Flux Loop for Tape Machine Calibration

[iomegaman]

Yea I found that and popped my tape/recorder speed into word since its just a simple text file...


"For any Calibration Tape and any Desired Playback among the following three speeds and equalizations, there is NO correction required: the response is flat. 30 in/s AES (IEC2) 15 in/s IEC (IEC1) 7.5 in/s IEC (IEC1) You can play any of these Calibration Tapes at any of these speeds, set the reproducer equalizers for flat response, and have a correct calibration."

I just got the 1/2" 30 ips AES...my machine is IEC1...

 

[Brian Roth]

I guess that some of us need to collect all of Jay McKnight's papers from the MRL website and post them in the Tech Docs section before that website goes away. I also have some other of Jay's papers on my drive that were NOT at the MRL site.

Kinda like many years ago when I heard that Barry Porter had passed away. I quickly grabbed everything and just a few days later, Porter's website was gone. Yes...I know about archive.org but it sometimes doesn't have all the files from a site. Two come to mind...Kubarth and the now-defunct MCI forum.

Bri

 

[sodderboy]

I had issues using X speed tapes at a different speed. A meter of 15ips and 30ips MRL tape will each have 320 nW yes, but you are exposing the PB heads with twice the energy in the moment when playing a 30ips tape at 15ips. The repro/sync level adjustments have to be compensated, and it's not linear like "oh, just adjust to 0 instead of -3dB" for +6 (thinking 2" 24trk).
I would re-cap, play the tape, and see what you get. They specify Fostex tapes for alignment, not sure of the flux density. Because you are using the audio output for level and not the LED bargraph, getting the channels flat first is important.
On that B16 machine you are printing lightly because of the track density and leakage.

A flux loop as far as I can tell won't help with azimuth...I've heard of a method where you record a tone, flip the tape over and play it back to check azimuth...but it seems tedious at best...

Back in the day az was more of an issue when you were bringing tapes with tones other studios, and then wanted to get your machines straight again. One co. had three rooms with a total of seven machines and I checked az only twice a year because everything was in-house and tapes only traveled between the three rooms.
Now with 16/24trk the same reel is used, transferred, and wiped for another session, so as long as REPRO is aligned to REC, I would forget about checking az.
Mike

 

[waltzingbear]

The page I was referring to is in that paper, http://mrltapes.com/eqtables.pdf .
All the combinations

 

[Brian Roth]

Hmmmmmm...."404 Not Found."

Bri

 

[Tubetec]

I will say this from my experience with tape ,
if you notice even tiny ripples in the tape as it passes over the rollers,guides or heads or have any kind of up/down osscillatory movement it signals mechanical wear or missaligment
Paying close visual inspection of the tape path always ,
even a bit of tape shed can compromise things , very often does nowadays ,

When you put spectral analysis on a tape path in motion any tiny tape flutter reveals itself ,likewise minute adjustments can be made to both record and playback azimuth so a peak recording level at 10khz is observed , with your machine and your tape formulation . I never saw azimuth adjusted when someone showed up from a different studio with tapes . Sometimes minute imperfection in tape width cause issues especially with 2 inch tape ,who you gonna call then ? other times tapes arrived stretched from missaligned machines
I remember we having to send back batches of the Ampex 456 because there were problems with how it ran across the heads ,


Using the demag as transducer for line up sounds great , but with a multitrack machine how to you ensure repeatabillity as far as distance is concerned , proximity to each pole piece in the stack has a relationship to level you see on the meters

In any case the induction loop method tells us nothing about the state of our tape path ,and if thats not right to begin with you might as well be throwing the tape test tape out the window anyway.

 

[iomegaman]

Yea I think I might be straining at gnat farts here...I have no anticipation of another studio using these recordings, heck I don't even know of other studios with the B16...so really its about getting levels correct and moving on, mostly.


The Bouse APD 1600 is still being reversed engineered...I'm working on the repro cards now drawing out schematics when I'm in the mood...probably no definitive way to calibrate it other that a few minor test so I'm probably not going to invest in a 2" MRL tape...it is 16 track as well...but wired and carded for 24...just would need a different set of heads...

Frankly 16 tracks is plenty for the kind of stuff we are considering using it for...mostly color and forcing people to commit...

Thats the one thing about tape that DAWS ignore...you're paying more coin for the medium so the performance has got to be the best it can be...it kinda imposes a commitment AND a commitment to excellence...at least in theory.

And I have yet to find a tape plugin that sounds like real tape...mind you they are good as emulations...but that natural compression and sonic saturation...its nice.

We do need to be snatching up the MRL Links though...

 

[sodderboy]

I will say this from my experience with tape ,
if you notice even tiny ripples in the tape as it passes over the rollers,guides or heads or have any kind of up/down osscillatory movement it signals mechanical wear or missaligment
Paying close visual inspection of the tape path always ,
even a bit of tape shed can compromise things , very often does nowadays ,

tru dat, yo^
Mizzike
^ "I absolutely concur, sir!"
PS: yes, was it the tape or the machine, always the first decision.

 

[aurt]

I'm kind of crushed that MRL is going away. Inevitable, I suppose, but saddening. In a way, it's more the end of analog than the loss of Quantegy or BASF was. I'm going to have to digest this for a bit before getting my mind around it.

I also have to convince some studio owners to buy their last chance tapes, and do so myself. Not an expense I was expecting.

 

[Rob Flinn]

Like a pheonix MRL seems to have risen from the ashes. https://www.mrltapes.com/