Ampex MM1100 playback level
« on: April 28, 2005, 11:29:08 AM »
Not really a diy question, but maybe you
could shoot a little advice:

I just picked up a 2'' ampex mm1100 and
am curious if I'm recording music (after
aligning the maching) at 0 vu and I've
set the machine up for +6 at 0 vu (if
that makes sense), should the playback
be the same level or lower?  When I play
back the music from the machine, the vu
meters seem a lot lower (maybe it's -6
vu lower) and the audio coming out is
a lot lower.  Any advice?

New to recording analog.  Lovin it though!

Mark


BYacey

    Where dogs wear thermal underwear, Alberta, Canada
  • Posts: 769
Ampex MM1100 playback level
« Reply #1 on: April 28, 2005, 12:02:55 PM »
Did you re-align the reference level on tape, or just the input / output levels? Once the reference level to tape is determined, you must calibrate the input and output levels for unity gain.
 ie: +4dB in > 250nW flux level to tape > +4dB out.

 You can change the reference level to tape (within reason) but ultimately you want the same signal level that appears at the input for recording to appear at the output upon playback.

 There are exceptions to this if a different output level is required by the console, but generally the above holds true.
Bill Yacey
"Adjust R116 for least smoke"

SSLtech

Ampex MM1100 playback level
« Reply #2 on: April 28, 2005, 12:37:16 PM »
Even when correctly aligned, kick drums and the like will come back lower if you nail them to tape hard. Don't fret level discrepancies with over-recorded material, but punch-ins on guitars etc shouldn't be accompanied by major tonal changes or level shifts.

Other than that, you need to align with a reference tape (MRL, Ampex, Webber or similar) to a level which may -or may not- be 0VU. This way, you need to set the playback level alignment, then the frequency response. Don;t bother with anything below 250Hz if it's a full-track tape. (If it isn't a full-track tape, it's not a real reference tape and it should be used for guidance only.)

After that you send tone to all tracks at 0VU in, then monitor repro while setting the record gain in the ball park. Once it's close, you set the bias -usually at 10kHz, and OVER[/b] drop (NOT under-drop) the meter by the appropriate amount as determined by the head gap, tape tupe and speed. -Quantegy 456 for example might need about 1.4dB at 30ips, but nearer to 3.5dB at 15ips on the same machine.

Once the bias is set, adjust the record level for 0Vu on repro. Then set 10kHz and 100Hz for zero as well.  -NOTE- the 100Hz adjustment should be on teh playback and NOT the record side; there shouldn;t be a record LF adjustment: if that's off you've got big problems! -The machine should now be about as close as it gets.

Remember that tpe can't handle peaks and softens them. For short, fast-decaying impulses, the result is that the needle under-reads on playback. For things like sustained, compressed bass guitar notes, punch-ins and input/playback switching should be transparent and seamless.

Keith
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

soundguy

Ampex MM1100 playback level
« Reply #3 on: April 28, 2005, 01:15:17 PM »
mark-

follow keiths advice there, without an MRL tape you cant calibrate the machine at all so...

I used to rely on a mm1100 as my main machine, if you plan on using it full time I would suggest taking the entire machine apart and thoroughly cleaning every single contact that you can find.  Every single connector, every pin, everything.  Take all the relays outt fo the cards and clean them.  Just take a weekend when you have time and rip the thing apart, the intermittant problems that lay in your future can be headed off to some degree if you put 40 or 50 hours worth of cleaning in that machine.  It takes a long time, but better to do it all when you first get it rather than constantly chasing a problem with it when you are in a session.  Also make sure that all your power supplies are in good shape, you might consider changing the one that is mounted right underneath the transport (cant remember which that was) but it always gave me problems on mine and apparently is pretty classic for doing so.

If you are so technically inclined, Id also reccomend changing all the caps that are inside the bays that the cards plug into.  When you remove the bay, take the cover off and on the back of the connector is a cap, change all those.  Theres a switching transistor back there as well which is a classic case for failure, I cant remember which one it was, but you could remember to look there when the switching screws up down the line.  Its been a few years since I had to fix mine, trying to remember...

If you ever need parts, I have about a machine's worth of 1100 parts as well, feel free to drop me a line anytime.  Good luck with your new deck, its a real pain in the ass to get them set up but they sound totally awesome.

dave

chips are good with dip...

BYacey

    Where dogs wear thermal underwear, Alberta, Canada
  • Posts: 769
Ampex MM1100 playback level
« Reply #4 on: April 28, 2005, 01:38:14 PM »
In my post I assumed you aligned to a reference tape. You can change reference levels up or down from the standard refeernce level, but you also need to make-up or loose gain on the inputs and outputs to accomodate this. Your meters also have to be re-calibrated at this point because "0 VU" is no longer 200nW or whatever the original operating level was. I hope this makes sense. Ampex or 3M used to have documents out with instructions on how to do this. Check out MRLs website for detailed information. http://home.flash.net/~mrltapes/
Bill Yacey
"Adjust R116 for least smoke"

Ampex MM1100 playback level
« Reply #5 on: April 28, 2005, 07:09:15 PM »
Thanks, I'll take a look at the machine over
the weekend and go throught the alignment
procedure again.  I have a 2'' ampex alignment
tape that I've been using.  As far as the cap's,
going through each board, would you change
them all out or just the ones at the rear of
the chassis?  Any good substitutes for the old
ampex cap's?

Mark

soundguy

Ampex MM1100 playback level
« Reply #6 on: April 28, 2005, 07:15:03 PM »
well, you could recap the cards too, but you could do that at your leisure overtime.  Id make a project of cleaning all the tin contacts and since you'll have to take the thing all apart, you might as well change the caps that are in the back of the trays since you'll have it open.  BC caps might be cool youd have to listen to a few and see what you like best.

dave

chips are good with dip...


 

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