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The Coppertone Saga Continues...

Started by Gerry Rzeppa, July 06, 2014, 08:33:37 PM

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Gerry Rzeppa

All solid state this time -- and it rhymes!

Roly

Very win!   :dbtu:

I like the organ pipe resonator idea.
If you say theory and practice don't agree you haven't applied enough theory.

tonyharker

Brilliant!  What chip does the MAH3 use?

Gerry Rzeppa

Quote from: Roly on July 07, 2014, 08:30:06 AM
Very win!   :dbtu: I like the organ pipe resonator idea.

In this case they don't give "booming" bass -- because the speaker doesn't put much out to begin with -- but they do smooth out the low end nicely. After some experimenting (by ear) I ended up plugging the four longest pipes (to lower their resonant frequency) and leaving the shorter three open. I like mounting the speakers backside-up so the high-frequencies are evenly dispersed. It's really nice being able to walk around while you're playing and not have the tone change drastically.

Gerry Rzeppa

Quote from: tonyharker on July 07, 2014, 10:45:01 AM
Brilliant!  What chip does the MAH3 use?

It uses a TDA7267A, a 16-pin dip, which is unique because all the pins on one side serve as a heatsink when soldered directly to a big pad of copper on the board. It also has a smaller chip surface-mounted on the back (I couldn't read the number but it's probably a 386 or something similar) that it uses to produce the "blues" and "fuzz" tones.

This little Velleman kit ( http://www.amazon.com/dp/B005VUCT5I/ ) is a minimum-parts version of the TDA7267A circuit and sounds remarkably good all by itself -- even playing clean -- with a 9v battery, a guitar plugged directly into one end, and an efficient speaker (SPL 90 or above) on the other. The better the speaker, the better the sound.