Looking for information on my Perspective speakers

Hi all.  I have a pair of Perspective speakers purchased in Switzerland in 1988.  They have been in storage for 30 years or so and just getting them back into use.  But I would like to find some data on them - originals lost.  They are true studio monitors using 2 back-to-back Davis 12 inch woofers, a Davis midrange and Scan-Speak tweeters.  They are intended for tri-wiring with nine input ports for banana plugs at the rear.  Made by Image et Sons but this firm seems to have migrated away from speakers to studio work.  Can anyone out there help me with any info and especially how to manage the tri-wire setup?  Fingers crossed here!


Probably T/M/W is top to bottom.

One could use a 1,5V battery and see which drivers shift when it is applied to the pairs if inputs.
Or maybe even tones or sweeps playing and hooking up a single amp to the wires.

The 9 ports is confusing, I would have expected it like Noah’s ark with 2x2 pairs for T, MR, W… but maybe they also supply a ground?

Do you have a “Digital Multi Meter” (DMM)? On should be able to use ohms/impedance to determine the wire connection idea.

Thanks for that holmz.  I've been working at the battery/DMM stuff and will try to distill the results to a simple story.  Maybe you can help me understand the matrix then!   Cheers

It is almost certainly the + is on the right hand side.
the DMM should read ~8 ohms from the left or middle to the right side.
If one of those left or middle shows 0 ohms to something like each other, or any metal, then those would be a ground..

or maybe it is possible that they are some servo type of signal? 
You basically have 3 combos on each row. From left to right you have bananas A, B, C. And from top down you have rows 1, 2 and 3.  fill out the table with ohms.:

  • A1/B1
  • A1/C1
  • B1/C1
  • A1/A2
  • B1/B2
  • C1/C2

we should be able work out the rest from there.


Here are the test results...

Have added some to your list on the left.  


A1/B1  6             A1/B1   6        B1/C1   0            A1/C1   0             
A1/C1   0            A2/B2   4.5        B2/C2   0            B2/C2   0
B1/C1   0            A3/B3   3.7        B3/C3   4.1        A3/C3   6
A1/A2   0            All vertical combos are zero (eg. A1/B1).
B1/B2   0            Tested with all drivers connected, all nom 8

C1/C2   0            2 x 12" Bass (back to back on cab. sides), 1 Mid, 1 Tw.

What you make of that?  For info A is White, B Black and C Red labelled.

I'm thinking maybe vert row B needs to be bridged if C used.


Sorry - I missed this from last week.

Look like it is a/b should be tried.
Do you have a tone generator app on a phone or iPad? and an small amp?
If so, then maybe do a low level sweep, and I would start with the row 3 (woofer?) and work up.

Probably best to do the MR using 200-500Hz.

And the tweeter using 1500-20k.


We sort of want to know whether there is a crossover (protection) to keep the drivers from playing out of their frequency range.

The row 3 is likely the woofer.
Row 1 and 2 probably have a capacitor inline which blocks DC, and will make the rows 1&2 B/C and A/C seem off.

No idea on the colours.

I unearthed an old Levell oscillator in my kit, rigged it up through an amp at low output level as suggested and ran the tests with results listed below.  I judged the speaker SPLs by ear, so some margin for error - to do a more rigorous test would need to get a dB level meter etc.

So.......first, confirming the input layout for these tests:
                   A                B                 C
White         Black          Red

1.  Using B3 as negative, +ve inputs to either A3 or C3 (in turn) operates the bass units only, at similar sound levels and frequency response, from low Hz to roll-off starting at approx. 3.3 kHz.

2.  Using B2 as negative, +ve input to A2 operates the MR only, with roll-in to good level at 350 Hz and roll-off from 7 kHz.

3.  Using B1 as negative, +ve input to A1 operates the HF only with roll-in to good level at 1 kHz and roll-off >10 KHz.


4.  Continuing with B2 as negative, +ve input to C2 operates the MR only, now with roll-in to comparable level at more like 500 Hz and roll-off from 5 kHz, and

5.  Using column B1 as negative, +ve input to C1 operates the HF but now with roll-in to comparable level at 2.6 KHz and roll-off from > 10 KHz.

To operate all speakers together requires a bridge to all column B inputs (ie. B1-B2-B3) as the common negative input, and bridge either column A (A1-A2-A3) as +ve, or
the alternate column C (C1-C2-C3) as +ve.

And from that I guess one could Bi-amp the bass (Row 3 only) and the (MR HF as a pair) with just the 1 and 2 rows bridged for the latter and providing a choice of crossover as column A or C alternate.

If correct, only a lonely Swiss could devise all that!  Be interested in your thoughts.

Maybe there was an external cross over? And they could wire the polarity whichever way they wanted for each driver?

i dunno.

Can You visually see the driver?
If so, then a 1.5V battery should make A3 either suck in, or push out… and C3 should do the opposite.

 A3 and C3 both have the same speaker phase.  I think it's just a case of 2 on-board crossover options and with individual inputs to each speaker other options for bi or tri amping. 

A3 and C3 both have the same speaker phase

Wow - I guess it makes sense(?), but it would be interesting to peek behind the curtain and see what is going on.



I tried that!  I obtained an Endoscope camera and tried to view the internals, crossover tec.  - very limited results.  Complex build with 54mm cabinet walls, coss-member bracing, tunnel for midrange, bass woofers connected back-to-back to another brace,   Yet to weigh but expect around 130 kg each.

Lovely piano black finish though and great sound.  But big !