Low Q Woofer in OB with High Zo Amp

[Pano]

Very Clever! The parallel resistor is a nice idea. That way you can tune the affect of the inductor.

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Last night I tried a 0.5 Ohm resistor in parallel with that previous 2.6mH inductor. It turned out very good. No more horrible on/off cone movements. Buzz noise didn't come back. 2 main goals were done.

Brief listening impression was very similar to the previous [inductor only] stage. As expected, there's a slight change in response curve, a little bit more SPL in 30-40Hz range, so a tad of heaviness. In fact the difference is very little, and I'm satisfied with the result.

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OK, here I summarize all these as follows:

Driver's Qes = 2 * Pi * fs * Mms * Re / BL ^2

And any series R in between driver and the [driving source] should be added into the "Re" in the above formula, thus we got a new (real) system Q. Or, we may set a target system Q, and determine how much series R is needed.

And the series R is made by http://sound.westhost.com/project56.htm

This is the simplied circuit diagram of my current setting (modification) of the plate amp for sub:


And for those who might be interested, attached spread sheet is my 'forecast tool'. In the table, you have to insert your own set of numbers, like the impedance data of the driver. Mine are exported from the mearsurement by WT3.

Any comments are welcome, and I hope someone can correct me on those calculations if anything wrong.

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It works with chip based amp, too. I think it'd be easier to try the concept with chips

Here:
Lm3886 current feedback

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Link correction for post#23: