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Author Topic: Testing HF limiting in a DSP?  (Read 3897 times)

Mark Wilkinson

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Re: Testing HF limiting in a DSP?
« Reply #10 on: September 04, 2018, 04:31:58 PM »

I get a reading of .4vac on the meter across pins 2&3 with a 60hz tone played thru the Dx46 with all the crossover and fir filters bypassed with the limiter starting to work.

The Temp limiter doesn't seem to have user settable parameters or even the ability to enable it.

Is the amp output 55v ?

Are you using IRIS-net ? ....to try to set thermal, I mean...
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Kevin Maxwell

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Re: Testing HF limiting in a DSP?
« Reply #11 on: September 04, 2018, 05:56:08 PM »

Is the amp output 55v ?

Are you using IRIS-net ? ....to try to set thermal, I mean...

725watts into 8ohms voltage gain of 36dB. Input sensitivity of 1.25 Vrms. So that should be about 76volts.

1100watts into 4ohms voltage gain of 36dB. Input sensitivity of 1.25 Vrms. So that should be about 66volts.

It look like if I change the threshold to -2dB in the limiter then the "Amp Thresh" will be 49Vpk (with an 8ohm load) and this calculates to 300watts. So I decided to use -2dB as the limiter settings (to be a little bit more cautious) and I will keep an eye and an ear out for the results.

The one time I have used this it seemed to get as loud as when using the passive crossover and the DR4800 for EQ and delay and the sub-woofer crossover. But the amps didn't seem to be working as hard. And the Dx46 didn't look like it was working anywhere near as hard as I have been pushing it on the bench when testing it to get the HF limiter to come on. So unless I get carried away I am hoping I will be safe.

I have tried to turn on the thermal limiter in IRIS-Net but it seems to be a manufacturer setting only. And it comes with the speaker settings that you can get from EV and the thermal limiters aren't yet enabled for these speakers.
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Mark Wilkinson

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Re: Testing HF limiting in a DSP?
« Reply #12 on: September 04, 2018, 09:16:36 PM »

725watts into 8ohms voltage gain of 36dB. Input sensitivity of 1.25 Vrms. So that should be about 76volts.

1100watts into 4ohms voltage gain of 36dB. Input sensitivity of 1.25 Vrms. So that should be about 66volts.

It look like if I change the threshold to -2dB in the limiter then the "Amp Thresh" will be 49Vpk (with an 8ohm load) and this calculates to 300watts. So I decided to use -2dB as the limiter settings (to be a little bit more cautious) and I will keep an eye and an ear out for the results.

The one time I have used this it seemed to get as loud as when using the passive crossover and the DR4800 for EQ and delay and the sub-woofer crossover. But the amps didn't seem to be working as hard. And the Dx46 didn't look like it was working anywhere near as hard as I have been pushing it on the bench when testing it to get the HF limiter to come on. So unless I get carried away I am hoping I will be safe.

I have tried to turn on the thermal limiter in IRIS-Net but it seems to be a manufacturer setting only. And it comes with the speaker settings that you can get from EV and the thermal limiters aren't yet enabled for these speakers.

Honestly, I say let go of the math...certainly forget watts.
The 3602 is way more amp than needed for your compression drivers....so it's just a matter of safe limiting.

Measure the amp's voltage limited output...that is reality...and all that really counts.
   
Then do the math, looking backwards,  to make it all tie together. 
I've trusted my math, and "nominal impedances" far too many times.....amp output doesn't lie.   FWIW :)
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Kevin Maxwell

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Re: Testing HF limiting in a DSP?
« Reply #13 on: September 05, 2018, 12:04:01 AM »

Honestly, I say let go of the math...certainly forget watts.
The 3602 is way more amp than needed for your compression drivers....so it's just a matter of safe limiting.

Measure the amp's voltage limited output...that is reality...and all that really counts.
   
Then do the math, looking backwards,  to make it all tie together. 
I've trusted my math, and "nominal impedances" far too many times.....amp output doesn't lie.   FWIW :)

Yes the PLX3602 is more amp then the horns compression drivers need. But it is much better than if we were to use the 2nd channel of the amp that is feeding the dual 12s, a PL380.

If measuring the output of the amp I assume that I would have to bypass all of the filtering and crossover and put a 60hz tone thru it. Don’t I also need an 8ohm load to get a proper reading? Since this is just for the horns I think I have a load that will work.

