I made simple 2 stage push-pull amplifier. It sounds quite nice and measurements are not so bad too.
More about it at http://www.moxtone.com/s2s.htm .
More about it at http://www.moxtone.com/s2s.htm .
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sounds like you're trying to say this is a bit of a hafler transnova clone. my croatian is REALLY bad :-(
never seen it done without using lateral MOSFETs at output.
mlloyd1
never seen it done without using lateral MOSFETs at output.
mlloyd1
vuki said:Please, take a closer look at the schematic and measurements.
That's not a source follower on output - output stage has voltage¤t gain!
Upupa Epops said:Voltage gain ? Really ?
Some background reading:
http://www.tubecad.com/2004/blog0006.htm
I guess Malcolm is his first name
vuki
Your project is quite interesting, at least schematic-wise, easthetics of your electronic circuit is awful.
Just joking, I know what "prototype" means.
Seriously I see a potential issue, namely suppllying huge gate current of output mosfets from jfet stage. You can see drop on frequency responce at rather low frequencies. Drivers would be helphul, but this won't be 2 stage amp anymore. Other solutions is increasing output stage bias and therefore transconductance, so that mosfets become 'lighter' load. You can also add some source to source caps at jfet differentials (Otala-styled phase lead) for some speed up. Value should be 0.5-2nF.
regards
vuki
Your project is quite interesting, at least schematic-wise, easthetics of your electronic circuit is awful.
Just joking, I know what "prototype" means.
Seriously I see a potential issue, namely suppllying huge gate current of output mosfets from jfet stage. You can see drop on frequency responce at rather low frequencies. Drivers would be helphul, but this won't be 2 stage amp anymore. Other solutions is increasing output stage bias and therefore transconductance, so that mosfets become 'lighter' load. You can also add some source to source caps at jfet differentials (Otala-styled phase lead) for some speed up. Value should be 0.5-2nF.
regards
@darkfenriz
Thanks for the suggestions and compliments
I'm really satisfied with this amp as it is - it sounds good and I don't think it measures very bad. Also, this was not a "blameless" type of project, because in my expirience "blameless"&co. amplifiers were far from blameless regarding sound.
The amp does round the edges of the high frequency square waves, but I don't think it affects the sound very much.
Here is 20kHz sq. wave 2Vpp/8R
and in the next post is 200kHz. There is no signal attenuation, just somewhat rounded edges, but at that high frequencies my generator isn't perfect either (3rd post)
Thanks for the suggestions and compliments
I'm really satisfied with this amp as it is - it sounds good and I don't think it measures very bad. Also, this was not a "blameless" type of project, because in my expirience "blameless"&co. amplifiers were far from blameless regarding sound.
The amp does round the edges of the high frequency square waves, but I don't think it affects the sound very much.
Here is 20kHz sq. wave 2Vpp/8R
and in the next post is 200kHz. There is no signal attenuation, just somewhat rounded edges, but at that high frequencies my generator isn't perfect either (3rd post)
Attachments
vuki said:
This reminded me ODFNB amps from http://www.ne.jp/asahi/evo/amp/odnf/odnf.htm and other on Evolve pages.
I have built an amp of only 2 hexfets, and described it here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=57892
@padamiecki
I have used amp like that for some 10 years, but decided to "improve" the idea a bit, because "2 transistors" amp had small gain and was source-dependent. But, yes, with good preamp the sound was excellent and that was one of the reasons to make s2s amp.
Regarding your schematic - I couldn't get stable bias with resistor, so I used therm. coupled Vbe multiplier, but my PS was +/-34V.
I have used amp like that for some 10 years, but decided to "improve" the idea a bit, because "2 transistors" amp had small gain and was source-dependent. But, yes, with good preamp the sound was excellent and that was one of the reasons to make s2s amp.
Regarding your schematic - I couldn't get stable bias with resistor, so I used therm. coupled Vbe multiplier, but my PS was +/-34V.
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