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Old 5th January 2013, 06:43 PM   #7951
bcarso is offline bcarso  United States
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Quote:
Originally Posted by nigel pearson View Post
Mr PP and others . Is there a class D amp which can be built " dead bug " and is > 90 % efficient and < 1% THD . It would be great to have something to work on . I always suspected a NE555 and some FET's should be able to get us somewhere . Hypex is too much like a cake mix for me ( look mummy I made a cake ) .

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Old 5th January 2013, 06:56 PM   #7952
bcarso is offline bcarso  United States
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Originally Posted by nigel pearson View Post
Hypex is too much like a cake mix for me ( look mummy I made a cake ) .
The genesis of Hypex, whose products use, among other later developments, Putzeys' patent that belongs to Philips, is that Bruno started off when he was with Philips to make the lowest-cost class D amp, period. At the time he did it, Philips (having not yet spun off NXP) made certain parts from which the earliest UcD designs were constructed. As a result there are more discretes than might be seen today as cost-effective, although they are still pretty cheap. But it means that board area is larger than more integrated designs. Note that you can use exactly the original reference design if you use NXP semiconductors, no licensing fees required.

The surprise, though, was how well things worked. By requiring only a small delay inserted in the loop, essentially no hysteresis, and counting on the output L-C for most of the phase shift, one makes a self-oscillating amplifier with the output filter inherently enclosed in the feedback loop. Many benefits thereby accrue.
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Old 5th January 2013, 07:15 PM   #7953
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Nigel,
not sure what you're getting at.
maybe I should emphasize that IMO efficiency is not the biggest advantage of class D. my electrical bill is less than GBP 35 during the winter when I turn the electrical heater on now and then. and in all honesty, likely my bike with its low mileage does a decent job at getting few species closer to extinction so I'd be a hypocrite to pretend that I'm green. ok, lecture me, it won't help LOL
it's about size and weight that translates to price. and yes, I don't have an infinite income therefore I need to take that into consideration.
about Hypex, THD and efficiency, I'm even more confused.
the standard UCD180 datasheet lists efficiency at 92%, NCORE at 93%, full power. but as we all know, at idle the output devices still switch so...
I have done distortion measurements with my implementation. at ~100W into resistive 4.7ohms, a 18k+19k intermodulation tests gave a highest product at -80dB. pretty decent. Stereophile reviewed the Channel Islands amp and their measurements pretty much confirm it (actually -70dB at 50W but there must be something wrong in their methods as I have personally tested it).
and NCORE? as per Hypex datasheet it's pretty much unequaled.
so, you don't like Hypex? cake mix? I don't get it. no I'm not a fan boy. I own one but I have no problems admitting it has its issues. in no way perfect. quite the contrary I'd like to find out what's wrong.
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Last edited by mr_push_pull; 5th January 2013 at 07:22 PM.
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Old 5th January 2013, 08:03 PM   #7954
dvv is offline dvv  Serbia
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Looking over the sites of some digital audio amp manufacturers, I noticed that when one added all the extras, which are supposed to make them work and sound better, in the end, they turn out to be not at all cheap. While for the price they will produce nominally more power, I still feel that for the money, I can do better in analog sound-wise, even at the cost of the power output

Of course, every new technology has its gestation period, the time during which its milk teeth need to fall out and be replaced by proper teeth, and I have no doubt that the future belongs to them.

I also feel their time is yet to come. In the meanwhile, I'll stick to analog.
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Old 5th January 2013, 08:17 PM   #7955
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I am using the ClassDaudio mastering amp. I have some very expensive tube amps running in triode. I find the ClassD to be better in all regards.
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Old 5th January 2013, 11:29 PM   #7956
a.wayne is offline a.wayne  United States
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Well run it at 1 ohm and let me know ..i can do that with the ab amps here

Quote:
Originally Posted by mr_push_pull View Post
Nigel,
not sure what you're getting at.
maybe I should emphasize that IMO efficiency is not the biggest advantage of class D. my electrical bill is less than GBP 35 during the winter when I turn the electrical heater on now and then. and in all honesty, likely my bike with its low mileage does a decent job at getting few species closer to extinction so I'd be a hypocrite to pretend that I'm green. ok, lecture me, it won't help LOL
it's about size and weight that translates to price. and yes, I don't have an infinite income therefore I need to take that into consideration.
about Hypex, THD and efficiency, I'm even more confused.
the standard UCD180 datasheet lists efficiency at 92%, NCORE at 93%, full power. but as we all know, at idle the output devices still switch so...
I have done distortion measurements with my implementation. at ~100W into resistive 4.7ohms, a 18k+19k intermodulation tests gave a highest product at -80dB. pretty decent. Stereophile reviewed the Channel Islands amp and their measurements pretty much confirm it (actually -70dB at 50W but there must be something wrong in their methods as I have personally tested it).
and NCORE? as per Hypex datasheet it's pretty much unequaled.
so, you don't like Hypex? cake mix? I don't get it. no I'm not a fan boy. I own one but I have no problems admitting it has its issues. in no way perfect. quite the contrary I'd like to find out what's wrong.
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Old 5th January 2013, 11:31 PM   #7957
a.wayne is offline a.wayne  United States
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Quote:
Originally Posted by john dozier View Post
I am using the ClassDaudio mastering amp. I have some very expensive tube amps running in triode. I find the ClassD to be better in all regards.
Well i guess the death of tubes John , finally .....
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Old 5th January 2013, 11:46 PM   #7958
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Originally Posted by a.wayne View Post
Well run it at 1 ohm and let me know ..i can do that with the ab amps here
I re-read my post that you quoted and I haven't been able to find the part where I said that my amp is/should be able to drive 1 ohm loads. I say "my car won't start" and your reply "yeah and it doesn't do 300 mph either".
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Old 5th January 2013, 11:57 PM   #7959
a.wayne is offline a.wayne  United States
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Ok , but can it do 300 MPH after we start it ....
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Old 6th January 2013, 07:59 AM   #7960
dvv is offline dvv  Serbia
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Originally Posted by a.wayne View Post
Ok , but can it do 300 MPH after we start it ....
No, it can't, it's an 8 Ohm car.
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