now days, the PCM4222 ADC is direct coupled so the low end goes to DC. Now I have the low end and the clear fast transients in the high end. I only miss the smell of tape now.
There may be something wrong in my monitoring chain (or is it my ears), I can't hear DC.

Jay Kadis:
Geoff Emerick de Fake wrote on Wed, 16 February 2011 10:53
Jim Williams wrote on Tue, 15 February 2011 10:28
 30 IPS takes those levels twice as good as 15 IPS due to twice the magnetic particles to charge.

No. The length of tape in the record head gap is the same, whatever the speed.

Since it is the rate of change of flux in the gap that produces the voltage, tape speed does matter.  It's not because there are more particles, it's because they move by faster.

Geoff Emerick de Fake:
Jay Kadis wrote on Wed, 16 February 2011 13:08
Geoff Emerick de Fake wrote on Wed, 16 February 2011 10:53
Jim Williams wrote on Tue, 15 February 2011 10:28
 30 IPS takes those levels twice as good as 15 IPS due to twice the magnetic particles to charge.

No. The length of tape in the record head gap is the same, whatever the speed.

Since it is the rate of change of flux in the gap that produces the voltage, tape speed does matter.  It's not because there are more particles, it's because they move by faster.

I didn't say that tape speed doesn't matter. I said that higher speed doesn't allow more flux. Speed matters indeed, that's what I meant when I mentioned 6dB more level.

Fletcher:
Warning - lazy bastard at work... I didn't feel like formatting the thing for individual calls and responses to I rolled in RED... if someone else wants to roll responses to my comments... I'd recommend BLUE

Geoff Emerick de Fake wrote on Wed, 16 February 2011 13:53
Jim Williams wrote on Tue, 15 February 2011 10:28
Run at +9 and you can improve the s/n ratio 6 db over standard + 3 operating levels.


Higher operating level => less headroom.

Which matters not if you work within the operating level / headroom parameters of the tape.  Starting at an elevated level is a question of "gain scaling" which means you're balancing the operating levels of all the amplifiers in the signal path... a good practice at all times!!

Quote:
 30 IPS takes those levels twice as good as 15 IPS due to twice the magnetic particles to charge.


No. The length of tape in the record head gap is the same, whatever the speed.

Uhhh - no.  The width will indeed remain constant, but the length needs to be measured over time [or there is no length]... so as the calibration states, you're running 15 inches of tape over the gap per second at 15 ips and 30 inches of tape over the gap at 30 ips

Quote:
 THD is also lower at 30 IPS.


You can't have it and eat it. More level or less distortion is your choice. That's the compromise. Be happy with the fact that you have only 3dB more noise and 6dB more level.

Heh?  You can increase the level without a significant increase in distortion so long as you stay under the MOL of the tape formulation.  I'm sure I'll be sorry, but I have to ask - 3db more noise and 6db more level than what?

Quote:
 I always used 30 IPS back in the golden analog days, 1/2" and 2".  Loved the top end, hated the low end, or lack of. Fortunately, this was before 24" detuned kick drums and 5 string basses became popular.


Low end can be equalized without adverse artefacts. High end that may be missing at 15" is difficult to recoup.

You still introduce an element of phase distortion when you equalize in the analog domain... its the nature of the beast, its how an equalizer works.  If it is possible to get an effect without [i.e. "larger bottom"] without adding an additional unit... then you're kinda on the bonus plan.  

On the top end the main difference in that region is that when you go after it with an equalizer you're bringing up tape noise as well as the original signal... its one of the reasons that people tracked "brighter" back in the day [there is even a "stunt alignment" for that]

Quote:
 Now days, the PCM4222 ADC is direct coupled so the low end goes to DC. Now I have the low end and the clear fast transients in the high end. I only miss the smell of tape now.


There may be something wrong in my monitoring chain (or is it my ears), I can't hear DC.

The higher a circuit rolls off on the low end the greater the quantity of phase distortion caused by the filtering of the audio [see "equalizer" for details]... by getting to DC on the bottom you get no such resultant phase distortion - the net result being a "clearer" - "truer" low frequency response.

Sometimes, especially if you're from the school of recording where you want back EXACTLY what you put in - this is indeed a positive condition... whether or not your monitors can reproduce DC [or even 10Hz for that matter] is absolutely inconsequential to ancillary artifacts that are created by the filtering process.  

This phenomenon is why [for a large part, but not the only part] that a Neve desk has "better" low end than a Mackie.  The Mackie is only flat to 20Hz on the low end where a Neve is flat to 8Hz... there is a really large difference in phase shift / distortion that is realized by the filtering process occurring an octave and change lower... and THAT you can hear in no uncertain terms


Peace.

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