[thousandshirts]

Hello, prodigal folk:  I have a few questions.

To preface, I have been approached by my local University radio station, and asked to help with equipment.  As a former student I know some of the people there, and they recalled that I do Ham radio and work on tube amplifiers.  They expressed an interest in improving their current equipment, and I stopped by to have a look at the way things worked.

The station currently broadcasts solely on the internet.  Upon learning this (I had never tuned in to a broadcast), I reflexively reminded the folks at the station who were showing me their gear that regardless of improvements made to their equipment, they would still be facing a quality issue on the receiving end, strictly by virtue of their broadcasting format.  They did go on to say, though, that radio towers for three campus locations had been brought up, as well as the rental of tower services from a local telecom provider, and that one of these two alternatives would be put into play in the near future.  They insisted that they were interested in tube signal processing gear, and I reminded them that even with actual radio towers, they were looking at improvements (by buying or having me put together) tube gear that would primarily be only for their own enjoyment, and comparatively less to the benefit of folk on the listening end. 

Anyways, I should be able to help them out with equipment, and in most regards I can understand what they are after, but I am curious about compressors for radio broadcast of music.  As I understand it, it may be the limiting aspect that they are most after, as opposed to a pure compressor.  Perhaps a radio broadcast compressor is like a mixdown or mastering compressor? 

I seem to remember reading that the Fairchilds (660/670) were developed for radio use.  Does anybody have any experience here? 

Many thanks.

[jp-apb]

No direct experience, but look at an Orban OptiMod processor.
Originally developed for radio broadcast but increasingly used for
Webcasts & Podcasting.

JP

[doubleroger]

I think (but might be wrong) that the Fairchild were created for vynil cutting lathe, not for broadcast. They are quite an expensive build, and probably not really suited for your use.
As far as compressing signal for broadcast (DIY), I think the pico (no tubes sorry) could be good. Also a varimu compressor (but this is not a limiter) might be a good idea, provided you have controls over time constants.

[jackies]

Look on ebay for used Aphex Dominator II.
Radio stations usually use multiband compressors to maintain homogenous sound and optimal modulation levels.

[dandeurloo]

i know a few radio and tv stations are using the rolls super stereo as well.  Maybe that could be a good fit?

[gemini86]

All I know is that the stations around here over compress the crap out of everything...so don't buy/build whatever does that and save the world, one station at a time...

/rant

[PRR]

> They insisted that they were interested in tube signal processing gear

"Come back when you grow up, kids."

When I was in radio, we still had some tube gear. But at that time, I did NOT have to ask anybody for advice about tube-gear maintenance. These kids are looking for fashion and begging for dead-air.

> broadcasts solely on the internet.  .... facing a quality issue on the receiving end, strictly by virtue of their broadcasting format.

Disagree. The quality of good internet radio is ahead of FM and miles above the AM we used to have. True, most PC speakers are crap. But most radio speakers are crap.

> compressors for radio broadcast of music

Commercial radio is dominated by a need to be LOUD, so super-compression is the order of the day. Internet radio has less of a problem with that, and non-commercial special-interest programmers do not need SUPER-compression to hold their audience.

Over-modulating a radio transmitter not only makes you sound like crap, it can spray crap into OTHER channels. Those licensees will not be pleased. Total non-issue on the internet.

AM rarely beats 40dB S/N, FM often only 50-55dB. IF source material has larger dynamic range (most doesn't), compression/limiting allows soft passages to be heard above static.

Vinyl levels varied all over the place; vinyl has no hard limit-level, just a trade-off between level and time per side. So with inattentive DJs, limiting was a practical necessity.

I don't notice such differences across CDs or MP3s, because these formats do have hard limits, and I just bet they are not broadcasting from vinyl. I would almost say: just set a Rikki Martin CD to not-quite clip the ADC or modulator, and be done.

Maybe they don't need a limiter. Maybe they just need to learn to set levels.

> radio towers

You mean, actual AM/FM Broadcasting? This is strictly controlled by our Governments. A US transmitter smothered Canadian stations. A Mexican transmitter blew a megawatt up to Hudson's Bay. The NYC news stations beam east to protect some little station in Iowa. Even low-power unlicensed broadcasters are not allowed to radiate harmonics into police or aircraft bands. As a Ham, you know the idea; but Broadcasters are under strict FCC (or Canadian) oversight and regulation. There are Engineering firms who handle compliance. If they are going to spray more than a Watt on an isolated campus, they will need to buy expertise. Including limiters. 

