Compressor/ Gate adjustment.

[ke7trp]

Can someone give me some friendly advice on setting up the compressor and gate?  I got a DBX 266xl. I spent a half hour pumping the audio into my Eton XM1 monitor rxer on the line in jack.  Then Into the Globe king 500C and dummy load.  I think I have the concept down pretty well. When I bypass, I have about 75% mod.  When its on, I have right at 100% and the percieved loudness more then doubles. My voice jumps out at you..

I am using mostly default factory settings. I understand the gate threashold.. I turned it up just until the fan noise went away. I dont understand the Ratio for the gate or the compressor ratio. I read the manual 5 times.

My understanding was that the unit would keep audio levels equal even if I leaned back in chair or turned my head to look at the meters ect.. This effect is not really shown.  If I get closer to the mic, I am louder. If I back off, I am softer. Should a compressor not clamp and boost to give you a constant avg output?

Thanks for any advice!  The unit really sparked up the audio!  I got great reports saying that I am louder and clearer with the unit on.. So I guess its doing something.

Clark

[KD6VXI]

Can someone give me some friendly advice on setting up the compressor and gate?  I got a DBX 266xl. I spent a half hour pumping the audio into my Eton XM1 monitor rxer on the line in jack.  Then Into the Globe king 500C and dummy load.  I think I have the concept down pretty well. When I bypass, I have about 75% mod.  When its on, I have right at 100% and the percieved loudness more then doubles. My voice jumps out at you..

I am using mostly default factory settings. I understand the gate threashold.. I turned it up just until the fan noise went away. I dont understand the Ratio for the gate or the compressor ratio. I read the manual 5 times.

My understanding was that the unit would keep audio levels equal even if I leaned back in chair or turned my head to look at the meters ect.. This effect is not really shown.  If I get closer to the mic, I am louder. If I back off, I am softer. Should a compressor not clamp and boost to give you a constant avg output?

Thanks for any advice!  The unit really sparked up the audio!  I got great reports saying that I am louder and clearer with the unit on.. So I guess its doing something.

Clark

A.  Look at the Bird when you're adjusting it.  The "perceived" loudness you hear people telling you about is actually an INCREASE in your avg power output.  This must be done on the AVG scale.  I triple my avg output when I put my compressor / gate / etc. chain inline I sent to you, while the PEP output stays the SAME!  You can also see this with an oscope.

B.  The compression ratio is the amount of dynamic range you want to LOSE.  You can crank them to 20:1, but you really sound like a monosylabic idiot.  I use a multiband (5 bands and a 3 band), so mine sets up different than your's.  HOWEVER, what you want is enough compression that your avg power is pretty much maxed (if your not using the SB220!!!  The Xformer in it won't handle super levels of 'talk power'), PEP maxed, and you have no negative excursions beyond 100 percent, or better, 95 percent.

After that, it's all in eq and getting on the air reports from PEOPLE YOU TRUST to have a good ear.  Getting an audio report from someone running > 100 percent + and - isn't in your best interest, find someone running hifi and have them help you.... They'll have the RECEIVER to do it, more than likely.  Getting someone that likes to run slopbucket only in contests probably isn't in your best interest, either.

And then when you get that audio chain completely correct, feed it into the 440 / 2 meter station!  I did, and it's FUNNY to get responses from people like WTF, that's not communications audio.  Guys up on 2 have NO idea about hifi audio!

--Shane

[Steve - WB3HUZ]

Mike - W2ZE has written a great tutorial on audio processing.

http://amfone.net/ECSound/processing101-1.htm

[Bill, KD0HG]

The gate ratio (sometimes called expansion ratio) on some mic processors can be adjusted from maybe 1.5:1 up to 10:1. You already know what adjusting the threshold does, what the gate ratio sets is how much the audio is muted when the gate kicks in. At 10:1, the processor will completely kill audio when gated off, at 1.5:1, there's more of a slight "ducking" effect. You'd use the higher number when broadcasting from an extremely loud location when you really wanted the audio to clamp down between words or sentences. Does that make sense?

