Setting ideas for an Optimod 9100a

[macmike]

I Need some sitting ideas for an AM running an Oldies format. Sounds currently like it needs loudness and more dynamic range. The only processor in the chain. Being feed from studio via phone lines. The optimod feeds a new 1KW BE transmitter. Any setting ideas appreciated.

Macmike

[W2XJ]

First, by Bob Orban's own admission the input compressor is not as good as it should be. Use it very sparingly. Many people put a leveling device at the studio end. Often, although not my first choice, Aphex Compellors are used.

On the 9100, use a little of the input compressor, then put in enough multiband for density and signature. During this tuning phase use zero clipping and stay under 100% modulation. Once you have the sound you like, crank in clipping to the point of it feeling intense and then back it off a bit. Then set the transmitter to between 90 and 95 percent negative modulation, no more. This is best done with the help of a scope.

A 9100 could be over 35 years old and should be completely rehabbed. Also, there may be less expensive and better sounding means to feed the transmitter than phone lines. YMMV.

[ChuckG]

I wouldn't touch the Optimod until sweeping the phone line for frequency response and distortion. There aren't many telco techs left who know how to EQ them correctly. The audio out of the Optimod will never be better than the audio going in.
Along those same lines, your antenna system is a big deal in AM and can definitely affect audio quality. High Q, narrow bandwidth networks were common years ago, particularly in DA's. Opening them up can make a noticeable difference.
That BE can be a very nice sounding transmitter with a good load and good audio.

That said, I have little to add to what W2XJ wrote. Often I find audio processors with everything set to "11" when in reality less is often more. If everything is flat and lifeless, the correct control direction is probably down, not up.

[W2XJ]

Somehow I get the feeling that if the station is still using a 9100 that investing in antenna broadbanding is not in the cards. Sweeping the phone line is simple enough and a great idea but while I have no idea of the specifics, I am fairly sure the station could save a lot of money by using a more modern STL method.

[Lee_Wheeler]

I am fairly sure the station could save a lot of money by using a more modern STL method.

Check the price for a dry pair. There are mountains of Tellabs equalizers floating around. I have at least a dozen that have been abandoned at various transmitter sites and I would be happy to mail you one along with a power supply and a case. It is a snap to equalize your own lines so long as there are no loading coils on the phone line. Ideally you would have a Western Electric 111C repeat coil at the studio but those bring big money on eBay. Any decent 600 ohm:600 ohm audio transformer will work.

It depends on tariffs, which are state set, but I could get a dry pair for about 10% of the monthly rate of an analog equalized circuit back when I was actually using phone lines at various stations. You can't be too far away from the transmitter site but I have done a bunch of lines that were 5 or 6 miles.

...Lee

[W2XJ]

Good luck finding actual copper anymore.

[Dale H. Cook]

Good luck finding actual copper anymore.

That is a growing problem, even in smaller markets. I know of AM stations that had been using Comrex codecs over dialup who had to switch to internet delivery of programming because of deterioration of and frequent problems with copper. I have only three client AM stations left who are still using copper, and two of those have their studios at their transmitter sites. The third station is using Comrex codecs for program delivery, and they will probably have to get off of the copper within a year or so because of increasing problems with keeping good pair at both ends.

[Deep Thought]

Good luck finding actual copper anymore.

Truth is, in most markets there aren't any people left who can install a dry pair even if it were physically possible. Most program circuits have been provided with what is basically a nailed-up ISDN line and the telcos are trying to get rid of that now, too.

[TPT]

And "black boxes" are multiplying in what one assumes is copper end to end. Neighboring county is small telephone company, local exchange, Frontier.
Used to be a cable along the main highway between the two central offices..

Then even on POTS remotes we would hear a delay. Comrex works sometimes, other times, not at all. Someplace between the two systems lurks an evil digital device.

[W2XJ]

STLs can be a problem these days. Forget about new copper lines. That really leaves some kind of IP path as the only choice. Microwave works well if there is a path. Wired lines or even fiber lines are subject to various forms of failure. Too many TX sites just have too little access to reliable telecommunications infrastructure.

[Shane]

Amen.

Somehow, so far, our experience has been OK with Comrex POTS units (Hotline & Matrix). We have one circuit running as a hot standby over the state line (Missouri River). It's been reliable enough I'm tempted to use it as the primary feed. One end, the studio, operates in STL mode so it tries to reconnect after a drop. Different telcos on each end.

We have an 8k PTP (nailed-up ISDN) now as primary and a 3k as a confidence monitor. The Comrexes would be an improvement for the return circuit and not much different for the program feed. Our backup would then be another telco service with a coupler which would be likely to have also failed so that's not good.

Telco providing our 4 PTP services is CenturyLink and they claim they have no immediate plans to drop the service. One of the 4 is an old analog 8k which has been generally more reliable than the ISDNs so we're hanging on to it as long we can. The moment we get an amplifier go down, it will be toast and they will convert it to ISDN. Or we'll call Lee for something out of his stash! They have told us the codecs they use are getting hard to come by.

We have begun to shift to IP over internet delivery with mixed results. The transmitter with the Comrex backup is just a bit too far out in the sticks for internet service yet. Two translators are fed over Internet from day one.

Whatever we wind up with, it won't ever be as reliable and "hole-free" as what we have or had. Omaha is not flat and a radio STL isn't in the cards yet.

[Slab Bulkhead]

I help take care of an outfit that has an 8k analog circuit feeding an AM and a 15k digital (nailed up ISDN) feeding the FM translator. Since the telco charges on distance, and the sites are just 2-3 miles from the station, it was cheaper to use PTP circuits. I suppose we are screwed if they decide to get rid of the service or something breaks. I would try to get my hands on some extra amps but ownership doesn't believe in backups...until it's too late.

Unfortunately, microwave isn't an option due to line-of-sight issues and I would imagine being in a downtown area the zoning types won't allow construction of a tower to see over the building across the street.

They have a couple far flung sites that used to be on PTP circuits but were changed to IP to save money. The IP hasn't been as reliable, of course, but cost savings trumped reliability. I tried to sell them on using POTS codecs to backstop the IP connections but again, ownership doesn't believe in backups...

[W2XJ]

Microwave is not an option when one fails to deal with line of sight issues.

[Dale H. Cook]

Comrex works sometimes, other times, not at all. Someplace between the two systems lurks an evil digital device.

It is probably not just that it is a digital device that makes it evil for Comrex codecs - it is likely that it does bit reduction. I have found that, when using a VOIP or other normally bit reduced digital telephone circuit, if you have a "fax line" at each end the Comrex codecs are generally pretty happy.

[Shane]

Microwave is not an option when one fails to deal with line of sight issues.

Thought actually expressed by a corporate engineer: "(not an exact quote) go find those trees impinging on the Fresnel zone and have them cut down!" This same individual would probably recommend bringing in a wrecking ball to solve Slab's line-of-sight issue! Not having been part of that conversation, I can't tell you if the guy was joking or not.

if you have a "fax line" at each end the Comrex codecs are generally pretty happy.

Also known as an analog port.