[StephenGiles]

> They insisted that they were interested in tube signal processing gear

"Come back when you grow up, kids."

When I was in radio, we still had some tube gear. But at that time, I did NOT have to ask anybody for advice about tube-gear maintenance. These kids are looking for fashion and begging for dead-air.

> broadcasts solely on the internet.  .... facing a quality issue on the receiving end, strictly by virtue of their broadcasting format.

Disagree. The quality of good internet radio is ahead of FM and miles above the AM we used to have. True, most PC speakers are crap. But most radio speakers are crap.

> compressors for radio broadcast of music

Commercial radio is dominated by a need to be LOUD, so super-compression is the order of the day. Internet radio has less of a problem with that, and non-commercial special-interest programmers do not need SUPER-compression to hold their audience.

Over-modulating a radio transmitter not only makes you sound like crap, it can spray crap into OTHER channels. Those licensees will not be pleased. Total non-issue on the internet.

AM rarely beats 40dB S/N, FM often only 50-55dB. IF source material has larger dynamic range (most doesn't), compression/limiting allows soft passages to be heard above static.

Vinyl levels varied all over the place; vinyl has no hard limit-level, just a trade-off between level and time per side. So with inattentive DJs, limiting was a practical necessity.

I don't notice such differences across CDs or MP3s, because these formats do have hard limits, and I just bet they are not broadcasting from vinyl. I would almost say: just set a Rikki Martin CD to not-quite clip the ADC or modulator, and be done.

Maybe they don't need a limiter. Maybe they just need to learn to set levels.

> radio towers

You mean, actual AM/FM Broadcasting? This is strictly controlled by our Governments. A US transmitter smothered Canadian stations. A Mexican transmitter blew a megawatt up to Hudson's Bay. The NYC news stations beam east to protect some little station in Iowa. Even low-power unlicensed broadcasters are not allowed to radiate harmonics into police or aircraft bands. As a Ham, you know the idea; but Broadcasters are under strict FCC (or Canadian) oversight and regulation. There are Engineering firms who handle compliance. If they are going to spray more than a Watt on an isolated campus, they will need to buy expertise. Including limiters. 

and that's telling you

[thousandshirts]

Thanks for the thoughts.   The Orban OptiMod looks out of their price range.   The 'Roll' Super Stereo looks like
it might be reasonable, and the Aphex Dominator II is definintely affordable for this station.  They are currently
using a type of plug-in software compressor.

>The quality of good internet radio is ahead of FM

Ahh, PRR, how are things?  My 45/100 is working smoothly now, thank you for your help here on the forums some
months ago.  The radio station: They're not broadcasting good quality internet radio.  With their current bandwidth,
FM will be an improvement. 

>and I just bet they are not broadcasting from vinyl.

When I went in, they had a turntable or two at each desk.  Apparently they do quite a bit of vinyl broadcasting.
They're using these players that have USB outputs, direct to computer.  I have my suspicions about these, too.

>These kids are looking for fashion and begging for dead-air.

I'm finally watching the last season of Sopranos on TV now (cable gets to my part of Canada slowly).  Imagine
a college level radio station office filled with emotional copies of the distraught kid in the Soprano family who is
constantly lamenting: "Things are terrible in the Middle East and Darfur, yet we sit and do nothing. Oh, and I
want a tube compressor."

>"Come back when you grow up, kids."

Right.  But as an "alumni" I can't be too rough.  The motivation is that I have an interest in learning a bit more
about their end of radio.  Admittedly nobody at the University station is able to teach anything about radio, but
I'll be able to learn a few things from their equipment.

>You mean, actual AM/FM Broadcasting?

They've been licensed by the CRTC (Canadian FCC).  At 300 watts, it's not a high power license (I get a 1000 watt
maximum as an advanced amateur).  There are a number of regulations, and inspections are to be carried out by a
CRTC agent prior to any on-air (non-internet) proceedings take place.  Inspections are not cheap, and as a result, 
the station has been working on consultations with a number of professionals in an attempt to minimize the number
of failed inspections.  I forget the exact inspection fee (per inspection), but it was over $2k.  The station will be
provided with a series of statistical requirements regarding their future broadcasts, including what will be needed in
terms of compression or limiting, so there will be numbers to work with at some point.

