Styx said:Yes you can but what is the point!!!!
Direct Mains.
You would still need a XFMR to provide mains isolation
This gives you 0-DC_High
Output stage is now made up of 4 switches in H-bridge configuration (as opose to a phase-leg).
This then needs to feed a more complex L-C filter arrangement to then drive another XFMR to step the voltage down to speaker-level
So all in all you end up with two XFMR (instead of one), two extra switches and a more complex output filter
Styx said:I thought the original poster was after building a Class-D amplifier?
If so I would want a XFMR in there for isolation.
Yes SMPS can have isolation, but I didn't think that was what he was asking, I might of mis-read
Death By Bass said:Styx said:I thought the original poster was after building a Class-D amplifier?
If so I would want a XFMR in there for isolation.
Yes SMPS can have isolation, but I didn't think that was what he was asking, I might of mis-read
my idea, would have a high frequency transformer on the high voltage, high frequency class D output from the amp, which would provide isolation from the mains...
Nigel Goodwin said:Death By Bass said:Styx said:I thought the original poster was after building a Class-D amplifier?
If so I would want a XFMR in there for isolation.
Yes SMPS can have isolation, but I didn't think that was what he was asking, I might of mis-read
my idea, would have a high frequency transformer on the high voltage, high frequency class D output from the amp, which would provide isolation from the mains...
It sounds a pretty pointless exercise?, and has the HUGE disadvantage that it's not got a regulated supply, and that the entire workings will be live to mains! - don't forget, you would also have to provide isolation for your input!.
You don't have your location filled in?, but it's quite possible that you're in a country with a fairly unreliable mains supply?.
Dean Huster said:You don't want a regulated supply for a power amplifier because it wouldn't be able to handle transients involved with bass and percussive instruments.
NOW, if you're going to have a Class D amp, what's the point of a 40-pound power transformer?
Dean Huster said:Nigel, that's always been the argument against using a regulated supply for an audio power amplifier. The supply voltage to an op amp or an output amp has no affect on the output voltage for a given input voltage. In only affects how high that input voltage can be before clipping the output. If you have to be able to handle the current levels of any signal using a regulated amp, the regulator has to be capable of regulating at those high current levels, meaning a supply that is at least four times larger than necessary for most program material.
Please don't insult me, as I'm not a golden-eared audiophool nor a 5th Avenue marketing man. I measure my amp power in RMS watts and also specify the distortion at that level. To tell you the truth, I've NEVER seen an audio amp with a regulated supply, whether Sansui, Pioneer, Marantz or whatever.
Nigel Goodwin said:Dean Huster said:Nigel, that's always been the argument against using a regulated supply for an audio power amplifier. The supply voltage to an op amp or an output amp has no affect on the output voltage for a given input voltage. In only affects how high that input voltage can be before clipping the output. If you have to be able to handle the current levels of any signal using a regulated amp, the regulator has to be capable of regulating at those high current levels, meaning a supply that is at least four times larger than necessary for most program material.
But that doesn't apply to a class-D amplifier, changes in the power rails are transferred directly to the speaker - as will mains hum on the supply rails.
spuffock said:I think this argument has gone off at a tangent. We seem to be using a SMPS to power something which is basically a SMPS. Why the hell can't we just modulate the first one?
Death By Bass said:use 12volts, at high current, switching it (class D amp), then stepping the voltage UP!!! (bit safer to try this, than a mains powered amp)
Nigel Goodwin said:Death By Bass said:use 12volts, at high current, switching it (class D amp), then stepping the voltage UP!!! (bit safer to try this, than a mains powered amp)
It's common practice, most modern car amps do just that!.
Death By Bass said:Nigel Goodwin said:Death By Bass said:use 12volts, at high current, switching it (class D amp), then stepping the voltage UP!!! (bit safer to try this, than a mains powered amp)
It's common practice, most modern car amps do just that!.
no they don't... I'm yet to see a single amplifier that does actually. :?
- but way back, before switch-mode supplies were used in car amps!.
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