Custom Biquad programming....

[bobkatz]

Dear John: I know this question is out of the ordinary, but if anyone has the answer I know it will be you. I am consulting for a studio client and he is getting a Mini DSP unit, the 4x10 HD. He is using the Kii 3 speakers, which are FIR-corrected and have a latency of 89 ms. We are considering using a crossover inside the Mini DSP and feeding his Genelec subwoofers to supplement the KII.

This means we're going to have to delay the feed to the subs by at least 89 ms. This Mini DSP unit has a maximum delay of 30 ms. per output channel. I'm wondering if by using the biquad we can steal some dsp by not using all the filters and get more than 30 ms of delay out of that. Does the biquad syntax support delay? It's a 96 kHz sampling unit. Any ideas?

 

[bobkatz]

Actually, it only has 15 ms. available delay per channel, normally! With the 96 kHz plugin.

 

[John Mulcahy]

You could define some all-pass biquads to delay the sub range, though you only get about 4.5ms per filter for a 100 Hz, Q 0.7071 all-pass. Could also loop the 4x10HD output back through another input to double up on the delays.

 

[bobkatz]

Thanks, John. Well, 4.5 ms. doesn't get me very far towards 90 so it's not going to help. Even if I lose all 10 filters I wouldn't hit what I need!

 

[bobkatz]

And I thought about doubling up but there aren't enough inputs and outputs to accomplish much.