How does composite clipping affect a mono fm? Are the same bad effects present?
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
Cascading Audio Processors
- Thread starter GeneSavage
- Start date
dpries8873 said:
If you literally mean "mono FM" (with no pilot tone), then you can take advantage of the fact that the composite clipper will produce spectral content above 15 kHz but the receiver will be "deaf" to this. You will still need to use some sort of lowpass filter to guarantee that your RF occupied bandwidth is within legal limits. If the pilot tone is present, then the receiver will decode the distortion as L-R information. Because the decoded harmonics no longer have a harmonic relationship to the sounds that produced them, this sound is very similar to the sound of aliasing distortion. (For example, the third harmonic of 10 kHz is 30 kHz, which the stereo decoder will decode as 8 kHz and place out-of-phase in the stereo soundstage. In this case, the distortion actually appears below the frequency of the original unclipped waveform.)
In the "pure mono" case, you can get a somewhat brighter sound than you can by 15 kHz band-limited clipping because the third harmonics of frequencies between 5 and 15 kHz will fall into the permitted 53 kHz baseband bandwidth and therefore do not need to be removed by a 53 kHz lowpass filter. The "Gibbs phenomenon" allows the energy in the 5 - 15 kHz region to theoretically exceed 100% modulation because the presence of harmonics decreases the peak value of the sum of the fundamental and harmonic frequencies. This trick is explained in Optimod-FM manuals under the heading "Getting the Bass Sound You Want" in Section 3 because the basic principle also applies to clipped bass waveforms.
If you do not use RBDS or SCAs, then you can use a 99 kHz lowpass filter instead or 53 kHz, which will reduce overshoot caused by the filter. However, you will still need some sort of overshoot compensation.
Sonically, the clipper will produce much the same distortion signature as a hard clipper that is band-limited to 15 kHz except, as stated above, that you will be able to achieve a brighter sound between 5 and 15 kHz.
Bob Orban
That's exactly what we did at Jukebox Radio... except the mono signal was picked up off air to feed the translator. Then lightly used single ended noise reduction with a sliding bandwidth to limit some of the noise and then fed it to a composite clipper with about 1.2dB of clipping. Sounded nice and bright in mono, and was louder than anyone else on the dial due to the fact that we didn't need to run a 9% pilot.
Made a 35 watt translator sound big!
Made a 35 watt translator sound big!
I'd like to thank Mr Orban for the kind response. I am in process of putting a Class 4 AM with a 250 watt translator on the air as a labor of love. Oldies, in mono. I will re read section on bass sound. I searched all over for a 8100a1, will be running in mono as side mounted on a grounded AM tower. Studio and microwave link both mono.
celar said:
Same here... ;D
dpries8873 said:
Translator in Mono? Begs the question of why? Is this purely for loudness? Many translators run stereo having a side chain that feeds the translator. The first Am translators on FM were both in stereo, thus, not simulcasting the AM but being independent of it. I have heard several translators simulcasting their AM via an AM receiver and it sounds horrible.
There is some thought process that no one notices stereo in the car as long as the pilot is on. Several tests in Indianapolis over a 6 month period (largely due to a malfunction) had no complaint calls in an urban format when the station was mono with a stereo pilot. The minute the pilot was gone however the calls came.
dpries8873 said:
Translator in Mono? Begs the question of why? Is this purely for loudness? Many translators run stereo having a side chain that feeds the translator. The first Am translators on FM were both in stereo, thus, not simulcasting the AM but being independent of it. I have heard several translators simulcasting their AM via an AM receiver and it sounds horrible.
There is some thought process that no one notices stereo in the car as long as the pilot is on. Several tests in Indianapolis over a 6 month period (largely due to a malfunction) had no complaint calls in an urban format when the station was mono with a stereo pilot. The minute the pilot was gone however the calls came.
Going mono increases coverage quite substantially. In my experience, very few people seem to notice mono vs stereo. This seems to hold true for both music and talk programming. A very few folks do miss the "stereo" light, but with displays busier now, most people never notice if the little "ST" icon is even on.
In our town, all of the local FM talk stations are now mono as are the translators and 2 of 3 LPFMs. All of the mono stations have Optimods or equiv, but choose to be mono to get maximum coverage.
I have a translator running 100W at 360' in a fairly small town. Coverage from that facility is good enough that it can run in stereo.
In our town, all of the local FM talk stations are now mono as are the translators and 2 of 3 LPFMs. All of the mono stations have Optimods or equiv, but choose to be mono to get maximum coverage.
I have a translator running 100W at 360' in a fairly small town. Coverage from that facility is good enough that it can run in stereo.
I was just wondering about the use and if the mono broadcast extended the range. I ahve full power FM's doing the same thing. I guess it depends on the town size and the coverage needed. Thanks for the additional information.
I did wonder too if the programming being non talk was determined to be lesser as stereo was not used. Up til the mid 70's all music was in mono on the most listened to stations. Do you run rds on any of the stations in mono?