A properly adjusted gate can be a huge advantage when dealing with feedback from a modulation transformer rattling. I have that problem here.

A compressor itself can't keep your audio level the same from a whisper to a shout, 15 to 20 db of compression is the top limit. For decent audio, hold the compression to maybe 15 db. If you try to compress too much, you'll pick up background and breathing noises and sound like mush when you close-talk the mic. Learn how to work a mic, like many DJs do. You have to talk at a similar level at similar distances to the mic.

No compressor is going to give you the ultimate improvement in loudness. They just work too slow. If you want to get louder, you need a fast peak limiter or clipper after the compressor. Classic clippers include the CBS Volumax 400 or 4000. Or the late-70s vintage Orban Optimod 9000 or 9100. Or you can build one. As opposed to the slow action of a compressor, a clipper works on each cycle of the audio waveform. Many clippers allow you to manually select the 'loudest' audio polarity, or they will flip the polarity automatically for you.

That is the classic AM broadcast setup. A compressor/mic processor/EQ followed by a final clipper/peak limiter.

Remember a processing rule of thumb: Just as a little salt is essential to a good meal, too much will ruin it.

[K5UJ]

Clark,

>My understanding was that the unit would keep audio levels equal even if I leaned back in chair or turned my head to look at >the meters ect.. This effect is not really shown.  If I get closer to the mic, I am louder. If I back off, I am softer. Should a >compressor not clamp and boost to give you a constant avg output?


I don't know anything about that DBX in particular.   Sounds like the performance you are looking for is what you get with an extremely tight peak limiter.  You need not a studio limiter but one used on AM broadcast rigs, that will clamp a certain level and prevent over modulation.   But first, it's a good idea to have a scope, dummy load and separate receiver to hear yourself with before you start working with outboard audio gear.  It's also a good idea to run the audio equipment output through an isolation transformer in the line to the tx if ur having any hummm.  I'm also assuming the last audio box before the tx is somewhat matched to the audio input Z of the rig and the tx is passing audio flat from around 20 hz to up beyond your high frequency cutoff and ur rx or diode detector-->AF amp has a flat rx response.  An AF signal generator is nice to have too, to work all this out.      

Okay.  With a real tight limiter riding herd over your audio, you can scream into the mic but you won't overmodulate yet you can back off and let the compressor boost your low level sounds.  Of course you can dramatically reduce your dynamic range and wind up with a lot of processed sounding density if you overdo the compression.   Back off on the compression and let the limiter curb your peaks.  The CBS Labs audimax/volumax combos did that too and were the secret behind the old 1960s loud rock stations like WLS.  Anyway, if you have good modulation and linearity you should be fine.  So, the cheapest broadcast limiter I know of is the Inovonics 222.  You can sometimes find them on eBay for around $500; maybe less.  They used to be cheaper, as low as $100 used, but part 15 AM broadcasters discovered them and drove the prices up.   The 222 gives as much as -12 dB extremely fast gain reduction, up to 130% pos. modulation and in most models a 10 KHz low pass filter.  If the 500C doesn't like that you can always dial in 100% pos and neg.  the filter isn't of much use to hams since we probably tx out around 5 Khz or less from carrier but I've heard that Inovonics will supply components to give you a lower freq. cutoff.   I realize the money may seem like a lot for an audio box but for AM once you get one and start using it, you'll feel like you got a really good deal.  Happy testing one two three and don't rely on audio reports off air from other hams.  Listen to yourself (use a good pair of headphones Sennheiser HD280s are good cans) or get guys with good receivers to email you mp3 files of you taken off-air.  Dig around in here:  http://amfone.net/ECSound/  good audio advice in there from K1JJ et al.  it can be quite a revealing experience.  The first time I swept my rig I discovered it was no where near as flat on tx as I thought.  I also discovered I was hitting 100% on low freq. vowel sounds, wasting power on sounds that were rich but lacking in intelligibility.  Make sure ur GK is flat, ditto for ur rx audio gear then start adding in the outboard processing boxes.   the limiter should be the very last box before ur rig. 

