I am now running the MiniDSP product OpenDRC-DI (digital I/O only) for my super tweeters at 96kHz. A helpful poster at the miniDSP forums gave me the correct information. I needed to obtain the miniShark 4x10 plugin. That was not the plugin linked at the OpenDRC-DI product page.
Once I got the correct plug-in, it should have been simple, but I messed things up and I spent 4 hours sorting it all out. Now it is running a LR4 crossover at 17220 Hz just as with the previous plugin, but now at 24/96 instead of 24/48. This is more suited to a super tweeter setup which (supposedly) responds up to 40kHz.
Once I finally got things sorted out, i re-measured the time alignment and readjusted the time alignment of the leading large edge of the supertweeter response (assuming the tiny edges to be digital pre-ringing). This seems to require 1.30 ms more delay than with the 24/48 plugin, possibly partly because of reduced latency downstream.
There is little use in doing a "cancellation" type of delay adjustment with the super tweeter, and the crossover isn't really that well worked out. The acoustic crossover of the Acoustats is a combination of their own falling response (down at 18kHz) and the LR4 lowpass I have added at 20kHz (to avoid wasting amplifier power into the capacitive load of the Acoustats). This approximates, but not perfectly, a lowpass around 17 kHz, but it needs to be fine tuned better.
Anyway, the leading edge of the output of both Acoustats and super tweeters are fairly easily measured, and I believe it is quite close to exact time alignment required for these drivers (the subwoofer needed 1ms less delay than the leading edge alignment, but subs are different).
It's possible the best type of delay optimization for the super tweeters would come from looking at the impulse response. But that should be done in combination with analyzing better crossover curves.
Once I got the correct plug-in, it should have been simple, but I messed things up and I spent 4 hours sorting it all out. Now it is running a LR4 crossover at 17220 Hz just as with the previous plugin, but now at 24/96 instead of 24/48. This is more suited to a super tweeter setup which (supposedly) responds up to 40kHz.
Once I finally got things sorted out, i re-measured the time alignment and readjusted the time alignment of the leading large edge of the supertweeter response (assuming the tiny edges to be digital pre-ringing). This seems to require 1.30 ms more delay than with the 24/48 plugin, possibly partly because of reduced latency downstream.
There is little use in doing a "cancellation" type of delay adjustment with the super tweeter, and the crossover isn't really that well worked out. The acoustic crossover of the Acoustats is a combination of their own falling response (down at 18kHz) and the LR4 lowpass I have added at 20kHz (to avoid wasting amplifier power into the capacitive load of the Acoustats). This approximates, but not perfectly, a lowpass around 17 kHz, but it needs to be fine tuned better.
Anyway, the leading edge of the output of both Acoustats and super tweeters are fairly easily measured, and I believe it is quite close to exact time alignment required for these drivers (the subwoofer needed 1ms less delay than the leading edge alignment, but subs are different).
It's possible the best type of delay optimization for the super tweeters would come from looking at the impulse response. But that should be done in combination with analyzing better crossover curves.
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