PM Limiter!!

Hi,

In one of the club install done by our SI, 3 RMU 105 have failed in quick succession, and my fear is that others may fail as well (Total 10)

8 nos 105 are being driven by individual channel of PM8500, with proper Limiter settings and PEq and 2*105 are connected in parallel driven by single channel (Mono LZ)

Being a club, system is being driven to the limits!!!

DO I need to change the Limiter settings in this case..., What kind of Limiter is there in PM? (Hard or Soft Limiting)

Regards

Navin

Original Post

Hi Ashraf,

As I had mentioned, PEq selected is of RMU 105 in Low-Z mode, along with corresponding Limiter settings..

Two speakers are paralled together and driven by one channel of PM 8500.(Project view attached)

These RMUs are used as fills, and being a club application, system is always being played around max volume..

Despite of standard Limiter systems applied, RMUs are failing..!!

Not sure if the LIMITER  used in PM DSP is a Hard Limiter??

Question is, whether I should suggest to the SI to lower the Threshold of Peak Limiter???

CSD File attached..

Regards

Navin

Attachments

Hi Navin,

From my experience with this speaker (RMU105) I always set the crossover frequency @ 160 Hertz when used with Subwoofer. The limiter is not sufficient to protect the 5,25'' woofer of the RMU105 and the compression driver (EMB2) is much more efficient.

Otherwise, I apply the simple formula for limiter settings:

U=√PxZ        =√200Wx4Ω      = 28,28 Volts for RMU105

(same value for the limiter if you have one speaker or two in parallel)

Best regards

 

Hi Guillaume,

Thanks for your reply!!

At this site, there is no subwoofer nearby the area which RMUs are catering to... Apparently, DJ is trying to boost LF from mixer, causing LF driver to blow. In two of the three failed units, LF driver was found to be faulty.

Temporarily, I have moved the HP to 120HZ..

I am also considering to lower the  Peak threshold of the limiter. I think the limiter used here in PM may not be with ∞:1 limiting ratio...

Regards

Navin

Hi Navin,

If you have an ESP before the PM8500N Amp, you can also do that kind of multiband compression to protect the woofer more efficiently (see enclosed picture).

The crossover inside the RMU105 is set @2000 Hertz if you look at the technical sheet (between Woofer and Compression). So I have set the frequency @2000 Hertz too in the X-Over of the ESP-880. The only thing is that you will use two channels on the ESP-LINK card or two analog channel to send the signal to the PM8500N.

You will also have to set the Matrix of the Amp like enclosed picture #2 to keep the whole frequency response.

Best regards

Attachments

Photos (2)
Guillaume-at-Bose posted:

Hi Navin,

If you have an ESP before the PM8500N Amp, you can also do that kind of multiband compression to protect the woofer more efficiently (see enclosed picture).

The crossover inside the RMU105 is set @2000 Hertz if you look at the technical sheet (between Woofer and Compression). So I have set the frequency @2000 Hertz too in the X-Over of the ESP-880. The only thing is that you will use two channels on the ESP-LINK card or two analog channel to send the signal to the PM8500N.

You will also have to set the Matrix of the Amp like enclosed picture #2 to keep the whole frequency response.

Best regards

Hi Guillaume,

did you listen to the sound quality of your 2x Xover ch. suggestion?
I'm interested in two aspects:
- How it sounds at the Xover region (you are putting a DSP Xover upon a speaker passive Xover) 
- How it sounds when only one of the two channels starts to limit
We should have some kind of 'limiter activation link', so that when one of the two freq ranges starts to limit, the other starts to limit too even if its own freq range doesn't need it at that time.
This way the sonic LF&HF balance is preserved.
(this feature is in Powersoft X8 amps, really useful for ShowMatch systems)

Best regards

 

 

 

Good catch Moreno :-)

My suggestion is only intended to protect the speaker but it will also modify the tonal balance for sure.

And as we can't link two different Comp/Lim in the ESP the compression block of the HF will not follow the compression block of the LOW MID.

But, once again, it is much more to protect the woofer from overdrive.

I've not tried this experience since now but I think it could work pretty well if the limiter settings are correct.

And it could be better to know what kind of passive filter is used inside the RMU105 (is it 12, 24 or 48 dB by Octave???) to adjust the same filter settings in the ESP-880.

:-)

 

Arno-at-Bose posted:

Hi Moreno,
You can link Limiters in PowerMatch.

Right click on the limiter block, go to "Add To Link Group" and select the Link Group.
Do this also for the second limiter.

BR
Arno

Hi Arno,
So the link you indicate permits to have one limiter limiting only because the other limiter in the link is starting to limit? Even with limiters with different parameters?

 

Guillaume-at-Bose posted:

Good catch Moreno :-)

My suggestion is only intended to protect the speaker but it will also modify the tonal balance for sure.

And as we can't link two different Comp/Lim in the ESP the compression block of the HF will not follow the compression block of the LOW MID.

But, once again, it is much more to protect the woofer from overdrive.

I've not tried this experience since now but I think it could work pretty well if the limiter settings are correct.

And it could be better to know what kind of passive filter is used inside the RMU105 (is it 12, 24 or 48 dB by Octave???) to adjust the same filter settings in the ESP-880.

:-)

 

The problem is that when you use speakers always at the full power, as in discoteques, you always use the speaker in the limiter activation range.
This means that the LF/HF balance is always changing if you use LF/HF limiters with unlinked activation.
If the scenario is this one, I think the best solution is simply to reduce single limiter threshold for that speaker. I'd like to have also a knee parameter in the limiter block, but we haven't unfortunately... :-(

 

Arno-at-Bose posted:

Link Group - The limiter may be assigned to one of four link groups, or may act independently (no assignment). When channels are linked the presence of limiting on any of the linked channels engages the limiter on all linked channels.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :-)

 

Hi.

As far as I see it from the wiring diagram, the 105 passive x-over lowpass is 2nd order and the highpass is 3rd order.

As a sidenote: it'll be interesting to see the MF failure mode before making any conclusions. If it's a burned voice coil, then lowering peak limiter changes may make things even worse since crest factor is reduced and you start to send 'square waves'. If it's mechanical damage instead (peak excursion exceeded), things are different.

Best,

Thomas

Add Reply

Likes (0)
Having trouble signing in?

We recently updated our sign-in procedure and if you have old sign-in data cached, this can create a problem. Please:

  1. Clear your browser cache and cookies
  2. Then close the browser (not just the window)
  3. Open the browser and try again
Thank you

Please make sure that your profile is up to date
×
×
×
×