Gain Reduction Meter vs VU Meter

I am getting one of these:
1 gain reduction meter Black, black scale as per as Audio and
Design compressor, dimens 49w x 42 h lettered 0-20 right hand zero
Anybody any ideas on what type this is?

I have read the 1176 threads and it talks about using a VU meter
Jakob says

you should remember that the meter output is a current-through device - and that the only metering that can be connected here in a simple way is the mentioned moving-coil VU-meter...

and in the SSL threads..

The last use of the rectified, timed and and buffered signal is driving the 1mA GR-meter for monitoring of the ongoing compression. This is linear scale, at about 50uA/dB, making a 1mA meter showing 20dB full-scale

So by reading between the lines,
1176 = metered on AC
SSL = metered on DC ("rectified" - see I do pay attention)

there is no chance of a SSL and a 1176 can use the same meter.
hopefully the one above
If they can by use of a circuit - can somebody point me in the direction of where I should be looking

If you only want to display the GR in the 1176 you can use the DC meter. But if you also want to display the output level you need to use a VU meter.

Check this info.
I made my own VU with a selenium bridge rectefier....not really acurate but it looks ok though.

> 1176 = metered on AC

I don't think the 1176 GR function is AC. I think they apply DC to a second GR element controlled in parallel with the audio GR element, and measure the GR-ed DC that comes out.

As Michael says: if you want to switch between readin the level and the GR, you will need an AC meter (or meter driver) for the audio. Since the old audio shops had lots of VU meters around, the VU (which will read DC fine) was the usual GR meter.

Get your meter and hook it up through a 10K resistor to some few-Volt AC/Audio and DC sources, you'll soon know what it is behind the pretty face.