Happy New Year!

Happy New Year to you too, Pimpom, and to all the SED crowd.

Cheers

Phil Hobbs

Six hours early, here.

Sounds like fun but we'll be in bed _long_ before 4AM(LT). We never go out on NYE, anymore. It's for amateur drunks, here in the US. We were at a neighbor's for Christmas but tonight and tomorrow, it's just the two of us at home.

You'd better invite your neighbors. ;-)

Happily, the society here is not yet at that stage where anyone would seriously resent neighbours having some noisy fun as long as it doesn't happen more than a few times a year. And my colony is somewhat isolated too.

What sort of design have you in mind? Conventional or something odd?

Happy New Year!

NT

Sydney had it's New Year celebrations rather earlier. We watched the firewo rks from our balcony - we can't see the Sydney Harbour Bridge, because some body built a forty-story apartment tower between us and the bridge, but we can see at least three fireworks barges along the harbour, and they look be tter in real life than they do on the TV (which we left on so that we could see bridge extravaganza, when it finally happened).

When I was working in the Science Faculty workshops at Nijmegen University in the mid-1990s, I got to hear about their kilowatt audio amplifier system which got rolled out for big students events. We lived about kilometre awa y from the university, so we also got to hear it in action from time to tim e, though not at hearing-damaging levels.

The "these sessions" made it sound like you did this often. ;-) We once had a neighbor put a pool in their back yard. From then on, they had an all-night party *every* weekend during the summer months. It got old pretty fast.

In 1981 I saw Pink Floyd performing "The Wall" at Earls Court in London. My memory is a bit hazy, and I could be wrong, but from what I remember from the programme notes a total of 55kW of amplification was used, of which 18kW was for "subsonic" effects when the wall was brought down near the end. But would a building - even as big as Earls Court - really require 37kW of amplification for the music?

It was a quite remarkable concert, and probably one of Pink Floyd's greatest live performances.

Nothing really powerful - maybe a couple of hundred watts. Quality-wise, I'm aiming for "good" rather than audiophool stuff. For the power amp, I'm weighing my own Class AB design against the convenience of using cheap Chinese Class D modules. For the "odd" part, I thought I'd try my hand at building Karlson speakers to get good bass from a compact system.

I'm still undecided about the mixer. I don't need a zillion input channels and I like building my own stuff. Still, with the very limited facilities available here, I don't know if I should undertake the extensive designing and mechanical work involved in building a full-featured mixer from scratch - balanced and unbalanced inputs, phantom power, equalizers, gain, pan and effects controls, reverb, level indicators and so on.

If it spends most of its life putting out a watt or 2, class AB/B would be extremely inefficient, costing you unnecessarily. These days I'd be tempted to go class D. To get 200 real watts you'll need about 2 million Chinese w atts. I can't imagine what you'd need 200W for though.

Piezo tweeters are great for efficiency. Frequency response tends to be a b it uneven but they still sound pretty good.

NT

Not always. They have plenty of modules based on chips made by ST, TI, Philips, etc. with known specs. E.g.-

All I'd have to do is add a power supply and place the whole thing in a well ventilated box.

This is to be a sound reinforcement system for belting out numbers karaoke-style or with live instruments on my front yard. The last occasion was my son's wedding a couple of months ago when we hired a small PA system. The 150-watt set was barely adequate.

cheap for what they are. I don't doubt they'll come with cap failures down the line, fan too probably, but that's life.

Speaker efficiency varies a lot. But then amps are cheap, relatively.

NT

I've been using many Chinese products for a long time. Some *are* as bad as a lot of people make them out to be but not all of them, especially if you know what to expect and take certain precautions.

I'd go with class-D, though the power supply is likely to be the biggest problem and dominate the cost/work.

How about a DSP Evaluation Kit? An ADI Sigma-200 will have enough resources for a pretty sophisticated 2-channel mixer/equalizer. Feed the digital out directly to the class-D amp module.

Ditto. Trouble is there's no way of knowing which is which.

NT

Some of the Chinese test equipment is quite good. I dumped a Tek DPO2024 as my bench scope, in favor of a 500 MHz 4-channel Rigol.

We don't need no amplification We don't need no tone control No wow and flutter in the tape deck Just leave those sound effects alone .. HEY! LAYMAN! Leave those knobs alone! .. All in all, it's just a Happy new year to y'all.

Cheers

Well, they're a hell of a lot better than they used to be, generally speaking.

That's relatively small beer. Deep Purple probably used the most amplification ever during their recording session at Montreaux in 1972 where they used the mountains behind the resort as a natural echo chamber. The noise level was equivalent to all four of Concorde's engines held on full throttle. Douglas Adams parodied them in the Hitchhiker's Guide to the Galaxy:

"Disaster Area was a plutonium rock band from the Gagrakacka Mind Zones and was generally regarded as not only the loudest rock band in the Galaxy, but also as being the loudest noise of any kind at all. Regular concert goers judged that the best sound balance was usually to be heard from within large concrete bunkers some thirty-seven miles away from the stage, whilst the musicians themselves played their instruments by remote control from within a heavily insulated spaceship which stayed in orbit around the planet - or more frequently around a completely different planet.

"Their songs are on the whole very simple and mostly follow the familiar theme of boy-being meets girl-being beneath silvery moon, which then explodes for no adequately explored reason.

"Many worlds have now banned their act altogether, sometimes for artistic reasons, but most commonly because the band's public address system contravenes local strategic arms limitations treaties."

I don't know about "generally" but the better stuff is quite good. The not so good stuff is still absolute junk or downright unsafe. I certainly wouldn't trust a UL stamp on anything Chinese (that didn't have a US manufacturer's name on it). I don't by anything electrical from Harbor Freight, for example.