The Loudspeaker - Some things never change

It's "Peak Music Power" so the audiophools will think they have more than they really have >:-} ...Jim Thompson

while "Peak Music Power" is usually some ridicules made up number, I'd think some form of number to indicate the peak output does have some merit

like in a class-h amplifer with limited power on the high voltage rails

-Lasse

I think current state of the art in serious long-throw speakers is subwoofers that use position feedback and closed-loop control of the coil.

I don't know if the extra throw that you'd get from a multi-phase motor would be worth the gain in stroke.

If RMS is fiction, then what is the real way to say "ACTUAL WATTAGE"?

For example, I have a GE Tube manual, it says the maximum signal power output for TWO 6L6GC tubes on a Push-Pull class AB audio amplifier, with

(I'm using "tubes" because I'm more familiar with them than transistor amplifiers, and 6L6 is thill used regularly on Guitar amps).

Anyhow, I now know what the maximum power output wattage is for a guitar amp with two 6L6 output tubes. Which can be lower if the plate voltage is lower than 500V as well as other variables in the circuit. But lets assume that I have a guitar amp that is rated at 50W. Meaning they are almost using the full capability of these two tubes.

This figure is a FACT! It's a fact because these 6L6 tubes are designed to produce a maximum of 55W, and they are receiving close to 500 volts on their plates, so they are running at their Max, or close to it.

Given this information, what is this 50w (or 55w)? Is it RMS, or is it something else?

I only know the term RMS, because it's been in use for decades. Honestly, I am not exactly sure just what it means as far as the mathematics involved. All I know that amplifiers as well as speakers used to be rated (in the 1950s thru at least the end of the 70s) as RMS, and there was always a secondazry rating called PEAK, which was usually close to double that figure. Based on those figures, if I bought a speaker for a 50W RMS amp, with Peak ratings of 100W, I would choose a speaker rated at least 100W to be sure I did not "blow" the speaker.

So, if RMS is not the correct way to express this power rating, WHAT IS?

FYI:

The max plate voltage for a 6L6 is over 2kV.

The max dissipation is about 30 watts average power.

Using a 750V plate supply and 400V screen supply plus using low class AB bias so the idle dissipation is only 10 watts per tube - you get a 100W output stage. The max plate voltage will be under 1.5kV and the max dissipation is under 30W.

Same as the AC power coming from the wall.

.... Phil

Loudspeaker motors are hideously inefficient. Linear synchronous motors can be remarkably efficient - and at some point you have to worry about the c oil heating some magnets above their Curie temperatures. Nd2Fe14B magnets h

them.

First production was in 1982.

Meanwhile they continued to produce the earlier model, first sold in 1957 as single speakers for mono use.

**The ESL-63 is a di-pole radiator - so does not excite room resonance modes at low frequencies like box speakers do. They only seem bass shy to listeners who expect to hear such resonances and think it is for real.

.... Phil

An extra plus is the impedance curve of the speaker is much nearer to flat, compared to other electrostatics that show a dramatic drop starting at some high frequency.

.... Phil

des >at low frequencies like box speakers do. They only seem bass shy to li steners >who expect to hear such resonances and think it is for real. "

Resonance is my nemesis. I do not put speakers in corners for example, I al ways try to orient them along a wall, not quite center, then the other one on a perpendicular wall. I find this yields less overall bass, but smoother bass.

Though I will admit to being a bass freak, I am very picky about it and I a m sure the Quads would be alright with a little bit of a boost. Never heard a pair though. Fact is I would probably prefer a Martin Logan hybrid, but at the moment they are out of my price range.

In fact I am not really much in the market for anytthing. What I got is not all that great but then again neither is my hearing. I was just impressed with the numbers on those Quads.

So it took them 19 years to gt to market eh ? Wonder who paid for all that. What's more it wasn't just some eggheads sitting in a room, it had to have taken some trouble and money to get the materials just right as well as th e design. Did they wind their own transformers ?

or >sound that originates about 30cm behind the centre element. There are t wo >rectangular bass panels as well, mounted above and below the ringed uni t. "

I saw the print for that. Logically, for them to have that virtual point th ey would have to have a flatter wavefront. So the middle rings are fed prog ressively delayed signals.

Would be interesting, with the right equipment/analysis, to see the effects of the rear radiation, which obviously would have the inverse effect due t o the delay(s) actually do to room resonances. I would assume they are more dispersed which would probably aid in removing room resonances from the so und actually heard.

The dispersion is the same in all directions and rather better than other electrostatics while there are no phase anomalies on or off axis.

An ESL-63 can produce a pretty good square wave at 1kHz and matching between units is very close.

... Phil

een >units is very close. "

I'll have to get some to calibrate microphones. No actually I am jokiog abo ut that but it really is something I would like to do for speaker evaluatio n purposes. Of course there is no rush.

Now the trivia question - A long time ago I read/heard about a speaker comp any that actually had one reference speaker to which all production units w ere compared. They did use a square wave and they wired them out of polarit y. A microphone was placed right in between them and the sound was expected to null out.

Was that Quad by chance ?

tween >units is very close. "

bout that but it really is something I would like to do for speaker evaluat ion purposes. Of course there is no rush.

mpany that actually had one reference speaker to which all production units were compared. They did use a square wave and they wired them out of polar ity. A microphone was placed right in between them and the sound was expect ed to null out.

Sounds more like KEF.

tween >units is very close. "

bout that but it really is something I would like to do for speaker evaluat ion purposes. Of course there is no rush.

mpany that actually had one reference speaker to which all production units were compared. They did use a square wave and they wired them out of polar ity. A microphone was placed right in between them and the sound was expect ed to null out.

There is/was a pic of the factory set up on the net.

.... Phil

Just keep it away from anything that releases ozone, like UV lamps - ozone destroys rubber.

I knew I could remember something. Now I know what it was. LOL

Hmmmmmmm..... That's not what the tube manuals say. I looked at a GE and a RCA. Both say 500v max. (plate volts).

I just read an article which said something about 6L6 tubes are almost the same as a 807 tube, but the 807 has the cap on top, because the early 6L6s were known to arc-over in the socket (plate pin). But that was mostly eliminated with better sockets materials.

I've worked with a lot of 6L6 power amps (guitar amps, etc). I have never seen an arc-over, nor have I ever seen a voltage over 500 on the plates.

I do have a schematic for a push-pull TRI-parallel, using SIX 6L6 tubes. That looks interesting. I'd try it if I could get a suitable output transformer that was affordable.

Please remember that in a typical push-pull arrangement, the peak anode voltage is twice the supply voltage during the opposite audio cycle, when the other tube is fully conducting due to the autotransformer action of the center tapped audio output transformer primary.

So you really have to check what those maximum voltages represent, power supply voltage or actual peak anode voltage when overdriven. Those various limits from various manufacturers seem to be due to this.

In Europe, the EL34 is a similar audio output tube. I have seen bass guitar amplifiers delivering 100 W using 2xEL34 (at +800 V power supply), the most common 100 W guitar amplifier configuration was

Only the Telefunken EL34's seemed to survive in the 100 W 2xEL34 bass guitar configuration for any longer period of time.