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Azimuth scares the pants off
everybody. Why?
Because it's done with a mechanical screw on the heads that the
manufacturers often put that transparent "don't-mess-with-this" glue on
- so we all assume that it's so delicate, we'd better not mess with it.
Not a bad idea, but it's also not that difficult. Many studio owners
don't own an oscilloscope (best method), but it can be done with a
simple meter on your console (VU is best). This adjustment is best done
before the record eq settings -- but you may need to do the other
alignment stuff (see previous page) first
to get things in the ballpark - particularly if the machine hasn't been
used in a while or maintained well.
Put on the 1k tone from your
alignment tape at the speed you're going
to record. Set the output to REPRO (playback) so that you're reading
the signal coming off the alignment tape - it's helpful to set the
output to the elevated level you plan to use. If
there's
a switch that allows you to pick a manual knob to change the output
level -- and a smaller internal preset level -- select the preset
level. Don't use the knob for now - it's more designed for
on-the-fly
adjustments.
Bring both channel outputs
of the machine up on two console faders panned to the center of the
stereo buss (or simply assign both channels to a regular buss that's
easy to meter). Set the your faders so that the signal you see on the
console reads 0 VU.
Uncover the head stack so you can see the mounting plate that
holds the
heads. On the playback head (to the right) you'll see several screws,
or
possibly some holes where either a long small screwdriver or hexwrench
will fit. CHECK YOUR MACHINE'S MANUAL TO BE SURE which adjustment is
the one to make azimuth adjustments (or contact the technical/repair
department
of the company).
(1) Playback head rough azimuth adjustment:
Now play the mono-summed 1k tone off the L-R outputs of the playback
head, looking at the buss output meters (turn those monitors
LOW). Carefully, get a non-magnitized
screw driver (probably phillips or hex wrench) and slowly turn the
azimuth screw. Here's where I put the disclaimer that I'm not
responsible for any screw-ups. You should see the output of your buss
meter change. No need to make huge movements - you're not installing a
door! Turn the screw until you see the console meter reading go
down a bit
and then back up to 0 VU. Look carefully - you'll find
that turning the screwdriver either direction should make it go down
and up, depending on the closeness of the phase of the L-R channels.
Don't do this by candle light. Rechecking is a good idea. In most
cases, heads will be decently close to a peak (high output) if the
machine hasn't been thrown off a pier.
(2) Record head rough azimuth adjustment
(optional): You can now put the machine into sel-sync (playing
off the record head) and repeat the above process for the record head,
but ideally, you want to wait and use some blank tape and actually be
in record to do this.
(3) Playback fine azimuth adjustment: Now
play the 10k tone in the repro mode and do the same thing, only slower.
Often the 10k
region isn't as stable as the 1k. It's smaller frequencies up there....
Do the same thing as step (1) - slowly turn the screwdriver left, then
right. You'll see where the VU reading will go down and back
up. You want to leave it set when the console VU reading is at
it's max, whether or not it's at ) VU or not. You want the max
(peak) reading.
Go back to 1k (we're always in playback mode doing this) and check to
see that the 1k tone is still up around ) VU. If it's changed,
reset the console faders so that the meter reading is 0 VU.
Go back to the 10k tone and double check to be sure you're seeing a
peak. Slowly turn the screwdriver left then right then back till
you see the maximum readout on the console meter. It doesn't have
to be 0 VU like the 1k tone, it just has to be the greatest
ouput. Things will continue to change as the alignment goes
along.
(4) Record rough azimuth adjustment (the
real one): Now TAKE OFF THE ALIGNMENT TAPE and put on some
blank tape, preferably preferably 1 1/2 to 3 mintues of the kind
that you'll be using for the session. Put some white leader tape at the
beginning and the end of this section of tape. Do not plan to
record any music on this section of tape. This is called a
"record pad."
On your
record pad (see here), send a 1k tone from
your
console oscillator or tone generator to your machine. Record 1k onto
the blank tape.
The console and machine should be set up the same way. You should still
be in playback - you're seeing your setting via the playback head's
output. Turn the comparable azimuth screw on the record head (NOT THE
PLAYBACK
HEAD) (check your manual) and adjust the record azimuth to give you the
greatest peak meter reading.
(5) Record fine azimuth adjustment: Turn
your oscillator to 10k, roll back
the tape (you can go over the same section of tape to make these
adjustments) and adjust the fine azimuth setting. Same stuff as above -
record 10k to tape, and still reading playback, turn the screwdriver
left then right (on the record head) till you see the maximum meter
reading on the console. Recheck. Leave the playback screw alone or you
get to
get out the alignment tape (and turn off record ready) and start over!
Recheck your 1k setting. Recheck your 10k setting. Recheck your
playback settings. You're done setting the azimuth!
Whew! Later, I'll get into setting erase peak adjustments... for now I
think I'm ready to go watch a movie or something...
.
.
.
Ok, I'm back from my movie. Erase peak is a cinch. Er, well, you have
to be very careful with this one or you could turn you speakers into
shrapnel...
Get some blank tape, preferably the kind you're using for most of your
sessions (BASF rules, in my opinion). Record a test tone (from your
oscillator or tone cd) for a good two or three minutes, usually
anything from 400 to 1K, at 0 vu on tape. Now roll back the tape, and
TURN DOWN YOUR MONITORS. Click here
to see the best monitor controller available on the market today!
Turn your oscillator OFF and just start recording dead air on tape...
and bring your monitors up (listening to one channel only of the tape
playback) slowly till you are just hearing tape hiss, or some remnant
of tone that's being erased on your tape. Find the erase peak adjust
control (of that channel) inside your machine (manuals can help) and
turn it down slowly till you start hearing the tone come up. Start
turning the erase control pot back up and you should hear the tone go
away. (If you hear no change, be sure you're monitoring the same track
that your adjusting.)
Keep raising it till you hear the tone appear again. Turn the pot down
and up till you sense the peak, or middle spot where the tone is erased
down the farthest. That's the peak point where the erase bias is
working the best. Erase bias is just a LOT more bias than the amount
that goes to the record head.
Then just repeat the same process for the other channel. BE SURE
BE SURE BE SURE that whenever you stop the tape
YOUR PLAYBACK MONITORS ARE TURNED DOWN. You have to crank them up in
order to hear this process, and if you take the machine out of record
when there is still tone going, it will come on LOUDLY and abruptly if
your speakers aren't turned back down!
This process can be done even using plain old music on tape - it's
simply finding the place where the erase bias works best. Not rocket
science, but if holding your alignment tape makes you queasy, this
wouldn't be the first thing I'd recommend that you do. If you want even
more precise alignment, contact a super-duper tech person who knows
machines and have them do bias choke optimizing, erase wrap and full
head alignments. These pages are designed for general analog machine
use, and are part of full maintenance upkeep that makes analog
recording ...still... the best sounding to date.
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