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Sound / Volume Limiter Installation

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Sound / Volume Limiter Installation

Postby The Bunk » Tue Jan 28, 2020 5:40 pm

Need helps guys!
I work at a gym / sports club which has dance, spin studios etc. Long story short, we have bought a sound limiter for our spin studio; it's an Eagle G920D.

https://www.electrovision.co.uk/homepag ... =0&tl=1318

I assumed it would be a straightforward matter of sticking it between the amp/sound system

https://www.sound-dynamics.co.uk/index. ... ct_id=3866

and the speakers. Seemingly not so...It works very well in that it has limited the volume, but limiting it to absolute zero is not exactly what we wanted.
We've tried with no success to get some sort of installation guide from the manufacturers. The manual is all but useless. Anyone had any experience with this sort of thing? It's possible that we've missed something obvious but...well nothing seems "obvious" at the moment!
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Re: Sound / Volume Limiter Installation

Postby Kwackman » Tue Jan 28, 2020 5:51 pm

There is a manual on their site under the download tab in the link you posted.

But, I think this unit is designed simply to turn off the amp if things get too loud, I don't think there's an facility to reduce the audio. Could be wrong though...
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Re: Sound / Volume Limiter Installation

Postby BigRedX » Tue Jan 28, 2020 5:52 pm

AFAICS from the information supplied about the attenuator, it works at line-level and not at speaker level. It is designed to go between the mixer and a power amp. Unfortunately as your mixer/amp is all in one and it doesn't appear to have any insert points, the two aren't really compatible.
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Re: Sound / Volume Limiter Installation

Postby MarkPAman » Tue Jan 28, 2020 5:54 pm

Can you explain a little more about how you've got this hooked up?

I assume you trying to use this function,
"It also has an audio input and output so that it can attenuate the signal between mixer and amplifier if the sound level is too loud"
rather than the mains relays.

The trouble is that your mixer and amp are in one unit so you can't put this unit between them. Are you running speaker level through it?

I guess you could run the amp's power through the relays, which should quickly educate uses about how loud they can go.......
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Re: Sound / Volume Limiter Installation

Postby Hugh Robjohns » Tue Jan 28, 2020 6:03 pm

The manual seems rather confused!

Ignoring the mains power-switching functions (which are a fab way of destroying the power amp and source equipment)... it would appear to also provide a muting function on a line-level audio feed (balanced or unbalanced).

However, although your mixer has an unbalanced line output, it doesn't have a line in to the amp, so you couldn't mute the signal there... and the only other sensible option would be to mute the signal between the source and mixer amp itself. The relays won't cope with speaker level signals (for long)...

REturnign to the confused manual, in one place it says: "The G920D can be set either to disconnect the audio for a fixed period of time and then reconnect it, or to disconnect the audio until a remote RESET switch is pressed." And then elsewhere it says: "It may also be used to attenuate the audio signal between mixer and amplifier. In
this case, the attenuation is adjusted continuously to keep the sound level below the
maximum level."

... but that could just be a Chinese translation problem, and it could mean it mutes the signal as necessary to keep it below the threshold level...

I can't see anything obvious to change modes between a full mute and a continuous limit... and from the photos in the manual it doesn't look like there is any active VCA circuitry in there either to continuously control the signal level, just a muting relay and a simple mic preamp/comparitor circuit.

So I don't think this box does what you want it to do!
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Re: Sound / Volume Limiter Installation

Postby The Bunk » Tue Jan 28, 2020 7:03 pm

Thanks Guys,
Yep, I've a horrible feeling this is not what we actually need, although we did try with a previous experiment of bringing a mixer into the set-up but that resulted in basically a horrific sound overall. What doesn't help is instructors twiddling knobs and you just can't avoid that.
What it does look like this thing can do is cut out the power altogether but we really don't want to go down that route. Anyone who's played in a band that has been on the wrong end of one of these things - and I include myself here - can vouch for that.
So basically our instructors plug their iPhone etc (or bluetooth it) to the all-in-one sound system and the headmic unit is also plugged into that unit. They both go directly out to the speakers.

So if that's the case, Is there another unit / device which will do what we want, does anybody know? Alternatively, I'd be happy if someone can (or knows someone who can) come along and give some professional advice (dependent on the scale of fees which I'd expect to meet).

