"Mighty Mite" Single Ended Amplifier - Page 2

wrenchone · 16th October 2008, 05:04 AM

Just as a statement of purpose, the aim of this amp was to test an alternate approach to biasing the final stage. The standard approach of cathode biasing using a resistor shunted by a large cap would have been a minimum parts solution, and would've worked ok. The purpose here was to present a biasing scheme that would be less compromised during large transient excursions. Another approach would have been to use an LED array like SY did in his "Red Light District" amp, but I didn't want all the gaudy lights and we'd sort of tossed the gauntlet down in a friendly fashion at the last Burning Amp when I mentioned this particular idea. So, here it is - an amp biased with a fast semiconductor-based voltage source. I look forward to some listening tests with sensitive, well-articulated speakers. There was certainly some "slam" using the Paradigms.

ErikdeBest · 16th October 2008, 12:57 PM

Hi Wrenchone

Looks like a nice project, and I hope it sounds very good, to motivate me to put the 21LR8's I received yesterday to good use.

I am curious about your subjective evaluation of the biasing block. I have to admit that I do not yet understand how it works, but if evaluation of the amp is positive at the festival I will spend some time trying to get a grasp on it.

Erik

wrenchone · 17th October 2008, 03:40 AM

Erik, if I were you I would go ahead and build a 21LR8 amp with whatever circuit makes you comfortable. The FET loaded front end with a passive cathode biased UL output would sound quite nice and be very simple. With the proper construction, other output bias schemes could be built on perf board and retrofitted as desired. After all, the amp you have will sound much better than the perfect paragon you haven't gotten around to building just yet...

wrenchone · 20th October 2008, 04:57 AM

"Mighty Mite" saw its day in the sun (there was actually some in the afternoon) at BA. The only fly in the ointment was that few people had speakers quite efficient enough for a flyweight amp like this one. I'll runs some plots of the voltage across the bias circuit during square wave excitation (just for SY - and for my curiosity), but I think the concept has proved its worth sufficiently to try it with a higher powered amp.

16th October 2008, 12:57 PM	#12
ErikdeBest diyAudio Member Join Date: Mar 2003 Location: Itoculo	Hi Wrenchone Looks like a nice project, and I hope it sounds very good, to motivate me to put the 21LR8's I received yesterday to good use. I am curious about your subjective evaluation of the biasing block. I have to admit that I do not yet understand how it works, but if evaluation of the amp is positive at the festival I will spend some time trying to get a grasp on it. Erik __________________ my surname is indeed 'de Best': neither misspelling nor snobbism! Ask SY!

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16th October 2008, 05:04 AM	#11
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	Just as a statement of purpose, the aim of this amp was to test an alternate approach to biasing the final stage. The standard approach of cathode biasing using a resistor shunted by a large cap would have been a minimum parts solution, and would've worked ok. The purpose here was to present a biasing scheme that would be less compromised during large transient excursions. Another approach would have been to use an LED array like SY did in his "Red Light District" amp, but I didn't want all the gaudy lights and we'd sort of tossed the gauntlet down in a friendly fashion at the last Burning Amp when I mentioned this particular idea. So, here it is - an amp biased with a fast semiconductor-based voltage source. I look forward to some listening tests with sensitive, well-articulated speakers. There was certainly some "slam" using the Paradigms.

17th October 2008, 03:40 AM	#13
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	Erik, if I were you I would go ahead and build a 21LR8 amp with whatever circuit makes you comfortable. The FET loaded front end with a passive cathode biased UL output would sound quite nice and be very simple. With the proper construction, other output bias schemes could be built on perf board and retrofitted as desired. After all, the amp you have will sound much better than the perfect paragon you haven't gotten around to building just yet...

20th October 2008, 04:57 AM	#14
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	"Mighty Mite" saw its day in the sun (there was actually some in the afternoon) at BA. The only fly in the ointment was that few people had speakers quite efficient enough for a flyweight amp like this one. I'll runs some plots of the voltage across the bias circuit during square wave excitation (just for SY - and for my curiosity), but I think the concept has proved its worth sufficiently to try it with a higher powered amp.

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