OT: power conversion

[Bob Mannix]

Well, why I'm not sure, but calculating power as voltage squared over impedance is perfectly reasonable and no cause to bring in the air temperature! It's some sort of average that takes into account the dynamic voltage range of the system. Not that I care, but someone might.

As to the loudness of speakers, efficient speakers are loud and low quality, high quality speakers are inefficient and quieter (generally speaking) so you make your choice. Notting Hill Carnival sound system, go for efficiency and b*gg*r the fidelity, you want to rattle windows, Self absorbed, anally retentive, solo, esoteric hi-fi listening, low efficiency speakers and big amps ;o) !

[Dave Plowman (News)]

Indeed. Recently re-heard some Lowther super efficient speakers mounted in horn loaded cabinets. Driven off tiny amps. And they sounded horrid - extremely coloured sound. Might be worthwhile where power was a problem, though.

[The Natural Philosopher]

Not necssarily.

Best speakers we used in my time making rigs, were JBL horn copies by DAS About 110dB/watt.

Those and bullet horn tweeters covered about 800Hz upwards very very well. superb low distortion a but the frequency response had a few little peaks in it.

IIRC we used 8 or 12 inch units at around 92-95dB/watt - massive magnets on em.

And twin 15" or a single 18" unit to go up to 200hz or so in reflex cabs. Us of lighweigght foam composite cones and BIG magnets gets a very decent efficiency out of even those.

What you are thinking of is crappo hifi. Its easy enough to take a poorly damped speaker and strangle it to get a flattish reponse, and people want '100W speakers' not 'speakers capable of doing 120db SPL'. It sounds ok, its just chap. My DAS studio monitors were massively more efficient. Sadly they have decoiled and need a recone..after 25 yars..

Or if its loud you want, cheap magnet, ultra thin paper cone, a celestion! and into a box..and hey folks, its the Vox AC30!! a very good soundboard for an electric guitar, with multiple interesting resonances and fed from a ovrdriven 100 ohm impedance valve amp with all negative feedback removed for gain!. You cant get better than that ;-)

Loud, for 30watts..

[Dave Plowman (News)]

As do all horns. That's why they're useless for true Hi-Fi.

[The Natural Philosopher]

Well, its a tradeoff. Between sensitivity and flat response. And wide bandwith..

Remember we were only spanning IIRC about two octaves with each unit.

Tweeters came in around 4k, mid horns 1k-4k, lower mid 250hz-1k Bass units 50-250hz More or less.

I don't think I have ever hard better high power clarity than from those horns. Quad ESL'S. yes, but at abysmal power output.

You have to pay real money though. The knock off plastic copies are rubbish.

And decide whether its low intermidulation you want, or a razor flat frequency response. Since any room you put stuff in and any hall you recrd in buggers up the frequency response I don't count it as a huge problem. But rooms don't distort ..loudspeakers do. It jut makes the recording dull.

OK if there is a major and high peak or notch, you can hear it, but not a minor rippling across the band.

Iv always liked top quality horns, but I have never hard them much outsid what we were doing..not in the hifi stores anyway.

[Arfa Daily]

Curved Air ! Boy, that takes me back. Back Street Luv was one of my favourite singles of the 70s ...

Arfa

[Dave Plowman (News)]

Not uncommon to use controlled distortion for an effect. Or are you saying only you could hear the clipping?

BTW - if it had a red section it was a VU meter and doesn't read peaks. So your 'engineer' was pulling your plonker.

[The Natural Philosopher]

I am saying the engineer didn't even bother to listen..

No, he simply thought if it was in the green, it was OK!!!

[Dave Plowman (News)]

Not a sound engineer, then.

No green section on any VU I've seen. Must have been domestic gear which explains a lot.

[The Natural Philosopher]

Figuratively speaking. I should have put invertd commas round it.