73

Rob K5UJ  

[ke7trp]

Thanks to all

Gate:
After playing with the unit more with the use of headphones, I can really see how the gate works.  A carefull balance is hard. I can hear the Gate turning off and on. Maybe this cannot be heard over the air though.  The fan noise in the room is pretty high.  Its nice to have the noise gone.. But its not nice to have it PUMP on and off between words. I think I will end up using very little GATE and let the ambient noise come in at times.

Compressor:
I figured out that If turn the compression threashold knob to -10 the over all signal drops 10DB. I can see that on the meter. But if I then Set the output control to +10, I get all that back plus about double.  With this set, in normal talking I see about 6DB to 10 DB on the compression meter.  When I go to bypass my overall sound is MUCh lower.  I am using the Overeasy feature (soft knee) which is much smoother on the ears with my voice.

I found a ratio of 2 to 1 seems to work well.  If I run less its not enough and I have run more it seems like to much.

Attack and release:   I use the AUTO feature.  This enables the DBX system and I cant seem to improve upon it.




 

[ke7trp]

Sorry for the double post.. But ever since I upgraded to a new PC with Windows Vista, This forum is a major pain to use. I can type TWICE the speed the forum software will except and if I type more then the one window, The text jumps up and down.. Anyone have a way to fix this?


Part Two of post:

The main thing learned was that the Compressor is removing signal and to get that compression, You then boost the output of the device. 

I find I am really missing the limiter function.. I see the 166XL model has the limiter.. Its another $100.  Should I stop now.. Return this Compressor gate and just buy the 166XL Compressor, gate, limiter?     

I say this because I was expecting to be able to set a hard output level. This way, I could NEVER over modulate the King.

Clark

[Ian VK3KRI]

Try recording your audio and playing back rather than listening to yourself in the cans while adjusting the setup.
You want to hear the sound through the audio chain, not the combination of the audio chain plus direct conduction through your head .                         Ian VK3KRI

[K5UJ]

Clark,

I just thought of this--if the broadcast limiters mentioned are too expensive you could try a negative peak limiter circuit such as this:  http://www.classeradio.org/3-diode.jpg

I have not tried this -- I bought my broadcast limiter originally for SSB where a diode clipper won't work, and when I got into AM I decided to keep using it (I mean, it was designed for AM so why not  ) but this simple circuit or something similar to it might limit your negative peaks in the Globe King and cost a lot less!

73
Rob K5UJ

[flintstone mop]

Hi Clark
The adjustments you made in your last post are pretty close to mine. It should have a pleasant sound on the air without heavy processing. And the increased modulation will give you an edge when conditions are rough.

Fred

[KD6VXI]

Sorry for the double post.. But ever since I upgraded to a new PC with Windows Vista, This forum is a major pain to use. I can type TWICE the speed the forum software will except and if I type more then the one window, The text jumps up and down.. Anyone have a way to fix this?


Part Two of post:

The main thing learned was that the Compressor is removing signal and to get that compression, You then boost the output of the device. 

I find I am really missing the limiter function.. I see the 166XL model has the limiter.. Its another $100.  Should I stop now.. Return this Compressor gate and just buy the 166XL Compressor, gate, limiter?     

I say this because I was expecting to be able to set a hard output level. This way, I could NEVER over modulate the King.

Clark

Why not try the virtual rack I sent you.  It has a De-Esser, De-Syballant 'machine', hard limiters, a simple compressor, 5 band compressor, 31 band eq, 3 band compressor, C-Quam stereo encoder, etc.  It even has studio echo and reverb, should you want that old style studio AM sound.

