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Information needed on Gentner Lazer FM limiter and stereo encoder

B

BROADCAST

I am looking for a user/tech manual for the Gentner Lazer limiter and stereo generator.
I have this unit but do not have the optical encoder that came with this unit.

The optical encoder is an a/d converter and outputs a fibre optic output for the Lazer to compress/limit and stereo encode.

I cannot find any info for this old processor ?

I am looking for information to the output standard of the optical encoder, sample rate etc ?

I am hoping it may be some spdif standard so i may possibly substitute the missing optical encoder for some standard a/d converter that may be compatable.

The Gentner Lazer unit seems to do all the pre emp and compression and limiting, so the optical encoder seems to be just a a/d converter and nothing else.

Any info would be appreciated.

Paul.
 
Wow. Had one in 1991.

I accept the widely held belief that the 8200 was the first dsp based processor.

In fact, Lazer was. Had a synthetic quality, as I recall.
 
From what i now understand, it consisted of 3 units,
1= optical encoder
2= prizm 4 band agc
3= lazer limiter and stereo encoder.

So as i only have the last unit it looks to be doorstop material !
 
Paul, as an older unit, it is probably 32 Khz/16 bit. DSP's in that era worked hard to crunch 44.1 & 48 Khz material. Early on, many limited to 32 Khz, as it's Nyquist was still greater than FM.
 
No manuals on hand, but I do have all three Gentner lazer units. They were working when removed from service in 1993. I think the manuals were lost in a station move. IIRC, the optical encoder feeds the prizim box. Then another optical goes to the limiter / encoder.
 
My guess would have been 32khz sample rate too.
I wonder if the optic data is in a standard spdif standard, or different custom standard ?

If standard format, it would allow some room for adaption, as i have the final box (limiter/stereo encoder), i could possibly feed some compressed audio to it ?

It would be interesting to see if the optical encoder fed direct to the Lazer limiter encoder worked without the Prizm agc box in between.

Otherwise i have another useless box from the mist of time.

Internally there is a 4 way dip switch and optic jumpers 1/2/3 next to the optical input of the Lazer limiter/encoder unit.

Paul.
 
I have tried 32khz optical input but no joy.
A long shot may be that the input may need to be scms free ?

In the menu system i can access the optic power exp and optic power nrm readings, both of these respond to the optical input, but that is all.

Other parts of the setting setup are password protected, but i cannot past this, it asks for 4 digits, i have tried all combinations of button pushes but access denied.

I cannot find any reset on the internals to clear the password, so looks to be scrap.
Internally i even swapped the 2 eproms temporarily, which lost the settings, but it still asks for a password !

Paul.
 
I couldn't find anything in my searching. This was the most I found and it is only useful for the pictures.

http://www.worthpoint.com/worthopedia/gentner-fm-stereo-broadcast-253232367

Old processing interests me. Have you tried 48Khz? I would try 32, 44.1, & 48. With copyright bit on and off.

Always hate to see something like that junked. I take it you have done the standard button presses... 1,2,3,4 or 4,3,2,1... Even then odd, odd then even, etc... Lots of possible combo's there.

I sent an email to someone I know that may or may not still be at Comrex.
 
Yes i have tried 32/44.1/48khz, with copy protection on.
I do not have an optical source with copy protection off, i will need to get a coax to toslink converter to try.

Regarding password entry, i have been trying the mode/enter/escape/up/down buttons in various combinations without success.
These are the only buttons on the unit.
Before i swapped the eproms to force a reset, the preset name did not give me any clue where it came from.
Also where i obtained it from could not help me.

By chance i contacted Glen Clark to see if he could help with the data link, he could not help me.

Paul.
 
The optical encoder came after the Prisms. The Prisms were strictly analog.
 
It's been over 20 years since I've seen one, but IIRC that the Lazer came with a 4 band, all-digital version of the Prizm designed specifically to drive the Lazer. I think that the digital Prizm had no analog input. I don't think it had an analog output either, but I can't recall. That was kind of a negative at the time because one could not easily use the digital Prism to drive anything but the Lazer. I think that the Lazer could be used with other analog pre-processors by putting the optical encoder in front of the Lazer instead of the Prizm. I only ever saw pre-production units at NAB and I never heard one on a real radio station.
 
Yes the optical encoder was the first box, this converted analogue to digital with optical output.
The second box is the 4 band compressor, called the Prizm (not to be confused with the Texar/gentner prism),.
This 4 band digial prizm has optical in, and optical out.
The third box is the Lazer limiter/stereo encoder box.

So in all 3 boxes with 2 fibre optic "leads" connecting the 3 boxes.

It would be interesing to know if feeding the optical encoder o/p straight to the Lazer limiter/encoder box would pass audio, just to see if the data standard was the same ?

As i have the final box that has pre emp/3 band limiter and stereo encoder, i am just trying to make use of it with other outboard gear, rather than just bin it.
But as i also cannot seem to get the box to recognise a optical spdif type format, as well as cannot get past the password denied problem, it looks to be a fruitless effort.

Paul.
 
Fun project, but you'd be miles ahead using breakaway or stereo tool (fave) on a pc.

If i needed a processor and didnt have a fortune.....just sayin'. Neither have failed me.a
 
BROADCAST said:
It would be interesing to know if feeding the optical encoder o/p straight to the Lazer limiter/encoder box would pass audio, just to see if the data standard was the same ?
Click to expand...

Paul, I thought I read in some incarnation of the Audio Prism manual that the Lazer could be used after an analog Prism by placing the optical encoder in from of the Lazer instead of the digital Prizm.
 
It makes sense that the data standard between the 2 optic data connections would be the same.

Whilst installing Breakaway or Stereo tool would no doubt be superior, the reason for getting the Lazer limiter/encoder to work is just making use of spare equipment to make a working processor setup.

These units are really odd beasts !

Paul.
 
The only one I ever saw in use had the analog Prism II's in front of it, with the optical encoder preceding the Lazer.

Never even saw the "Prizm" anywhere in actual use!

I wonder if the optical encoder was outputting AES over the fiber instead of S/PDIF? That might be why the Lazer isn't recognizing anything you're throwing at it.
 
Whilst i have not studied the differences between spdif and aes, except the difference in level and balanced and unbalanced, the 8200 optimod digital src input accepts spdif on it's input.

Also my Cambridge audio dac input also works fine with the optimods aes output attenuated down to it's input.

Paul.
 
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