At any rate, the case I keep trying to explain to these folks is that budgeting $2-3k for a "tube compressor" is the
least of their worries.  They are using USB turntables and USB "podcasting" microphones. There seem to be a number
of fairly weak points  in the signal chain.  And there are more problems with the people sitting in front of the
broadcasting microphones, too, but I'm not a professional in those fields.

[Junction]

If you intend to put a compressor across the studio output, then you really need a muti-band agc/compressor/limiter, this is going to be fairly expensive ala Orban Optimod and the like. Putting a single band compressor/limiter across the chain is not going to do a lot in terms of level control or possibly loudness unless you drive it hard and then it is going to sound like crap.

Whilst most stations are targeting loudness, really what is (or should be) actually happening is that you are trying to clean up the discrepancies in average listening levels between the various sources ..... current pop/rock music is generally already compressed to buggery, so you don't need to do much except get the play levels rights. However the studio microphone is not compressed, so without some sort of gain/leveling/compression/limiting device, you will be happily listening to the music in the car and then when the Jock talks, you cannot hear them. This is where the AGC or Leveller comes into play ... to lift lower level stuff and then add some subtle compression just to tame the peaks.

Unfortunately most Jocks do not know how to read a VU meter, some think that lots of red is good and loud, some are so frightened of ever getting near the red thinking that something will blow up and then some don't even look at the meters because they know the Optimod will clean up the mess.

Building a multi band device would be a serious build and a Fairchild, LA2 etc will not really give you the control you really need. An Orban 5300 is as good as the higher end unit, just a no frills unit at a fraction of the price. To get similar results from the Aphex gear you really would need to get three units ... the Leveller (AGC), Compellor (Compressor) and Dominator (Limiter)

Cheers
Michael

[PRR]

> At 300 watts, it's not a high power license (I get a 1000 watt maximum as an advanced amateur)

Fine point: at least when I was young, ham limit was 1000W INPUT. Measuring MHz power is tricky. Measuring DC voltage and current is trivial. So if you had 3,000 VDC on your final tube, you could load it up to 332mA plate current legally. Actual output could be anything less (conservation of energy enforces that); 600W-800W would be typical. Whereas Broadcasters are assumed to have/hire the skills to know their actual output, and a broadcast license states true RF power (or now, in the higher power classes, a nominal field-strength and radiation pattern).

So you got twice the power. However none of the general ham bands are near-enuff the AM or FM bands for propagation to be real comparable; also ham receivers accept lower signal strengths than most music listeners will tolerate. Their range will be far shorter than yours (but you can work the whole world, one lucky-skip night at a time). 300W -will- get out: range is about 1/13th of a 50,000W station. 50KW AM station range is screwed-up by skywave, but 10 miles on 300W ought to be possible.

The USB-output turntables are not unworkable. I use one to transcribe for my Dean and even my University President. Yes, I go over the files in the DAW, but more for disk-damage than USB trouble.

> been licensed by the CRTC

Probably some Cultural Diversity program at work. A fear in the US is that "all" radio stations are being bought-up by just a few media moguls. The old local-ownership and ownership limits have been eroded.

> They're not broadcasting good quality internet radio.  With their current bandwidth, FM will be an improvement.

FM-quality innernet is not particularly difficult. I remember when CPU and network-speed issues dominated, but even when my clip-server was on a 10MbpS LAN I was serving 128K and 192K clips.

> there are more problems with the people sitting in front of the broadcasting microphones

{sigh} I think the #1 duty of an audio engineer is to control the meters; but this was never a DJ priority.

This seems to be a troubled studio, and it seems you are not a studio person. Is there another student-run radio in the area? That would be a source of up to date how-to info, at a level these folks can see is valid.

I also think they should make friends with used broadcast gear shops. Some commercial operations upgrade routinely, and perfectly good gear comes on the market. In particular, a lot of stations have gone totally automated: they pull music from a central server, edit playlist suggestions, insert commercials: the "studio" is a rack PC plus a director somewhere else uploading lists. The preceding generation of live-person gear is still valid for college radio.

