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#21 |
AudioMaker.Tech
diyAudio Member
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One of my other hobbies is building crystal radio sets.
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#22 | |
diyAudio Member
Join Date: Nov 2002
Location: Singapore
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Quote:
Thanks a lot ... looking forward to the table... ![]() |
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#23 |
AudioMaker.Tech
diyAudio Member
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If you build Figure 11, with a 16 Ohm speaker, 1W THD goes to around .5%.
With the adjustable version (Figure 10) with a 50V volt supply, I found a nice sweet spot at around Id=2.42A and Vds=19.9V. There, the 1W THD was .069%, which is pretty nice. You'll get more gain, but less power, so your 16 Ohm speaker needs to be pretty efficient. Now, the point of minimum distortion won't necessarily be your favorite spot. You may want to play with the setting a bit and see what you like best. As for impedances much lower than 8 Ohms, I wouldn't use this little amp with 4 Ohm speakers.
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#24 |
diyAudio Member
Join Date: Dec 2006
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![]() is the 10uf input cap is obligatory? cheers rohan
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#25 |
AudioMaker.Tech
diyAudio Member
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You must mean Figure 10?
There's a table of possible supply values and operating points a little further down the page. Somewhere between 45-55V is good. The cap? I'd just leave it in, but If you're absolutely certain your preamp output is cap-coupled, you could eliminate the cap.
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#26 |
diyAudio Member
Join Date: Jul 2003
Location: California
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juanitox,
Fig9 is just a test setup. Fig11 is probably the easiest to build because it does not require a separate bias supply or the input cap. I am interested in how Fig11 would behave with R3 bypassed with a cap. I suspect that you get much of the advantage of Fig10, but without the added complexity of the external bias supply. |
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#27 | |
AudioMaker.Tech
diyAudio Member
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Quote:
About that input cap: Given enough leakage current, the input will be offset from zero, so eliminating the input cap isn't a slam dunk. Having tested only four parts and and not knowing what to expect from the universe of 2SK82s, I put one in the drawing.
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Visit AudioMaker.Tech Last edited by Michael Rothacher; 4th December 2011 at 05:40 PM. |
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#28 |
diyAudio Member
Join Date: Dec 2006
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#29 |
AudioMaker.Tech
diyAudio Member
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Not necessarily. You could just build Figure 10 instead.
Have a look at the complete schematic I posted at the very beginning of this thread for more info. L'Amp: A simple SIT Amp
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Visit AudioMaker.Tech Last edited by Michael Rothacher; 4th December 2011 at 06:44 PM. |
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#30 |
diyAudio Member
Join Date: Jul 2003
Location: California
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Hi Michael,
I am curious to know more about the effect of leakage current in this circuit. Specifically, what sort of non-zero voltage would be expected at higher leakage numbers? Also, any thoughts on cap bypass for the source resistor? I would like to try the circuit as drawn below. |
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