BillFitzmaurice.info

Thanks for the other possible uses CoronaOperator

escapemcp wrote:Quick related question:

I have been testing my mixer to see the point at which it clips. I have used sine waves (as you can easily hear clipping with these) at various frequencies. If I can get my mixer to, say, +8dB when it clips (happens at the same point with all sine wave freqs), can I safely assume that I can take a broadband signal to +8dB without any clipping?

I currently HAVE made that assumption, and have soldered in some resistors into the XLR chain in order to reduce the levels going into the DEQ, so that clipping on the mixer happens at the same time as clipping on the rest of my kit. This keeps SNR ratio high and avoids any nasties from dropped mics, needle thumps etc.

Sorry I missed this part earlier!
A position of a slider isn't a guarantee,it still depends on content of signal!

Grant Bunter wrote:I did suggest this on page one. But I wasn't sure if the OP has a DCX.

I started with the side chain compression.

I have both the DCX and DEQ. I have used the DEQ Dynamic EQ in the past, and it is quite good. But, I was not able to get it to lower the sound level. And I could not get it to work on the RMS values instead of the peak values. BUT...I will take another look and see if I can make it work.

bjm362 wrote: A position of a slider isn't a guarantee,it still depends on content of signal!

Then explain how this "hard knee" limiter works :

CoronaOperator wrote:

bjm362 wrote: A position of a slider isn't a guarantee,it still depends on content of signal!

Then explain how this "hard knee" limiter works :

I really like that one !!!! OLD SCHOOL TO THE MAX!!!!!

It is still possible to overdrive that. However they would have to be trying really hard to do it! Whoever pulled it off might come to understand the old adage "Nothing goes Ping like an aluminum bat"!

I did some preliminary bench testing with the dcx2496 dynamic EQ's to see if it may help some with the overzealous DJ's out there. I never did any listening so far, just laptop, pink noise, room EQ wizard, Tascam audio card and the DCX2496.

Here was the setup:



First was calibration. Running pink noise from Room EQ wizard's tone generator through the Tascam via usb, out to the DCX inputs, outputs back to the sound card and displayed on the Room EQ wizard RTA gave me a nice flat line to start with.



After playing with various settings on the dynamic EQ's menus I was able to get "most" of the frequency response (more on this later) to remain fairly constant (within 2-3 dB fs) over a 15 dB input increase. After an increase of ~15 dB input, the output begins to rise again with increased input. I also set the limiter to engage just after the increase. The way I had it, -30 dB input would hold the output steady until about -18 dB input, then rise a dB or 2, then the limiter would kick in and hold the output steady. That gives 15 dB of leeway for the DJ's to push their outputs until the limiter kicks in and destroys the sound quality.

So far so good right? Well, first off this was just a bench test, no listening was done and no music was being played so still lots more testing to do to see the audible results. Also, the dynamic EQ's do not buffer the entire audio spectrum:

Here is a pic of the high shelving EQ engaged as much as I could:



... and a pic of the low shelving EQ engaged to maximum (sorry, no smoothing on this one) :



As you can see, it is holding the lower parts of the graph steady except at either end it was allowing the signal to rise.

At first I though this would be a problem and tried to stack a dynamic EQ on the input, then one on the outputs (one HP, one LP). Trying to line up the graphs was trial and error and couldn't really be done without the RTA giving me a visual reference. Here is a graph of the best results I could get combing the two EQ's:



It looks ok, but as the input is increased or decreased, the graph would get a little bit wonky in the highs, might be able to play with the settings and get a better result. The biggest problem with stacking the EQ's is that if you change the output gains on a channel, the ratio of buffering between the lows and highs would change. Also, using too many DEQ's on the DCX will quickly eat up processing power. The DEQ2496 would be a better tool for stacking the EQ's as you can stack up to 3 DEQ's on each channel, might try that next.

Another insight I had is that we don't run our channels full range. A low shelving dynamic EQ on the sub channel would be fine, however a high shelving EQ on the tops still give a slight increase from about 200 hz down to your crossover frequency (see the graph above). However it is still only +5 dB @ 80hz, +2-3 dB @ 100 hz with a +15 dB input. Not the end of the world I guess.

Looks promising for either DCX or DEQ users if it turns out to sound ok. Limitations so far are that it only buys you a 15 dB buffer zone, might be enough as you can always throw your limiter right after it gives way. Once I play with it some more and am happy with the results I'll post some of my settings. I plan on going live with it on Sat if it sounds ok .

CoronaOperator, any chance you will try that live soon and let us know how well that works. I for one appreciate testing gear at home or in other environments...but really appreciate knowing how well it worked live!

I may be looking at it from the wrong perspective...but the next to the last pic looks like it depicts a lot of distortion where the limiter is really clamping down.

The other thing is having dropped out of live performances for so many years I am kind of behind the 8ball on some of the modern technology, so I really do appreciate what you posted!

