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RE: My DIY Story: nanoDIGI DSP based active crossover and 4 subwoofer integration

Posted by dumpingground (A) on January 3, 2020 at 09:11:46

In Reply to: My DIY Story: nanoDIGI DSP based active crossover and 4 subwoofer integration posted by dumpingground on March 17, 2019 at 16:15:16:

I just thought I might update this thread. After living with the nanodigi based active crossover for some time I am still very happy with the results. I have since started experimenting with different power amplifiers. Given the nanodigi active crossover, I can use different amps on the tweeter vs woofer circuit.

I started with the Parasound HCA1000a power amps on both tweeter and woofer circuits shown in the head of this thread. But I am now using a Nelson Pass Class A Aleph 3 clone on the tweeter and a Panasonic XR57 Class D amp on the woofer.

The Class A amp on the tweeter adds a tremendous amount of air and live feeling to the upper frequencies. The Class A amp is rated 30w/8ohms and 60w/4ohms. So it is lower power, but for the tweeter circuit you need much less power overall.

I will say that the Class A amp in general measures like crap. But if you read Nelson Pass's whitepapers on distortion vs the simplified no feedback designs you can see that there are many benefits to his approach to amplification.

My measurements of my Clone Amp:
https://www.audiosciencereview.com/forum/index.php?threads/class-a-aleph-3-clone-measurement.10646/

Pass whitepaper on Class A amps:
http://www.firstwatt.com/pdf/art_dist_fdbk.pdf


The Class D XR57 is taking the SPDIF digital directly out of the nanodigi and there is no extra DAC in the path. The XR57 was discussed as a giant killer amp years ago and I had one in storage. For two channel only it has an automatic "dual amp" feature which allows the XR57 to drive the left and right woofer with a total of 4 amp channels increasing the current/wattage produced. The Class D amp is great for the woofer circuit adding what sounds like an extraordinary amount of control to the woofer bass frequencies.

Measurements on my XR57:
https://www.audiosciencereview.com/forum/index.php?threads/panasonic-sa-xr57-multi-channel-receiver-review.10480/
https://www.audiosciencereview.com/forum/index.php?threads/critique-my-measurement-setup-panasonic-xr57-avr-example.10589/

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