Ampex 1100 Notes.......
AMPEX MM 1100 notes
The MM 1100 is more or less an "under-developed" 1200. In a large part the cards
are interchangeable... the audio cards, the basic transport cards and the power
supply cards are basically the same. Heads stacks are inter-changeable.
The major changes are that the 1200 has a greatly improved audio control box, the
audio bays have a removable Audio Switcher card, and the Power Supply design
has been beefed up. Perhaps the greatest change is that the MM 1200 has a much
better motor drive amp. Later series 1200's were sold with an optional card that
changes the take-up tension as the reel loads up, though this card can also be
installed in an 1100 machine as well.
Of course there are a lot of minor changes, most improving performance in one
way or another.
Some of the small but irritating problems of the 1100..........
1) the audio system has a small but sometimes noticeable "click" when going into
record. THIS IS NOT RECORDED ONTO TAPE ! What you're hearing is the
monitor relay switching between sync and the Input mode. In the 1200 series
Ampex installed a FET muting system that eliminates this click.... it's still there,
but you don't hear it.
2) You can't put some channels into Sync and others into Repro mode. It's an all
or nothing command from the Audio Controlbox. In most cases this is just fine.
3) The switches in the Audio Controlbox wear out after 10 years of service.
Meaning of course, that you'll have to replace some of them soon...
4) Very early 1100's had a mechanical counter, and switches under the take-up reel
that gave the unit it's necessary "true direction" tally. Those switches sometimes
go bad, and the mechanical counter isn't accurate... it's 20 years old by now..
Some 1100's were sold with an Eventide "nixie tube" counter before Ampex
designed the "normal" Ampex Search to Cue system that came standard on most
MM 1100s.
5) The MDA (Motor Drive Amp) is poorly cooled. Without fail, you MUST
install a fan blowing air into the MDA heatsink. And you MUST install a good
AC spike protector on the AC line to the machine. Get one that "clamps" at 400
volts or lower. You'll need one that can handle 20 amps.
6) There is a 'hidden' 5 volt power supply between the reel motors. This supplies
the electrical power for the Search to Cue counter/locator.
7) There are 3 relays on the Audio Motherboard for EACH track. These are the
Sync/Repro, Record and Input relays. From time to time you'll need to change one
or more of these relays, and they're very very difficult to get in and out easily. I
use either a large flat-head screwdriver, or a large flat piece of wood to position the
relay into it's socket. It's almost impossible to re-install the relay's holding spring
back over the relay (unless you remove the whole bay). So don't re-install the
holding spring, but make SURE to remove it so it cannot short anything out !!!!
8) Replacing a bad Audio Motherboard means you must pull out the whole
Electronic bay (each Electronic Bay contains the audio cards for 4 tracks).
Though this isn't a difficult thing to do, it takes a bit of time.
Are the 1100 machines a good buy? You bet they are. If you've a small studio, or
don't need the improved reliability of the 1200, and the ease of quick service of the
1200, the MM1100 will be thousands of dollars cheaper, yet you'll get that same
great FAT Ampex analog sound. You can pick up 1100 16 tracks in the range of
$500 to 1,000 in good shape with good heads, and 24 tracks for $500 to 1,500 in
good shape.
Always have the heads checked out... I use John Austin from the now closed
Sprague Magnetics facility in Sylmar California (email him here:
email John Austin from Sprague Magnetics
REMOVE THE "X' IN THE .comx IN THE EMAIL LINK !!! tell 'em goreski sent you...).
Yes I have Motherboards, transport cards and some other parts for the MM1100's....
Why would you want a 1200? Because its a more recent machine.... it has
removable Audio Switcher cards... you can put one or more channels into sync
and all the rest into Repro mode if you want... the MDA is better..... the audio
cards have minor improvements..... the Power supply is better......
But the sound is basically the same............