Who has cascaded two Current-Conveyers/Current-Mirrors ? With buffer on I/O... CFA style.
Thx-RNMarsh
Thx-RNMarsh
is there a simple top-notch class D DIY audio design which accomplishes this? can you point me to the site or schematic etc. Class D has moved quickly in a past few years.
Thx-RNmarsh
Dadod ?? I browsed his thread. Cascoded 2nd stage took my
PSRR about to the same point as the zeners on the diamond.
PS- I'm trying to "stabilize" my parts count 😀 .
Some are "scared" of more complexity than (symasym/badger/DX).
OS
One of the interest of laterals is that at their best thermal point (flat at ~150mA) the quiescent current is perfect for class A at normal listening levels with good efficiency speakers (a requisite for me).
About class D, i believe the problem is the pulse is very short at low levels. So the slightest commutation time error has a great influence. But we are far from CFAs.
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I do it as my sim result shows a little better thd and a better psrr. But again my complete diamond buffer Runs from 15 volt supply.
And part count explodes. Ostripper i right about that DIY people like it simple.
- Sonny
OS it looks as if the green curve is THD only while the others are THD+N, so can't compare?
Jan
No not at diy level, but commercially yes. Bruno's products leave lots of traditional amps in the dust, especially the ncore products with their 5th order compensation loop which includes the output filter as part of the fb loop.
Jan
Dear OS,
cool pictures with cool numbers but missing something like THD20k@100W@8R
It's hard to compare with other simulations if we see a picture with 110V pk-pk and 0.001% THD but don't know which load was attached... 😉
Please forgive me if I have overseen something ...
Happy New Year!
Br, Toni
Dear Jan,
You are right and not. If we measure class AB and class A amplifiers like a class D with a 20kHz filter attached we get better THD curves especially at higher freqencies as shown in the above picture of OS.
(BTW: OS green curve must be without noise while the other curves include noise)
Br, Toni
Hi ontaba
I have always had good mid and highs on my amps. Detailed yet sweet almost a signature on CFA. But they have always been a little weak In the bass Section. But i will go so far to say it was lack of headroom. It is fixed with This one which has 180watt Into 8r
Hi astx,
You are correct about distortion measurements when comparing conventional class AB amplifiers to class D amplifiers. THD-20 is usually pretty meaningless for class D amps.
It is crucial, in my opinion, to measure HF distortion in class D amplifiers with the 19k + 20k (or similar) CCIF IM test. Then the distortion products of greatest interest lie in-band. John Atkinson does this in his Stereophile measurements.
This is NOT to say that Bruno's fine amplifiers do not outperform many conventional amplifiers in this test as well.
Cheers,
Bob
That would be a 380W /8R - for 3 pairs NJWxxxx most likely a peak rating.
At 70V rails - I could get 130v p-p (almost 500W - very short peak/SOA).
The graph I posted comparing Ncore to CFA was giving the Ncore a break.
My THD curve was at 20Khz.
Doesn't LT integrate model noise into the error report? It surely shows model noise (below).
OS
Attachments
... so during your simulated THD analysis you have had attached an 8R resistor, 4R or none or anything else?
110V pk-pk is RMS ~ 190W@8R or am I wrong?
BTW: noise from simulation input doesn't even reflect any real measurement - don't forget every instrument has it's own noise floor. So if you compare real life measurements from Ncore with your amps simulated one is like comparing apples and oranges ... 😉
Br, Toni
I am on hollyday and forgot my ltspice book so i cannot answer on This
This bring me to it: Wurth Electronics has released an ltspice handbook which Linear Technology would not Publish . It cost ~50€ and pretty good.
Well, make a class-AB amplifier with 5th order compensation then, or even better, a fifth-order class-A amplifier. It should be easier than a fifth order class D and distort less.
Dear Bob,
full agree! IMHO Bruno Putzey's class D amplifiers are world class. His paper about negative feedback is well known too.
Happy New Year!
Toni