Audeze LCD-3

[justin]

^That's what I don't understand about all this Dark Star stuff. I couldn't listen to that thing at all on the high gain setting. And I'm pretty sure that was with the cans that are supposed to be such beasties to drive.

i think colin was saying that you cant listen to two amps at ~20% of their rated power output and make a determination on which one is more powerful. that is generally done with psychoacoustic crap like looking at how much or how little you had to turn the volume knob. the reason for the ridiculously high gain on some amps. the gain on the BHSE is actually 1/2 what Stax puts on their amps because i think its excessive with all but the lowest output phono stages.

Edited October 20, 2011 by justin

[visualguy]

The main "selling point" of the KGSSHV is that it fixes how the third stage is handled (adds a CCS where the old one uses resistors) which was the main weakness of the old design.

So, what sound deficiency did this weakness cause, and how did fixing it by adding a CCS improve the sound of headphones connected to the amp? Would you be able to tell the difference in a blind test?

Just curious...

[morphsci]

Even double-blind I can tell where this is headed.

[kevin gilmore]

First of all, some people that say that since electrostatics are capacitors and therefore the impedance

is imaginary, there is no real power. This is absolutely wrong. In fact the real power to O2's

can be in excess of 1 watt.

All you have to do is put an amplifier on a scope, and then connect and disconnect headphones

with test signals applied to prove that the amplifier is delivering real power. On some amplifiers

when you connect one pair of headphones, the slew rate gets cut in half. Add another set of

headphones and the slew rate slows down even more. This is real power, not imaginary power.

The T2 has the largest voltage swing of any amplifier out there and has the most amount of power

behind that voltage swing. Something like 20 watts per channel. The BHSE is second in this

regard, less voltage swing, and slightly less power, something like 16 watts per channel.

The added current source in the kgsshv and the toshiba output transistors make a big difference

in both the slew rate, and distortion. Even at moderate volume levels, the difference between the

kgss and kgsshv is significant.

There will be a new version of the T2 with a solid state input stage. With output current sources

based on the same toshiba transistor, you can now up the voltage rails to +/-600 volts. And push

up the power to about 30 watts per channel. This will also increase the slew rate.

Its not about how loud it goes, Its all about how well it handles the loud.

Although i don't have lcd3's yet, with lcd2's, the new balanced and supersymmetry dynahi

is lots of fun, lively and exiting. And its much more than the 120 volts peak to peak that

this amplifier can produce that makes it sounds so good.

Edited October 21, 2011 by kevin gilmore

[Dreadhead]

One doesn't even need to hook up a scope: the headphone is creating sound. This represents energy. Energy comes from work, the time derivative work of is power. QED.

Edited October 21, 2011 by Dreadhead

[dBel84]

Thanks for the clarification KG, i am starting to assimilate information on stats and constructive information is very helpful..dB

Edited October 21, 2011 by dBel84

[aardvark baguette]

There will be a new version of the T2 with a solid state input stage.

Commercial or DIY?

[kevin gilmore]

Commercial or DIY?

DIY of course. A commercial version done to the craftsmanship level of headamp would

be well into the $20k range. Parts cost with the step attenuator will still be close to $4k.

[gurubhai]

Thankyou Mr. Gilmore for the explanation.

I was reading up a bit in tubecad journal & here's a quote :

The drive requirements for an electrostatic headphone are lots of voltage but not that much current, a set of requirements that the vacuum tube meets readily. A power tube is not even required, as a 6SN7 or a 6BX7 can easily put out 250 volt peak voltage swings.

But voltage is only half of the complete equation. Current is needed as well. This requirement is often overlooked, as a charged capacitor requires no current to maintain its charge. AC signals are altogether different. The higher the frequency, the more current will be needed, as the reactive impedance of the capacitance falls off with frequency. For example, a 1 mF capacitor represents about an 8,000 ohm impedance at 20 Hz, an 800 ohm impedance at 2,000 Hz, and an 8 ohm impedance at 20 kHz.

To determine how much current will be needed to drive a set of electrostatic headphones, the required slew rate of the peak voltage swing at the highest frequency being reproduced must first be calculated:

Slew Rate = (2¶FVp) / 1,000,000.

