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Author Topic: PRINT THRU  (Read 5864 times)

QUEEF BAG

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PRINT THRU
« on: February 23, 2011, 06:52:54 pm »

ok...
ATR 102 HALF INCH RUNNING AT 15 IPS.
SET UP AT +6

print a mix, play it back and print thru
on the tape.

RMG 900 tape.  

this should take months or years to happen.
if at all.

WTF ?

anybody else have this problem?
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Michael Brebes

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Re: PRINT THRU
« Reply #1 on: February 23, 2011, 07:00:07 pm »

The hotter the signal on tape, the higher the level of print-thru.  It doesn't take months or years to happen.  I remember hearing it on recordings all the time, even in the vinyl days.  It's one of the factors of recording to tape. Always has been and always will.
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QUEEF BAG

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Re: PRINT THRU
« Reply #2 on: February 23, 2011, 07:12:45 pm »

the tape is not being slammed, VU peaks at 0dB

tape tension is not excessive, bias is spot on.

this is for sure more than the average print thru...

about on par with that one Zep tune.

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zmix

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Re: PRINT THRU
« Reply #3 on: February 23, 2011, 11:58:00 pm »

Do you hear print through after the first pass on virgin tape or is it possible that the erase head is not functioning properly?

MagnetoSound

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Re: PRINT THRU
« Reply #4 on: February 24, 2011, 03:17:23 am »

Quote:

SET UP AT +6


+6 over what?

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Greg Reierson

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Re: PRINT THRU
« Reply #5 on: February 24, 2011, 10:48:38 am »

MagnetoSound wrote on Thu, 24 February 2011 02:17

+6 over what?

One would assume 250.

Magnetized heads / guides? Seems very strange. Is the music very quite or sparse? Have you tried other tape?


GR
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zmix

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Re: PRINT THRU
« Reply #6 on: February 24, 2011, 02:28:43 pm »

Greg Reierson wrote on Thu, 24 February 2011 10:48

MagnetoSound wrote on Thu, 24 February 2011 02:17

+6 over what?

One would assume 250.


I assumed +6/185...

Greg Reierson

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Re: PRINT THRU
« Reply #7 on: February 24, 2011, 02:35:04 pm »

Damn! Memory fade.... Chuck is correct!


GR
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radardoug

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Re: PRINT THRU
« Reply #8 on: February 24, 2011, 02:45:59 pm »

Can you measure the level of the print through relative to the main audio?
Print 1 kHz at your reference level. Then with no input, record over the 1 kHz tone. Tell us or supply files of the erase level of the 1 kHz tone.
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QUEEF BAG

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Re: PRINT THRU
« Reply #9 on: February 24, 2011, 07:50:31 pm »

+6 over 185nW/m  or 355 nW/m

250 nanos is +3dB over zero referenced to 185 nW/m

At the time this standard was established 185 nW is all
the level the tape of the day could handle.
so the 0dB reference still in use today is referenced to 185.
when 456 came out the ads said "Now i can record at +6
and tape hiss is no problem." eveyone just knew what the
superstar engineer of the month in the ad meant.
499 and scotch 996? we just said "sweet now we can go +9!"

any ways... rebiasing for a different tape gave a clue.

after setting the high eq for zero i always look at 15k or 16k
just to see how flat thing are further up.
the API console has 10k then 20k on it's oscillator.
so when i looked at 20k (after setting zero at 10k)
it was -15dB down on the left side and -20 on the left!

derr...that ain't right.
ok so i check the head wrap on the record head as i am
recording 20k... still pretty solid, frickin' low
checking the repro head - whoa! there's the top.
we are not getting good contact on the repro head.

(i won't take the time at the moment to explain except to say
you should ues a Q-tip instead of your finger)

so i swapped in a head stack from another ATR, and
the wrap was fine.
(yes repro and record cal again with different heads)
only down a quarter dB or so at 20k about what i would expect at 15 ips

i also swapped master bias cards, thinking this would be the
most likely of a machine induced problem.

still print thru.  damn

the tape is being erased.
it is not an erasure issue.

i am pretty sure it's a machine issue.
yet another machine in the building has no problem with
this issue.  it is being used in session for another day
in the other room, or i would use it now.

if i have a chance, i will try to make a file or two, but that is not
likely today.

no sense in gettin' to concerned, when i originally posted, i
hadn't ruled out the tape at that point.
i was just wonderin' if other people had any similar experience with RMG.




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Bill_Urick

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Re: PRINT THRU
« Reply #10 on: February 25, 2011, 12:42:02 am »

I jus' wanna nough,

is there a plugin that does this?

If so I want it.
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slothus

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Re: PRINT THRU
« Reply #11 on: February 25, 2011, 01:22:41 am »

Shouldn't it technically be over 180nWb/m these days....?

Err, anyways...

900 fine with a 102 here this week, last week, the week before. Good luck in the hunt.

I want that plug too Bill. Actually, I'll just check that other website to see if I really do want it.

Brent Punshon
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radardoug

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Re: PRINT THRU
« Reply #12 on: February 25, 2011, 02:13:18 pm »

+6 over 185nW/m or 355 nW/m

Queef, which is it??? You must know. The flux level of the alignment tape is written on the box. Precision, my boy!