Once you fool with it (it has over 100 different machines you can add), go purchase something that does what you want, rather than sitting here throwing money away after something you're not sure you can get with what you got already.....

Try the rack on the computer.  I did.  Sounds just as good as the 'real rack', and only requires audio in and out.  I haven't used iso transformers, and have ZERO problems with it.  Matsushita caps work best, the 220uF being the smoothest coupling cap I've seen, as well as many of the ESSB guys (that's where I got the idea to try it).

--Shane

[k4kyv]

A.  Look at the Bird when you're adjusting it.  The "perceived" loudness you hear people telling you about is actually an INCREASE in your avg power output.  This must be done on the AVG scale.  I triple my avg output when I put my compressor / gate / etc. chain inline I sent to you, while the PEP output stays the SAME!  You can also see this with an oscope.

A clear demonstration of what I was saying in the previous thread on the subject.  It is AVERAGE power, not PEP, that determines the loudness and effectiveness of a clean signal, and therefore its interference causing capability.

The Bird 43 does not give a true average power reading for a complex, non-sinusoidal modulation envelope, but for what you are trying to do here, it gives a relative output indication, which is all you need.

[KD6VXI]

A.  Look at the Bird when you're adjusting it.  The "perceived" loudness you hear people telling you about is actually an INCREASE in your avg power output.  This must be done on the AVG scale.  I triple my avg output when I put my compressor / gate / etc. chain inline I sent to you, while the PEP output stays the SAME!  You can also see this with an oscope.

A clear demonstration of what I was saying in the previous thread on the subject.  It is AVERAGE power, not PEP, that determines the loudness and effectiveness of a clean signal, and therefore its interference causing capability.

The Bird 43 does not give a true average power reading for a complex, non-sinusoidal modulation envelope, but for what you are trying to do here, it gives a relative output indication, which is all you need.

EXACTLY!!!  I remember being laughed out of conversations when trying to explain what at the time was "my crazy theory" about talk power, etc.  Then, I was the first that got a 43P in my "group", and that pretty much ended the conversations.

And thanks, in retrospect, for the discussion before.  It would be interesting for someone to put something together about processing AND wattmeter dynamics, too.  I mean, this is a SERIOUSLY misunderstood phenomenon, just tune the bands and you can see that MANY people don't know how to adjust their processors, etc. to get them right.

Here's a ? for ya.  If you wanted to adjust your processing chain for max loudness, crispness, etc.  we know you can't do it on a single tone, or using a set of tones like an IMD test.  Think it's possible to create a 'complex waveform' (like someone did to pulse tune amplifiers on this reflector about a year ago) that WOULD allow us to do just that?

--Shane

[ka3zlr]

Yea,.. everybody has them now,, Slopbuckets, AM.ers,, Regular Hams,, CBers on sideband using Amateur Gear..Yea it's contagious Audio Processing.....

Now it's Become the Norm of Amateur Radio, all across the bands, Lotsa Audio Processing going down...

73
Jack.

[Bill, KD0HG]

One basic rule needs to be mentioned.

The louder your audio, the more you push it to the edge, the lousier it will sound.
You need to pick the appropriate tradeoff point- "Loud enough" and clean vs. DX pileup audio, mush and distortion.

[ke7trp]

I have decided more and more that I need a limiter.  The one in the globe king is not working for some reason. I dont like it anyways. Its not adjustable.

I would like to limit my outbound modulation to 100%. Then, Use the compressor up against the limiter. I think this will make for the best punch and sound. 

Shane, I dont have that program anymore. What was it called? I can try it out. I just need some cables. I can run it through the effects loop on the mixer.

I would rather just use a D104.. LOL.  But on my Globe king, You cant get above 80% audio when you run into the First Preamp tube. It does not have enough kick to move the rest of the chain.  If you drive the second tube with the mixer, I can go 125% easy.

Thanks for all the help!  I will try recording and playback today!

