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Scott Dorsey
 
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Default aligning revox pr99 without manual

mr c deckard wrote:
the facts:

1) i need to align my pr99mkIII very soon for a mix session. recently
had the heads relapped, got an alignment tape . . .

2) i'm having quite a hard time finding a manual for a revox pr99mkIII


Get a B77 manual. The alignment directions will be the same.
Or ask on rec.radio.broadcasting. There are a lot of those things out
there and someone will be willing to make you a copy.

what information will i need from the manual? can anyone supply this
info?


Not all that much but you should still read it over. DO NOT TOUCH the
bias trap adjustments. Just do the azimuth, level, play eq, then go
do the record bias and eq. Using the modern overbias method is probably
better if you are using modern tapes. The manual may tell you how to use
the old 1KC method with no overbias.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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mr c deckard
 
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Default aligning revox pr99 without manual

thanks for the replies, everyone. i did find a .pdf version somewhere
for $30usd, so i might do that for now. . .

the controls are indeed accessable from the bottom, and well-marked, i
think someone addressed the DIN monitor connector in another thread,
although i'm not sure they gave a pin-out.

i do have an oscillator, voltmeter and oscilliscope, so, i think i'm
in ok shape (although i understand a distortion analyzer can be
useful).


chris deckard




Generally alignment procedures are pretty much the same for any
machine. What you'll need the manual for is to locate the adjustment
points for playback level and equalization (if any), bias, record
equalization, record level, and meter calibration.

If you open the case and find a diagram or the controls are marked,
forget the manual. Just find a generic alignment procedure somewhere,
hook up your oscillator and voltmeter, and go. You've got those, of
course?

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William Sommerwerck
 
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Default aligning revox pr99 without manual

i do have an oscillator, voltmeter and oscilliscope, so, i think i'm
in ok shape (although i understand a distortion analyzer can be
useful).


You definitely want to check harmonic distortion at 0VU at 1kHz when you're
finished. It should be about 0.2%. If it's much higher on a ReVox, you're
probably underbiased.

My experience is that most decks, regardless of brand or format, tend to be
overbiased for the recommended tape. This produces poor HF response, both in
terms of flatness and extension.



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mr c deckard
 
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Default aligning revox pr99 without manual

i dunno, mike. they looked like a legit distributor with many, many
..pdf manuals, but i didn't look too long since i really want a
hardcopy (just for less than $250!). i found them via a google search
.. . .

i'll probably sit down in a few days with a bunch of printouts off the
web and see what i come up with, waiting for the folks at savoy-hill
to hopefully locate one.

thanks again for the help, everyone.

chris deckard
st louis moe


Sad when people rip others off like that, but if it gets you where you
need to be, I guess that's OK. If you had said "someone offered to
scan it for me, put it into a PDF, put it on a CD, and mail it and
wanted $30 for his time" I guess I wouldn't have said anything. Maybe
that's the case, but "find" suggests that someone had it, it didn't
cost him anything, it won't cost him anything to send it to you, and
he just wanted to make some money off your need. Capitalism, supply
and demand, whatever.

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Fletcher
 
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Default aligning revox pr99 without manual

mr c deckard wrote:


i do have an oscillator, voltmeter and oscilliscope, so, i think i'm
in ok shape (although i understand a distortion analyzer can be
useful).


An MRL tape will come in handy as well... in fact, I'd say it was
absolutely mandatory.

As far as distortion analyzers go... they can net you some information when
you're done... but frankly a 'real time analyzer' hooked up to the 'repro'
output of the machine will often be of greater assistance during the
alignment process. By looking at a 'real time analyzer' you can kinda get
a good frame of reference on where the top flattens out vis a vis bias.

Another stoopid pet trick for determining your overbias is to run a signal
into the deck at around 10Hz and listen to the output... at one spot you'll
achieve a sort of balance between 'noise and popcorn' which is usually the
optimal overbias for the deck with a specific tape formulation. Once you
find that spot, run a 10kHz tone into the deck and figure out where your
overbias is sitting... finish your alignment with that overbias, listen to
the product. If it sounds like you have a clear top with minimal noise,
you hit the spot... if you have too much noise, you have too little
overbias... if you have a 'clamped down' sounding top then you have too
much overbias.

Best of luck with it.
--
Fletcher
Mercenary Audio
TEL: 508-543-0069
FAX: 508-543-9670
http://www.mercenary.com
"this is not a problem"


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William Sommerwerck
 
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Default aligning revox pr99 without manual

As far as distortion analyzers go... they can net you some information when
you're done... but frankly a 'real time analyzer' hooked up to the 'repro'
output of the machine will often be of greater assistance during the
alignment process. By looking at a 'real time analyzer' you can kinda get
a good frame of reference on where the top flattens out vis a vis bias.


