I'm trying to bias my mm1100 for the first time and am running into some
problems. I've read the manual, but it's not making sense.

I've read online that you want to overbias your machine about 3 1/2 db. I've
tried to adjust the bias adj pot on my machine, but it only peaks and it won't
drop back if I continue to turn the pot clockwise. I guess once you reach the
peak it's suppose to drop back the other way. Is this correct?

I'm inputting a 10k signal at 0vu and recording at 15ips. I've got
all channels in ready mode and all switches turned to bias. Do I set the
machine in play or record mode?

Thanks for the help.

Nathan

I believe you want to have the switches NOT set to BIAS, but set to playback.
You should be watching the audio playback of your 10k tone and overbias by the
desired amount while watching that.

Hopefully you have done a playback alignment FIRST so you have a fluxivity
reference from which to work.

CP

"GymnastBarbie379" wrote in message
...
I'm trying to bias my mm1100 for the first time and am running into some
problems. I've read the manual, but it's not making sense.

I've read online that you want to overbias your machine about 3 1/2 db. I've
tried to adjust the bias adj pot on my machine, but it only peaks and it won't
drop back if I continue to turn the pot clockwise. I guess once you reach the
peak it's suppose to drop back the other way. Is this correct?

I'm inputting a 10k signal at 0vu and recording at 15ips. I've got
all channels in ready mode and all switches turned to bias. Do I set the
machine in play or record mode?

Thanks for the help.

Nathan

I've done the playback alignment, but wanted to make sure the bias was set
before I did the record align.

The switches only let me choose from normal, set up and bias. I'll assume that
the normal mode would be the playback mode. Is that correct?

In article writes:

I've read online that you want to overbias your machine about 3 1/2 db. I've
tried to adjust the bias adj pot on my machine, but it only peaks and it won't
drop back if I continue to turn the pot clockwise. I guess once you reach the
peak it's suppose to drop back the other way. Is this correct?

First off, the meter switch "Bias" position isn't where you adjust the
bias. It's a reference point so that if you have to change the bias
to accommodate a visiting tape, you can return to your original
setting without going through the normal bias adjustment procedure.
It's essentially a voltmeter across the bias voltage that's fed to the
record head.

To adjust the bias, you need to be recording and monitoring the repro
head. That meter switch needs to be in Repro (I think - I'm far away
from the picture at the moment). Anyway, what you want to see on the
meters is what's coming off the tape. Put in 10 kHz at 15 ips or 20
kHz at 30 ips, and adjust for a 2 to 3.5 dB drop after reaching the
peak, depending on the type of tape you're using. If you aren't sure,
3 dB is usually OK. After you've set the bias, you can then turn the
meter switch to the Bias position and adjust the calibration pot for 0
so you'll have a handy reference.



--
I'm really Mike Rivers - )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article writes:

The switches only let me choose from normal, set up and bias. I'll assume that
the normal mode would be the playback mode. Is that correct?

Thanks for the reminder. I don't remember the difference between
Normal and Setup but it seems to me that I left the switches in the
Setup position all the time, whether making adjustments or making
recordings.

Incidentally, there are those who think that the machine sounds better
when you put that switch in the Bias position. It transfers the VU meters
from the audio output to the bias driver, removing the non-linear load
of the meter rectifier from the audio. (no, it doesn't recitfy the
audio output - that would be too easy to spot) I never noticed a
difference, but then I don't really have golden ears.


--
I'm really Mike Rivers - )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

GymnastBarbie379 wrote:
I'm trying to bias my mm1100 for the first time and am running into some
problems. I've read the manual, but it's not making sense.

Okay, the manual first of all talks about biasing at 1 KC with no
overbias. The modern method is a little different since you are going
past the peak with a 10 KC reference tone.

I've read online that you want to overbias your machine about 3 1/2 db. I've
tried to adjust the bias adj pot on my machine, but it only peaks and it won't
drop back if I continue to turn the pot clockwise. I guess once you reach the
peak it's suppose to drop back the other way. Is this correct?

Right. If you can't get to the peak then either you are using a tape that
requires more bias than yout machine can deliver, or else you have another
alignment issue. Did you do the playback and record azimuth first? Azimuth
errors can screw all kinds of stuff up.

I'm inputting a 10k signal at 0vu and recording at 15ips. I've got
all channels in ready mode and all switches turned to bias. Do I set the
machine in play or record mode?

You're in record, and you have the switches turned to REPRO rather than
INPUT or BIAS. You want to be listening to what is coming off the head
rather than what is going down onto it.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."