What's *really* frustrating with all this is that we're doing this for a local resident who claims that the noise from our spin classes, particularly the bass, is a "noise nuisance". In my honest opinion, it's not. It can be heard, just, but at very low levels. I mean you've really got to listen out for it (and wait for passing cars to go, planes to stop flying over, birds to stop singing, the wind to stop - seriously). Once everything dies down, it is just about but barely audible. We've had proper noise risk assessments carried out and they've found we're not at a level that is likely to be harmful to the instructors or the attendees in the class. This resident is probably 50 odd metres away. But they are just not letting it go. So we're still trying to go along the "best PR" route and this is our last resort.
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Re: Sound / Volume Limiter Installation

Postby The Bunk » Thu Jan 30, 2020 5:50 pm

OK had a bit of a rethink and another look at this and what we reckon is...

Headmic/ iPhone (instructor / music source)

Into

The SD 500 (line in / bluetooth)

Line out to

The Eagle G920D Sound Limiter

Line out to another amp such as this:

https://www.amazon.co.uk/Skytec-SKY-240 ... 36&sr=8-36

(This will be kept out of reach)

Into speakers

Does that sound about right?
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Re: Sound / Volume Limiter Installation

Postby MarkPAman » Thu Jan 30, 2020 6:30 pm

Will the amp will happily drive your speakers? It's not an exact match for the old one which could drive a 2Ω load. How many speakers do you have & what's their impedance?

If that's OK, then my guess is that you'll get some sort of control from the limiter unit, but I've no idea how good it will be.
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Re: Sound / Volume Limiter Installation

Postby MarkPAman » Thu Jan 30, 2020 6:35 pm

Another approach could be to use the mains relays (it says it has 4) on the speaker lines.

Will kill the sound dead of course, but most people will learn quickly how to keep below the limit. Shouldn't do any harm to a modern amp.

However, I don't know that unit, and would want to be very sure that its relays are well isolated from any other mains if doing this.

Has the advantage of no extra cost!
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Re: Sound / Volume Limiter Installation

Postby Hugh Robjohns » Thu Jan 30, 2020 6:39 pm

The Bunk wrote:Does that sound about right?

Well, it inserts the device into the signal path between the controller and the power amp... which is good from a single path point of view.

But you're still stuck with the issue of full muting when the threshold is exceeded rather than the automatic level control you were hoping for.

H
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Re: Sound / Volume Limiter Installation

Postby The Bunk » Thu Jan 30, 2020 7:20 pm

Thanks guys, helpful responses as always and some more looking into to be done at my end.
The issue seems to be though that we get a full on "mute" as opposed to a hard limit as it were; and yes that's not ideal in a spinning class and it frustrated the hell out of me and the punters when I was in a band and it happened.
Mark, we have 4 speakers and I'll look into their impedance. No idea at the time of writing.

I don't suppose a straight compressor would do the job would it?

That said if I could take the humans (instructors) out of the equation that would be my preferred route :headbang:
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Re: Sound / Volume Limiter Installation

Postby MarkPAman » Thu Jan 30, 2020 7:59 pm

Having worked with, installed and observed many such devices over several decades, I really do think that educating the human part of the system by killing the sound is the best solution in the long run. Provided, of course, that it’s done in an equipment friendly way.

Limiters or other attenuation systems often just lead to the first stages getting overdriven as uses fight against the system.

I also worked “raves” and other DJ events for a long time, (music crap but money good) and again found that no automatic device works well - though than needs a different solution.
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Re: Sound / Volume Limiter Installation

Postby James Perrett » Thu Jan 30, 2020 9:54 pm

I'd have to agree with Mark - a limiter is not what you need. With a limiter you may restrict the peak level but they can still increase the average level by turning the volume up (unless the limiter release time can be set to a few seconds). You'll end up with highly compressed music that could actually damage your speakers if they're not generously rated.

The neighbours are most likely to be annoyed by the bass so a high pass filter might help here (set to something like 120-150Hz at a guess). If the problem is with higher frequencies then you need to look at the building construction and work out where the weak points are.
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Re: Sound / Volume Limiter Installation

Postby shufflebeat » Sun Feb 02, 2020 1:54 am

MarkPAman wrote: ...educating the human part of the system by killing the sound is the best solution in the long run.

I suspect most folks here have chosen to learn irresponsibly how to bypass/override the limiter instead. I've only ever met one that beat us and that was because they posted a lookout to watch for "shenanigans" (actual quote).

+1 to limiting (audio squashing) will only encourage them.
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Re: Sound / Volume Limiter Installation

Postby Sam Spoons » Sun Feb 02, 2020 10:06 am

I remember sneaking a 20dB pad in the mic line to one once.....
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