New book: Current-Driving of Loudspeakers

[audio amateur]

That settles it!

rw

lol, how did I know you were going to quote that?

[rakeford]

Two approaches to analysis of electronic circuits include Thevenin’s and Norton’s equivalent circuits (see figure). Thevenin’s equivalent circuit reduces a complex two terminal network to an equivalent impedance, Zeq and an equivalent voltage source, Veq. Norton’s equivalent circuit reduces a complex two terminal network to an equivalent impedance, Zeq and an equivalent current source, Ieq. Since both circuits represent the same network, Veq = Zeq * Ieq. The approaches are different, but the results are identical. The dynamics of the network components (resistors, capacitors, inductors, diodes, transistors, tubes) may make the mathematics easier in one of the two approaches. Which circuit to represent any given network is entirely a matter of choice and convenience.

[pixelthis]

That settles it!

rw

PRETTY MUCH.
A amp hasnt changed much in basic design ever since Lee Deforest invented the vaccume tube.
Its basically a valve controlled by an input source.
This allows a voltage/current that can drive a loudspeaker.
But its never the signal itself driving the speaker , or phones.
The source just controls what drives the speaker.
There is no real technical reason you cant have a high current speaker, but it will need voltage.
All I am saying.

[pixelthis]

Two approaches to analysis of electronic circuits include Thevenin’s and Norton’s equivalent circuits (see figure). Thevenin’s equivalent circuit reduces a complex two terminal network to an equivalent impedance, Zeq and an equivalent voltage source, Veq. Norton’s equivalent circuit reduces a complex two terminal network to an equivalent impedance, Zeq and an equivalent current source, Ieq. Since both circuits represent the same network, Veq = Zeq * Ieq. The approaches are different, but the results are identical. The dynamics of the network components (resistors, capacitors, inductors, diodes, transistors, tubes) may make the mathematics easier in one of the two approaches. Which circuit to represent any given network is entirely a matter of choice and convenience.

One is series and one is paraell.
And the "math" for series is a lot more simple than paraell.
So whats your point?
You need to start off with something easier with this bunch, like how there is no current without voltage.
The basics, in other words.

[E-Stat]

But its never the signal itself driving the speaker , or phones.

Who said otherwise? A cartridge with a one millivolt output certainly won't drive anything by itself. And in my case, the signal voltage output by the amplifier itself must be stepped up to a 10 kV level in order to drive the electrostat's stators. Little in the way of current but LOTS of voltage. Along the way, there is lots of voltage conversion going on starting with one thousandth of a volt ending up at ten thousand! While the rail voltage in the VTL amps I use is 550V, the tube amps in the original Acoustat X I used thirty some years ago drove the stators directly at 3kV.

rw

[pixelthis]

Who said otherwise? A cartridge with a one millivolt output certainly won't drive anything by itself. And in my case, the signal voltage output by the amplifier itself must be stepped up to a 10 kV level in order to drive the electrostat's stators. Little in the way of current but LOTS of voltage. Along the way, there is lots of voltage conversion going on starting with one thousandth of a volt ending up at ten thousand! While the rail voltage in the VTL amps I use is 550V, the tube amps in the original Acoustat X I used thirty some years ago drove the stators directly at 3kV.

rw

None of which is beans compared to a 30,000 volt power supply for a plasma TV.
My point is that if the current gets too high you will have to swap voltage, is all.
AND larger speaker coils(or whatever you electrostat types run) will have to weigh more,
cant help sensitivity..
The best speaker "floats like a butterfly, stings like a bee", to quote a certain champ.
FUNNY that a high current speaker would be the mirror image of an electrostat, the
electro being high voltage-low current, and the high current being the opposite.
Also funny the way people keep inventing the wheel, I take it you like your stats.
We need KEX to weigh in on this, hes the resident speaker guru.

[E-Stat]

None of which is beans compared to a 30,000 volt power supply for a plasma TV.

The difference is that the voltage in a plasma is sealed from the environment where the bias charge in an electrostat is usually exposed to the air. Otherwise, you would get an impressive Dr. Frankenstein arc effect with 30kV! Using a higher bias charge improves efficiency, but you always have to deal with what the ambient air can take, which varies with humidity. When I had Acoustats, their relatively tame 3kV bias was constant and never required any adjustment. The Sound Labs run the bias far higher and it is variable - which allows you to run it optimally. Before each listening session, I take a moment and run each speaker's control to where I begin to hear a crackling sound, then back it down to just below that threshold.

The very first full range electrostat I heard was the Dayton-Wright. It approached the air-dielectric issue differently. It sealed the panels using an outer mylar diaphragm and filled it with sulfur hexafluoride gas. SF6 is an electrical insulator and allowed them to run the bias up about 12 kV without having to worry about the condition of the air around the panels.

My point is that if the current gets too high you will have to swap voltage, is all.