The second to the last show outdoor show of the season is this Wednesday (which by the time I am finished writing this will be today) and I hope to use the Dx46 for this show. I just don’t want to blow up the horns, because I am the one that is pushing for this Dx46 to work. From what I have heard so far I really like the improvement in the sound. I just so fussy I want to make it as good as it can be and I want to make sure it is as safe as I can make it.
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Mark Wilkinson

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Re: Testing HF limiting in a DSP?
« Reply #14 on: September 05, 2018, 07:22:32 AM »


If measuring the output of the amp I assume that I would have to bypass all of the filtering and crossover and put a 60hz tone thru it. Don’t I also need an 8ohm load to get a proper reading?


No, you don't need a load to make a good reading.  That's the simplicity in all this, and the reason to think only in terms of voltage.

Here's a link to the Danley FAQ  mentioned earlier, that might help .... https://www.danleysoundlabs.com/support/frequently-asked-questions/#question_8

Good luck with the show !
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Kevin Maxwell

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Re: Testing HF limiting in a DSP?
« Reply #15 on: September 06, 2018, 11:51:47 AM »

I ran out of time again to tweak it to my satisfaction, I am real fussy. The band showed up early and I didn’t think I could get everything done in the time I had left. When testing it we were able to get playback louder and clearer then I think we ever had done in the past. And we were nowhere near the limiters coming on and the amps were barely reading much signal. I didn’t meter the amp output the boss didn’t feel it was needed. Before next season we will need to find a place to set this all up and tweak it to my satisfaction.

We went back to the DBX DR4800 with doesn’t sound bad at all to do the show, because we have all the setting already in there that we have been using for a while.

I also have the FIR setting (that EV sent me) for the Dx46 for the speakers (EV ZX3s) that we have hung for musicals in a venue that we do a lot of work in, so we are planning on going into that venue when we have no hard time limit and plan on playing with getting that setup tweaked as best as I can. We use one of those as a front fill speaker for these outdoor concerts and recently I played with the Dx46 settings for that and I think it will really help for the speakers for the musicals.

Thank you everyone for all of your help and advice.
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Tim McCulloch

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Re: Testing HF limiting in a DSP?
« Reply #16 on: September 06, 2018, 09:10:15 PM »

I ran out of time again to tweak it to my satisfaction, I am real fussy. The band showed up early and I didn’t think I could get everything done in the time I had left. When testing it we were able to get playback louder and clearer then I think we ever had done in the past. And we were nowhere near the limiters coming on and the amps were barely reading much signal. I didn’t meter the amp output the boss didn’t feel it was needed. Before next season we will need to find a place to set this all up and tweak it to my satisfaction.

We went back to the DBX DR4800 with doesn’t sound bad at all to do the show, because we have all the setting already in there that we have been using for a while.

I also have the FIR setting (that EV sent me) for the Dx46 for the speakers (EV ZX3s) that we have hung for musicals in a venue that we do a lot of work in, so we are planning on going into that venue when we have no hard time limit and plan on playing with getting that setup tweaked as best as I can. We use one of those as a front fill speaker for these outdoor concerts and recently I played with the Dx46 settings for that and I think it will really help for the speakers for the musicals.

Thank you everyone for all of your help and advice.

Good to hear everything went well but not so much about not being able to experiment, measure and listen to the results.
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Kevin Maxwell

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Re: Testing HF limiting in a DSP?
« Reply #17 on: September 06, 2018, 11:56:02 PM »

One of the last times we worked with the singer that will be preforming next week I remember him saying he really needs his monitor loud because he is losing his hearing, or something like that. So maybe for that show I will bring the Dx46 and use it just for his monitors. I should be able to deal with that quickly during our normal setup. With the amps we bring to these shows I should relatively easily be able to do 1 bi-amp monitor mix for him and 5 other monitor mixes and one front fill besides the main speakers. Last time with him and his band we only used 4 monitor mixes. BTW we use EV ZX3s for monitors and as I have mentioned I have speaker setting for them with the FIR filters from EV. And I will be able to compare it to the other monitors on stage that are as we normally use them.
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Re: Testing HF limiting in a DSP?
« Reply #17 on: September 06, 2018, 11:56:02 PM »


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