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Author Topic: SRX718s help needed  (Read 629 times)

Plamen Milev

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Re: SRX718s help needed
« Reply #10 on: September 22, 2021, 06:59:22 AM »

I'm not convinced setting precise voltage limits prevents damage, because we have heat based damage, but also physical damage by 'over-excursioning' - I'm not at all sure that these drivers, with their odd design with big heat sinks gets damaged from continuous loud signals, but the sudden quite violent movements faults and clipping make them do? I have no proof at all - it's just a feeling, so I'm now looking at how effective these quick limiters can be at toning down these sudden, destructive peaks, rather than the overall level. I have no idea if this is a solution apart from what's happened recently and the failure I've had with a simply nasty sounding show, while a louder, continuous level show that was more 'musical' caused no grief?

I do understand that there are RMS limiters but in my situation I haven't got access to such equipment. Heat based damage - well heat is produced by the power feeded so surely a limiter would limit this. I understand the concept of limit peak power and thus the RMS power can increase but in my case this would lit the limiters as well as produce a compressed sound. And that would be noticeable either way so it will work for me.
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Paul G. OBrien

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Re: SRX718s help needed
« Reply #11 on: September 22, 2021, 10:25:06 PM »

I did a gig and had limiters set up to 1600W@4 bridged but my tops couldn't keep up with the subs so I had to reduce the gain on the bass.

This is your own personal system correct? If so you don't have to worry about a rogue operator abusing the system, when you see the limiters activate you know that is as loud as it will go so I'm sure you won't just keep pushing it harder. It's also a good decision to err on the conservative side with powering subs, depending on the genres you play they may have to absorb a lot of continuous energy. The limiters in the DCX aren't state of the art by any means but they do a good job none the less, so yes use them.
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Tim McCulloch

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Re: SRX718s help needed
« Reply #12 on: Yesterday at 03:46:45 PM »

I do understand that there are RMS limiters but in my situation I haven't got access to such equipment. Heat based damage - well heat is produced by the power feeded so surely a limiter would limit this. I understand the concept of limit peak power and thus the RMS power can increase but in my case this would lit the limiters as well as produce a compressed sound. And that would be noticeable either way so it will work for me.
Piston transducers primarily die for 1 of 2 tech reasons:  heat or exceeding mechanical specs (over excursion).

I take this onboard, it makes sense to me. It also gives me an idea that the limiter should be closer to the continious power rating of the speakers for pre-recorded music. I think I should go for 80-97V measured at the output of the RMX4050. Maybe closer to 80V. Surely at the set up and check stage before a gig I can see if I'm hitting those limiters and take note of my levels at the mixer stage.
Limiting at max power is a bad idea.  The heat never dissipates and it's very likely you'd be exceeding Xmax or Xmech anyway.  In developing limiter setting for a popular 2x18" sub I started bringing in the power (RMS) limiter when the subs demonstrated power compression.  Just because a speaker will not burst into flames when you add +3dB of power, does not mean you are getting +3dB of AUDIO from the sub.  When you reach that point of non-linear operation it's time for your limiter to have begun working...  The amount of power will be surprisingly low - for the nominal rating of 2k+ Watts, the threshold for the long term power limiter was around 500W IIRC.  There were peak and average voltage limiters, too (the amps were Gen 1 Crown ITechs) for other protection.

The attack and release for the RMS limiter is measured in seconds, as it's meant to manage heat.  The voltage limiters are there to offer excursion and peak protection and their voltage thresholds, attack and release times were independently variable.

Keeping a sound system "appliance-simple" and operator error resistant is a whole thing by itself.
« Last Edit: Yesterday at 03:49:20 PM by Tim McCulloch »
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Plamen Milev

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Re: SRX718s help needed
« Reply #13 on: Yesterday at 05:24:55 PM »

Piston transducers primarily die for 1 of 2 tech reasons:  heat or exceeding mechanical specs (over excursion).
Limiting at max power is a bad idea.  The heat never dissipates and it's very likely you'd be exceeding Xmax or Xmech anyway.  In developing limiter setting for a popular 2x18" sub I started bringing in the power (RMS) limiter when the subs demonstrated power compression.  Just because a speaker will not burst into flames when you add +3dB of power, does not mean you are getting +3dB of AUDIO from the sub.  When you reach that point of non-linear operation it's time for your limiter to have begun working...  The amount of power will be surprisingly low - for the nominal rating of 2k+ Watts, the threshold for the long term power limiter was around 500W IIRC.  There were peak and average voltage limiters, too (the amps were Gen 1 Crown ITechs) for other protection.

The attack and release for the RMS limiter is measured in seconds, as it's meant to manage heat.  The voltage limiters are there to offer excursion and peak protection and their voltage thresholds, attack and release times were independently variable.

Keeping a sound system "appliance-simple" and operator error resistant is a whole thing by itself.

Tim what is your suggestion then?
I only have a peak limiter that I can use.
In my case I limit a bridged RMX4050HD to 1600W @4R or 80V. This is to feed two SRX718s in parallel.
They are rated at 800/1600/3200W each at 8R

Based on what I see in this forum my limit is quite conservative but then I deal with pre-recorded music so it must be.
« Last Edit: Yesterday at 05:27:42 PM by Plamen Milev »
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Re: SRX718s help needed
« Reply #13 on: Yesterday at 05:24:55 PM »


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