TOPIC:

[justify]Hi,[/justify]
I use a MINIDSP FLEX.

I use all 2036X2 TAPS for FIR.

Can i use still BIQUAD coefficient, enough DSP with FIR ?

Because Biquad doesn't work on my MINIDSP FLEX : the vumeter is high on channel with BIQUAD +FIR used and i have to reset -> and sometimes noises and Clack, near to break my speakers

I just want to create inversed ALLPASS FILTER to adjust phase : doesn't work with all excel BIQUAD files.....

Disapointed (FIR works fine but not BIQUAD)

I Want this ALLPASS but with PHASE inverted :

100HZ
SR : 96000
Q: 0.71

Normal ALL PASS PHASE :

biquad1,
b0 =0.990824070391112,
b1=-1.990781430252510,
b2=1.000000000000000,
a1=1.990781430252510,
a2=-0.990824070391112

Same ALLPASS with phase inverted ?

biquad1,
b0    value ? 
b1    value ? 
b2     value ? 
a1     value ? 
a2     value ? 
(i've found a xls on web for inverted allpass, but doesn't work with minidsp flex)

please help

Regards,

Olivier
 

Just use the invert button.  You don't need to change your bi-quads.

Dave.

No, don’t Work. With invert Button the whole channel is inverted. ( my Crossover Phase too)
i want the bquad Phase to be inverted only with all pass to correct linkwitz lr4 24. ( whitout use fiR already used for other )

Maybe you're confused regarding polarity and phase.

You can't "invert" the phase using IIR functionality because that would become an unstable configuration.
The only way to accomplish it would be using the FIR capability.  For a standard LR24 crossover that's easily done using rePhase, or other utilities.

Dave.

I use REPHASE to fix LR24 crossover 100HZ LR24 for my SUB, and export .bin in FLEX

i USE 2036 TAPS for TOP LEFT and 2036 for TOP RIGHT. with maximum 21ms FIR latency.

Latency is not a problem for me, but they is not enough taps.... to correct SUB bass reflex phase and TOP bass reflex phase....

but i've note enough taps in FIR to fix phase of bass reflex top and subs.... so i just want to use allpass filter...

but you answer : impossible to do this with allpass....

I'm not sure if you are understanding.....but you can't unwrap the phase distortion of a crossover using an IIR all-pass filter.
All-pass filters would add 'more' phase distortion.

You need to use your FIR functionality to accomplish this.

Dave.

ofrappier wrote:

I use REPHASE to fix LR24 crossover 100HZ LR24 for my SUB, and export .bin in FLEX

i USE 2036 TAPS for TOP LEFT and 2036 for TOP RIGHT. with maximum 21ms FIR latency.

Latency is not a problem for me, but they is not enough taps.... to correct SUB bass reflex phase and TOP bass reflex phase....

but i've note enough taps in FIR to fix phase of bass reflex top and subs.... so i just want to use allpass filter...

but you answer : impossible to do this with allpass....

 

you import  the fir into the dsp …… from rephase file that was generated in rephase 

an fir filter is not biquad …. Diffrent filter topology completely 


and it can be enough taps if you center the impulse at like try 15ms 

in rephase impulse centering , manually type in box  15ms (lower case)

try different centering values 

also use rectangular windows 

and make sure fir is ieee754.bin 

and also make sure it’s at 96000 as fir speed