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Gentner Prism AM

S

Studio1

What's the difference between the AM Prism and the standard version?

Can an AM Prism be modified / changed back to standard?

Anyone know where I can find the manuals online for these units?
 
While it's been ages since I've seen one, I believe the AM Prism (which may have also been called a "Phoenix") had an asymmetry control on it, which to me implied that it could feed an AM transmitter directly and wouldn't have to be used as a pre-processor to another unit. Mind you, it's been about 20 years since I've seen the unit in person.
 
Bill is correct. The control was/is a little box on the cover of the unit. It can be removed and the unit will behave like all the FM ones.
 
I own one. The Phoenix had AM controls on top for a limiter/clipper, symmetry control and release controls for the limiter. It's not very loud and there are issues with it making the NRSC mask. Also, pre-emphasis control wasn't the best.

It did a good job as a pre-processor for an Inovonics 222.
 
I run a Texar AM on 'Radio Free Mexico', a little 500 watt daytimer. It's paired up with the 222 for NRSC. To be honest, it sounds pretty damn good for their format.
 
OKCRadioGuy said:
I run a Texar AM on 'Radio Free Mexico', a little 500 watt daytimer. It's paired up with the 222 for NRSC. To be honest, it sounds pretty damn good for their format.
Click to expand...

Yeah, the Phoenix is a great pre-processor and keeps things just right for the 222, which needs things to be kept "just right"
 
I'm a novice with AM processing, but to my ears it sure seems to me that you can get a nice very competitive sound and be loud on AM...yet use some good older or less expensive gear.

My ears don't detect a big advantage when using DSP on AM...at ALL.

FM, DSP...noticeable difference. Thoughts?
 
Sgeirk said:
I'm a novice with AM processing, but to my ears it sure seems to me that you can get a nice very competitive sound and be loud on AM...yet use some good older or less expensive gear.

My ears don't detect a big advantage when using DSP on AM...at ALL.

FM, DSP...noticeable difference. Thoughts?
Click to expand...

I think you will find that quite a few agree with you.
For example, I know of a number of AMs that are still using Optimod 9100 models. This includes most of the major 50kW's in NYC... stations whose capital budgets allow them to have just about any processor they would choose. The only thing they have changed is to put an Ariane in front.

Kind Regards,
David
 
David Reaves said:
For example, I know of a number of AMs that are still using Optimod 9100 models. This includes most of the major 50kW's in NYC... stations whose capital budgets allow them to have just about any processor they would choose. The only thing they have changed is to put an Ariane in front.

Kind Regards,
David
Click to expand...

I wish that were true. All but one of the big signals in NYC has digital processing now. Just follow this hiss to figure out the one that doesn't.
 
wgliradio said:
David Reaves said:
For example, I know of a number of AMs that are still using Optimod 9100 models. This includes most of the major 50kW's in NYC... stations whose capital budgets allow them to have just about any processor they would choose. The only thing they have changed is to put an Ariane in front.

Kind Regards,
David
Click to expand...

I wish that were true. All but one of the big signals in NYC has digital processing now. Just follow this hiss to figure out the one that doesn't.
Click to expand...


Well, wgliradio, you'd certainly be in a position to know about at least some of them... So, since I'm not in NYC at the moment... does the analog or the digital hiss? I mean, besides IBOC. ;)

Kind Regards,
David
 
I ran two heavily modified ones in Boston in the '90s on WHDH 850. Both had the crossover freqs. changed so the two upper bands actually did something for AM, they also were completely recapped and rechipped with Analog Devices IC's and film capacitors (even the potted NRSC filter-we managed to unpot it).
We also completely rebuilt/rechipped/recapped two BL-40 Modulimiters and inserted these between the 4 band compressor and the Phoenix clipper/filter.
These proecessors were LOUD, sounded GREAT and easily met NRSC. Of course, as soon as I left, in went the Optimod 9100. Problem was, it sounded 'honky' compared to these units. These units gave the station a really loud, clean, "smooth as silk" unique signature sound-and when the 9100 went in, they just sounded like everyone else (who were all running 9100s of course).
 
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