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Author Topic: Liquid Lightning Mk II  (Read 5542 times)

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kevin gilmore

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Re: Liquid Lightning Mk II
« Reply #10 on: March 17, 2013, 06:09:51 PM »
time for more negative karma

I did not say it was dishonest, I said the results were wrong.
The 200k resistive load for one thing is not even close to
what the load of the headphones is, which is 99% capacitive.
The only real resistance of the heaphones is that of air, and
something way past 5 meg even at 20khz.

Not enough voltage to generate a plasma which would reduce
the resistance substantially.

There is a peak at 60hz, and another at 180hz, but none
at 120 hz. That does not make sense either.
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shipsupt

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Re: Liquid Lightning Mk II
« Reply #11 on: March 17, 2013, 06:20:38 PM »
Don't sweat the Karma deal, there's nothing really to it.  Most would agree that if you aren't getting some negative marks you're not having much to say that matters (not sure what that says for me).  Negative karma is sort of a badge of honor.
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Yeah, well, you know, that's just, like, your opinion, man.

kevin gilmore

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Re: Liquid Lightning Mk II
« Reply #12 on: March 17, 2013, 06:34:04 PM »
I rarely sweat anything. I've been known to cause sweat however.
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AstralStorm

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Re: Liquid Lightning Mk II
« Reply #13 on: March 17, 2013, 06:37:30 PM »
Quote from: dBel84 on March 17, 2013, 03:31:26 PM
I can assure you no dishonesty was involved, stock amp tested as such by an engineer who reported to have the equipment necessary to measure according to STAX standards. Done more out of curiosity and Alex's desire to start getting some independent data on his equipment.

I know, just I wouldn't use this measurement to establish SNR. It's clearly geared towards showing harmonic distortion, power supply distortion (the 60 Hz/180/... "peaks") and any easy to trigger jitter. (it's no J-test) That's why I suspect heavy averaging - but that would distort THD+N figure, unless noise was measured separately.
This low THD is not typically measurable without such modifications or a high end multiplier (unlikely at that high voltage).
I wouldn't worry about SNR of it, it's certainly way better than necessary, but I wouldn't cite it anywhere based on this measurement.

Electrostatics should have actually very high resistance (it's a break in the electrical path), on the order of MOhms. It can be considered "voltmeter" resistance. 200 kOhm is neither here nor there, but closer to the voltmeter range.
That's also why e.g. Tyll doesn't measure it - there's really no meter around with GOhm impedance required to gauge it meaningfully and bridges don't work for lowering resistance that well - you'd need a huge parallel one.
« Last Edit: March 17, 2013, 06:42:36 PM by AstralStorm »
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kevin gilmore

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Re: Liquid Lightning Mk II
« Reply #14 on: March 17, 2013, 06:42:19 PM »
Its actually really easy to measure the true resistance of the headphones with
stock equipment. As long as you measure at 20khz or more to bring
the numbers down into range. Measuring at DC is also meaningless.
And the 200k load is very low considering it matches the impedance of
the feedback loop. Most of the good DVM's are 10meg input, and almost
all the scopes are a baseline of 1meg input impedance.

Practically the LL2 probably measures very close to almost all the other
electrostatic amps out there, a thd of .01%

The all tube amps (es1,es2,rays disaster, craigs new thing...) measure much
much higher. My es1 after repairs measures about .15%, originally it was
close to 1%. ray's disaster measures close to 1.5%

The reason tyll does not want to measure it is because he does not want to
blow up his lifeblood. Even If I send him all the probes and stuff necessary.
I would have to fly out there and do it with him, and agree to pay the repair
bill should something evil happen.

Although really tyll should know how to do this, he spent 10 years repairing
electron microscopes, and 1600v peak to peak does not even get on the
graph compared to 250kv (or more)
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AstralStorm

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Re: Liquid Lightning Mk II
« Reply #15 on: March 17, 2013, 06:44:01 PM »
I'm pretty sure (can't be certain, never done it) that even at 20 kHz resistance of electrostatic headphones will be very high.
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AstralStorm

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Re: Liquid Lightning Mk II
« Reply #16 on: March 17, 2013, 08:08:45 PM »
Oh, so you say he doesn't have ultrafast fuses on his very expensive scope? Hmm well, they would degrade most other measurements...
MOVs are darn fast and reasonably linear in audio range. (as in a circuit break.)
« Last Edit: March 17, 2013, 08:14:30 PM by AstralStorm »
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ultrabike

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Re: Liquid Lightning Mk II
« Reply #17 on: March 17, 2013, 09:10:59 PM »
Quote from: kevin gilmore on March 17, 2013, 06:09:51 PM
time for more negative karma

I did not say it was dishonest, I said the results were wrong.
The 200k resistive load for one thing is not even close to
what the load of the headphones is, which is 99% capacitive.
The only real resistance of the heaphones is that of air, and
something way past 5 meg even at 20khz.

Not enough voltage to generate a plasma which would reduce
the resistance substantially.

There is a peak at 60hz, and another at 180hz, but none
at 120 hz. That does not make sense either.

Interesting. Didn't the OP mentioned a 120 pF cap as a load there? If I remember correctly, that is about 66 kohm at 20 kHz which may match with your observations (assuming you meant 66 kohm by "j66k at 20khz".) Put that in parallel with 200 kohm resistor and one gets about 50 kohm at 20 kHz, correct?

Is that not even close to what the load of the headphone is? I maybe reading things wrong, but according to Stax the impedance of the SR-009 @ 10 kHz is 145 kohm (i.e. 110 pF cap), which you also seemed to have pointed out. A 120 pF cap yields about 132 kohm at 10 kHz, and drops to 80 kohm if put in parallel with a 200 kohm resistive load (assuming it is resistive.) So maybe you have something there, though I wouldn't say 80 kohm is nowhere in the vicinity of 145 kohm...

As far as those distortion numbers, obviously they look very good, and seems that Spritzer suggested doing something like what the OP presented... Do you have such numbers available for the BHSE by any chance?
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kevin gilmore

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Re: Liquid Lightning Mk II
« Reply #18 on: March 17, 2013, 09:18:14 PM »
Need to brush up on complex impedances huh?

A capacitor is an imaginary load. That is the
Phase is 90 degrees off. Voltage vs current.

Very big difference from a resistor.

That's what j- omega is all about

Go and look it up.
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LFF

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Re: Liquid Lightning Mk II
« Reply #19 on: March 17, 2013, 09:24:43 PM »
Quote from: kevin gilmore on March 17, 2013, 09:18:14 PM
Need to brush up on complex impedances huh?

A capacitor is an imaginary load. That is the
Phase is 90 degrees off. Voltage vs current.

Very big difference from a resistor.

That's what j- omega is all about

Go and look it up.

 p:8
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