Ian Stirling wrote:

The Natural Philosopher wrote:


Its within range of a bridged single chip car stereo type chip actually.

Especially if run off 15-18v DC. And being used for audio rather than
sine waves or guitars.Where avreage power is probably less tahn a watt,
and smaller heastinks will work.


Yeah.
I'd like a fairly bullet-proof device, and am not really keen on
smaller heatsinks.



Believe me, it doesn't matter. Those all in one chips have thermal
shutdown anyway.

I spent a large part of my life designing audio power stuff. For disco
or gutauisr/keyboarsd use, yes, the bugers run em at full power
contnsuoly. For PA or music uses below the level of gross distortion,
teh peak to mean levels are something like 3-10:1.

I actually think that 'music power' is indeed a meaningful thing. Its
possible to design an amp that may have an RMS rating of 20W, that
sounds as loud for teh same distortion as a 100W true RMS amp.

It depends on what you want it for. For HiFi use I'd rather have peak
power than RMS power, tho both togther are nice.


I was just wondering if someone had stuck a nice class D amp in a little
box.
The Maplin 50W 6 channel amp for 45 quid would almost suit, but i'd really
like the amps seperate.



Class D sucks by and large. Not very hifi - even today.


(I have signal wiring, but not speaker wiring to the speaker locations).

Oh well.

I suspect I'll watch ebay for a while, to see if anything very suitable
pops up.
Thanks.



Someone was selling a mixed bag of car radio chips on there. These are
really incredibly easy to get working - just follow the manufactureres
design notes. Fed from a 12v AC transformer/rectifier/capacitor (about
4700uF) to give about 16-18v DC, (could use nice LV lamp toroids etc)
you get either 5W stereo into 4ohms, or 20W mono in bridge format. Perrt
clean power - usually around the 0.2% distortion at sensible power
level...couple that up to a decent car speaker in a box, and you have a
nice localised sound source. Anyway 5W to 20W is only 6dB, and you can
get 6dB by buying a better than average loudspeaker...
Not sure what the final application is - I asume some way to spread Jazz
FM throughout the house?

Second hand car radioscan be pirated as well.