In this case, where 20 kHz is highest frequency and 500 volts is the peak voltage swing,

Slew Rate = (6.8 x 20,000 x 500) / 1,000,000

Slew Rate = 62.8 volts per microsecond.

Think of slew rate as a measure of the steepness of the waveform at its sharpest slope.

The next step is to measure the total capacitive load represented by the electrostatic headphone's stators and its cable. The Stax Lambda Pros come in at 130 pF stator to stator. Then this quantity is multiplied against the slew rate to reveal the needed amount of current to charge and discharge the capacitance at the desired frequency and voltage swing.

Current = SR x Capacitance.

In this case,

Current = 62.8 x 0.00013

Current = 8.16 mA.

This may seem like a fairly trivial amount of current, but do not forget the 250 volt voltage swing and the high voltage power supply, which when multiplied against the current equals a fair amount of power.

Once we have determined the peak current requirement, we can begin designing the amplifier.

It seems that the key variables are :

Headphone capacitance ,

Highest Audio frequency desired : 20k for all practical purposes,

Slew Rate of the Amplifier,

& the Voltage Swing of the amplifier .

I was just hoping if someone could provide these specs for various headphones & amps but it seems that the question did not go too well with some folks here.

Edited October 21, 2011 by gurubhai

[Pars]

Kevin,

Nice post... thanks for taking the time to explain stat requirements to the unwashed.

Curious as to whether you have listened to the LCD-2s on your original Dyanhi, which IIRC was single ended (not balanced)? Listening to a borrowed pair on both my Dynalo and Dynahi didn't reveal much difference, or scaling, based on amp power. Maybe balanced changes this?

[kevin gilmore]

I have listened to the lcd2's on my original dynahi, very Very good.

Remember that balanced doubles the slew rate.

Also the lower impedance input due to the super symmetry

widens the frequency response a fair amount.

[spritzer]

i think colin was saying that you cant listen to two amps at ~20% of their rated power output and make a determination on which one is more powerful. that is generally done with psychoacoustic crap like looking at how much or how little you had to turn the volume knob. the reason for the ridiculously high gain on some amps. the gain on the BHSE is actually 1/2 what Stax puts on their amps because i think its excessive with all but the lowest output phono stages.

Colin would be correct since the only thing you can look for at these levels are the amps simply not being able to perform adequately. Sure, in direct A-B comparisons you can pickup small differences but these have much more to do with distortion etc.

Stax are also lowering the gain of the amps from the looks of it. There is certainly no need for the 60dB these days and lowering it can only yield better performance.

I was just hoping if someone could provide these specs for various headphones & amps but it seems that the question did not go too well with some folks here.

These specs aren't something any manufacturer would post. Just see how many speaker manufacturers flat out lie about the most basic specs and they would never post the exact impedance plots for their speakers. That's why we need places like Hi-Fi News who do measure this. Same thing applies to the headphones as one would have to measure each of the sets.

[FrankCooter]

Wow! Seems I stepped in a pile of shit of my own making over on H.F. My intention was to counter the perceived impression that power in an electrostatic system could somehow be equated to a traditional low impedance speaker system. I realized at the time that I was oversimplifying (any electrical circuit that creates mechanical energy, charges and discharges a capacitor, or even passes a current at all, no matter how small, of course has a power component) . I apologize for any factual errors and appreciate K.G.'s explanation and correction.

My understanding of electrostatic theory comes primarily from the Broskie articles mentioned above, Morgan Jones, and of course the forum posts here and on H.F. There is actually surprisingly little published information available. I'm sure that K.G. and Spritzer get tired of going over the same old ground, it would be really useful if there was some sort of "primer" available. I'm sure I'm not the only one that knows "fuck all" about electrostatic theory and operation.

Once again, I apologize for posting incorrect information.

[limp]

I have listened to the lcd2's on my original dynahi, very Very good.

Remember that balanced doubles the slew rate.

Also the lower impedance input due to the super symmetry

widens the frequency response a fair amount.

