JezA;433895 Wrote: > You might get a 20w amplifier to drive a speaker to 'deafening levels' > but the reason you would be being deafened is that it will be clipping > transients horrifically on any material with a decent dynamic range > played back at a decent level. Sure a horn loaded loudspeaker will make > a lot of noise with a low powered amp, but at the expense of some > dreadful colourations, not to mention lots of money. I agree with > Labarum, a 20w/channel amp in a £1k product is just odd, most modern > decent speakers just aren't sensitive enough to be driven effectively by > such a product. I suppose you could listen very near-field though, but > if it was me I'd be looking for a decent amp, that didn't constrain my > choice of speakers or playback dynamic range. After all Phil, you > yourself are using a 90w/ch amplifier to drive a tweeter!
Erm...yes, part of the benefit of using active speakers is to avoid the 3-6dB insertion loss of the passive crossover, making more "watts" available as sound and less as heat... It's a peculiarity of the Linn active approach that ones ends up with identical amps driving all speakers when 20W would be more than adequate for the tweeter. Other manufacturers (Meridian, ATC) use different sized amps for the different drivers. About the clipping. A well-designed 20w amp will not clip, it will give full power bandwidth delivery into a stable load cleanly up to the limits of its supply rails. The deciding factor in "will it go loud enough?" becomes the effeciency of the speakers. For a properly designed amp with a GOOD power supply, Clipping should not occur unless the load impedance falls below the expected range (4-8 ohms) or the input is overdriven. Let me try it another way... any amp you buy these days should not clip at all at full volume into a non-reactive 8-ohm load and with the correct input signal...regardless of whether it is 20w or 200w rated. This became an issue when CD was introduced because many pre-amps of the day couldn't handle the line level signal (2V) and were merrily clipping away which in turn overdrove the power amps into full power near-square waves and a few tweeters got fried! In the 80's there was a passion for complex crossovers (Apogee Scintilla's, 'Bariks etc) which could drop to 1-2 ohms impedance at certain frequencies and even some otherwise very good amps couldn't handle that. Earlier, in the 70's, many tweeters got fried because the amp power supplies were rubbish and couldn't deliver the demanded power cleanly and clipped inelegantly. The NAD3020 was the first amp I remember that had a "soft-clipping" option to try and mitigate against the limits of its internal power supply. Modern box speakers (not horns) can achieve 90dB/w/m sensitivity and thus only demand half as much amplifier power as one rated at 87dB/w/m for the same SPL. The other part of the equation is, how big is the room? In a typical UK room - say 6m x 4m? - with a listening position of 2-3m from the speakers - I reckon 20W into effecient speakers will produce an adequate level for most people. Sure it won't have the dynamic headroom for realistic Telarc cannons... or sound like your head is stuck in the bass bin at a Deep Purple gig... but it should sound fine most of the time. Back in the 60's - early 70's, 20W was considered to be a lot of watts :o) Most of the revered valve amps (until more recent times) didn't give up more than 50w... Quad, Radford, Leak, Rogers etc, but then again valve watts are different anyway ;o). As I recall it was the emergence of the Mosfet tranny amps that kick-started the high power years. Some really nice Class A tranny amps (MF A1, various Sugdens) were around 20W. It really does boil down to how well designed the amplifier is and how loud you need the volume to be in your room. There's no law of the universe that says 20W can't be very loud indeed with the right speakers/room.... and into the same speakers, 200w is only twice as loud as 20w :o) Finally, the maximum level you can achieve is governed by teh max clean SPL of the speakers as well as the power deliverycapability of the amp. Regards Phil -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... SB3 (wired) - TACT 2.2X (Linear PSU) + Good Vibrations S/W - MF Triplethreat(Audiocom full mods) - Linn 5103 - Aktiv 5.1 system (6x LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Townsend Supertweeters, Blue Jeans Digital,Kimber Speaker & Chord Interconnect cables Outdoors: Boom ------------------------------------------------------------------------ Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=64680
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