So I purchased 3 of these ISD1820 recorder/loopers. I planned on running all three in parallel, with speed/pitch controls to make a fun recorder/playback/looper toy for my 2.5 year old son.
So I wired them up, and used 100k resistors on the output of each board and ran them to a 386 amp. The recorder boards work. I can record and they play back. but they all interact with each other, and it sounds VERY quiet, yet very distorted. So I tried a simple summing amp with an opamp. Sounds exactly the same.
I have no idea what I'm doing wrong. Anyone have any ideas?
Running each board individually works beautifully. Its just when trying to mix them together is when I run into problems.
Here are the boards I bought:
http://www.ebay.com/itm/Voice-Sound-Board-Recording-ISD1820-Recorder-Playback-Module-On-board-Microphone-/221570303609?hash=item33969e8679:g:~H8AAOSwr81UNLZgand here is some info on the board along with the schematic:
http://gotronik.pl/img/isd1820_module_manual_v01.pdf
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