Clark

[KD6VXI]

Yea,.. everybody has them now,, Slopbuckets, AM.ers,, Regular Hams,, CBers on sideband using Amateur Gear..Yea it's contagious Audio Processing.....

Now it's Become the Norm of Amateur Radio, all across the bands, Lotsa Audio Processing going down...

73
Jack.

If you'd like to hear a decent system, on 27.025 there is a gentleman called Prime Minister.  He's running a direct injected Flex radio, with another system set up with ProTOOLS audio processing.  This runs into a 3CW40K, so should be NO problem hearing him when he is transmitting.

The audio quality of that system is just short of amazing.  Guess when you are a professional recording artist, the sky's the limit. 

MANY of the guys on the 'superbowl', so to speak, have been watching the amateur boards, direct grid feeding their boatanchors, flex radios, etc.  I've made, and another gentleman is making modulator boards allowing direct fed audio into ANY transmitter, for HiFi AM / collector modulation.  So far, we've got neg peak clipping, hard limiting, switchable controlled carrier AM, etc. 

Anywho, you are correct, the processing bandwagon is wide open...  Shoot, there are guys on 2 meters now with processing!

--Shane

[KD6VXI]

I have decided more and more that I need a limiter.  The one in the globe king is not working for some reason. I dont like it anyways. Its not adjustable.

I would like to limit my outbound modulation to 100%. Then, Use the compressor up against the limiter. I think this will make for the best punch and sound. 

Shane, I dont have that program anymore. What was it called? I can try it out. I just need some cables. I can run it through the effects loop on the mixer.

I would rather just use a D104.. LOL.  But on my Globe king, You cant get above 80% audio when you run into the First Preamp tube. It does not have enough kick to move the rest of the chain.  If you drive the second tube with the mixer, I can go 125% easy.

Thanks for all the help!  I will try recording and playback today!

Clark

I'll resend you email I sent, it had the effects rack in it.

The programs I use are Adobe Audition 3.0 as well as Reaper.  MANY of the superbowl guys are on ProTOOLS now, since it costs more than anything else, it must be better, right?

Anyway, I'll get the effects rack.  I use it with my D104, and it works great for me.  I put an RCA on the side of my Silver Eagle, and I still use it for PTT, etc.  Audio just wraps through the computer.

--Shane

[k4kyv]

One basic rule needs to be mentioned.

The louder your audio, the more you push it to the edge, the lousier it will sound.
You need to pick the appropriate tradeoff point- "Loud enough" and clean vs. DX pileup audio, mush and distortion.

That depends on how you do it, and whether or not you are exceeding the headroom at any stage along the audio chain.  Then it depends on the type of "processing" you are using.

The purpose of processing is to keep your average audio level as close as possible to the point of overmodulation or to the saturation point of the weakest link in the audio chain on voice peaks, without actually reaching that point.  It usually consists of some form of agc to keep the average level more steady, followed by some form of peak limiting or clipping to take care of errant peaks.  When done properly, it can produce minimal distortion of the signal. Don't expect to achieve a 10 dB increase in "talk power".

Anything that alters the voice waveform to make the audio sound "louder" for a given percentage of modulation, inherently produces distortion.  Every human voice has a characteristic peak to average ratio.  Anything you do to alter that ratio is, by definition, distortion.  Some forms of distortion are more objectionable than others.

The simplest and dirtiest method of generating "loudness" is simply to turn the mic gain clockwise, to hell with the distorted sound it produces and the splatter that results.  You hear plenty of this during any slopbucket QuaRMtest.

[KD6VXI]

Shane, I dont have that program anymore. What was it called? I can try it out. I just need some cables. I can run it through the effects loop on the mixer.
Clark

Email is sending now.  It's 10.7 megabytes.  I sent it to your newer email addy, not the one that's decades old...  Lemme know if you need it split up, and I'll do that.

Instructions to install are included in my email.  Lemme know if you need more.