Sorry for butting in in such a rude manner, I mean no dis-respect, but doesn't such an argument rely on the slew rate and frequecy response of the Dynahi being less than sufficient?

If going by the specifications posted on Headamp for the GS-1 is accurate enough, this isn't the case.

Doing a rough calculation it seems less than 2V/uS is needed in the LCD-2s case (I get 1.4 for 11Vpk at 20kHz). I'm sure the Dynahi is well past this mark.

[dBel84]

Once again, I apologize for posting incorrect information.

I will take that responsibility thank you. ( it was I who quoted you ) Frank , I view you as one of the DIY demigods and likewise have not been able to read much on stat theory. I am sure there is a ton in various articles but I read near constantly in my own field and have little time to research in depth around the subject. I have a good handle on dynamic operation and have been in the hobby long enough to know what appeals to my sensibilities. Stats are foreign ground other than I know that I have enjoyed the experience on occasion. I hope we can all continue you learn in a positive environment , that is what keeps me interested ..dB

Edited October 21, 2011 by dBel84

[spritzer]

Wow! Seems I stepped in a pile of shit of my own making over on H.F. My intention was to counter the perceived impression that power in an electrostatic system could somehow be equated to a traditional low impedance speaker system. I realized at the time that I was oversimplifying (any electrical circuit that creates mechanical energy, charges and discharges a capacitor, or even passes a current at all, no matter how small, of course has a power component) . I apologize for any factual errors and appreciate K.G.'s explanation and correction.

My understanding of electrostatic theory comes primarily from the Broskie articles mentioned above, Morgan Jones, and of course the forum posts here and on H.F. There is actually surprisingly little published information available. I'm sure that K.G. and Spritzer get tired of going over the same old ground, it would be really useful if there was some sort of "primer" available. I'm sure I'm not the only one that knows "fuck all" about electrostatic theory and operation.

Once again, I apologize for posting incorrect information.

My rant wasn't targeted at you Frank but rather the people out there who are selling amps and do know fuck all about electrostatics (Ray, Rudi, Woo and Cavalli). That said, a primer to go into the details is needed but Kevin and I are swamped beyond belief. I've yet to finalize a basic guide to electrostatics for Tyll and I started it in July. Way too many things to do and no time...

The simple fact is that electrostatics do soak up a fair bit of power and Stax even had to find a way to cool the SR-009 stators as them heating up is naturally a very, very bad thing. Notice the hole in the center of the drivers, that's for cooling them. With the 007 this isn't a problem since they are sitting on the FR4 substrate.

[kevin gilmore]

Sorry for butting in in such a rude manner, I mean no dis-respect, but doesn't such an argument rely on the slew rate and frequecy response of the Dynahi being less than sufficient?

As i remember the dynahi is something in the 40 to 50 v/us range. I completely disagree with the analysis that says only a 2 v/us is required

because i can deliberately slow down an amplifier and the sound changes dramatically. Changes in the way the feedback works which

decreases the delay time also makes a big difference.

The new balanced supersymmetry dynahi definitely sounds slightly different from the original and gives me the

same feeling as listening to the T2.

[n3rdling]

Regarding electrostatic drivers, are they edge clamped?

[limp]

As i remember the dynahi is something in the 40 to 50 v/us range. I completely disagree with the analysis that says only a 2 v/us is required

because i can deliberately slow down an amplifier and the sound changes dramatically. Changes in the way the feedback works which

decreases the delay time also makes a big difference.

The new balanced supersymmetry dynahi definitely sounds slightly different from the original and gives me the

same feeling as listening to the T2.

Ah, feedback, didn't factor that in.

What about negative effects from excessive slew rate, can it be too much?

[Beefy]

What about negative effects from excessive slew rate, can it be too much?

Oscillation, perhaps.

[spritzer]

Regarding electrostatic drivers, are they edge clamped?

Well, the diaphragm is naturally attached to the charge rings/spacers at the edges but I wouldn't call them clamped due to the over all diaphragm tension and where the stators are. The typical Lambda driver (or SR-007, HE60, HE90 etc.) has the stators suspended above the film some distance away from the edges. The only headphone I can think of with any clamping inside the driver is the Micro Seiki but that was due to the diaphragm material they used.

