SRX 715 bi amp settings

[jlb]

 

Wondering if there are any potential issues with these settings. I have A/B between passive and;bi amp and the overall performance of the 715 is improved. The setup:;Crown ITech 4000, channel 1 low's channel 2 highs. It was recommended that I use the tunnings found in the dbx 4800. Supposedly the the ITech DSP is based off the 4800. Please advise.

Crossover settings:

 

Lows;;

HPF 91.86 Hz LR 48

LPF 1.14kHz LR 48, ;gain -1.7db

Polarity +;

Delay .208ms/ 0.23ft

Highs:

 

HPF 1.12 kHz LR 48

gain - 16db (I adjusted this to -13 db to brighten up the high end)

Polarity -

 

EQ filters:

 

Lows:

1. 6 db octave Shelf 183.72 Hz + 3db

2. Bell 500Hz -1.5 db Q .92

3. Bell 93.6 Hz +3.5db Q 2.92

4. Bell 250Hz -2db Q2.92

 

Highs:

1. Bell 12.7kHz +6.5db Q 2.46

2. Bell 2.38khz -3db Q1.95

3. Bell 5.55khz -3db Q 4.13

4. Bell 1.62kHz -1.8db Q 1.74

 

Limiters:

Lows:

RMS 800w 4 ohms attack 4sec release 6 sec

Peak 110v 4 ohms attack .010sec release 1sec

Highs:

RMS 75w 4ohms attack 4sec release 6sec

Peak 30v 4ohms attack .010sec release 1sec

Thanks for fixing the forums!

[agedhorse]

Is this for using with a sub or not?

 

What I see that does not match my experiences developing DSP for client SRX series is that the 91Hz HPF is questionable or plain wrong unless using with sub. There is a LF shelving eq that doesn't make sense either.

In the HF section, -16dB of HF gain relative to -1.3dB of low gain is too much difference, The net should be between 10 & 12dB which your change to -13dB corrects for.

You might take a look at the 260 settings and see what the differences might be. I have found there to be errors in the 712 settings throughout the DSP models so I would expect this to be possible on the other models.

Also, I would take the RMS limiters down to an attack time of 1 scond on the HF as well. If you have a 4 second "loss of good judgement" event in the HF range, you have big problems happening and that's an expensive to replace.

[jlb]

I am using 4 718's for subs. LPF 88.6 Hz LR 48 -2.7db gain

 

The DR 260 specifies 0 gain for lows and -14db for highs. Also the delay is on the highs at .21ms. No polarity differences between the lows and highs with the DR 260 settings. There is also a L shelf filter at 183Hz

 

Thanks Aged

[agedhorse]

It's possible that the HF lift eq extends low enough to require less HF gain. I can't find any of my info or worksheets on the 715 to doublecheck.

Every engineer has their own personality when it comes to developing DSP. Many come to the same or similar point but some are just plain goofy with multiple wrongs attempting to make rights...

[jlb]

The tunings you came up with for the 712 a while back are much better than the DR 260 settings.

 

Would you recommend setting the RMS limiter attack time to 1 sec for the low and sub? All my RMS limiters are set at half the drivers RMS rating.

[jlb]

I used these settings for a recent gig and had to adjust the levels dramatically in every bandpass. With the original settings I was clipping my inputs way before any output limiting. I adjusted the subs to + 12db, mids +10db and highs to -3db. This did the trick and the system sounded/performed great. I was told a while back not to run any bandpass below 0 with the ITechs.

[agedhorse]

 

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jlb wrote:

 

I used these settings for a recent gig and had to adjust the levels dramatically in every bandpass. With the original settings I was clipping my inputs way before any output limiting. I adjusted the subs to + 12db, mids +10db and highs to -3db. This did the trick and the system sounded/performed great. I was told a while back not to run any bandpass below 0 with the ITechs.

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That would indicate a poor DSP algorithem IMO. Where did you have the input sensitivity controls? On some DSP amps, this can be a major issue and input clipping can occur if they are substantially below wide open and being driven hard to compensate.