Engineering News

Keep trying. Phillips built this 1,000 Watt behemoth using tubes!

You can see it in operation here performing a pipe organ passage.

That was awesome; it wouldn't look out of place in Frankensteins laboratory.

I don't see the point!

If you are at home, then 5-10 w/ch is usually enough for Widor's Toccata (even less for better pieces), 20-50 w/ch if you've got a really big listening room and inefficient speakers. Beyond that, you need to be at the church/cathedral where the organ is located (sorry, perhaps we are lucky here in Europe).

A venue that is large enough to require 1000 watt amps will lose all the benefits of valve (tube) vs, solid state, so what is the point, beyond saying "we do the biggest!"?

Where does all the Power Go?

For the home, 1,000 Watts is overkill unless you have some inefficient speakers. However, I will show you how a typical set of modern speakers can eat up those Watts faster than you think.

For commercial sound reinforcement, 1,000 Watts is totally another matter.

First, consider that power (Watts) versus SPL (sound pressure level) is not linear. You must double the power in Watts for every 3 dB increase in SPL. The human ear can discern about 1 dB of SPL change. So, 3 dB is not that much louder as far as the ear goes because it operates on a logarithmic scale and not a linear scale.

As an example, my speakers are efficient at 94 dB/Watt. I have a 50 Watt per channel amp. That means I can produce about 110 dB peaks at 50 Watts out of a single speaker. That is about what a typical symphony produces, but there is also another catch! I'll explain that one shortly.

Many modern home speakers are only 84 dB/Watt. To reach the same SPL volume that my speaker delivers at 50 Watts requires about 500 Watts! 1,000 Watts would only raise the bar another 3 dB to 113 dB. Maybe that isn't so pointless.

Back to my speakers. That 94 dB/Watt rating is at 1 meter. SPL also falls off at the square of the distance. At 10 meters that SPL of 94 dB effectively becomes 74 dB. That is not much louder than a typical vacuum cleaner.

In a large concert hall the distances are even greater. 1,000 Watts is a trivial amount of power at such venues.

Also, remember, that 1,000 Watt Phillips amp was built in the days when vacuum tubes were the only way to make amps work, so it was quite a technological wonder back then. Back then speakers were very efficient, too. They had to be because amps were pretty anemic by today's solid state standards.

Today, you can easily buy 1,000 Watt per channel amplifiers for sound reinforcement as well as home audio. Heck, they even have such behemoths for your car. They are not hard to miss. Just listen for those cars where all the body panels are rattling lose.

As one *acoustic* watt at one metre at 100% conversion efficiency counts for 120dB (ie, @1W-m), that 94 dB (@1W-m) figure you cited is one way of saying that your speakers' conversion efficiency is well under one percent? Yes? Why so low? The astronomical acoustic-impedance mismatch between the transducer (your speakers) and free air, perhaps?

Not just yours, AH, but typically?

What is being done to remedy this DISMAL situation generally? (Quite apart from mounting your amp's circuit boards in, say, glorified engine blocks as might new entrants in the Audio Security industry and charging $115k per, for instance).

Anyone? Lots of room for improvement in this area. Lots!

Yep. 1 percent is good on a good day.

In the speaker, there are at least these losses -

crossover networks

resistance in the voice coil, lost as heat

"electro-motive, not steam locomotive" drive of the drivers

Crummy, really, for the most part, magnets and magnet engineering. Other than changing from iron ferrite to alnico to neodymium, there's not much happening in magnetism that can give higher voice coil gap flux density.

After Organic Chemistry and NMR qualitative analysis, I always knew with the right money and enough liquid helium to get superconductive, we could make an electromagnetic driver and get the gauss up to something that was approaching the danger zone for home use - around 2 tesla or so... kidding. Maybe .01? Still hundreds of times higher than most speaker's permanent magnets.

"hey yall come check out my speakers from GE Imaging Science... you can hear them a mile away, and get an MRI at the same time..."

The free air resonance of the driver is never a match for the FB of the box so there's "acoustic friction" there.

There's resistance in the wire. Not as much if you use Hg wire, just don't touch it.

Mechanical losses because the driver has to be strong enough to withstand the voice coil shove, while light enough to accelerate quickly. See carbon fiber woofers, et al, for more examples.

And while not exactly a reason -at every step in the chain, from Vocal Chords to Vocal Masters, everything in audio that boosts signal boosts noise. So it's no wonder that speaker builders are reluctant to add in active circuits - other than those that have on-board amps.

It's been "more drivers, more power" for a long long time. Even the new trends in line arrays, which are getting smaller, are getting there because of Class D amps that can shove Three Mile Island down the 18AWG.