I had a case years ago where an ATR100 had magnetised roller guides.
This would cause a type of print through, in that it would reprint the bias frequency, and it would beat against itself, producing a variable frequency whistle. Try demagging all the bearing guides, and of course heads, lifters etc.
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QUEEF BAG

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Re: PRINT THRU
« Reply #13 on: February 25, 2011, 05:13:22 pm »

sorry if i wasn't clear
355 is +6 over 0vu
what i should have said, i guess is
i am set up for +6 operation which is 355nW/m
what i meant was you could call it +6 or 355, same thing
i was typing as if i was talking.
if i was standing next to another tech looking at the machine,
i would just say +6 refering to the levels it was set for.
or i could say 355nW/m.  usually we just refer to the number of dB over 0.

the machine in the other room is set at +12
i have no idea how many nanowebers that is  : )

i"ll be swapping machines soon, so i can chase this a lttle more





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radardoug

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Re: PRINT THRU
« Reply #14 on: February 26, 2011, 01:45:18 am »

See this is where I have the problem. What you are interested in is the flux level of your reference tape. Then you can convert your repro gain setting to a level x dB relative to the reference, or to a flux level.
0 VU is meaningless unless you can reference it to a flux level.

So your reference is 185 nWb?
And you are operating at 6dB above the reference?
I would have thought it more likely that your test tape is 250 nWB.

Interestingly when I was doing a lot of tape testing back when 456 was the common tape, the 3% total harmonic point was generally around 14 dB above 185 nWB. I didn't have a wave analyser and could only do THD. So people operating at an operating point of +6 relative to 185 are already crushing transients quite a bit, bearing in mind the true program level is 10 to 14 dB above what the VU meter shows.

Most newbies have terrible trouble understanding the concept of flux level, and messy references by people who should know make it even harder. Then add in the fact that to increase recording level, you wind down the repro level, and I can see the glazed eyes.

Anyway, this will not affect printthrough apart from the fact that printthrough will occur more with significantly elevated levels.

And one other thought, if you Dolby it you will reduce the obviousness of the printthrough.
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QUEEF BAG

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Re: PRINT THRU
« Reply #15 on: February 26, 2011, 04:02:39 am »

yup level will exasorbate print thru,

and the offending program material was very transient in nature,
though it wasn't slammin' loud.

the other machine does not have any print thru problems with the same
project at all.

at the moment i'm convinced it's the machine.
tho i could be wrong.  the next thing to swap is the audio cards.
if that yeilds no results, it's time to look at the bias signal.


as far as i know tape machine operating level is ALWAYS referenced to 185 nW/m
that IS zero vu on repro

there is always that thing of setting up a machine for +6 with a +3 tape,
then during repro set-up you would make the meters read -3...
but you know about that.
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slothus

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Re: PRINT THRU
« Reply #16 on: February 26, 2011, 08:22:47 am »

QUEEF BAG wrote on Sat, 26 February 2011 20:02

yup level will exasorbate print thru,


And shuttling the tape can reduce it somewhat. Thermal Idiots can be manipulated to a small degree that way.
Quote:


the other machine does not have any print thru problems with the same project at all.


Exact same reel of tape on the different machine calibrated exactly the same and same level to tape?

Quote:


as far as i know tape machine operating level is ALWAYS referenced to 185 nW/m
that IS zero vu on repro

there is always that thing of setting up a machine for +6 with a +3 tape,
then during repro set-up you would make the meters read -3...
but you know about that.



You're right but I maintain it should be notated as over 180nWb/m (ref/1Khz) these days. This equates to the old Ampex operating level of 185nWb/m at 700hz. +6 with a 700hz reference tone is a different fluxivity than with a 1K tone. Using 185nWb/m assumes a reference frequency of 700hz but then calling +6 355 nWb/m assumes a 1K reference tone.

I've had a few disagreements with assistants when I've asked for a particular cal on a machine over this. They've usually been wielding one of those old Ampex slide chart things as absolute proof that "+6" is 370 nWb/m, and could never be 355nWb/m.


Brent Punshon
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radardoug

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Re: PRINT THRU
« Reply #17 on: February 26, 2011, 02:25:14 pm »

250 nWB is now a common reference level, probably more than 185 or 180.
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QUEEF BAG

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Re: PRINT THRU
« Reply #18 on: February 26, 2011, 04:22:56 pm »

yeah i don't know anyone with a 185 or 180 nW/m tape.
they are all probably sticky by now.

i have seen 355 to 370nW/m on the side of +6 calibration tapes.
that has always bugged me.

different companies seem to have different ideas?

yeah same exact set up on the other machine.
no print thru. same reel of tape.

it is now just a puzzle, not a desparate issue now that
the other machine is in there and working fine, but
it will have to be fixed.  now i will have the time to find it.

i'll let ya know wuzzup

and thanks to eveyone!
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Greg Reierson

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Re: PRINT THRU
« Reply #19 on: February 26, 2011, 08:27:27 pm »

Try swapping transport parts like rollers and heads between decks. You might also look for a stray magnetic field from a motor or solenoid. Do you have a Gauss meter?


GR
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QUEEF BAG

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Re: PRINT THRU
« Reply #20 on: February 27, 2011, 01:55:55 am »

i do have a gauss meter, haven't used it yet.
good idea though.
degaussed everything in the tape path, including pinch roller
(old scully 2" story about that one)

the guys in studio B don't wanna give up that machine yet,
they loved the sound of it, except the print thru
and in spite if the fact we got the next machine tweakd to sound just
the same.

who am i to mess with the bond that that can develop between
man and machine ?
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radardoug

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Re: PRINT THRU
« Reply #21 on: February 27, 2011, 02:32:57 pm »

Are you sure its not audio getting from output back to input while its in record, and therefore adding an echo to the signal? You could prove this by recording at the front of a reel, and then at the back. Print through is the adjacent layer of tape printing, so at the front of the reel the print will be short delay, and at the end it will be long. If it doesn't vary, then its feedthrough, possibly in the in/out assembly. Use a burst of tone, easy to hear the starts and ends then.
Does the in/out assembly have its transformers fitted? Any funny loading on the outputs? Missing or dodgy ground to the in/out assembly?
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