I did wonder too if the programming being non talk was determined to be lesser as stereo was not used. Up til the mid 70's all music was in mono on the most listened to stations. Do you run rds on any of the stations in mono?
Composite clippers seem to be an individual taste thing with most engineers I've known.
Didn't Clear Channel have a home grown clipper called a C4? Folklore says that Randy Michaels had something to do with that. Anyone know if any of that is true?
All I know is that I had a modified 8100 XT followed by one of the alleged C4 clippers. One word L-O-U-D!!!
And it didn't kill the audio quality either.
Didn't Clear Channel have a home grown clipper called a C4? Folklore says that Randy Michaels had something to do with that. Anyone know if any of that is true?
All I know is that I had a modified 8100 XT followed by one of the alleged C4 clippers. One word L-O-U-D!!!
And it didn't kill the audio quality either.
When you only had 35 watts right next to the George Washington Bridge, every bit of coverage helped. Also, when your primary was 80 miles away and it was hopping through another translator to get there, mono was the only option that would produce a useable signal. Couple that with the fact that any type of high speed (T1) line to the tx site was supremo expensivo, AAC mono 128 was the only way to get decent audio up there, then mono it was.
I've only used the composite clippers on that mono translator. Never pushed them on a stereo station. Either had the 8100a with the zero card or a newer processor that was loud enough without it. The most I ever dialed in the composite clipping on an Omnia or Orban was .2dB, just to catch any overshoots that were left over from the previous clippers/filters. Didn't degrade the sound or affect the L-R to any noticeable degree, so that's where it stayed. Sometimes I think the .2dB of comp clipping/processing being a little bit louder was just psychological and all in my head.
In answer to translator in mono, translator is on same tower as AM in question. The studio output thru the stl to the tower site is mono. Translator added to existing AM site. Path of least resistance, split output of stl (marti) at Tx building, and process the AM and FM thru 2 separate chains. Have not yet done anything with translator, other than simulcast AM talk. The 250 watt FM, in mono, is loud. Using a BW 600 tx, internal processing following 2 light stages of compression/leveling.
First stage is aphex compellor used primarily as leveling before STL. Second stage is also aphex compellor, post STL. Will be adding 8100 a1 with texar card, and turning off BW internal limiter.
First stage is aphex compellor used primarily as leveling before STL. Second stage is also aphex compellor, post STL. Will be adding 8100 a1 with texar card, and turning off BW internal limiter.
Smiths and Smittys said:
Yes
http://www.1150wima.com/pages/667westmarket/engineering/manuals/CC C4 Operating Manual.pdf
Anyone still using one of these?
I'd imagine with the newest offerings from Omnia, Vorsis and Orban it's kind of a moot point now.
I guess it would be good between a composite STL and the exciter to catch any overshoots. But most major markets I know of are using either a T1 or some form of digital STL. Composite STLs for backup purposes only.
I'd imagine with the newest offerings from Omnia, Vorsis and Orban it's kind of a moot point now.
I guess it would be good between a composite STL and the exciter to catch any overshoots. But most major markets I know of are using either a T1 or some form of digital STL. Composite STLs for backup purposes only.
wgliradio said:
I'd love to get my hands on one of those and do some experimenting...
Anyone have one gathering dust?
Smiths and Smittys said:
It is CC Engineer Mike Gideon's design.
I've seen a few still in operation, but never the manual or schematic. A few other corporate black boxes are out there as well. Most of them are very similar in design to the Modulation Sciences CP803 or the Jim Somich MicroCon DBE1000 (Fleximod and Kamikaze). I guess the C4 was a guarded secret for quite a while.The Wattcher said:
I have a CP-803 and the Jim Somich Flexmod box,both in great shape for sale.The Flexmod has the famous C limiter .It can sound LOUD and punchy not squashed and distorted like the CP-803 tended to sound IMHO. That c limiter secret had a short lived life.Maybe some of you guys that used these in the past can chime in.I read where Frank posted Mr Somich seemed to like that red light on the CP-803,guess he thought it stood for operating level.lol.
Mike's CC clipper clips the pilot (which doesn't matter if you keep the clipping to a db or so - the whole Eric Small thing was a great marketing tool for his MSI CP 803 clipper which many of us considered inferior). It is also DC coupled, which means no tilt. It's one weakness is the fact that it used a bipolar opamp on it's input, which made it sensitive to RF. I had a prototype that I put on in Tucson at CC's Hip Hop station and it sounded great-until the AM station down the street switched to its day pattern (50 kW non-d). Let's just say they had an FM simulcast for a short while, until I could put an AD711 in the clipper (bifet input stage).
Composite clippers are good for about an additional db or so of loudness. They are also effective in clipping off overshoots from a composite STL (and trust me they are there - try running a 1 kHz squarewave through one).
Composite clippers are good for about an additional db or so of loudness. They are also effective in clipping off overshoots from a composite STL (and trust me they are there - try running a 1 kHz squarewave through one).
- Status