The issue with driver efficiency has more to do with cost. I am not an expert by any means on transducer design, but the general rule of thumb for transducers is that it is cheaper to make a good driver that is less efficient (i.e., 82 dB) verses a good one that has a higher efficiency.

Further, with today's solid state amps it simply is not necessary to make transducers with 100 dB efficiency since power is cheaper to manufacture than high efficiency transducers. That applies to home use. High efficiency drivers for sound reinforcement are still a valuable tool.

In the 1960s it was easy to find high efficiency transducers because the tube amps of those days had very limited power. This drove the industry to make transducers that were both high efficiency and quality reproduction.

Once the solid state revolution hit the scene transducer design (as well as cabinet design) followed suit.

While it may seem that acoustic designers are "slacking off" in the innovation department with regard to transducers, they are not. The field is very complex and fraught with many challenges that make better designs nearly impossible. The idea of building speakers may seem old hat to most people, but it is a deep science that requires a comprehensive understanding of math, physics, and human anatomy.

Yes, there is lots of room for improvement in the field and if you have anything that will advance the state of the art you stand to be a very rich and renown man.

Saying you don't need watts for your sound system is like saying you do't need HP for your vehicle to go some place.

Granted some like riding a bike (5 - 10 watt sound systems) and consider that more than enough to get the job done.

Then there are those of use who drive trucks (500 - 1000 watt sound systems) and see the point and necessity behind the power.

Also where you put those watts is everything. A 1000 watts all at the tweeters would make your teeth shatter and your eyes explode but a 1000 watts in a good deep sub woofer just makes the drums reach out and grab you where it tickles and by golly some of us love that tickling feeling of having our music go from purely sonic pleasure to an outright tactile experience!

(Personally I don't consider it good home theater or car audio until its starts reaching 2000 watts RMS at 100 Hz and below myself.)

AH and TCM are both right, and both correctly explain their different "need for speed".

The key to Boulder's design, and to most all of these slightly oversized (for most uses) amps is that in esoteric audio, trying to achieve the "absolute sound" (forgive me HP, I love your mag) requires us to never hear the amp straining to keep up.

Best way to do that? Big, massive power on reserve. 40 or 60dB of power in reserve is quite handy. No problems with power supply anemia, no prolonged slew rates, no muddy undefined low end.

Another key thing these beasts do is hang on tight to the drivers. That's called damping factor. Not only can they accelerate the woofers at nearly perfect response to the most demanding attack of percussion, they also can reproduce low cello and double bass like most listeners have never heard - that is unless you've heard them live and up close. Damping plays a big roll in mids and highs as well but it not as physically challenging. When that giant woofer coil starts barreling toward your couch, it has a huge velocity and momentum. We want that, but we also want it to stop and go back toward the fireplace. If an amp is sloppy, the woofers can over-extend, to the point that the voice coil can pop out of the gap. Over-excursion is bad - unless it's show and tell time at CES or SEMA or physics club. Going back the other way, the dust caps can bottom out, not as mechanically bad for the driver, but still sounds gawd awful. Of course either of these is clear indication of either out-of-control power, lousy speakers including those Acoustic Supsension sealed boxes with User-Defined holes drilled in them for "experimentation" (or hiding the super skunk), or both. Or maybe you have Thunderstruck dialed up to the requisite 11.

Tube amps generally have lower damping factors, much lower than transistor amps, so it's no surprise that big amps like the Crown K2 with a damping factor of over 10,000 at 100Hz is going to make tighter (better?) TCMTech Tinglies than Bob Carver's new Cherry 180. But which one sounds better from 400 to 8000Hz??? That may be impossible to determine unless you are deciding with your ears and your tastes.

My favorite system is still my music professor's 600 watt mono block set up with his Quad ESL 3's. No, it doesn't shake the walls. Heck, you can hardly hear it in the kitchen. Those electrostatics can't really do that. But you can stick your head inside the string section. You can hear the piano keys, and the hammers and the strings. When you listen to For Duke (M&K realtime) and can hear when Scotty Hamilton changes reeds you know you got hold of some accurate gear. That accuracy can't be had if the drivers are all flapping around like valve train on a Cavalier.

On Power and Majesty, it's easy to differentiate the hail from the rain, even individual hail stones and their direction. In my experience, and I've listened to it on at least 500 systems, it's just not possible to get there with less power.

And that's why an 89 year old clarinet player has 2 30A 220V outlets in his library.

txmed, yours is easily one of the best, most lucid, most well-written, most passionate posts I have read anywhere, bar none. Bravo!!

(Damn shame this here 'GA button' is too simple-minded to distinguish truly Great Answers from ones that are merely Good, and award accordingly. Sorry!)

I must say I have wished for the Mega GA (MGA) since I joined as well. It would be well-suited to many of your posts.

Thanks.

The contributions of damping factor has been long and severely overplayed in the industry.

