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Studer A-800 12 track mod
Old 23rd May 2015
  #1
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leeharveyosmond's Avatar
 

Studer A-800 12 track mod

I'm curious about modding a 24trk head to a 12 trk..
By wiring track 1 and 2 of the head in series or parallel to the electronics of track 1 , 3-4 to 2 ect.. making a 12 track . each channel having more surface area..
has anyone tried this?
Old 23rd May 2015
  #2
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Why not just record to 2 channels, without going to all the trouble of re-wiring everything?
Old 24th May 2015
  #3
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the concept I guess would be to get more surface area and band width to 1 set of tape machine track electronics..
like 16trk over 2" and the bennefits that brings..
I have a spare 24 track head stack... I was curious about the effect of different ohmage, voltage ect.. on the tape machine electronics..as well as the surface area, although then being greater than a 16trk area, it is not continuous..

this mod would be easier and less costly than trying to find a decent 16trk head stack for my A-800MKIII
Old 24th May 2015
  #4
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Quote:
Originally Posted by David W. Jones View Post
Why not just record to 2 channels, without going to all the trouble of re-wiring everything?
You don't really accomplish anything by doing that. You add another set of electronics which negates the benefit.
Old 2nd June 2015
  #5
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I'd love to hear from a tech with head expertise
Old 2nd June 2015
  #6
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Why not ask John French at JRF Magnetics?
Old 2nd June 2015
  #7
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It would require quite a bit of circuit modification to use two tracks with one set of electronics.
The inductance of each track's winding is matched to the electronics, so if you did calculate how the channel electronics needed to be modified it would be a permanent modification unless you devised an elaborate switching system.

You can double the tracks up and record the same signal to a pair of tracks.
This was once often done on 1/2" 4-track machines in order to create what was referred to as a "poor man's 1/2" 2-track."
I conferred with both Tony Arnold and John French before doing this with an AG-440C-4.
You pick up an improvement of somewhere in the neighborhood of 2 db in the noise floor (an actual 1/2" 2-track head has an improvement of 3 db.)
In this situation, in repro mode, the 2-track head would be picking up the two tracks of recorded information as well as the un-recorded area in the guard band between the two tracks.

If you were to record the same signal to an adjacent pair of tracks on a 24 track machine and then play the recording back on the same machine you would probably pick up an improvement of just short of 3 db in the noise floor.
I have done this on a 2" 24 track where I recorded the kick to tracks 1 & 2 and the snare to tracks 3 & 4.
There was a marginal improvement on the kick track sound.

You can do test recordings if you like.
The result of recording to adjacent pairs would be about the same as modifying the electronics to record to two tracks.
Old 2nd June 2015
  #8
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Quote:
Originally Posted by dbbubba View Post

You can double the tracks up and record the same signal to a pair of tracks.
This was once often done on 1/2" 4-track machines in order to create what was referred to as a "poor man's 1/2" 2-track."
I conferred with both Tony Arnold and John French before doing this with an AG-440C-4.
You pick up an improvement of somewhere in the neighborhood of 2 db in the noise floor (an actual 1/2" 2-track head has an improvement of 3 db.)
In this situation, in repro mode, the 2-track head would be picking up the two tracks of recorded information as well as the un-recorded area in the guard band between the two tracks.

If you were to record the same signal to an adjacent pair of tracks on a 24 track machine and then play the recording back on the same machine you would probably pick up an improvement of just short of 3 db in the noise floor.
I have done this on a 2" 24 track where I recorded the kick to tracks 1 & 2 and the snare to tracks 3 & 4.
There was a marginal improvement on the kick track sound.

