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Old 16th March 2009, 02:17 AM   #1
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Default How could you run a set of speakers with two different amp classes?

For example how could you power one set of speakers with a class A and AB1? Cheers for any help this has proper got me scratiching my head!
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Old 16th March 2009, 09:35 AM   #2
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http://www.zen22142.zen.co.uk/Circuits/Audio/gem100.htm
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Old 16th March 2009, 11:06 AM   #3
Khron is offline Khron  Romania
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Either that, or Dr. Self's "Trimodal" amplifier
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Old 29th March 2009, 03:56 PM   #4
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I'm contemplating modulating a SMPS with audio to produce a varying voltage for driving a subwoofer in a way not completely different from the "ampliverter" idea.
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Old 29th March 2009, 08:19 PM   #5
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That would be a class D amplifier then, if you get it to work.
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Old 30th March 2009, 11:24 AM   #6
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Back in my early audio days I remember getting all the reference material on audio amplifier design that the college library had. I saw information on the "Tigersaurus" and later-published information on class G and then later, class H. The Tigersaurus was a very brute-force way to increase the SOA of the output stage and was based on the earlier Tiger design. It was later when I was given a copy of Electronics World that I was intrigued by the c. 1966 design of a class D amplifier.

I'm not sure at this time what to call the idea of modulating the hot side of a SMPS to produce a varying signal on the secondary side. Maybe that way offers no real advantage from regular class D, where the power supply voltage on the secondary side remains rather stable.
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Old 30th March 2009, 01:24 PM   #7
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Quote:
Originally posted by Electrone
Back in my early audio days I remember getting all the reference material on audio amplifier design that the college library had. I saw information on the "Tigersaurus" and later-published information on class G and then later, class H. The Tigersaurus was a very brute-force way to increase the SOA of the output stage and was based on the earlier Tiger design. It was later when I was given a copy of Electronics World that I was intrigued by the c. 1966 design of a class D amplifier.

I'm not sure at this time what to call the idea of modulating the hot side of a SMPS to produce a varying signal on the secondary side. Maybe that way offers no real advantage from regular class D, where the power supply voltage on the secondary side remains rather stable.
Varying the supply voltage is known as "dynamic supply voltage" and can be used with analog, digital, and hybrid amplifiers. It is normally used to decrease supply voltage at low volume settings for better efficiency. It is not currently used for modulation of the supply voltage in time with the signal as it would be hard to design a power supply fast enough for that. However, it is possible to implement with digital by adding a FIFO buffer to add a delay.

There's an implementation for an analog amplifier that switches the supply voltage.
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Old 30th March 2009, 01:51 PM   #8
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I've played with the idea a bit, first by driving a speaker in class A mode with the output of a modulated SMPS, and later by doing simulations of a power supply that provides tracking power to a subwoofer amplifier. The response of the power supply was limited, but it should work for a subwoofer amplifier.
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Old 31st March 2009, 10:45 PM   #9
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Use a plain unregulated SMPS and a class D circuit fed with the output rails. It gives the best performance.
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Old 1st April 2009, 02:27 AM   #10
star882 is offline star882  United States
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Actually, decreasing the power stage supply voltage at low volume settings reduces the switching losses. (The logic operates from an independent power supply.)
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