[PRR]

Interesting ad at the bottom of this page just now:
http://www.wholehousefmtransmitter.com/fm-transmitter-conspiracy.php

Do Not Buy Any FM Transmitter Until You Have Seen Our FM Transmitter...

[thousandshirts]

PRR wrote:
>Interesting ad at the bottom of this page just now:
>http://www.wholehousefmtransmitter.com/fm-transmitter-conspiracy.php

I have purchased a similar device for my portable MP3 player.  Given the price I paid I think it was a fantastic deal.

>300W -will- get out: range is about 1/13th of a 50,000W station. 50KW AM station range is screwed-up by skywave, but 10 miles on >300W ought to be possible.

And they don't need much more than that, as far as I can tell.  The license is upgradable, though, so at some point in the future, improvements could be made.

>The USB-output turntables are not unworkable. I use one to transcribe for my Dean and even my University President. Yes, I go over >the files in the DAW, but more for disk-damage than USB trouble.

That's interesting to hear.  I've never tried a USB-table.

>{sigh} I think the #1 duty of an audio engineer is to control the meters; but this was never a DJ priority.

My experience here confirms the same.

>I also think they should make friends with used broadcast gear shops. Some commercial operations upgrade routinely, and perfectly >good gear comes on the market. In particular, a lot of stations have gone totally automated: they pull music from a central server, edit >playlist suggestions, insert commercials: the "studio" is a rack PC plus a director somewhere else uploading lists. The preceding >generation of live-person gear is still valid for college radio.

That seems like a tremendous suggestion.  When I look at it that way, they may have missed the boat on this a bit, given that this trend of automation seems to have struck locally just a few years back, but with any luck at all they ought to be able to find some recently replaced equipment of a decent quality.  As always, these are excellent points, PRR, and thank-you.

Junction wrote:
>An Orban 5300 is as good as the higher end unit, just a no frills unit at a fraction of the price. To get similar results from the Aphex >gear you really would need to get three units ... the Leveller (AGC), Compellor (Compressor) and Dominator (Limiter)

Thanks Michael!  I'll have a look into that, for sure.  The Orban stuff is 'jamais-vu' for me. Looks spendy, that's all I know as of now.  I sent a message to a local Orban dealer for some quotes.

[Junction]

Good suggestion PRR, look out for used Orban, CRL or Aphex gear, should be plenty around one thinks with all the new Orban and Omnia models coming out every year ... just make sure you go multi-band compression, minimum 3 bands or preferably 5 to give that little bit of extra control when you need it, it has got to have AGC or Levelling and of course some limiting.

Good Luck
Michael

[MikoKensington]

What about used serviced gear like a Dorrough DAP, Pacific Recorders MuiltiMax, or Inovonics MAP? 

[djlightning]

Thought I might chime in on this one for the following reasons..
I am a Ham Op
I am DJ (on a couple different levels)
...and I have worked both in broadcast and internet radio

The only broadcast station I worked at was actually smaller than what you have and I think we had a maximum 100W output with a small collinear array up about 70 feet.  As a ham you should know that when working with low power that antenna height and gain/efficiency is everything.  Might be an idea for the EE students to design and build an antenna.  Then again I am not sure with your laws if there is anything with maximum effective radiation restrictions.

We only compressed the mics as the format was primarily dance music and like it was mentioned before it was pretty compressed to begin with.  In short we were able to get by with a minimal amount of processing while still achieving a "decent" sound quality while staying within legal limits.

Now my question is why use a turntable(s) to play your media?  Unless you will have DJ's mixing dance music this will probably be disaster waiting to happen when dealing with unexperienced college kids.  Recording levels are all over the place, record wear, cleanliness play a huge factor in fidelity.  I also I have yet to find any one needle that sounds great on all records especially when dealing with very old records back in the 30's and 40's, god forbid if you have acetate or 78's records.  To many variables when dealing with that as well due to stylus types and tip shapes.  Last but not least when dealing with turntables the other thing to factor in is tonearm height, weight, and skate.  These adjustments all change from stylus to stylus and play a huge role in the fidelity and record/stylus wear.  Improperly adjusted you can screw up some records and needles real quick.