You can do test recordings if you like.
The result of recording to adjacent pairs would be about the same as modifying the electronics to record to two tracks.
How do you conclude this? If you record to two tracks you just have two tracks of the exact same thing, how would this improve the noise floor or anything else?
Old 2nd June 2015
  #9
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Quote:
Originally Posted by Sounds Great View Post
How do you conclude this? If you record to two tracks you just have two tracks of the exact same thing, how would this improve the noise floor or anything else?
It's double the track width.
It is no different than a track width that is twice the width of another.
It is the same concept as a mono machine versus a 2-track or 16-track versus 24 track although the mono and 16-track width isn't quite double that of 2-track or 24-track.
Basically, there are twice the number of magnetic particles being arranged/effected and there is twice the amount of "information" recorded on the tape.
It doesn't matter than two channels of electronics are recording the information onto the tape.
Because we are talking about storing and then reproducing a signal onto a magnetic medium it is different than having two identical signals on two console channels.
The difference here is because consoles have summing amplifiers which by design don't amplify like signals.
Recording two identical signals onto two tracks of magnetic tape is not summing.

This is all commonly known and accepted performance specs of analog magnetic tape recording/reproduction.
The numbers that I quoted came from John French and were backed by Tony Arnold and Jay McKnight (that is quite a "brain trust.")
If you want to argue with or dispute their statements then you can contact them.

Last edited by dbbubba; 2nd June 2015 at 02:47 PM..
Old 2nd June 2015
  #10
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I've read plenty of discussion on this in the past. There is not consensus that there is an improvement. And in my opinion, it defies logic.

The only real potential benefit is in the specific case where there may be a flaw in the tape itself causing a distortion or drop out. If the flaw is not distributed evenly across the tape, there is a possibility that you could lesson the effect of it if one (or more) of the duplicate tracks is not getting hit by this flaw.

Otherwise, as far as signal to noise or distortion numbers, please explain why multiple tracks of the exact same thing should improve these numbers.
Old 3rd June 2015
  #11
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I'd imagine buying a 16 trk headstack would be waaaay easier. You could let go of one of the audio supplies to help fund it. (though probably best to have a spare).
Old 4th June 2015
  #12
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Quote:
Originally Posted by Myles83 View Post
I'd imagine buying a 16 trk headstack would be waaaay easier. You could let go of one of the audio supplies to help fund it. (though probably best to have a spare).
Yep
Old 4th June 2015
  #13
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Quote:
Originally Posted by Sounds Great View Post
I've read plenty of discussion on this in the past. There is not consensus that there is an improvement. And in my opinion, it defies logic.

The only real potential benefit is in the specific case where there may be a flaw in the tape itself causing a distortion or drop out. If the flaw is not distributed evenly across the tape, there is a possibility that you could lesson the effect of it if one (or more) of the duplicate tracks is not getting hit by this flaw.

Otherwise, as far as signal to noise or distortion numbers, please explain why multiple tracks of the exact same thing should improve these numbers.
Who was involved in the discussions that you had?

If you want to argue with the views and findings of the guys that I mentioned discussing the matter with then feel free, but they make up the short list of some of the most respected authorities on the subject of analog magnetic recording that there is.

Again, note that the s/n ratio does not improve significantly, but you are spreading the information over a greater area of the tape.
That makes a big difference.
There is more "signal" being recorded (more iron particles re-arranged) and the playback will generate more output level.

The concept of recording two separate tracks with the same signal is basically no different than having a wider track width with the same signal.
In fact, when using two tracks of a 24 track head the combined track width would be slightly larger than the track width of a standard 16-track head.

I am not well versed enough to describe things on a magnetic/electrical level, but I can tell you that the difference is that magnetic tape recording reacts differently than merely summing two identical tracks.
It is important to remember that magnetic tape recording IS NOT a linear process.

Last edited by dbbubba; 4th June 2015 at 02:28 PM..
Old 4th June 2015
  #14
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Quote:
Originally Posted by dbbubba View Post
If you want to argue with the views and findings of the guys that I mentioned discussing the matter with then feel free, but they make up the short list of some of the most respected authorities on the subject of analog magnetic recording that there is.

Again, note that the s/n ratio does not improve significantly, but you are spreading the information over a greater area of the tape.
That makes a big difference.
There is more "signal" being recorded (more iron particles re-arranged) and the playback will generate more output level.
I completely disagree. Please link to one of these experts stating so with their reasoning, because the performance level of the machine is the same on every track. Whether you play back one or you sum 24 of these tracks, you are NOT going to boost the signal and you are not going to increase the performance. In fact the only possibility, though slight, is that you could decrease the performance if there are any phase differences from track to track.