Headphones do things a bit differently compared to ESL given the much smaller driver size and far lower bias voltages. No matter how much you stretch the film in a large speaker you are going to run into issues with the whole assembly not being stiff enough to withstand that tension and the film moving. That's why you have spacers (Clearspar or something like that in the M-L crap) to keep everything in alignment while spending as little as possible on the speaker assembly. You also have the normal issues of large perforated metal pieces being used as stators (again M-L) and these will overlap the edges where the diaphragm is glued.

[HeadphoneAddict]

Well, based on what I posted and what KG has recently posted, it wouldn't be unreasonable for me to expect an apology here. Even without KG posting I should have been offered an apology. Of course nobody actually expects that to ever happen.

I made reasonable posts and impressions, and I just read all of them again to be sure - and in the context that they were posted I still would NOT change anything that I wrote. It's a shame that any useful impressions of LCD-3, 009, or Cavalli amp that I made are lost in the turmoil of the alligators fighting over their prey. It seems to be more fun here to ridicule and reduce "lesser folk" to ashes than to accept anything useful they have to offer, old or new members. I know - thick skin and all. But, for Christ's sake you guys are like playing with wild animals that look nice and pretty when you're petting them, but will rip your head off when you're not looking.

Every time I start to feel welcome here I get a clear reminder than I am not one of you. And I'm hoping that if I start to become like some of you that someone will call me on my bullshit and tell me to straighten up and stop being an asshole. And the next person who posts a photo of a Whaaambulance can be that asshole.

[jgazal]

Please be patient with me as I am layman and naive.

Definition of physics from wikipedia:

Physics (from Ancient Greek: φύσις physis "nature") is a natural science that involves the study of matter^[1] and its motion through spacetime, along with related concepts such as energy and force.^[2] More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.

Sound is air motion. It is a mechanical force.

A transducer transform one form of energy to another form of energy (of course no transducer is perfect and the input energy might be transformed into other forms of undesired energy, such as light or heat). For bulb lamps light is interesting, but heat is not.

An electrostatic audio transducer aim to transform electrical energy into sound energy (air motion).

I see that electrostatic transducers are driven with little current. I also understand that no current flows through the transducer, which acts as a capacitor, but there is current flow in the signal path (alternated). Dr. KG said once the current pass on the imaginary plain (which I assumed as a mathematical description - square root of -1 – instead of some exotic hidden dimension).

If you need to transform electrical energy into sound energy, how a transducer would not “waist” real power on sound energy?

Electrostatic transducers could be highly efficient and consume little current, but as far as I understand, it would be impossible to consume no current and to deliver no real power.

Is that correct?

How much real power a dynamic transducer transform into sound energy (don’t take into account power loss in other forms of energy)? Is that so much different of 1 watt?

[spritzer]

There is really no end to your delusion, is there? Your posts were pretty much worthless since they lacked even the slightest bit of common sense when it comes to comparing amps, let alone doing comparisons over a length of time with different sources and other unfamiliar equipment. Now you being clueless is nothing new, just a bit sad. Hell, you had NoNoNoNoNoNo build an amp for you and promoted Warren Audio as something besides a scam. Does anybody notice a trend here?

[kevin gilmore]

Lets take a pure resistor. The voltage across the resistor and the current thru the resistor

are in phase. There is actually no such thing as a perfect resistor, all resistors have some

inductive component and some capacitive component.. So at higher frequencies the

voltage and current are not in perfect phase.

Lets take a pure capacitor. The voltage across the capacitor and the current thru the

capacitor are 90 degrees out of phase. There is no such thing as a perfect capacitor

as all capacitors also have some inductive and resistive component.

Air does have a resistive component which also depends on the humidity. So the

electrostatic transducer looses energy into the air because of the resistance, and

the electrostatic transducer also looses energy as it transfers the energy to the

air in the sound wave.

So while electrostatic transducers are more efficient than dynamic transducers at

producing a sound field, they still are only at most 10% efficient whereas dynamic

transducers are at most 2% efficient.

It still takes real power to make an electrostatic transducer create a sound field.