Grrr - this is a common and seemingly self-perpetuating error. You don't
mean RMS watts, you mean mean (i.e. average) watts, for a sine wave, into a
resistive load. You mean the product of the RMS output voltage and current
into the load. This is the average value of the power delivered - the
'heating power' in other words. That's the whole point of using RMS values
for voltage and current, but it's nonsensical to talk about "RMS power".
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.
(i) skip. Find any old cheapo radios etc and adapt them.
(ii) as pointed out computer speakers if you want the speaker as well.
(iii) roll your own PCB including supply etc - useful if you need 10plus.
I'd like a fairly bullet-proof device, and am not really keen on
I was just wondering if someone had stuck a nice class D amp in a little
The Maplin 50W 6 channel amp for 45 quid would almost suit, but i'd really
like the amps seperate.
(I have signal wiring, but not speaker wiring to the speaker locations).
I suspect I'll watch ebay for a while, to see if anything very suitable
Believe me, it doesn't matter. Those all in one chips have thermal
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.
Class D sucks by and large. Not very hifi - even today.
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.
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