--Shane

[KD6VXI]

The simplest and dirtiest method of generating "loudness" is simply to turn the mic gain clockwise, to hell with the distorted sound it produces and the splatter that results.  You hear plenty of this during any slopbucket QuaRMtest.

You know, I used to show that to guys in the shop as well.  Put the Bird meter inline, and start turning the Auto Mod Control to disable it.

It would result in an increase in the AVG Pout UP TO A POINT....  And then all of a sudden, the OScope would start to pinch off, and the AVG power would start to DROP, while the PEP stayed the same or would continue to increase.

Was easy to convince truckers that clipping the modulation limiters was NOT the best idea after showing them that test.

Also won many a 6 pack of beer with that bet   I'd even let them bring in their own radio to show them.

--Shane

[WBear2GCR]

You might want to install the famous "3 diode limiter" in the modulator, to prevent baselining no matter how hard you drive it? A good idea, even if you prevent overmod via an external limiter... the info is sitting around here on a link probably to the amwindow site...

           _-_-bear

[ka3zlr]

Yea,.. everybody has them now,, Slopbuckets, AM.ers,, Regular Hams,, CBers on sideband using Amateur Gear..Yea it's contagious Audio Processing.....

Now it's Become the Norm of Amateur Radio, all across the bands, Lotsa Audio Processing going down...

73
Jack.

If you'd like to hear a decent system, on 27.025 there is a gentleman called Prime Minister.  He's running a direct injected Flex radio, with another system set up with ProTOOLS audio processing.  This runs into a 3CW40K, so should be NO problem hearing him when he is transmitting.

The audio quality of that system is just short of amazing.  Guess when you are a professional recording artist, the sky's the limit. 

MANY of the guys on the 'superbowl', so to speak, have been watching the amateur boards, direct grid feeding their boatanchors, flex radios, etc.  I've made, and another gentleman is making modulator boards allowing direct fed audio into ANY transmitter, for HiFi AM / collector modulation.  So far, we've got neg peak clipping, hard limiting, switchable controlled carrier AM, etc. 

Anywho, you are correct, the processing bandwagon is wide open...  Shoot, there are guys on 2 meters now with processing!

--Shane

Shane,

First of all I didn't Know The Flex Rigs are able to operate on Chicken Band...LOL....that's a piece of news to me.  

And this Direct Injection System.,,? that's feeding the Balanced Modulator Directly right, as I understand it I don't do it so I'm just working on a wim here. There are some benefits to that, ESSB..


73
Jack.

[W8IXY]

Part of my job is to design the parameters of the Omnia AM broadcast audio processors.  I start with about a 2.5:1 ratio slow wideband AGC leveller, followed by about a 3:1 ratio multiband compressor, and thats followed by a brick wall limiter.  Hit the limiter with about 2 to 4 db hard limiting.  A gating function can be applied to both the slow AGC and the multiband compressor.  I adjust the gate to "freeze" the gain changes whenever the input audio drops below a user set threshold.  That avoids pumping.  Also, some mic processors also have a compression, downward expander, and gating function (such as a Symmetrix 528).

The key to generating a dense but not overblown punchy processed voice signal is to apply brick wall limiting ONLY at the final stage of the processor, immediately before the transmitter audio input.  Also, the flatter the response of the transmitter, the more you will be able to utilize aggressive processing.  For amateur radio use, set about a +6db shelving boost starting at about 1.8 kHz, and sharply filtering out anything above about 4.5 kHz.  If you have a lot of room noise, close talk the microphone to keep the ambient noise level down.

When you listen to your audio as you are adjusting it, you will find the point where adding processing does little to add loudness, and too much makes it sound more compressed and/or distorted.  Set your final adjustments to where you just approach the "sweet spot" where loudness maxes out, and excessive distortion has not set in.

73
Ted  W8IXY

[Todd, KA1KAQ]

If you'd like to hear a decent system, on 27.025 there is a gentleman called Prime Minister. 

That explains why we haven't heard Dale on 75m in a while - he's moved up the bands!