Hello everyone!
I recently got a PA system that came with speakers, subwoofer and the necessary amplifiers.
Currently, the signal chain looks like this:
Source –> DBX Drive Rack PA2 -> Hi/Mid/Low Bands -> one amp for each band -> Hi/Mid to Tops, Bass to Sub
In order to protect the speakers, I'd like to add a limiter, but as a newcomer to PA systems, I am not quite sure how it should be done.
I saw that the drive rack also has a limiter section, but I imagine the limiter needs to go last in the Signal chain, so this won't save my speakers.
Instead I probably have to get a separate peak limiter that can take three separate inputs and relay them to at least two outputs.
Is that correct?
Which devices would you recommend?
Best regard
Malos
I recently got a PA system that came with speakers, subwoofer and the necessary amplifiers.
Currently, the signal chain looks like this:
Source –> DBX Drive Rack PA2 -> Hi/Mid/Low Bands -> one amp for each band -> Hi/Mid to Tops, Bass to Sub
In order to protect the speakers, I'd like to add a limiter, but as a newcomer to PA systems, I am not quite sure how it should be done.
I saw that the drive rack also has a limiter section, but I imagine the limiter needs to go last in the Signal chain, so this won't save my speakers.
Instead I probably have to get a separate peak limiter that can take three separate inputs and relay them to at least two outputs.
Is that correct?
Which devices would you recommend?
Best regard
Malos
You might not want the lead vocals being pulled down by the kick drum. IMO, if a system's tonality is being noticeably altered because one section is that far into limiting, it was never enough Rig For The Gig to start with. A decent system operator should spot this and adjust their mix to accomodate.
Chris
Chris
For speaker driver protection each band/amp should have its own limiter, set so you don´t blow that speaker.
In principle, typical built-in Power Amp limiter is enough for big mean Bass drivers, which handle lots of power, so just preventing clipping there should be enough, unless woofers handle way less than what´s available which would speak of poor system design.
At the opposite end, HF drivers often handle way less than what´s available, say you use a 150W amp while driver handles 30W at the voice coil (even if it´s rated as "500W System power" or something).
There you set its individual limiter to, say, 20-25W RMS and no more.
Midrange setting depends on configuration, we don´t know what you are using.
In principle, typical built-in Power Amp limiter is enough for big mean Bass drivers, which handle lots of power, so just preventing clipping there should be enough, unless woofers handle way less than what´s available which would speak of poor system design.
At the opposite end, HF drivers often handle way less than what´s available, say you use a 150W amp while driver handles 30W at the voice coil (even if it´s rated as "500W System power" or something).
There you set its individual limiter to, say, 20-25W RMS and no more.
Midrange setting depends on configuration, we don´t know what you are using.
From a technical point of view I agree with this, from a sound point of view I don't.
The issue is, when you give each section it's own limiter, you run the risk of completely skew the total sound of the system. Which sometimes can sound horrible.
For a company I used to work for, we therefore put the limiter in front of everything. Although these were also all active speakers, so you have a lot more control.
Or maybe a better way of saying it, is let the limiter control all channels at once. (it wasn't necessarily in front of all filters)
The downside is that you have a little less SPL in the end, but the quality of the sound stays intact. Or at least even.
Obviously there are tradeoffs here.
When you're in control of designing the entire system, you can already take this into account by selecting the right drivers etc.
Idk, they record it that way most of the time. It used to be just FM did this, but digital recordings seem to be made that way these days. Part of the loudness wars I guess. It is especially noticeable playing quietly in headphones, or of the system has a noticeable lack of bass. When the bass hits and it’s not there you really notice it ducking everything by 10-15 dB.
And I’ve heard it happen live (woofers bottom for a second or two, goes into limit, sounding even worse) and the operator scrambles to punch in a 70 Hz high pass filter, and the rest of the band’s set has no bass - but at least the system quits misbehaving. “That’ll teach you….”
Speaker system processing and mix processing are two completely separate things, yes you can sorta/kinda do both with one processor but its far far from ideal and results in all kinds of very audible artifacts. Yes every audio band in a crossover should have it's own limiter.. it's the only way to keep all the drivers alive while getting maximum performance from them. I guarantee you any decent powered speaker is designed this way.
Live band vs DJ system limiting will vary somewhat depending on the gear in use, if the event requires a 20dB sub/bass haystack then the PA system better be equipped with enough subs to deliver that, otherwise there are going to be some very audible side effects happening. With an appropriate PA system on hand I like the results I get with all the PA system limiters activating at the same driver level.. more or less😉, I have tried it other ways and and it just ends up with unbalanced sound where the mids and highs outrun the subs.
Live band vs DJ system limiting will vary somewhat depending on the gear in use, if the event requires a 20dB sub/bass haystack then the PA system better be equipped with enough subs to deliver that, otherwise there are going to be some very audible side effects happening. With an appropriate PA system on hand I like the results I get with all the PA system limiters activating at the same driver level.. more or less😉, I have tried it other ways and and it just ends up with unbalanced sound where the mids and highs outrun the subs.
