I have an 8300 I'm trying to get to sound the way I think it should (classic rock) and I'm not sure about the Composite Out setting. I have it at 3.3 right now, but I have no idea what would be an optimum setting, especially with the Composite limiter (set at 1.0) and the Final Clip (set at -.4). Someone told me the Digit has a clipper built into it and the last thing I want to do is clip already clipped audio...
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Optimod 8300 vs. Harris Digit exciter
- Thread starter HadYourPhil
- Start date
"Someone told me the Digit has a clipper built into it and the last thing I want to do is clip already clipped audio."
Why not look at the manuals for both products? The manuals should tell you everything that you need to know.
Do not rely on something that "someone" told you. Find out for yourself.
Why not look at the manuals for both products? The manuals should tell you everything that you need to know.
Do not rely on something that "someone" told you. Find out for yourself.
Ouch.
I have the 8300 manual at hand, but the Digit manual hasn't surfaced yet. And, contrary to what you might think, I do consult manuals.
I have the 8300 manual at hand, but the Digit manual hasn't surfaced yet. And, contrary to what you might think, I do consult manuals.
1.0 is a lot of composite clipping in the 8300. That is going to be pretty grungy. I can't stand it over .5
As far as the digit, I doubt it's clipping by default. If you are going AES into it, you should be good. I do remember early digits having some sort of AES overshoot problem (or something of that nature).
As far as the digit, I doubt it's clipping by default. If you are going AES into it, you should be good. I do remember early digits having some sort of AES overshoot problem (or something of that nature).
HadYourPhil said:
By composite out, do you mean "composite level" control under the Optimod stereo encoder section? That control adjusts the amount of output need to drive the exciter to 100 percent modulation. The optimum setting is adjusting it until you reach 100 percent modulation. The Digit does not have a clipper if you are using the analog input module. The digital input module has a built in limiter, but I would advise you to stay away from the digital input module.
Make sure you are not feeding composite into a "digital input module" in the "back-up" mode. The digital input module has a way of accepting composite if the AES digital input would fail. If you are stuck with the digital input module, use the AES output of the Optimod with pre-emphasis, and lower the limiter threshold in the Digit so it is not working. Make sure the dip switches in the digital input module are set to not add any pre-emphasis.
The original Harris DIGIT had/has a composite peak limiter acting on the digitized waveform in the exciter when using an AES3 input. The limiter uses a "look ahead" technique, with no effect on the 19 kHz pilot, and was/is based by license on the WAVES L-1 Ultramaximizer(TM).
When appropriately and judiciously applied it is quite effective, and was used with good results in the Harris DIGIT exciters of one of the most prestigious classical music stations in a top-tier U.S. market.
The overshoot issue mentioned earlier is related to the use of certain processors that did not limit audio L&R bandwidths to ~15-16 kHz, during processing and conversion to a digital format.
R. Fry, Harris Broadcast FM Applications Engineer (retired 1999)
When appropriately and judiciously applied it is quite effective, and was used with good results in the Harris DIGIT exciters of one of the most prestigious classical music stations in a top-tier U.S. market.
The overshoot issue mentioned earlier is related to the use of certain processors that did not limit audio L&R bandwidths to ~15-16 kHz, during processing and conversion to a digital format.
R. Fry, Harris Broadcast FM Applications Engineer (retired 1999)
Thanks all...
I was thinking the composite level was too high. My previous experience with the Digit exciter was with the infamous 8200. I just 'inherited' this lash-up. Hopefully the Digit manual will surface today so I can see better what version of things I am dealing with.
I was thinking the composite level was too high. My previous experience with the Digit exciter was with the infamous 8200. I just 'inherited' this lash-up. Hopefully the Digit manual will surface today so I can see better what version of things I am dealing with.
HadYourPhil said:
I'm really sorry for my snotty-sounding response. I can't even guess how many times someone has called me for help ... only to find that they haven't bothered to read the equipment manuals.
Please accept my apologies.
Empirically, Digits sound better if you feed them good composite processed elsewhere, assuming you're using the Harris composite input module. The composit input on the AES module is purely a get-by.
If you can't get the Harris manual, you could always connect an oscilloscope to the composite output of your modulation monitor, then turn up the composite output voltage on the 8300 and see what happens. If you see the level increase, the Harris is not clipping. If you see more clipping, obviously the Harris did the clipping. 
Best regards,
///Leif
Best regards,
///Leif
Thanks again! Found the Digit manual today and spent time doing some "light" reading. I'll need to verify the Optimod's composite limiting versus the Digit's composite processing... Which I think is in use.
Remember, I just inherited this and it is far from the only fire I need to put out.
Thank you all for your input.
Remember, I just inherited this and it is far from the only fire I need to put out.
Thank you all for your input.
HadYourPhil said:
If your DIGIT doesn't use the Digital Input Module driven by an AES3 source, then there is no possibility for it to apply any type of limiting, whatsoever.
IOW, the DIGIT exciter has no capability to process/limit the dynamics of an analog composite input signal fed to either of its two possible audio input modules.
Goran Tomas said:
I would be inclined to agree. We have multiple Digits still in use and I remember (from 10 years ago) lots of discussion about how it is best to use the composite in...
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