Sure.

I take it you like your stats.

You betcha.

rw

[pixelthis]

Sure.


You betcha.

rw[/QUOTE]


Just seems like over-engineering to me, I tend to go for a more simple, elegant
solution.
BESIDES, one of these days that high voltage will bite you in the a***.
as for the 30k section in CRT and plasma being "sealed" what has that to do with anything?
I have seen them arc pretty decent anyway.
Glad you're happy with your stats, but its kinda like driving a mi1 abrams to the
stop and rob for a Diet coke.

[E-Stat]

Just seems like over-engineering to me...

The D-Ws are no longer in production. Improvements with insulating coatings over the past thirty years have rendered that approach unnecessary. Their diaphragms weren't nearly as wispy as the 2.5 micron ones used by SL and involved two - counting the outer seal. They were, however, spectacular speakers in 1975. They left an indelible impression to one eighteen year old at the time. Including one time when former TAS reviewer JWC had to replace one of the panels. During the process, he put some SF6 in a coffee cup for me. Since it is heavier than air, it just sits there. If you place your finger in the cup, you feel but not see its presence. As one who sings bass in a symphony chorus, he has a powerful and low voice. He inhaled a bit and sung a few bars. The result was the exact opposite of what happens with helium. It was hilarious - like Lurch at the Met! SF6 is not very popular with the greenhouse gas folks either.

BESIDES, one of these days that high voltage will bite you in the a***.

As you observed, there is little current involved. It's more like the Van de Graff generator you played with in science class.

Glad you're happy with your stats, but its kinda like driving a mi1 abrams to the stop and rob for a Diet coke.

Their gentle and transparent nature doesn't evoke your heavyweight image to me. Yours is more appropriate for kilowatt powered horn systems.

rw

[pixelthis]

The D-Ws are no longer in production. Improvements with insulating coatings over the past thirty years have rendered that approach unnecessary. Their diaphragms weren't nearly as wispy as the 2.5 micron ones used by SL and involved two - counting the outer seal. They were, however, spectacular speakers in 1975. They left an indelible impression to one eighteen year old at the time. Including one time when former TAS reviewer JWC had to replace one of the panels. During the process, he put some SF6 in a coffee cup for me. Since it is heavier than air, it just sits there. If you place your finger in the cup, you feel but not see its presence. As one who sings bass in a symphony chorus, he has a powerful and low voice. He inhaled a bit and sung a few bars. The result was the exact opposite of what happens with helium. It was hilarious - like Lurch at the Met! SF6 is not very popular with the greenhouse gas folks either.


As you observed, there is little current involved. It's more like the Van de Graff generator you played with in science class.




Their gentle and transparent nature doesn't evoke your heavyweight image to me. Yours is more appropriate for kilowatt powered horn systems.

rw

Regardless, its still a long way around for sound reproduction.

[E-Stat]

Regardless, its still a long way around...

Some think that of my choosing manual transmission in the cars as well.

rw

[audio amateur]

Some think that of my choosing manual transmission in the cars as well.

rw

Clearly they don't have any interest in driving. But I can understand that when 95% of automobiles in the US are automatic.

[audio amateur]

I bet the pedals in the S2000 are ideal for heal and toe. Must be a blast!
http://www.youtube.com/watch?v=VWWPg8_Xlw0
(unfortunately no camera on the pedals in this one)

[E-Stat]

But I can understand that when 95% of automobiles in the US are automatic.

That's part of my craziness. 100% of mine are not.

I bet the pedals in the S2000 are ideal for heal and toe. Must be a blast!
http://www.youtube.com/watch?v=VWWPg8_Xlw0
(unfortunately no camera on the pedals in this one)

The S has a tight cabin that works well for compact guys like me. Both it and the TL have good dead pedals, too.

That was a fun video. Notice the pilot kept the engine on boil most of the time just touching the 9k redline every once in a while (my petite wife has discovered the fuel-cutoff limiter at 9200!)

The 6-speed A Spec TL does pretty well, too with 0.9 G cornering and similar acceleration and top speed - that is easier to achieve with the larger motor's torque. Its shifter, like all Hondas moves like a rifle bolt, although the throw with the S is so short so you can nearly shift using wrist movement alone.

rw

[audio amateur]

Both it and the TL have good dead pedals, too.

What do you mean by dead pedal?

That was a fun video.

