A question for all op-amp gurus

[wonderfulaudio]

Hi,

Please see section 4.2.3 (page 22) in application note https://www.ti.com/lit/pdf/tidu035, there is a 3rd order all-pass filter producing a fixed delay of 155.28uS from 20Hz to 3.814Khz. The time delay of filter is shown Figure 31.

How do I modify this filter to produce a delay of 72.5uS till 6900Hz?

Thanks in advance.
Warm Regards,
WonderfulAudio

 

[Mark Tillotson]

Scaling the 100nF capacitors down to 47nF is a factor of 2.13 will give about ~73us till about 8.1kHz I believe

 

[wonderfulaudio]

Thanks Mark. You mean I should scale C11, C13 and C14, right? What about C12?

 

[abraxalito]

C12 doesn't have an effect in the audio band so its best left as it is.

 

[Mark Tillotson]

C12 is for stability at RF.