Current-Amp to drive bass guitar cab? - Page 2

gruni · 18th February 2011, 05:55 PM

Sounds interresting that current feedback is already used in some amps.

The bass top i use is a quite cheap one, but its good enough for me: basskick 707

JMFahey · 3rd December 2011, 01:39 PM

Quote:

Sorry, but that sounds a completely silly idea - the speakers won't be damped correctly, and you're throwing away most of your power.

No, it´s not silly at all ... in a musical instrument amplifier.
1) that´s the point: the speakers won´t be damped (or *much* less than before) , which is good.
There will be a bass peak at the resonant frequency: good.
2) there´s no power wasting at all, because there´s no physical 8 ohm power resistor in series with the load, but the feedback is so configured for the power amp to *sound* like if it was there.
Well, you will lose *a little* power in the current sensing resistor.
I have made such amps for almost 40 years , almost 10000 of them, and I typically use a 0.1 ohm sampling resistor in series with the 4 ohm speaker load, so in a 100W amp I lose 2.5W.
I can live with that.

Printer2 · 3rd December 2011, 02:44 PM

If you like one note bass then I would say the peak is good. If you want more bass why not use the bass control?

JMFahey · 3rd December 2011, 05:13 PM

Well, in the musical instrument world, the peak is good.
And it´s not "one note" (like those horrible bass systems so popular in Car audio).
The effect is like rising 6dB (which is not *that* much) a single slider in an otherwise flat Graphic EQ.
And, after all, that´s exactly what classic tube bass amps do (Fender, Ampeg, etc.).
And the audible effect is not at all the same as rising the bass control by 6dB, because the regular tone control works on a very wide band.
Good, but different.

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18th February 2011, 05:55 PM	#11
gruni diyAudio Member Join Date: Feb 2008	Sounds interresting that current feedback is already used in some amps. The bass top i use is a quite cheap one, but its good enough for me: basskick 707

3rd December 2011, 02:44 PM	#13
Printer2 diyAudio Member Join Date: Apr 2010	If you like one note bass then I would say the peak is good. If you want more bass why not use the bass control?

3rd December 2011, 05:13 PM	#14
JMFahey diyAudio Member Join Date: Mar 2009 Location: Buenos Aires - Argentina	Well, in the musical instrument world, the peak is good. And it´s not "one note" (like those horrible bass systems so popular in Car audio). The effect is like rising 6dB (which is not that much) a single slider in an otherwise flat Graphic EQ. And, after all, that´s exactly what classic tube bass amps do (Fender, Ampeg, etc.). And the audible effect is not at all the same as rising the bass control by 6dB, because the regular tone control works on a very wide band. Good, but different.