Sound / Volume Limiter Installation

[The Bunk]

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!

[Kwackman]

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...

[BigRedX]

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.

[MarkPAman]

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.......

[Hugh Robjohns]

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!

[The Bunk]

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.

[The Bunk]

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?

[MarkPAman]

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.

[MarkPAman]

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!

[Hugh Robjohns]

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

[The Bunk]

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

[MarkPAman]

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.

[James Perrett]

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.

[shufflebeat]

...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.

[Sam Spoons]

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

[shufflebeat]

Ooh, clever.

...and very, very wrong.

Did you leave it there?

[Sam Spoons]

Did I buggery, spent good money on it I did.....

[The Bunk]

I suspect most folks here have chosen to learn irresponsibly how to bypass/override the limiter instead.

Guilty Yeronner.

Well plan "A" looks like a no-go then (other than saying we've installed such a thing to the complainants as a sort of PR move). Plan "D" or "E" would be to physically glue all the relevant knobs so that they can't be moved but that's obviously likely to damage several £00s worth sound system. However one issue that doesn't help is that the speakers are directly underneath some of the the room's extraction vents...so the sound is effectively travelling straight out. One of my lads has suggested some sort of acoustic diffuser / panel that will still let the air circulate but limit the amount of sound getting straight out. So we'd place these over or very close to the vents. Worth a try I'd have thought?

[James Perrett]

I don't know how large your vents are, but for domestic room size vents you would normally use a baffle box. A single baffle plate doesn't sound like it will make much difference (but I'm not an expert). I understand that acoustic ventilation design is Max's day job so it would be worth making contact with him.

[Wonks]

You'd need a proper silencer section in the ductwork, but that may have to be boxed-in acoustically as well. And a silencer means more pressure loss, so the extract fan may have to be replaced if the system can't simply be rebalanced.

But a lot of what is/isn't achievable will depend on the exact configuration of your walls and ventilation system. You may already have a small silencer section fitted.

Do I recall the club already having a regular building services engineering company/consultancy? It's the sort of outfit that needs to look at the problem.

[The Bunk]

Do I recall the club already having a regular building services engineering company/consultancy? It's the sort of outfit that needs to look at the problem.

Correct, Wonks, and well remembered! The trouble is, they have already done so and have taken readings from the area where the complaint has arisen. And "proper" readings too...I'm at home now so haven't got the report to refer to but it's got the lot...frequencies, averages, considerations for "ambient noise", different types of dB levels etc. etc. (I can give those details in due course if needed!) But, in summary, they've said it's audible...but "only just"...To my mind (and ears) it is not a Statutory Nuisance. I've been out to their residence and done tests with them...they're saying "I can hear it...." and I can't, not without waiting for the wind to die down etc etc, and even then I have to consciously listen for it.
And this guy is the only complainant from around 60 local residents. I really am very close to saying "go to the local Council if you're not happy...". It may well be that they know the implications of that, of course.
There were no such complaints before they moved in a few years ago. The amount of grief it's causing me (it's pretty much a weekly complaint) is, to me, completely disproportionate to where it is on my list of things to worry about at work.

[Sam Spoons]

The difficulty you may have is that the local Environmental Health Officer will say "if it's audible it's too loud". I had a similar situation when I was employed (by the venue, it was a condition of their temporary licence) to monitor sound levels outside* a wedding venue. I had only one meeting with the EHO and he said that music was audible at a level that I could not hear without holding my breath, and could not possibly measure or record with 'normal' equipment. I recorded and logged noise levels every 15 mins from around 10 p.m. until 1 a.m. when the venue closed and, in reality, I was recording ambient noise only. My real job was to call the manager if I could hear 'music' so he could go and tell the DJ to turn it down. A totally thankless task, I was relieved when, 18 months later, they finally lost their case to extend the temp planning for another year.

* I was positioned on the road, 400 metres from the venue outside the nearest houses, the venue was actually a large permanent marquee.

[shufflebeat]

There is a live venue in Manchester which was plagued by complaints from the flat above (how unreasonable) despite many pounds being spent on treatment. Eventually the owner bought the flat and moved in.

[MarkPAman]

I've been brought in by a club to try to offer technical solutions to stop a dispute.

To cut a long story short-ish, they £1000s spent on "sound proofing" (they've probably cut their heating bills dramatically but made almost no difference to the sound) and many £100s more on various types of limiters & cut off systems. The PA was really quiet inside, let alone outside. I imagine showing football on the TV would have made a louder noise than any band or DJ ever could.

I visited several times, met with the EHO, and made measurements myself. As above, what with a main road railway, and some refrigerated storage units close by, it's not possible to get any meaningful figure for the music but it can just be heard sometimes.

On one visit, I met the chap who complains, going into his house, which I was standing outside with a meter, so I explained that I was there to try & help. He invited me in to hear for myself (though I couldn't really) & produced some bottles of beer! So after a bit of a chat, I left, went back to the club and explained the real problem.

For many years, he'd been happily parking his van in a corner the club's car park, but they'd recently started charging and issuing fines for non members parking there & this had really p****d him off!

I suggested to the club that they gave him a parking pass, which I'm told the committee agreed to at their next meeting.

I've not been called back since, so assume that fixed it.

Probably no help here, but it may just be with checking if the noise is really the problem.

[The Bunk]

The difficulty you may have is that the local Environmental Health Officer will say "if it's audible it's too loud".

Honestly, I wouldn't have a problem with that, unless it ends up with us having to turn the volume down so low that it kills the class. Spin classes obviously require a fair bit of "oomph" from the music for motivation, even if it doesn't need to be "nosebleed techno" level. I'm stuck in the middle of it a bit here though...members moan when I've been in and turned the levels down, and a common gripe is "you're ruining the class because of ONE resident complaining"? The other thing is that these classes are obviously held at sensible times of the day, and only last an hour max at a time. It's not like we're banging out "Born Slippy" until 2am on a Sunday morning...