Sometimes either the market doesn't have quite what you want, or you just want to scratch an itch. I wanted an amp with the following features and thought folks here might be interested in what I came up with:
The key components are:
Feel free to ask any question or post your thoughts, the whole thing was a lot of fun to do!
On the measurement front, all channels look much like this at 10W into 4.7 ohms. I'm using Archimago's recommended settings for RTA measurement of amps with REW. I'm no expert but seems OK:
Front panel (and heroic dummy load):
The state machine for the 12v trigger, music and front panel button is like this:
And the guts are like this:
- 8 channels to drive 4 way active speakers (Linkwitz LXStudio)
- Really compact to fit in a sideboard
- 100W per channel at < 0.1% THD
- 12V trigger in and out
- Music detection
- Low/no standby power
The key components are:
- 4 x 3eAudio TPA3255 BTL - while each channel can do 250W into 4 ohms, that's at quite high distortion. I'm only using 100W/ch, if that
- 1 x Connex SMS800RS - 48V single ended, and 800W continuous power.
- An auxiliary power board providing +-5v and +-12v, as well as a relay to turn on the main power supply. My word PCBs are cheap to order these days.
- A controller board to run the show, with Raspberry Pi Pico, 12V trigger optoisolator, RMS signal measuring chip, etc. A cheap PCB and a few passive components, plus a lot of interface pins and an OLED display
Feel free to ask any question or post your thoughts, the whole thing was a lot of fun to do!
On the measurement front, all channels look much like this at 10W into 4.7 ohms. I'm using Archimago's recommended settings for RTA measurement of amps with REW. I'm no expert but seems OK:
Front panel (and heroic dummy load):
The state machine for the 12v trigger, music and front panel button is like this:
And the guts are like this:
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