AMI K amp hookup question
Mark Heiss
to the AMI-K amp? My K is stereo, but with only one speaker (horn &
woofer combo) in the cabinet this machine needs a satellite speaker to
hear stereo... but there are about 20 terminal screws on the amp that
are not labelled in a useful way. I have the schematic, but the
terminals are shown as simply taps on a transformer, somewhere there
must be a chart to indicate which tap is for 8 ohm, 4 ohm, left
channel, right channel, et cetera.
Please post a response or send directly to "he...@snet.net".
Thanks in advance for the help.
Mark.
Jay Hennigan
:Does anyone have the chart that shows how speaker connections are made
:to the AMI-K amp? My K is stereo, but with only one speaker (horn &
:woofer combo) in the cabinet this machine needs a satellite speaker to
:hear stereo... but there are about 20 terminal screws on the amp that
:are not labelled in a useful way. I have the schematic, but the
:terminals are shown as simply taps on a transformer, somewhere there
:must be a chart to indicate which tap is for 8 ohm, 4 ohm, left
:channel, right channel, et cetera.
This came up on the mailing list a while ago. The "Stereo-Round" of
AMIs of that vintage is a bit strange. For cabinet stereo speakers,
each channel has a lower level of the opposite channel out of phase.
For satellite speakers, straight left and right are OK. You can use
70-volt speakers with transformers and connect them to terminals E1
and E6 on each channel. For proper phasing, the left channel E6 is
hot and the right channel E1 is hot. This is the way AMI did it,
they used 70-volt speakers with transformers.
E4 is chassis ground. Using 16-ohm speakers , connect as follows:
For left, connect the speaker hot to E2 and ground to E4. Reverse
the phase on the right side, speaker hot to E4 (chassis ground) and
speaker ground to E2. Note that it's this way because the mono cabinet
speakers are bridged, and the cartridge is wired with the right side
out of phase so you need to "flip" the speaker to compensate. Eight-ohm
speakers are as above. but E3 and E4, not E2 and E4.
For fun and an experiment, connect a 70-volt line speaker behind you
from E1 on the left to E6 on the right, or an 8-ohm speaker from E3
on the left and E5 on the right. It should be mostly quiet on a mono
record and give a surround effect on a stereo one.
The K/Continental is like this, per channel:
E1 - Blu - 70-volt +
E2 - Yel - High-level output ~ 16 ohm
E3 - Grn - Mid-level output ~ 8 ohm
E4 - Wht - Common ground
E5 - G-W - Mid-level inverse-phase ~ 8 ohm
E6 - Slt - 70-volt -
The MM and TT are similar, but:
E1 - Yel - Highest voltage output (also feedback to 12AX7 cathode.) ~ 16 ohm
E2 - Grn - Mid-level output ~ 8 ohm
E3 - Br-W - Low-level output ~ 4 ohm
E4 - Wht - Common ground
E5 - Bl-W - Low-level inverse-phase ~ 4 ohm
E6 - G-W - Mid-level inverse-phase ~ 8 ohm
70-volt on a separate terminal strip blue and slate
--
Jay Hennigan - CCIE #7880 - Network Administration - j...@west.net
NetLojix Communications, Inc. - http://www.netlojix.com/
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Mark Heiss
Thanks for the info. Yery helpful. I will give it a try. I only
realized the phase difference recently from examining my friend's
Continental2. I always thought the amp on my K sounded weak until I
swapped one channel around.
But up to this point even my stereo records played mono due to the way
the single set of cabinet speakers are wired.
It is odd that a stereo jukebox would come equipped with only one
woofer/tweeter pair in the cabinet. The Continental2 is a better
design with the side mounted mid-range speakers.
Mark.
j...@west.net (Jay Hennigan) wrote in message news:<SpY48.547$d4.1...@newsfeed.avtel.net>...
Jay Hennigan
:Jay,
:
: Thanks for the info. Yery helpful. I will give it a try. I only
:realized the phase difference recently from examining my friend's
:Continental2. I always thought the amp on my K sounded weak until I
:swapped one channel around.
I would expect that it sounded very weak, and somewhat "weird", especially
on stereo records.
:But up to this point even my stereo records played mono due to the way
:the single set of cabinet speakers are wired.
:
: It is odd that a stereo jukebox would come equipped with only one
:woofer/tweeter pair in the cabinet. The Continental2 is a better
:design with the side mounted mid-range speakers.
In those days a jukebox wasn't typically a standalone item like a
pinball or video game. They usually had at a minimum a remote volume
and cancel switch and remote speakers, as well as wall boxes. Thus
wiring a pair of satellite speakers was probably the norm. These were
the early days of stereo, with somewhat bizarre mix-down of records, like
the vocals exclusively on one channel and instrumental on the other, etc.
In addition, for a good stereo effect you really need better physical
separation of the speakers than you're likely to get in the width of
a jukebox cabinet. Side speakers like on the Continental 2 and the
DS-160 "ears" on the Seeburgs helped. But face it, from across the
room a Seeburg 222 might as well be mono in terms of sound. Stereo
was probably more of a marketing thing during that era than a reality
in terms of music. And I don't think that 45 singles were produced in
stereo in the early days. 12-inch albums were, of course, but I think
it was a while before the record makers went to stereo on 45s due to
vertical compliance limitations of the typical 45-RPM player of the era.
