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Author Topic: Mixing to 1/2" at 30ips or 15ips  (Read 5561 times)

burns46824

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Mixing to 1/2" at 30ips or 15ips
« on: February 14, 2011, 12:19:12 pm »

I'm tracking at 30ips on a Studer 820.  Any advice as to whether I should mix at 30ips or 15ips for 1/2"?
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Dominick

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #1 on: February 14, 2011, 03:52:27 pm »

15 ips - LF head bumps down an octave, less HF headroom
30 ips - LF head bumps up an octave, more HF headroom
What works for your program material?
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Dominick Costanzo

David Bock

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #2 on: February 15, 2011, 01:00:15 am »

 is thicker, but really, you can't go wrong with 1/2"

burns46824

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #3 on: February 15, 2011, 01:21:27 am »

I assume mixing at 15ips has more noise, yes?
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Fletcher

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #4 on: February 15, 2011, 07:24:41 am »

Actually mixing at 30ips has the same amount of noise as mixing at 15ips... the noise is moved up an octave [due to the tape speed] so a portion moves out of the audible range... but its there, and guys like Jim Williams can still measure it [one of the reasons to get insane about alignments - and do things like run "Audio Precision" tests when doing alignments like Jim does].

Peace.
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch.  
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

Jim Williams

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #5 on: February 15, 2011, 11:28:21 am »

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.
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Jim Williams
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Geoff Emerick de Fake

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #6 on: February 16, 2011, 01:53:11 pm »

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.
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Jay Kadis

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #7 on: February 16, 2011, 02:08:21 pm »

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

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #8 on: February 16, 2011, 04:46:03 pm »

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.
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Fletcher

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #9 on: February 18, 2011, 09:22:43 am »

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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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch.  
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

Jim Williams

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #10 on: February 18, 2011, 11:15:09 am »

That about covers it. One other thing, It's very difficult to EQ up the low end from 30 IPS. If you do a AP sweep and very carefully tune and match a parametric EQ, maybe you can do a bit, bit you really need to test and sweep to see if you nail it or make it more sloppy and worse.

The roll-off slopes are pretty steep after the head bump, probably exceeding 12db/octave. Then you will get some weird phase sweeps afterwards.

Back in the RAP studio I used to work out of, I bought them a dbx 120X subsonic synth. They of course overused it and managed to blow 4 JBL 15" woofers a week. But they got their 25 hz off 30 IPS tape.
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Jim Williams
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Geoff Emerick de Fake

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #11 on: February 18, 2011, 11:26:13 am »

Fletcher wrote on Fri, 18 February 2011 08:22

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!!
Yes it does matter. Running at elevated level reduces by as much maximum level. For a given tape formulation and speed, the total dynamic range is a constant.
Quote:

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
The "length of tape per time unit is pertinent to the playback head voltage dPhi/dt, not to the flux, which is a tape formulation parameter. ...
Quote:

 
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.
There is significant increase in THD even before MOL. Typically starting 10dB below MOL, THD rises linearly from 0.3% to 3%.
Quote:

 I'm sure I'll be sorry, but I have to ask - 3db more noise and 6db more level than what?
Doublin speed increases dPhi/dt by a factor of 2 (+6dB) but noise due to increased number of particles increases according to sqroot hence only 3dB. ...  


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.
But that phase shift would be just what is needed to compensate the phase-shift created by the head effect.
Quote:

 
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]
That's exactly why I said that the disadvantages of 30ips can ve compensated without penalty, not for 15ips.
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.
Quote:

  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.
As you know, it's an extremely debatable subject. Audio excludes DC; what is the frequency limit where the HP filter "phase distortion" becomes audible/noticeable/intrusive?
Quote:

 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.
No system goes from DC to light. Extending the frequency response of one element of the chain is meaningless. If you want DC, you need the mics, preamps, mixer...pass DC.
Quote:



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.
[/quote] It has been proved times and times again that the phase of a single signal cannot be heard. The artefacts of phase-shift may be heard when there are several signals interacting, or when the effects of phase-shifting change the signal's peak factor.
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CWHumphrey

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #12 on: February 18, 2011, 12:20:41 pm »

If you go at 15ips, you'll get twice the recording time off of a reel.

How's that for a non-techy answer?

Cheers,
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Carter William Humphrey

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Bubba#$%Kron

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #13 on: February 18, 2011, 12:28:29 pm »

All the chicks are happy with my 8 inches per second!!! Wink
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"When we make music we don't do it in order to reach a certain point, such as the end of the composition. If that were the purpose of music then obviously the fastest players would be the best. Also, when we are dancing we are not aiming to arrive at a particular place on the floor as in a journey. When we dance, the journey itself is the point, as when we play music the playing itself is the point."  -Alan Watts

MagnetoSound

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #14 on: February 18, 2011, 12:34:43 pm »

I can only manage 7.5!  Crying or Very Sad
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Dominick

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #15 on: February 20, 2011, 10:05:04 am »

It ain't the meat, it's the motion
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Dominick Costanzo

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Re: Mixing to 1/2" at 30ips or 15ips
« Reply #16 on: February 21, 2011, 12:20:45 am »

If you use a high-output tape, most 1/2" machines will run out of headroom in the record electronics long before the tape does, so you won't get improved headroom or S/N at 30 ips. If you track at 30 ips, 15 ips might be preferable for mixdown in order to avoid "doubling-up" the head bump.
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