Aligning with noise rather than single tones has the advantage of using a test
signal that is more like music. This is especially important at slower speeds.

Has anyone made a study of how much "self bias" affects response at 7.5ips?

  #10   Report Post  
Scott Dorsey
 
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Default aligning revox pr99 without manual

William Sommerwerck wrote:

Aligning with noise rather than single tones has the advantage of using a test
signal that is more like music. This is especially important at slower speeds.

Has anyone made a study of how much "self bias" affects response at 7.5ips?


Some folks from Dolby did a study on self-bias and what it does to impulse
response at various speeds with various kinds of tape. It was in the JAES
some time in the eighties, I think.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."


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Mike Rivers
 
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Default aligning revox pr99 without manual


In article writes:

Another stoopid pet trick for determining your overbias is to run a signal
into the deck at around 10Hz and listen to the output... at one spot you'll
achieve a sort of balance between 'noise and popcorn' which is usually the
optimal overbias for the deck with a specific tape formulation.


Just a quibble with the terminology here. With this bias adjustment
method (as well as using a distortion analyzer or a spectrum analyzer)
don't determine the "overbias", you determine the "bias."

"Overbias" is the term that's applied to what you do when you
determine a reference point, then increase the bias a predetermined
amount above the level it takes to reach the reference point. For
instance, you adjust the bias so that a 10 kHz tone reaches peak
amplitude, then you increase the bias until the tone drops by 3 dB (or
whatever is appropriate for your tape, heads, and preference). The
BIAS is whatever it turns out to be when that 3 dB drop is reached.

We usually say that this is 3 dB OVERBIAS, but that's a colloquialism.
The bias current isn't necessarily (and in reality is never) 3 dB
higher than what it was at the reference (peak) level.

Once you
find that spot, run a 10kHz tone into the deck and figure out where your
overbias is sitting...


This is proper usage of the term "overbias" as we know it. You've
found the correct bias level by listening for minimum modulation noise
or adjusting for lowest THD. Now you un-adjust (reduce) the bias level
while recording a 10 kHz tone until the repro amplitude reaches a
peak. The difference in dB between the repro level where you decided
the bias was correct and the level of the peak at 10 kHz is the
"overbias." Having established that for your machine, you can adjust
the other tracks by setting the bias for a peak at 10 kHz, then
increasing it to drop the peak by your experimentally determined
"overbias" amount. (the newer old fashioned way)



--
I'm really Mike Rivers - )
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William Sommerwerck
 
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Default aligning revox pr99 without manual

Has anyone made a study of how much "self bias" affects response at 7.5ips?

Dolby has. This is why they invented (or maybe just named) Dolby HX.
It compensates for self-bias by reducing the bias when recording
something with a lot of high frequency content.


Correct. (Banging O discovered the effect, by the way.) But I was thinking of
speeds that would be considered "slow" by professional standards. (When I
recorded live, I rarely ran at 15ips. It used too much expensive tape.)

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Soeren Rasmussen
 
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Default aligning revox pr99 without manual

hi - you can download the things here http://www.schori.info/ regards

"simonstav" wrote in message ...
"mr c deckard" wrote in message

2) i'm having quite a hard time finding a manual for a revox pr99mkIII


http://www.savoy-hill.co.uk/


3) i've read the RAP FAQ, and some other documents, even did a google
search on RAP, but they all indicate a need to refer to the manual at
some point.


http://groups.google.com.au/groups?q....com.au&rnum=2

http://groups.google.com.au/groups?q....com.au&rnum=3

http://groups.google.com.au/groups?q....com.au&rnum=4

Regards Simon


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Soeren Rasmussen
 
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Default aligning revox pr99 without manual

hi - you can download the things here http://www.schori.info/ regards

"simonstav" wrote in message ...
"mr c deckard" wrote in message

2) i'm having quite a hard time finding a manual for a revox pr99mkIII


http://www.savoy-hill.co.uk/


3) i've read the RAP FAQ, and some other documents, even did a google
search on RAP, but they all indicate a need to refer to the manual at
some point.


http://groups.google.com.au/groups?q....com.au&rnum=2

http://groups.google.com.au/groups?q....com.au&rnum=3

http://groups.google.com.au/groups?q....com.au&rnum=4

Regards Simon


---

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Version: 6.0.520 / Virus Database: 318 - Release Date: 18/09/03

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