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!

dean75

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
1
2
3                
                  
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.

However,

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.