Edit: I really am going to have to learn a different perspective on these devices. I comfortable with using my active crossover, but not so much with my limiter/ loudspeaker management system. In the old days I could handle it myself at DJ gigs. I could ride shotgun at festival gigs/raves etc. However that won't work if I am on stage singing and there really isn't a sound guy! I can't be in both places at the same time!

bjm362 wrote: I comfortable with using my active crossover, but not so much with my limiter/ loudspeaker management system. In the old days I could handle it myself at DJ gigs. I could ride shotgun at festival gigs/raves etc. However that won't work if I am on stage singing and there really isn't a sound guy! I can't be in both places at the same time!

Your speaker management should be set and left alone during the gig. Once you have your crossover and limiter set (which should be before you ever reach a gig) - all that's left its to get the EQ right.....

I run sound off the stage for my band and have for the last 15 years. You have to get the PA right before you start and monitor the entire mix at your position. If you do that, it works just fine without a sound man.

Bruce Weldy, when you quoted me you left out the part about the experiential gap! The rest of my statement looks like nonsense with out it. If you take the whole statement together it makes even more sense.

My primary sound experience is as a DJ. I hove plenty of experience with crossovers and EQs, but the limiter/ loudspeaker management device with menus instead of knobs is new to me. It hasn't been that long since I acquired it, and I have not gigged any since then! Hence the comment that I was grateful for what Corona Operator posted!

BTW, do you have a thread around here about your band? What area? Are you on facebook? Does your band have a Facebook page?

bjm362 wrote: I may be looking at it from the wrong perspective...but the next to the last pic looks like it depicts a lot of distortion where the limiter is really clamping down.

CoronaOperator wrote: ... and a pic of the low shelving EQ engaged to maximum (sorry, no smoothing on this one) :

Hope I got this right.
It's not showing distortion, but that graph has no smoothing, and presumably, the other(s) do.
I made the "no smoothing" part bold.

That should clear that up...

bjm362 wrote: BTW, do you have a thread around here about your band? What area? Are you on facebook? Does your band have a Facebook page?

New band
https://www.facebook.com/armslengthband

Old band
https://www.facebook.com/pages/The-K-Ba ... 7869713897

Sound company
https://www.facebook.com/BWSoundNBTX

Just an update to report that I have nothing further to report, lol. I broke my hand in August and after working that Friday (second day back) my hand swelled up so much from over exertion I couldn't close it so have been taking it easy. Hopefully I'll get back to this project soon, it looks like it has some promise.

SoundInMotionDJ wrote:I get that a "hard limiter" can be setup to provide a maximum output for any input above a certain level. I have that now. But, it's not working. DJs who get on my system continue to push the DJ mixer into the red and produce an overcompressed mess...and I get the blame.

I am looking for an effect to help me keep overzealous DJs in check. I want a limiter that will allow the "maximum" volume to be passed when the mixer is at some 0dB level of output.

BUT...if the DJ mixer level is raised above the 0dB level, I want the final output to go down from that 0dB point. So, if the DJ mixer is at +6dB, I want the output of the limiter to be -6dB (or whatever ratio I set).

Is there such a device?

Yes.

I recommend a dbx 262 compressor for the task. These are available used for as little as $30. I currently see two online from the used equipment store Music-Go-Round. I recently paid $60 for my own third unit in excellent condition.

Like the older model 166 often seen in clubs in the 90's, it offers "negative" compression ratios, which effectively begin reducing output beyond threshold at up to a -1:1 ratio where it does precisely what you are asking (+6db comes out -6db). Locked in the amp rack and adjusted properly there's far less worry of actions by inexperienced sound board operators.

IMO, the dbx 262 is possibly one of the most overlooked compressor bargains ever. This might be due to the fact that it carries the "Project" label of which other devices in the so named series were for the most part inferior products.

While not feature laden it is a very good dual channel analog compressor. It does not support sidechain connection or provide ADSR style adjustments. I've found the latter to be window dressing anyway on most low end models. The gates in cheap processors rarely work well either.

What it does offer I hold in high regard:

Solid controls and construction
Excellent gain reduction metering
Selectable hard/soft knee operation
Unique Negative ratios
Stereo link
IEC detachable power cord
TRS Balanced 1/4" Input/Output connections
Good sound quality and high reliability


With respect to the negative ratio feature, this comes from the dbx manual:

"Negative ratios can also be used to prevent musicians from continually increasing the volume of their instrument (e.g., in live applications where there is no sound engineer to control the house levels). With their signal compressed by a negative COMPRESSION RATIO, each volume increase initiated at the instrument or amp would actually decrease the volume level at the final mix."

I've found that recording a snare drum with a negative ratio produces an very interesting effect, suppressing the "crack" but allowing the grace notes to breathe with the strainer buzz. Try it sometime.

If you can pick these up cheap they're a bargain. Where else can you get a line amplifier with balanced I/O for 30 bucks?


I know the original post is somewhat old, but I don't get back here often to catch up and thought this relevant to the OP. It was great reading some of the creative ideas in this thread too!

Nice. That's the ticket, safebet