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Class D Switching Power Amplifiers and Power D/A conversion

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Old 3rd September 2009, 09:29 AM   #11
luka is offline luka  Slovenia
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am yes you can, TA105a, or TA2500 from tripath, I think you could make 4kw amp
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Old 3rd September 2009, 12:59 PM   #12
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I am developing and planning to build something similar. Just one DC power supply without reference to ground, which becomes either negative or positive synchronously with the main half-bridge switching states. In terms of charges, Rdson and body diode, halving the Vdsmax requirements for mosfets is truly revolutionary to both distortion and efficiency.
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Old 3rd September 2009, 03:51 PM   #13
MOER is offline MOER  United States
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Default Multi-rail class D

We use variable rail switching in our class D mobile amplifiers.

Saves a lot of heat and also "helps" the MOSFETs

I have also designed a full tracking switchmode supply so one can then hang on a class D or a class B amplifier for ultimate efficiency


Steve Mantz
Zed Audio Copr.
Los Angeles CA
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Old 3rd September 2009, 04:42 PM   #14
fredos is offline fredos  Canada
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Just cascode some slow high voltage high current mosfet with fast low voltage high current mosfet! Dont forget recovery diode! That work up to 6Kw with +/-280V rail. In each half leg of your bridge, you use low voltage as standard mosfet and with the 12-15V supply of the mosfet driver, you simply feed the gate of the high voltage mosfet. In that way, the switching device never ''see'' more than 10-13V. I doo it with SMD high current mosfet, without heat sink! Nearly all lose pass trough the cacoded high voltage fet and recovery diode.
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Old 4th September 2009, 01:02 AM   #15
MOER is offline MOER  United States
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Default Multi rail class D

The slow MOSFETs sounds interesting but it still must be switched.

My power supply tracks the audio waveform so I can keep "X" volts across the MOSFET


Steve Mantz
Zed Audio Corp
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Old 4th September 2009, 04:01 AM   #16
Pafi is offline Pafi  Hungary
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Quote:
My power supply tracks the audio waveform so I can keep "X" volts across the MOSFET
Let's have X=0, and you can make amplifier from a wire!
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Old 4th September 2009, 04:55 AM   #17
MOER is offline MOER  United States
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Default Class D

Let's have X=0, and you can make amplifier from a wire!

Now this is what I call a real smart and constructive reply.
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Old 4th September 2009, 02:24 PM   #18
nitrate is offline nitrate  United Kingdom
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Quote:
Originally Posted by wg_ski View Post
Those motor drives are already going to be operating at a low frequency compared to a class D audio amp. Any global feedback employed would be painfully slow, even for a subwoofer amp.

If you wanted to eke out more efficiency in a sub amp (or get away with slow MOSFETs) lower the PWM frequency first before doing anything more elaborate. A sub amp may be quite happy with 10-20 kHz and switching losses should fall dramatically and there would be no need for any rail stepping. Unless of course, you were using those big industrial FET packs, and putting out 50kW (100 hp). You're not thinking about running 20 lab horns off a single amplifier, are you?
100 Horse power subwoofer sounds good to me!
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Old 4th September 2009, 03:34 PM   #19
Eva is offline Eva  Spain
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Those complex solutions look good... Until someone achieves similar or better efficiency and idle power consumption with a straight output stage
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Old 4th September 2009, 04:54 PM   #20
acid_k2 is offline acid_k2  Italy
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Quote:
Originally Posted by MOER View Post
We use variable rail switching in our class D mobile amplifiers.


I have also designed a full tracking switchmode supply so one can then hang on a class D or a class B amplifier for ultimate efficiency


Steve Mantz
Zed Audio Copr.
Los Angeles CA
I'm trying to imagine a SMPS modulated with audio signals... WITHOUT final stage (class D or class B amplifier).
Don't know if this thing exist, for audio application.
Maybe it's good for a subwoofer
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