Quote:
Originally Posted by dbbubba View Post

The concept of recording two separate tracks with the same signal is basically no different than having a wider track width with the same signal.
It is completely different. Recording to a wider track, like recording at a higher speed, increases the performance level. Recording multiple tracks does not. It just gives you multiple tracks of the same performance level.

Quote:
Originally Posted by dbbubba View Post
An analog would be the idea of adding additional pistons to an engine to increase the horsepower. You don't get double the horsepower, but each added piston (track) adds to the net result.
In both cases it is a case of transfer of energy except with magnetic recording the energy is being stored before it is used.
This is absolutely incorrect. You are not adding power, or transferring more energy. You have a duplicate of the exact same thing.

Think about it, you have two recorded tracks of the identical material (which includes this magnetic energy you speak of) and you send them to the mixer. Start with one track, you will set the mixer level to get the desired level in the mix. Now if you patch in the second track, you will set the TWO levels to come up with a combined output equal to the previous output of the single track. This will mean turning down the first track and turning up the previously unused track. The result will be the same output level (which is what you want) and the same performance level.
Old 5th June 2015
  #15
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Your mixer analogy and recording the same signal to two tracks is an apples and oranges comparison.
A mixing console uses a summing circuit.

Recording to two tracks is not summing (at the machine level.)
Old 5th June 2015
  #16
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I'm sorry, I got a few minutes and I'm going to let you have it.

Think of each track through the head, head electronics, any transformers, and input of the board as a single loop. Two recorded tracks make up two loops to the board. To play them back together is to sum the two loops together at the summing section of the mixer, following the two mixer input channels.

If you increase the space on the tape head in this loop, or raise the speed, or even add noise reduction, you are still within that loop and (possibly) have increased the s/n performance, or other increases to the signal quality.

Your engine analogy is only partially correct, because if you increase the number of cylinders, or size of them, or anything else to raise horsepower you are still within that one loop.

And when you record to multiple tracks you are simply creating more loops of the same signal, same signal quality, etc. Sending them both to the mixer and summing them will only result in the need to reduce each signal by half to reach a summed output equal to the original signal output. (not actually half but something similar, depending on the boards summing results).


The result of recording to multiple tracks on a tape machine has more negatives than positives in my opinion.

These negatives include using up an additional track, using up an additional input on the mixer, and leaving open the possibility of phase issues between the two tracks if there are any inconsistencies in head wear. The positive I see is possible protection from a drop out in the tape that effects one of the recorded tracks but not the other. This would reduce the effect of the drop out by fifty percent or some other number if you record even more than two tracks.

The problem is that you would most benefit from recording tracks as far away from each other as possible, to try to keep the drop out from hitting both tracks, such as tracks 1 and 16. But this is the opposite of trying to avoid possible phase issues, in which case you would want to record tracks as close together as possible.

And I haven't even gotten into the possibility that the machine was not biased perfectly and the two tracks are not matched correctly.
Old 5th June 2015
  #17
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And actually you don't want to record tracks right next to each other because you can get bleed at the tape head level from one track to the next that could cause even more extreme phasing problems.
Old 5th June 2015
  #18
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Quote:
Originally Posted by Sounds Great View Post
And actually you don't want to record tracks right next to each other because you can get bleed at the tape head level from one track to the next that could cause even more extreme phasing problems.
Are you talking about fringing?

Any constant anomalies (ie: fringing) would be compensated with an alignment/calibration.
Old 5th June 2015
  #19
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Quote:
Originally Posted by dbbubba View Post
Are you talking about fringing?

Any constant anomalies (ie: fringing) would be compensated with an alignment/calibration.
All I really know about fringing is that they recommend you don't record bass or other tracks with a lot of low frequency next to a sync track.

But I don't think bass or any other recording that is effected by this would be a constant. I would think it would definitely be non-linear as the program material is dynamic, bleed could not be predictable. So I'm not sure that alignment/calibration adjustments could compensate for this.
Old 5th June 2015
  #20
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Never mind
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