ARP Quadra Questions

Mark Smart smart at
Fri Jun 20 16:16:47 CEST 1997

> Hmm.. I am seriously considering buying an ARP Quadra (because they look 
> neat, and seem
> to be rather unique), and I was wondering, how difficult would it be to 
> replace a membrane switch
> on the front panel if one went to shit? Hmmm....
> Does anyone know where I can find an ARP Quadra, and maybe a replacement 
> front
> panel if one did go bad??, in the US, or UK, doesn't matter.
> Cheers
> Model500

A friend of mine has a Quadra, and a couple of years ago we did a total
overhaul on it, including building a whole new control panel for
was a HUGE pain, but it can be done.

Before doing this, I called around to a lot of places listed in the back of
the book "Vintage Synthesizers" to try to find a replacement membrane
switch panel and had no luck. I think all the ones in existence have
already been used as replacements. This was before I had Internet access,
though, and you might be able to find one by going this route.

Here's how we built the replacement control panel. First we completely
removed the existing mylar panels; both of them were completely hosed.
My friend had already figured out the switching matrix pattern of the touch
panel, i.e. which pair of pins on the connector gets shorted together for
each button. We mounted a buch of pushbuttons into two pieces of 1"
aluminum channel, which were then mounted on top of the control panel,
right below the row of LED's. We drilled a couple of 1" diameter holes in
the top on the extreme right and left side of the panel. Wires from the
pushbuttons ran through the holes and to two DB25 connectors inside the
body. These DB25's plugged into two more DB25's which were wired to the
places on the circuit boards where the ribbon-cable-munching connectors
were (we had removed them). With everything painted, it actually ended up
looking halfway decent, considering. But more importantly, it works! But
keep in mind, this was a large project which took a LONG time to do.
But it was worth it. After replacing all the blown chips inside and putting
the panel on, we had brought it completely back to life, and MAN does it
sound good!!

What I should do is take a picture of this synth and post it on my web site.

I saw your note on Analogue Heaven asking about the Quadra. One suggestion
is that if you just want the strings, you could get an ARP Omni II. The
Omni II is like the Bass, Poly Synth, and Strings sections of the Quadra
without the phase shifter. And, well, I happen to have several Omni II's
which are almost fixed, and could sell you one! (shameless plug time). 
Here's how I would list the advantages and disadvantages of the Omni II vs.
the Quadra:

	PRO: Has an AWESOME sounding phase shifter, lead synth with
	arpeggiator, pseudo-programmability.

	CON: Not very roadworthy (big and moving it tends to make things
	go flaky), mylar touch panel sucks.

OMNI2:	PRO: More portable and has realiable mechanical switches. Strings
        sound EXACTLY like the Quadra's sound (unphased)
	CON: No lead synth, no pseudo-programmability, no arpeggiator, no
	phase shifter.

If you want to hear the Quadra, listen to the spacey middle section of
"Come Sail Away" by Styx. If you have any other Quadra or Omni questions, I
might be able to help you since I have spent many hours digging around the
insides of both.

*     Mark Smart                               *
*     Network Technician                       *
*     University Communications Inc. (UCI)     *
*     smart at                      *

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