Application - not exactly hi-fi ... these will end up being part of a charity haunted house (sound effects and such).
Why use TA8251AH - only because I bought a pile of them for <$1 each, on sale at Goldmine Electronics.
http://www.datasheetcatalog.org/datasheet/toshiba/1386.pdf
Why build at all, when cheapo amps on dx.com could easily handle this application - I am sick in the head, and tinkering helps to keep me out of trouble.
So, areas of specific interest to me:
1) Referencing the input "ground" ... I chose to tie it at the chip, but I see some designs that tie it at the input power connector. The latter seems consistent with the star ground.
Example: page 9 of TDA7560 datasheet
http://www.st.com/web/en/resource/technical/document/datasheet/CD00001962.pdf
2) Thoughts on using multiple DC bus capacitors ... I chose to use more, smaller capacitors, whereas typical applications (like TDA7560 datasheet) use fewer, larger capacitors.
Other comments are also welcome. My preference is for inputs based on data or physics. For example, "Poured ground layer bad" is not as useful describing the offending current paths and specific consequences.
Many kind thanks in advance.
~hatallica
Why use TA8251AH - only because I bought a pile of them for <$1 each, on sale at Goldmine Electronics.
http://www.datasheetcatalog.org/datasheet/toshiba/1386.pdf
Why build at all, when cheapo amps on dx.com could easily handle this application - I am sick in the head, and tinkering helps to keep me out of trouble.
So, areas of specific interest to me:
1) Referencing the input "ground" ... I chose to tie it at the chip, but I see some designs that tie it at the input power connector. The latter seems consistent with the star ground.
Example: page 9 of TDA7560 datasheet
http://www.st.com/web/en/resource/technical/document/datasheet/CD00001962.pdf
2) Thoughts on using multiple DC bus capacitors ... I chose to use more, smaller capacitors, whereas typical applications (like TDA7560 datasheet) use fewer, larger capacitors.
Other comments are also welcome. My preference is for inputs based on data or physics. For example, "Poured ground layer bad" is not as useful describing the offending current paths and specific consequences.
Many kind thanks in advance.
~hatallica
Attachments
Answering my own, as I already tweaked it and built it.
1) Made the path from capacitors to Vcc and Gnd shorter and fatter.
2) Allowed for 4 inputs, or jumper for 2 inputs.
3) Allowed for Aux input. Signal trace bisects poured ground layer, presumably reducing noise between left & right sides.
4) Removed Mute function; separated connectors for Standby and Tj voltage.
5) Referenced input signal ground directly to input connector, and expanded signal ground poured area.
6) I kept my 5 x 470uF configuration, mostly for mechanical properties ... the ones that I have in stock are about the same height as the chip amp. Also, it allows me to distribute the capacitance.
I only had time for limited testing, but so far so good.
1) Made the path from capacitors to Vcc and Gnd shorter and fatter.
2) Allowed for 4 inputs, or jumper for 2 inputs.
3) Allowed for Aux input. Signal trace bisects poured ground layer, presumably reducing noise between left & right sides.
4) Removed Mute function; separated connectors for Standby and Tj voltage.
5) Referenced input signal ground directly to input connector, and expanded signal ground poured area.
6) I kept my 5 x 470uF configuration, mostly for mechanical properties ... the ones that I have in stock are about the same height as the chip amp. Also, it allows me to distribute the capacitance.
I only had time for limited testing, but so far so good.
Attachments
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