Yeah, please do. After all these changes and retries, I'm kind of lost
which one is final, working version.
Thanks for the kind words. Can you please elaborate (for us new to the field) on the clipping avoidance of quasi topology? Complementary push pull is not as good near clipping then?
17v clip limit means this is only a 36w amp?
It's a PC CPU heatsink with narrow slots for forced air cooling - if slots wider spacing natural convention would work better. It actually is not too hot - can touch it for 10sec without fan. With fan (reduced speed) it's barely warm. Fans have no noise since so slow. The heatsinks were only $4 so a great value for amps.
When the neg half cycle goes deep the phase inverter drops its collector down to the roughly Vbe of 1.6V when flowing 5A into the speaker. The quasi device directs all this current through the 0.33 ohm emitter and this voltage drop accumulates to 1.7 plus the saturated voltage of the npn. Total loss is around 4V and this is added to the rail sag which would be at least 3 volts at full output. So your neg half cycle clip at 7 volts less than the nominal rai. With 35 rails you would expect neg clip at -28V and the pos clip higher around 30v. Clean output would only be held to 28Vp however.
How does this amp compare with with Mile's Apex quasi Terry?
HD
How does this amp compare with with Mile's Apex quasi Terry?
HD
Ok thanks for the explanation. 28v clip is about 100w then? I have a couple of Circlophones (BJT and MOSFET) and I believe they could be called quasi complementary with same sex output devices and speaker connected in between. I suppose this amp does sound a bit like the Circlophone - which I really think is one of my better amps.
I believe 28Vp is about 20Vrms therefore about 50Wrms into a 8 ohm load.
p.s I'm happy with my 0.75W Darling amp so 50W is plenty..lol
Eric
p.s I'm happy with my 0.75W Darling amp so 50W is plenty..lol
Eric
Hi Hugh,
Which model is Apex's quasi? I don't believe I built that one.
EDIT: Ahhh, The NX14. I did build that one I just didn't remember it being called a quasi. I'm going to have to pull it back out now so I can compare them. It has the same front end as the AX14 so there is no offset drift that I can remember. I will do a comparison between the two in the next couple of days. It's my daughter's birthday today and tomorrow is church so likely Monday.
Blessings, Terry
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Whoa, wait a minute. Is this the amp you refer to?
http://www.diyaudio.com/forums/solid-state/167394-quasi-amplifier-beginners.html
I hadn't seen that one. Another amp to build.
http://www.diyaudio.com/forums/solid-state/167394-quasi-amplifier-beginners.html
I hadn't seen that one. Another amp to build.
Hi Terry,
I quite like Mile's simple quasi but very conventional. He has a great ability to distill the best ideas of electronics into the simple, low count part schematics. Very clever guy. But the one I mean is N10, which I have attached. It is not conventional, and uses a concept I first saw on a Siemens design in the 70s. The question is: how does it sound compared to Ranchu's design, which we now know is quite a fantastic performer.
Have you built this one, XRK and Terry?
Cheers,
Hugh
I quite like Mile's simple quasi but very conventional. He has a great ability to distill the best ideas of electronics into the simple, low count part schematics. Very clever guy. But the one I mean is N10, which I have attached. It is not conventional, and uses a concept I first saw on a Siemens design in the 70s. The question is: how does it sound compared to Ranchu's design, which we now know is quite a fantastic performer.
Have you built this one, XRK and Terry?
Cheers,
Hugh
Attachments
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Hi Hugh,
No, I haven't made this one - actually never even knew about it. Another amp to add to the Apex Directory thread.
Edit: I already added that a month ago. Did not realize it was a simple quasi though.
No, I haven't made this one - actually never even knew about it. Another amp to add to the Apex Directory thread.
Edit: I already added that a month ago. Did not realize it was a simple quasi though.
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Hi Hugh,
This is the first I've seen of the N10. If Prasi or someone will do a layout for it, it is only a day away from singing. I have all the parts. I assume the BD139 needs to go on the main heatsink,
Blessings, Terry
Hi Guillermo,
That is the Siemens topology but the symbols look very like Elektor. A beautiful schematic, thank you for showing it to us!
This circuit has very large loop gain difference between the pos half cycle and the neg half cycle. This gives high levels of H2 and sounds very warm. High THD however.
This early quasis used many pairs of early nmos; in those times because good pmos devices were not available. When complements were available they disappeared in the following THD Wars.
Thanks Terry, I am interested in your thoughts and if you could compare these very different quasis I would be most grateful.
HD
That is the Siemens topology but the symbols look very like Elektor. A beautiful schematic, thank you for showing it to us!
This circuit has very large loop gain difference between the pos half cycle and the neg half cycle. This gives high levels of H2 and sounds very warm. High THD however.
This early quasis used many pairs of early nmos; in those times because good pmos devices were not available. When complements were available they disappeared in the following THD Wars.
Thanks Terry, I am interested in your thoughts and if you could compare these very different quasis I would be most grateful.
HD
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Hi Thiago,
Congratulations!
You might like to remove R4, 47k from input base to ground. It is not needed because the base is set by by R5, which you have set 22k. This will make the amp quite difficult to drive and not much bass; I'd suggest 33k, if you have the energy after getting it going on!! I believe the trimmer will bring back the offset no problem.
How is the sound?
Hugh
Congratulations!
You might like to remove R4, 47k from input base to ground. It is not needed because the base is set by by R5, which you have set 22k. This will make the amp quite difficult to drive and not much bass; I'd suggest 33k, if you have the energy after getting it going on!! I believe the trimmer will bring back the offset no problem.
How is the sound?
Hugh