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[Gannon Kashiwa]

This sounds great!  It'll be good to check the sample rates and operating levels you've specified.  Since we're going to all this trouble, we might as well cover everything we can.  You've also specified the minimum amount of variables and careful level checks at each stage to ensure consistency so it will be as accurate as can be.

Like you said in your other post, it'll be good to walk in and know exactly what we're doing and not make anything up as we go.

Thanks and see you in a couple of weeks!

-GK

[electrical]

"fletcher"

If the desk in the CR in which this is happening has "TR" capability, a "TR" of the monitor mix is run. "TR" to be checked before each pass.

Total Recall? How's about just nobody touch the faders once we have the rough mix.

Just to clarify something Fletcher said in the original thread, my suggestion for making the digital reference 0vu= -15dBfs has nothing whatsoever to do with the reference level on the analog master tape, it is just a nice round number that mimics the headroom of any decent analog tape alignment.

We did a series of experiments here trying to establish proper operating levels with different tape formulations, and we established 500 nWb/m as our standard for GP9, 499 and BASF 900.

456, BASF 911 and 468 are all suitable for 320nWb/m.

406 is suitable for 250nWb/m, but I haven't seen a roll of it in years.

With any of these tapes at these alignments, 15dB of headroom is expected, but with any analog tape there is a soft boundary. There may be 10 or more additional dB of "usable" headroom before you reach MOL, but I certainly try to avoid running any tape that hot. There is some debate within the engineering community whether "slamming" the tape sounds good or not. Having conducted the experiment many times myself, I'm in the "it sounds like shit" camp.

So, I think 15dB of headroom is the absolute minimum you should expect from a digital system, though I have seen 14- and 16-bit systems set-up for 12dB with protection (limiting).

For the purposes of this test, I don't particularly care what the digital system's headroom is, but I suggest 15dB as a minimum of acceptable headroom. If we get overs, we can knock it down a dB or two, just like in the real world.

How do my other suggestions (metering the console inserts, making the A/B switch using the multitrack snake) sound to y'all?

[RKrizman]

A couple thoughts.

If you're doing a pass at -16 I'd at least be prepared for the possibility that you might get a few overs on your converter inputs, and decide in advance what you're going to do if that happens.  I assume you'll be turning off soft limit.

Also, does it make sense to also print this to tape, just to verify that it's not the mere act of going to digital that itself is causing the missing ingredients.  Certainly you can't pass it around that way, but it's a good way to archive and could at least be trotted out at an AES seminar or whatever.

-R

[rnicklaus]

Something that is becoming clear to me in this discussion is how much testing has been done over the years with analog tape.  And of course as it has been around and the medium of choice for so many years, this is not news.

It's down to how much level each brand and formulation can tolerate for each engineer's style of work.

Add in meter ballistics, slew rate of the electronics, tape formulation and speed means someone in the session must be very well versed in all of this to optimize the recording.

I know I come from the school of not wanting the tape recorder to alter the sound of my recordings.  I always look for what goes in comes back out - as close as possible with head bump, tape compression and noise, however so slight, being introduced.

Looking through this subject shows how far, I can only speak for myself, I have to go to learn the same detail in all things digital.

There seems to be no standard reference level for pro tools and there are a few levels being discussed and will be tested.  Bob O has talked about loading with Pro Tools converters and some consoles. On the other hand, the analog set up is going to be killer.  2" 16 track, and as stated aligned perfectly.

This test will be good for so many reasons.

There is a lot to learn.

For what it's worth I will always prefer to record analog but embrace the daw format with open arms as it's here to stay.

I have no dog in this fight.

[Mixerman]

RKrizman wrote on Fri, 04 November 2005 10:11

Also, does it make sense to also print this to tape, just to verify that it's not the mere act of going to digital that itself is causing the missing ingredients.  Certainly you can't pass it around that way, but it's a good way to archive and could at least be trotted out at an AES seminar or whatever. -R

That is precisely what the Radar is for: To prove that this isn't merely a "digital problem."

Fenris Wulf wrote on Thu, 03 November 2005 16:54

It looks like this will basically turn into a converter shootout.

To claim that this is merely a converter shoot-out, is to ignore the fact that there is a clock involved with this as well. Further, the impetus of this transfer is my claim that there is a glaring issue with the destruction of low-end energy that should be addressed by the HDs maker, rather than just a subjective issue of sound quality.

Just so we're clear, if this were an issue of the mid-range being  accentuated (as was theorized in the last thread), then the HD playback would sound louder than the 2" playback. In my repeated demonstrations of this problem, I never perceieved the HD playback as louder.

Mixerman

[ajcamlet]

might be cool to film this or webcast it?

[RKrizman]

Mixerman wrote on Fri, 04 November 2005 15:09

RKrizman wrote on Fri, 04 November 2005 10:11 Also, does it make sense to also print this to tape, just to verify that it's not the mere act of going to digital that itself is causing the missing ingredients.  Certainly you can't pass it around that way, but it's a good way to archive and could at least be trotted out at an AES seminar or whatever. -R That is precisely what the Radar is for: To prove that this isn't merely a "digital problem." Mixerman

That may be true, but at this point you don't want to have your methodology assume what you're trying to prove.

Having an example of the mix in which no digital conversion at all takes place might help to put the differences in converters in perspective.  If I were there and had a 2 track handy I'd definitely run some tape.  (The mix out of the console to tape and the mix through and out of the final 2 track converter to tape.)

OTOH, if the difference is as glaring as you have suggested then it probably shouldn't much matter what you mix it to, so no big.

