19 replies to this topic

[DG Phil]

Yes, good point.

Phil

[ May 04, 2003, 17:43: Message edited by: Incar Phil ]

[DrEvil]

Quote

Originally posted by Incar Phil:
3. A lot of people mistake a power increase for an SQ increase.

This was the 2c i was gonna throw in

Out of the people who have replied further up in this thread, it seems to me as though they have gone from a class A/B (which are not very efficient and producing low wrms) to a class D with a higher rms output and then finding the bass punchier etc.

We need to have some test days i think

[suparoo]

Class-D were originaly quite bad peices of kit, but like most things further development, has bettered them, Class-D amps have quite good THD measurements these days, and like most things it comes down to quality for THD levels. one thing they have always had going for them is there bag for buck power, cheap powerful, and efficient.
But virtually all amps will have a particular flavour of there own, weather its between classes or just brands, and there right about the THD difference not being too noticeable, THD comes into its own at the High end, most THD measurments are taken at 1khz and for a sub amp, youll never go there, down low there all much of a muchness. The dampaning factor will vary alot between classes and brands and basically comes down to the level of output capacitance which comes from the number and type of output transistors.
In my home sterio i run valve amps, Class-A SE amps, a/b and a class-D all have there own distinct flavour, pro-s and con-s, but it really comes down to user prefference, by what sounds good to you.

ps. im just happy your not calling them digital amps for once, cause theres nothing digital about them.

[the[K]id]

*sigh*

Quote

Originally posted by noidea:
Yes, infact the Class D amp is efficient but u have to forgo some of the SQ.

I have seen a Sound electrical book that actually explain this.

Don't believe *everything* you read In theory, yes, class D will have increased THD (esp at higher frequencies), however this is often offset due to a more stable voltage, both 12V and rail, and a larger amount of clean power.

quote:

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Originally posted by LongWay:
[b]the few things I've noticed between A/B and D amps:

*Lower damping factor on the Class D amps
*Higher THD- especialy the shredder- car audio mag tested it at 7.89%- good god!

The only real good thing those dirty amps are good for...is to get loud! But thats what they were designed for...SPL

I'll stick with my A/B amps The massive true class A amps have damping factors so low its not funny (try in the 20's for some) which is in the region where it does make a measureable difference. However these amps *do* have good SQ, are used by some highly regarded audiophiles (and not the kind who think copper makes the sound warmer because its not as shiny as aluminium...), and happily defy their measured specs.

Anyway, even with class AB amps most ppl have near 10% THD in the final sound, so who cares about 1 or 2% in the amp?

PS: As for 'dirty spl only setups' I have heard a concept 2400 (put in the same leage as the 'dirty' shredder) hooked up to a triple spider inhuman (spl sub) and it sounded, well, ****ing beautiful! Crisp, clear, well defined bass.

PPS: Enjoy your class AB powered 10% THD sub setup, hope your battery is good.

[fr0st]

Damping factor in class D comes from the output chokes used in the filter. A skimpy little inductor with high resistance will sound crap and give a poor damping factor. If you get a decent amp with a large inductor damping will improve.
Likewise with switching frequency and THD and more importantly the power supply feeding the amp. Noise filtering is especially important in class D amps since the output is connected directly to the supply rails (though a mosfet but it acts as a resistor). So if there supply ripple u get output ripple. This is combated with excess filter on the output.

Anything in amps will affect the end sound regardless of class. Its how the manufacturer implements it that counts.

If anyones interested in the technology behond class D here is a good example. Look at the datasheet and how things are effected.
Sorry if I talk sh*t