Interesting, I have seen many more than decent professional loudspeakers build differently.
Speaking from personal experience as well.
So that guarantee is only subjectively speaking and definitely not true as a general statement.
Btw, you don't have to protect all speakers, or just only put in worst case protection.
But a limiter/compressor should already kick-in way before that.
Like I already mentioned in my previous post, it's a compromise.
Are you going for max sound quality, but a little less SPL, or are you going for absolute max SPL but let the sound quality suffer.
In a good design, at least the way I design it, you let the woofer/low-end control everything and choice the mid-range as well as the compression driver on such a way to be able to sustain that with quite a bit of headroom and room for error.
Also you let the woofer max out on the cone excursion, before you max out on the total power.
For many people there still seems to be the idea that more is better when it comes down to sound reinforcement.
It most definitely isn't.
Being smarter, like proper speaker placement and creating proper zones, is far more important.
3dB less is hardly noticeable at these levels, yet will save you half the power already.
I never said anything about separately powered (I think that is what you mean with descretely powered).
I think all if not most modern systems have a different amplifier for each speaker or set of speakers.
Although I know from L' Acoustics that they use hybrids with passive filters in some of their speakers.
Which I find kinda weird thing to do, but in that case you can't give each speaker its own dedicated compressor.
(well you can, sort of/but not quite, with some tricks)
Also, we are talking here about ONLY the compressor, not the filters.
I am a bit reluctant to disclose flat out on a public forum post a couple of brands I worked for, because it's a bit (much) into confidential territory.
Since it says a lot about the sound quality and therefor the "magic" of a certain brand.
I think that is fully understandable for everyone.
But I think you can figure out some is all I am willing to say 😉
Luckily I can share stuff about things I didn't officially work on.
My point was just to share experience we all have about this and that there are more ways to skin a cat.
Which comes down to this;
Both options have their pros and cons, and therefor you will find both or hybrids with certain companies.
Whatever they think will give the "best product" in their opinion.
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I agree but you need to be careful that the kick or bass drum does not rule the roost. That can kill a mix stone dead.
The only limiters after the board I use is the one in the amps.
An analog PA, I hard set my gain structure. At the PA rack, I will use a -20db XLR balanced attenuator on the main left/right and -15 db xlr attenuator on the monitors. This gives me a lot of adjustment range on the mixer in the eq and gain. Then I make up my gain at the drive rack and external monitor EQ.
For the record this does not happen with the limiters is a PA processor, all output channel processing including limiters are independant of one another.
WARNING - Quotes are to be used with the proper meaning and wording left intact - Rule 12
sometimes.
I did and explained very extensively into detail just a few posts back, incl pros and cons of both variations and why both variations exist. As well as hybrids.
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None of that is relevent to the equipment at referenced in this thread, so how is it you are contributing to this thread?
Quotes are to be used with the proper meaning and wording left intact - Rule 12
Sorry, I am not gonna repeat again, I think the explanation is pretty clear and obvious and it directly gives an answer to the topic starter.
So the TS can make up his mind with the equipment he has.
In the case of the DBX Drive Rack PA2, there is one general compressor before all filters, as well as a limiter after each section.
Which is basically worst of both worlds if you ask me, one of the reasons why I never like these kind of baked in DSP's.
There are many reasons why.
If you wanna control a compressor per band, you most certainly want to have control over attack and release times.
Which also doesn't seem to be an option.
It's unclear what speakers we are talking about.
This information is necessary to understand where the limits will be.
So I assume that the cone excursion of the subwoofer would go first (as most generic subs do).
I guess that would be my focus and just setup all other limiters accordingly.
Although it's kinda pointless if you don't have a prefilter for the compressor, because it will trigger at any signal and frequency.
So it could be that the compression drivers have plenty of headroom left, yet the entire system will be triggered.
Maybe we can try to fiddle a bit with te pre-EQ to emphasize a certain area and compensate back with the 8-band EQ after.
Not the best way at all, quite messy way, but it's something.
But without any further information, this is just a guessing game.
Anyhow, the way this is setup, the main compressor controls everything at once.
So not individually.
Anyway, I doubt that the TS will respond actually, one post and last seen was a month ago.
When you're in control of the entire system, you design it to have ample headroom for the tasks it's intended to perform. Never having to get near a system's limits is both the best protection, as well as best assurance for sonic fidelity. I personally in the past have used bass sections of 10 double 18" (d&b B2) or 32 15", with mid-high frequency sections to match, for an audience of ~100 people. You run the system at ~-10 dB, the sound can be best put in words like "effortless pressure", and you never have to worry about anything. Of course you can and should still apply limiters, for protection vs. defective electronics (will likely never ever happen with quality components) - you will just never hit them.