First, damping factor is effectively nullified with a passive crossover. Even speaker wires will impact damping factor.

Second, the acoustic gains of an active crossover are mostly due to the advantages of the lack of large capacitors and to some extent inductors of a passive system.

Furthermore, active systems benefit largely from the vast array of poorly designed passive systems. That is not to say that all things being equal, a passive system is just as sonically good as an active system, but that the differences are not as much as one tends to read about.

Third, damping factor's main contribution is in the bass region of the audio spectrum. This is precisely the region where human hearing is most tolerant of distortion. In other words, it becomes increasingly difficult for your ears to resolve improvements in distortion as the frequency goes down.

Damping factor wars is another acoustic myth that is overblown with a sprinkle of truth thrown in for good measure and does not contribute nearly as significantly as other factors do when taking a systematic approach to the problem.

"it took a unique approach to theft prevention by making it weigh more than a couple of NFL linebackers."

Apparently, the writer has never heard the phrase: "One man can steal, what takes two men to carry".

I once had 2 ea 20 ton a/c units stolen off the top of a 5 story building overnight....If weight is the only deterrence, it is to laugh....

Shawne Merriman not fat at 275 lbs.....

Back in the 80's I went to somebody's house party. Couple of guys turned up in what I took to be a new make of Volvo, They took this humungous speaker off the roof, then had to take apart the window frame to get it in. They may as well have just crashed the car into the house. When they fired it up, the house near fell down. I can't dance to save my life, but with this thing going I was unable to stop.

I think we got that on film...

http://www.youtube.com/watch?v=66FKWKCs6dE

Drat, my secret is out !

Why would anyone spend $115,000 for

when, for a few more Gs, they could have

?

-----

(shown with optional concert hall, not included; see your dealer for details)

Where is the concert hall ? It doesn't look accoustically right, but I'm sure those things on the side are not just Royal boxes.

It's an Australian concert hall of course, not to be confused with Austrian, where that piano (a Bosendorfer Imperial Grand) is built.

If that's Oz, no way will I risk my life visiting the place.

I have a stool that looks very similar. hmm, I might just dust it soon. If Barkis Henry is a willing, who knows.....

No, no, no. The concert hall is just to *prevent theft*. They'll ship to your location and even install it for a nominal fee. Look closer: that piano isn't just sitting there; it's bolted to the stage - like you can do with top-end-yet-lightweight audio gear versus, say, using a lockable, secure rackmount enclosure for 1/20 the price and which has it's own security system including video, DVR and which calls the police on its own in case of break-in. Imperial Grands, on the other hand, are less suitable for rackmount installation thanks to the awkward form factor but, thankfully, they're big and heavy. In their case the weight actually *improves* the sound quality and doesn't have to be added on after the fact by some damn fool who's otherwise plum run out of ideas. That 450-pound boom-box is the dumbest damn thing I've seen in years, I swear.

Oh, so Boulder's high-end customers can't afford real security systems and so why not settle for the illusion of it? Is that what Boulder are saying? But not only? You mean there's more?

Aren't they also telling us that they're plum fresh out of truly innovative ideas (for which they're known) and must now resort to gimmicksmanship to make a sale? A sort of corporate version of the once-famous rock band cutting their first Christmas album (also known as a 'swan song'?)

Surely not!

Were I Boulder's CEO I would withdraw this product immediately. Its existence is far too revealing.

Ya, well, on my stereo the volume goes up to 11!

Sure saved me a wad o' dosh I'm tellin' ya!

(tip: when you're ready t' upgrade, jus' buy yoresef one o' them label-gun thingies at WallyWorld an' re-number th' dang thing. Not only. Git yoresef a bigger nob an' yew kin make it go ta 20. Maybe even 30! Those Oddyo File weenies wot spend all that dosh on gizmos an' thangamajigs an' whatnot? Heck, they're jus' throwin' good money after bad. Think we shud tell 'em?)

'Corse yew cud always draw little zeros after all them numbers. That's what Pappy done to his speed-o-meter.

Ha, that amp is just a budget weakling.

Here is a brand new amp that has 19,200 Watts of clean audio power!

Available at a sale price for $490,000, it's 6 feet high and weighs about 1,000 pounds.

Pivetta Opera One

Four more of those babies and you could drive the acoustic test chamber at White Sands Missile Range to simulate the effects of nuclear explosions on military hardware. The 'speaker' (singular) was a reinforced concrete exponential horn with the walk-in test chamber at the 'small' end. SPL inside the chamber was around 196 dB and would liquify a 20 oz. porterhouse steak in ten seconds flat. Basically walls of air (triangular density cross-section) at two atmospheres, peak, separated by vacuum, peak (the other way).

Shake n Bake.

Disaster Area. :)

Pretty much. :)