You betcha. I could spend days watching Best Motoring videos, those guys are awesome.
Problem is I just go mad because during term time when im not living at home i dont have a car which means I dont get to drive... and as you can probably tell I love driving (maybe I should say obsessed.) The Honda 2K engines are super high revving as you know which means you need to keep the needle up there (in this case digital) to maintain the power up.
Here is one of my favourites from Best Motoring, but notice it's not a race.
http://www.youtube.com/watch?v=aal9kG-EXeY
I just love how the Skyline's revs just fly! It is incredibly fast, more so than a Ferrari F-40. That's telling you something!
And here's a race with plenty of exotics, including my personaly favourite, the Murcielago. You can fast forward a little as it's quite long.
http://www.youtube.com/watch?v=VE5M_CHfWR8

The 6-speed A Spec TL

Pardon the lack of knowledge, is that an Acura? (Acura doesn't exist in Europe)

Its shifter, like all Hondas moves like a rifle bolt, although the throw with the S is so short so you can nearly shift using wrist movement alone.

I can imagine

[E-Stat]

What do you mean by dead pedal?

That's the old timer's term for a foot rest. It gives you a firm footing for hard cornering and provides a place so that you don't ride the clutch. The worst thing you can do with a clutch is ride it with a bit of pressure. I've known folks who've gone through them in 30k miles - where I'm accustomed to getting more than 100k miles.

Problem is I just go mad because during term time when im not living at home i dont have a car which means I dont get to drive... and as you can probably tell I love driving (maybe I should say obsessed.)

Moi aussi. I could never be an urban dweller for that reason.

Here is one of my favourites from Best Motoring, but notice it's not a race.

Thx for the links.

Pardon the lack of knowledge, is that an Acura? (Acura doesn't exist in Europe)

That's right. The TL is a fancier, higher performance Accord.

rw

[audio amateur]

That's the old timer's term for a foot rest. It gives you a firm footing for hard cornering and provides a place so that you don't ride the clutch. The worst thing you can do with a clutch is ride it with a bit of pressure. I've known folks who've gone through them in 30k miles - where I'm accustomed to getting more than 100k miles.

Oh right, I wasn't aware of that term (or any term which made reference to that 'pedal'). I always take my foot off the clutch pedal when I'm not shifting. It's also handy when you need to push yourself snug in the seat.

Moi aussi. I could never be an urban dweller for that reason.

Well then you can imagine my frustration. In the meantime, I'm being 'greener'. As a result I get to compensate for that when I do drive Unfortunately what I get to drive is a mark 3 diesel Golf. Not exactly the ultimate driving machine...

Thx for the links.

In my case, it got addictive!

That's right. The TL is a fancier, higher performance Accord.

ok!

[pixelthis]

I prefer a "stick" also, but thats because they are less complicated than an
automatic.
Like scotty said, "the more complicated the plumbing, the easier it is to clog
the toilet".
Or something like that.

[JoeE SP9]

I've owned more than 30 cars. None of them had an automatic transmission. None had more than 2 doors and most only had 2 seats.

[nightflier]

Glad to see there are a few other people here who still drive a stick. Same here, never had an automatic and while it makes car shopping a pain, I persist in looking for that elusive stick, even in the larger & luxury segment. Since my Saab 9-5 now has some new life in it, I'm actually thinking about chipping it and buying some upgrades.

Getting back to the OT, maybe before we tear each other new ones over the merits of current-driving loudspeaker technology, someone should buy the book and read it. I can't really say I'm a good candidate for that since most of the engineering involved will be lost on me. Anyone else have an inkling to buy it?

[audio amateur]

I've owned more than 30 cars. None of them had an automatic transmission. None had more than 2 doors and most only had 2 seats.

Joe, you have very good tastes

[JoeE SP9]

My friends blame it on my European upbringing. I was a military brat growing up there in the late fifties and early sixties.
Years ago while driving one of the larger auto's I've owned (big block Camaro) I picked up a girl and her girlfriend at a club. When I escorted them to my car the girlfriend commented "There's no room back there" about the rear seating area. I responded, "I don't care, I don't ride back there".

As for as the speakers being current driven argument; try running any (not digital) amp without power supply capacitors. Or, think about this, when a good amp doubles its power as the load impedance is halved where do you think the power comes from? It certainly can't come from higher voltage. It's producing more current. For those who are not mathematically impaired it's a simple application of Ohms Law. As I said in an earlier post, "voice coil type speakers are AC motors". AC motors are essentially current driven devices. This is fact!

[Feanor]

I've owned more than 30 cars. None of them had an automatic transmission. None had more than 2 doors and most only had 2 seats.

Gads!! Is this a bragging point?

In my almost 65 years I've owned precisely six cars, one with manual transmission. I might go back to stick next time, though.

Of my six cars, two were 2-doors, (the first two), two were 4-doors, and two were 5-doors, i.e. wagons. I often sit in the back seat when my wife drives -- nowadays I actually dislike driving.

[audio amateur]

big block Camaro

I really need to move to the US sometime soon...

Joe, which country were you in?

[JoeE SP9]

Feanor;
My real point was that I've never had a car with an automatic transmission.

You sit in the back seat! What's the matter? Is the windshield too close ?

aa; Mostly France, England and Germany. 12 years total.