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Class D Switching Power Amplifiers and Power D/A conversion

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Old 11th November 2012, 11:02 PM   #21
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I think ChocoHolic was talking about creating an optimal load for the output filter.
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Old 11th November 2012, 11:56 PM   #22
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Quote:
Originally Posted by Redshift187 View Post
That won't work. It'll reduce the impedance to the amp, but it won't increase power to the speaker, which is why the amp works better with lower impedances.

12V bridged amp maximum power into:
4ohm = 36W
8ohm = 18W
15ohm = 9.6W

And those are nowhere near the actual, once you take circuit efficiencies etc into account. You are likely only able to get around 3W of clean power into 15ohm speakers.
I have been looking at Pano's, How much voltage (power) do your speakers need? and according to his formula a 15 Ohm speaker requires less power than 4 Ohm speakers. I am accepting this as being correct because my old 15 Ohm Tannoys require less gain than the 8 & 4 Ohm speakers I have when connected to my T2020.
I had guessed that the Tannoys were drawing less than 3 watts but tomorrow, when the wife is at work, I'll set up for Pano's test, it should be interesting.
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Old 12th November 2012, 02:15 AM   #23
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Speaking very generally, the larger the speakers, the more efficient they are.
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Old 12th November 2012, 04:38 PM   #24
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Quote:
Originally Posted by cotdt View Post
I've tried wiring a TA2022 chip point to point once, and it ended up in 3-foot flames when I powered it on. Something must have been shorted on those little pins! Not recommended!
Yess.. I've had my moments of doubt.
Those pins really are tricky to identify... reliably.
Quadruple checking seems to help.. I hope .
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Old 12th November 2012, 05:57 PM   #25
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Quote:
Originally Posted by Pano View Post
Yes indeed. You just won't get much out of a 12V amp, no matter what the topology. 7 watts RMS into 8 ohms is about all you can expect from the amp running 12 volts on the power supply. 10 watts RMS if you push the supply voltage a bit. That's plenty for my speakers (Altec VOTT), but not for low efficiency speakers.

Clipping sounds nasty on these, so you can't really push it hard like you can a 7 watt tube amp.
Well, I have conducted your test and the voltage requirements for my old speakers is 0.4vac. Doing the math for 15Ohm I'm only drawing .085 watts and thats on Baroque music!
I guess this is why I love my little inexpensive Chinese chip amp so much.
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Old 12th November 2012, 07:37 PM   #26
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Quote:
Originally Posted by Redshift187 View Post
That won't work. It'll reduce the impedance to the amp, but it won't increase power to the speaker, which is why the amp works better with lower impedances.

12V bridged amp maximum power into:
4ohm = 36W
8ohm = 18W
15ohm = 9.6W

And those are nowhere near the actual, once you take circuit efficiencies etc into account. You are likely only able to get around 3W of clean power into 15ohm speakers.
Of course it will not increase the power to the speaker, but I understood that the sound would be the issue, not the power.

And now after your answer I am wondering why the power to the speaker should be the thing which makes the amp working better.
How should the amp notice when a 4 Ohms load is not a speaker but a combination of speaker and resistor?
Of course speakers are not purely resistive, but I strongly doubt the filter of the amp is optimized for the particular complex speaker impedance of any speaker. It is most likely designed to serve the range of 4 Ohms to 8 Ohms in a more or less acceptable way.

Last edited by ChocoHolic; 12th November 2012 at 07:47 PM. Reason: ...send the first answer without text...
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Old 14th November 2012, 07:47 AM   #27
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Default Thanks for taking me to school guys.

Wow Well thanks guys for schooling me. I just about agree with all said. The very same amp I had on the fe103 needle excelled on lower impedance and efficiency now that I think about it cheap little 4 inch woofer and tweeter 2 ways.. The other 2020 I have enjoyed is a pretty extreme implementation. I wish I still has a pick but they are all sold out off ebay. I never have seen such a beautiful board lay out. Phillips blue ten uf Polly's. The ones in the nagras. A board designed to tweak endlessly like a breadboard almost with large spacings on important caps and a grid of holes and large spaced gold plated tracks. And what I find most interesting and unique is they hand wound output inductors on plastic nuts and bolts(about ten mill rather then the usual ferrite). This could be a flaw as well as an advantage as inductance would probably would be less then most ferrite based inductors inviting instability. I found using this amp with high capacitance cable into 8 ohm coral coaxes running a large sla to be a lush warm and quiet enjoyable. Perhaps a lucky combination. But I allso have had it driving a multiway altec 288 on jabo 350hz cutt off ev horn set up playing great now that I recal too! As much as mum is scared of the sla's it is the obvious supply test allso.(She doesnt wanna charge them and I scared her telling her about my RC car lipo battery's bad habits lol)

I agree about tripath chip probably being fake or having quality issues as the older they get too. Thanks Guys aw some schooling.

I agree out at mums power supply's very much most likely have to be reassessed and also I am running one of those digital remote preamps off china ebay out there too. So that could be a factor. I Thought also to up my game and try build a neat Little el84pp for her lounge and give it a shot with the little digital preamp also. I will persevere with the 2020's a little longer having 5 of these 4 of still rapped up but I think I will leave the hypex go for a while until I can have a go at trying to talk her into a el84. I have all the parts already tens time over unlike the hypex.
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Old 14th November 2012, 08:03 AM   #28
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Try NXP89xx chips, they sound wonderfull (I have 8950th from Connex - but don't use them at the moment). They are pretty cheap and have good power from 50 to several 100 watt, and easy to bridge/parallel depending on the need for high power or low impedance.
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Old 14th November 2012, 01:25 PM   #29
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Hmmm I will check. I don't need that much power or to spend so much on a power supply to feed it. There was also A guy on ebay claiming a tiny little Yamaha chip and I mean "tiny" little chip was better then 2020. Here is a google DIY TUBE excerpt "There's a Yamaha class-D chip that may be better for some purposes, the YDA148. Similar power to the TA2020/TA20204, but with the bonus of built-in clipping protection. There's a "Y148" amp board on eBay for about $14 shipped, but I found a cheaper one at Dealextreme (which I ordered a few days ago). " I would like to try it too. """ i do wonder now how easy all these chips may be partially damaged by abuse""""

My hifi - YouTube I run into this Utube Funny Iam listening to this chip amp through my joey Roth chip and and usb dac and trans and techinics sb-f2 trying to figure out if it sounds better lol. Honestly No offense to ever it is. I couldn't live with that set up for half en hour. It seems to shriek like all low end fostecs to me that contain whizzers of the few different ones I have bought or heard so far. I do look foward to trying a really good set of hiend fostecs one day even there horn drivers.

The tinyier chip the more they appeal to me from Zen perspective. If I ever really new what that meant not being Asian Maybe they are just cute.

Last edited by fatbattery; 14th November 2012 at 01:29 PM. Reason: adding the zen
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Old 14th November 2012, 01:29 PM   #30
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I also have the Dealextreme YDA148 amp, but have only tested that it works, not how it sounds. I also have Arjen Helder TA2042 and MiniAMP (MiniDSP).
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