Any DIY Active Speaker Amp Recommendations?

[AetherDrive]

I've went the DIY route and built myself a 4-way active speaker and for the most part I've been pretty happy with it with the exception of the amplifiers running it. I was originally running the system with an AVR (Marrantz SR7008) Direct In and found that at moderate volume it will audibly clip, it also has a buzz which is audible on the tweeter during quieter passages. Recently I got the Fosi V3 to handle woofers and it was nothing short of transformative, the increase in headroom and just overall performance leaves the AVR in the dust and now I'm looking at getting three separate amplifiers to fill out the rest of the channels and retire the AVR. The main reason I'm not getting 3 more V3s is that on power down it has an audible pop and I'm worried that my lower power rated drivers, 15-20 watts RMS, won't be able to survive that as I do turn off my system when I'm not using it. I was also hoping that for the other 3 channels I could spend a little more, up to $200, to get a little bit better performance than the V3. I've been doing quite a bit of research into this but was hoping I could get some input from the community.

 

[Aaronb1138]

Pretty sure you should be safe with the V3s. I just tested my V3 switching on and off and I had to put my ear pretty close to the tweeter on a Kef Q100s to hear the power off pop and it was very soft. I did note it was more audible, but still soft after playing music at volume than simply toggling off and on. If yours is really noticeable, it might be defective. You should be able to check against Amir's numbers if you have some measuring equipment (e.g. an oscilloscope): https://www.audiosciencereview.com/forum/index.php?threads/fosi-audio-v3-amplifier-review.45757/

There is also the coming Fosi ZA3. Similar architecture as the V3 with the addition of bridged mono mode, and something potentially very useful for your setup - a 12v trigger that would let you turn them all on/off as a group if you have a trigger source (e.g. your active x-over / DSP or DAC). That said, it is still said to have a soft pop like the V3. See this post and other relevant discussion of the eval units: https://www.audiosciencereview.com/...anced-amplifier-za3.48552/page-8#post-1777991

The high-end route maybe a bit out of your price range are the multi-driver DSP Hypex nCore based plate amps for active speakers, e.g.: https://www.madisoundspeakerstore.com/speaker-amps/hypex-fusionamp-fa123/

You can check though this consolidated amp SINAD list for other options and check other reviews: https://docs.google.com/spreadsheets/d/1ZlTOYxmPs938gqHjtDABkWS-MApu7uJjzIGnJ2Elm6Y/edit#gid=0 More recent reviews from Amir usually have the on/off pops measured and mentioned when applicable.

Or you can DIY the next step up as far as a using some of the 3e audio modules, e.g. 260-2-29A, though the completed unit sent to Amir had much louder on/off pop than a Fosi V3 when tested - https://www.audiosciencereview.com/...dio-tpa3255-260-2-29a-amplifier-review.50208/ Adding a soft-start/shutdown circuit would be something you need source or design along with other glue components and PSU. The diyaudio forums probably have some direction there.

Edit: One additional protection you can put on the tweeters - a filter / protection capacitor appropriate for 1-2 octaves below their crossover frequency.