I'm just glad you guys are doing it at all, and am very curious about the outcome.  Whatever is observed, I hope a reason for it is also discovered.

-R

[RKrizman]

Mixerman wrote on Fri, 04 November 2005 15:09

Fenris Wulf wrote on Thu, 03 November 2005 16:54 It looks like this will basically turn into a converter shootout. To claim that this is merely a converter shoot-out, is to ignore the fact that there is a clock involved with this as well.

Good point.  I would consider a clock to be part of the converter, and I am assuming that each converter will run on its own clock.

-R

[CWHumphrey]

Quote:

To claim that this is merely a converter shoot-out, is to ignore the fact that there is a clock involved with this as well. Further, the impetus of this transfer is my claim that there is a glaring issue with the destruction of low-end energy that should be addressed by the HDs maker, rather than just a subjective issue of sound quality. Just so we're clear, if this were an issue of the mid-range being  accentuated (as was theorized in the last thread), then the HD playback would sound louder than the 2" playback. In my repeated demonstrations of this problem, I never perceieved the HD playback as louder. Mixerman

Then the question to you Mixerman is: What was your operating level and sample rate for PT when you experienced this problem?  There's a lot of haggling over those very parameters.

Since we have new thread that's specifically about the methodology, I think it would be wise to define the purpose of this test, namely: Does what goes into a Pro Tools HD system, come out of it?  Specifically the bass response.

The discussion about what Flux level and tape formulation seems to slip off the topic of test.  The tape is playback source (or control) operating at a standard level of +4dbu.  

Another question:  Is anyone body bringing an RTA to this thing?  I'd like to see 8 bars played off of tape, and then the same 8 bars off of PT and Radar.

-Carter

[Fletcher]

electrical wrote on Fri, 04 November 2005 13:02

So, I think 15dB of headroom is the absolute minimum you should expect from a digital system, though I have seen 14- and 16-bit systems set-up for 12dB with protection (limiting).

In my world headroom is set up in even numbers... so with RADAR in the fray the minimum headroom possible is 14... hence the 16 and 20 suggestion... we could do 14 and 20 if the congregation agrees [it don't matter on my end... but I have no idea what the PT thing can/can not handle].

...and yes, "don't touch the fuckin' console" should be the message/thought/mantra of the day... but shit happens and TR [meaning 'Total Recall' is a valid verification method].

[RKrizman]

Fletcher wrote on Fri, 04 November 2005 16:39

electrical wrote on Fri, 04 November 2005 13:02 So, I think 15dB of headroom is the absolute minimum you should expect from a digital system, though I have seen 14- and 16-bit systems set-up for 12dB with protection (limiting). In my world headroom is set up in even numbers... so with RADAR in the fray the minimum headroom possible is 14... hence the 16 and 20 suggestion... we could do 14 and 20 if the congregation agrees [it don't matter on my end... but I have no idea what the PT thing can/can not handle].

I don't think it's a question of what "the PT thing" can handle--unless I'm mistaken, it's a question of how hot the signals on the tape are and whether they will exceed digital zero when fed straight into the converters--any converters.  In a 24 bit system there's really no need to push it.  I have my Apogees (as opposed to my 192) aligned hot so that a typical transfer from tape will engage the soft limiting a bit.  But if I turn off the limiting, I get overs.

Might be worthwhile to get a solid recommendation from Digi and try to find out what levels MM used/uses.  And have a plan for what to do if during the transfer you get overs.

-R

[rnicklaus]

Rick brings up an interesting thought.

Some people may align 2" to +9 over 185 but be conservative going to tape.

Others may align to +6 and bang the shit out of the tape.

In case #1 playback levels from the 2" will hit it's intended target - console, digital xfer - at a reasonable level.

In Case #2 there may some hot levels hitting the target.  For a console the headroom may handle it - for a digital transfer it is a different story.

At the end of the day, both cases may have the same level on tape but the levels going out of the machine will not be the same.

Something to consider.

[Mixerman]

There seems to be some confusion here. The issue isn't the tape. What opertaing level I work at, what tape formulation I use doesn't matter. I have never, in 17 years of discussions with other engineers, actually debated someone over their choice of tape or operating levels, and I've witnessed some whacky-ass operating levels. So long as the recordist is happy with the playback of the tape machine, that's all that matters here. So long as the tones are being attended to based on playback, the tape will sound precisely the way the recordist intended.

In this case, Steve Albini will be bringing an analog multi-track recording that he has sounding the way he wants it to sound. He will make a static mix of that recording the way he feels it should sound. The decisions that he made as to how hard he hit what tape at what operating level are past decisions, and have no bearing on the transfer at hand. What is at issue, is what happens to the audio when this tape is transferred into the HD unit.

HD input levels can only be determined by how hot the level of the program material is coming off tape. See Randy's post above.

Mixerman

[RKrizman]

Mixerman wrote on Fri, 04 November 2005 17:55

HD input levels can only be determined by how hot the level of the program material is coming off tape.

Exactly.  So maybe it makes sense to make that determination when you actually run some signal from tape to PT on the day.  Pick a level that is fairly hot without going over, then another one 4 db down.

MM, when you do this how hard do you usually hit the converters?

-R

[rnicklaus]

Going a bit into MM's post -

An engineer having the sound they like on tape and the output level of the 2" machine have nothing to do with each other.

Again, someone could align the machine (I do not believe this will be the case here) and have reference tones for + 6 and then record 3 db or more hotter than the tones.

Analog does not have an absolute zero - digital does.