Re: One Subwoofer - Many Pins

Mark,
It's hard to say what the roll off is for each band on your equalizer,
but we are not dealing with anything approaching audiophile source
material, so it is certainly worth a try since you already have
everything, your EQ is fine.
A parametric EQ typically allows you to not only adjust the gain, but
also the bandwidth or Q, of each filter segment. Really overkill
unless you already have one.
I would start by maxing the 31.5Hz band gain, 0db on 63Hz, and
minimize everything else. Play from there and see what you get.
You might also engage the Loudness compensator, which will boost the
bass at lower volume settings, and set it to MONO to get both cannels
driven.
You essentially have what you need to try it on one pin, the only
issue is getting the signal from the pinball cabinet speaker to the
correct receiver input at the right level. Too high of an input level
will at least cause distortion, and could damage your amp and or
speakers.

If you're adventurous, try this - BUT AT YOUR OWN RISK PLEASE

Connect two wires, one to each of the two terminals of the cabinet
speaker, leaving it connected to the internal sound board.
Route the wires out through a vent hole, or one of the blind nut holes
under the coin box.
Keep track of which one is the grounded terminal, usually the one
without the stripe. You can disconnect them and ohm to ground to be
sure (with power off).
Connect these wires to the two outside terminals on a 500 to 5000 ohm
potentiometer. Actual size in that range is not crucial, too high of a
value may allow for stray hum and noise, too small and it could
overheat at high pin volume.
Finally, connect a RCA plug cable, with the grounded terminal wire to
the outside terminal of the RCA plug, and the center pin of the
potentiometer to the center pin of that RCA plug.
What this does, is create a variable voltage divider, that can adjust
from 0 to 100% of the speaker voltage. You leave the cabinet speaker
hooked up to provide proper loading for the pinball amp, and it
provides the localized cabinet sound you expect to hear.
Turn the potentiometer shaft almost all the way toward the ground
side, this will provide minimal output to be safe to start.
DO NOT turn it more than half way the other direction.
Plug the RCA plug into an Aux, Tape, CD, or other line level input, do
not use a phonograph input, too sensitive and it has a modified
response curve (RIAA EQ for you audio guys).
Start a game at a mild volume (e.g. WPC level 8), turn on your
receiver set to a low volume, say to 1 on a scale of 10.
You should hear everything normally at the pin, and probably a quite
level on the stereo. If not, shut everything off and verify.
Slowly rotate the potentiometer until you get a reasonably balanced
output volume from the stereo speakers, and you should be good to go,
play with the EQ to taste.
If you get clipping from the stereo at higher pin volume settings,
back off the potentiometer until it is gone.

Sorry for the length, but perhaps other mildly adventurous pinheads
out there may want to try this too, high grin factor :))
Once you get it to work on one pin, you will understand why I made the
mixer to easily connect many pins at once.
I've tried to be thorough, but as mentioned, experimentation always
incures risk, however remote. If any of this procedure is spooky or
unclear, don't try it.
I think you'll love the effect, let us know how it goes.

Scott


On Sep 26, 9:12 pm, wvpinballguy <wvpinball...@xxxxxxx> wrote:
Scott, those are all good points. While it's not parametric EQ, if I
could do this with stuff I have sitting here, I'll thought it's worth
a try. I'm willing to hook up the 10 band per channel EQ, turn down
the mid & treble controls on the speakers, & adjust the receiver
controls. If it would help, I'd cover the mid and treble drivers.
Are you saying that the big issue is that I need to avoid sending
anything over 80hz to the speakers? I understand about the
localization factor. Since I THINK the parametric lets you select
frequency and rolloff, then that's the big difference? My 10 band EQ
won't do well enough to filter out the higher frequencies? It does +
or - 15db at 31.5, 63, 125hz, etc. It's been many years since I
looked, but I assume the crossover in the speaker to the bass is
higher than 80hz. Thanks for the advice.
Mark M. (CARGPB5)


.

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