All tutorials related to equalization of a system with miniDSP platforms.
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 denver8me4dinner Topic Author Offline Platinum Member 3038564518 Posts: 503 Thank you received: 92 I have a set of 2x4HDs I use the APF function and it's fantastic for in car. So I can measure acoustic response and get it pretty good however is a 2nd order APF My question is How do I use biquad to make a phase shift by 11.25 deg and 22.5 deg? Would that be a first order APF ? I tryed using spreadsheet and it won't work right? Can anyone point me to a calc that doesn't use APF order but rather the degrees in phase (even tho one in same) just easier for me to figure out. Or explain exactly what a APF at what order and what Q would be a 11.25° and 22.5° Phase shift (at whatever corner frequency....I'll probably use the crossover point which could be anything. But that's important too... When I look at spreadsheet the Q determines how fast the phase changes but it never stops at a specific degree it keeps going to -180 any help much appreciated Cheers Please Log in or Create an account to join the conversation.

 dreite Offline Platinum Member Posts: 1827 Thank you received: 789 A first-order all-pass has a phase shift from 0 to 90 degrees. You could use the supplied miniDSP spreadsheet to create a first-order all-pass by inputting different formulas to process the Frequency and Fs values. In that case, the b2 and a2 coefficients will be zero. However, I'm puzzled by your objective. First-order and second-order all-pass functions are for duplicating the phase-shifts of appropriate crossovers. What characteristic/application could you have that would need a 11.25 or 22.5 degree correction?? Dave. The following user(s) said Thank You: devteam Please Log in or Create an account to join the conversation.

 denver8me4dinner Topic Author Offline Platinum Member 3038564518 Posts: 503 Thank you received: 92 A first-order all-pass has a phase shift from 0 to 90 degrees. You could use the supplied miniDSP spreadsheet to create a first-order all-pass by inputting different formulas to process the Frequency and Fs values. In that case, the b2 and a2 coefficients will be zero. However, I'm puzzled by your objective. First-order and second-order all-pass functions are for duplicating the phase-shifts of appropriate crossovers. What characteristic/application could you have that would need a 11.25 or 22.5 degree correction?? Dave. Thanks for the reply and help Dave! So , I use my dsps in a car as stated , There's another dsp on the market (helix dsp pro) For a car that has the ability to shift phase in 11.25° Increments. On another forum some folks say that feature is a APF but the corner frequency is fixed at crossover. It has a slider in the dsp that moves ALL the phase of that channel in even amounts. I've been using APFs trying to get the phase shift desired. I just recently got enough experience to gate my responces good enough for a car environment because early reflections are louder than source. So until now I haven't really been able to see the effects of my APF. Well it's shifting too much in some areas and I'm realizing a even shift across an entire channel (midrange in 4way) on one side need to be moved. I have the ability to do it in FIR or biquad just don't know how. I would like to keep it in IIR to free up my FIR Coefficients. However I've been successful using a even spaced shelf filters for phase in rephase, but than The 1024t bank doesn't have enough power to do the crossover I'm using it on. So I need to figure out a way to do it in biquad. I need it for car. Offset seating I have one midrange that moves between 11-22deg OFF fromdriver side midrange through the passband. I tryed using a low Q (.5) APF and it still isn't shallow enough it moves too much phase. I haven't been able to get 1st order to work using spreadsheet so I've been only able to use 2nd order (-180 reversal) If you know a way I'm all ears Much appreciated Andrew Please Log in or Create an account to join the conversation. Last edit: by denver8me4dinner.

 dreite Offline Platinum Member Posts: 1827 Thank you received: 789 You can create a first-order all-pass filter with this setup: b0 = (g-1)/(g+1), b1 = 1, b2 = 0, a1 = b0, a2 = 0, Where g = tan(pi*(Fc/Fs)) b1,b2,a2 are always 1,0,0, respectively. Dave. The following user(s) said Thank You: devteam, Wanderer Please Log in or Create an account to join the conversation.

 denver8me4dinner Topic Author Offline Platinum Member 3038564518 Posts: 503 Thank you received: 92 You can create a first-order all-pass filter with this setup: b0 = (g-1)/(g+1), b1 = 1, b2 = 0, a1 = b0, a2 = 0, Where g = tan(pi*(Fc/Fs)) b1,b2,a2 are always 1,0,0, respectively. Dave. Dave, Thank you! I had to re-watch some biquad building videos, I think I can get it now. Sorry I'm such a rookie . But this I'm pretty sure I can get to work. It might take a few try's:) Andrew Please Log in or Create an account to join the conversation.
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