Your best bet is to rip the vinyl down, clean it up and normalize it in a DAW then archive it to a hard drive and access via your station automation software. It will sound better due to the fact you will take DJ error out of the equation.  If you must have a deck I would recommend a Technics 1200 MK II or better and do a 78 RPM mod on it and also rip out the crappy cables on it and replace them with very high quality ones. Stay away from USB tables, A/D then to D/A conversion just seems to be unnecessary and lossy just to play a record.

Anyways thanks for the rant & 73,

Aaron

[thousandshirts]

Good suggestion PRR, look out for used Orban, CRL or Aphex gear, should be plenty around one thinks with all the new Orban and Omnia models coming out every year ... just make sure you go multi-band compression, minimum 3 bands or preferably 5 to give that little bit of extra control when you need it, it has got to have AGC or Levelling and of course some limiting.

Right!  We'll have a good look.  And we'll try to be sure about 3 and preferably 5 bands, with AGC/Levelling and limiting. Thanks, Michael!

What about used serviced gear like a Dorrough DAP, Pacific Recorders MuiltiMax, or Inovonics MAP? 

Added to the list.  Thanks, Miko!

Thought I might chime in on this one for the following reasons..
I am a Ham Op
I am DJ (on a couple different levels)
...and I have worked both in broadcast and internet radio

The only broadcast station I worked at was actually smaller than what you have and I think we had a maximum 100W output with a small collinear array up about 70 feet.  As a ham you should know that when working with low power that antenna height and gain/efficiency is everything.  Might be an idea for the EE students to design and build an antenna.  Then again I am not sure with your laws if there is anything with maximum effective radiation restrictions.

We only compressed the mics as the format was primarily dance music and like it was mentioned before it was pretty compressed to begin with.  In short we were able to get by with a minimal amount of processing while still achieving a "decent" sound quality while staying within legal limits.

Now my question is why use a turntable(s) to play your media?  Unless you will have DJ's mixing dance music this will probably be disaster waiting to happen when dealing with unexperienced college kids.  Recording levels are all over the place, record wear, cleanliness play a huge factor in fidelity.  I also I have yet to find any one needle that sounds great on all records especially when dealing with very old records back in the 30's and 40's, god forbid if you have acetate or 78's records.  To many variables when dealing with that as well due to stylus types and tip shapes.  Last but not least when dealing with turntables the other thing to factor in is tonearm height, weight, and skate.  These adjustments all change from stylus to stylus and play a huge role in the fidelity and record/stylus wear.  Improperly adjusted you can screw up some records and needles real quick.

Your best bet is to rip the vinyl down, clean it up and normalize it in a DAW then archive it to a hard drive and access via your station automation software. It will sound better due to the fact you will take DJ error out of the equation.  If you must have a deck I would recommend a Technics 1200 MK II or better and do a 78 RPM mod on it and also rip out the crappy cables on it and replace them with very high quality ones. Stay away from USB tables, A/D then to D/A conversion just seems to be unnecessary and lossy just to play a record.

I don't know where they get off using vinyl for on air broadcast.  As I said before it might sound fantastic in the studio, but not on the air.  A stellar listening experience for the DJ but not for the people with the radio is about the size of it.   And it's at the expense of the rest of the student body, who pays in a small percent from each tuition fee to the radio station.  Sure, I like my stereo setup at home, and I enjoy listening to it, because it is nice.  But I paid for it myself... These DJ's appear to be achieving their dream system on the 'company account...' And as to why I can't stop it -- I'm not really a part of the station.  I graduated years ago - these kids are almost young enough to be my own kids.  They think they're smooth operators...  The USB tables really made me shake my head.  Never tried one before, but I've heard many mixed reports.  I'm not the vinyl hound that other folks are, but I definitely enjoy my Rega... And you're right, a direct drive bit like the 1200MKII would definitely be a benefit.   We'll see how the rest of the story goes with the compressor end of things -- if they listen to reason there, maybe they'll listen to reason about other gear.   But probably not.  Thanks for the reply, Aaron, 73

[MagnetoSound]

Excellent advice so far!

I would just add that the compression that you (they?) are planning to introduce on the output lines will compound any physical coupling problems that the turntables might introduce.

Thumps, rumble and even LF oscillation due to feedback are all possible, and are likely to occur with such inexperience at the helm.

My advice, if you do go with decks, go easy on the compression, or at least make sure that all the operators know what to expect.


Dan

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