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

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dBel84

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Liquid Lightning Mk II
« on: March 15, 2013, 04:14:47 PM »
I thought I would start a thread here for anyone who wants information on this amp and maybe we can weed Alex out of the woods. I had a great conversation with him yesterday as he had contracted with an engineer to measure his amps. First up was the LL mkII which had been a subject of much discussion between us ever since the first rendition came out. The big problem with measuring electrostatic amps is that any load placed on the amp potentially adversely affects response. The engineer modeled his test parameters on the stax standard and was able to load the amp with 120pF ( not an insignificant load but comparible to driving the SR007 ) . As Alex had mentioned with this version of the amp , he essentially tried to accommodate requests from people wrt form and function. The amp circuitry is the same, the board layout addressed possible stray capacitances .
More on his web page
http://www.cavalliaudio.com/index.php?p=product_details&pId=4

http://www.cavalliaudio.com/index.php?p=morestuff&stuffId=8


To the gist of this post



The 1KHz spike is the signal used to generate the data , the rest is just awesome.

I do believe Alex designed this amp to have minimal overall distortion and did not engineer in any second harmonic distortion that some might prefer.

..dB

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MuppetFace

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Re: Liquid Lightning Mk II
« Reply #1 on: March 15, 2013, 04:33:06 PM »
Quote (selected)
I do believe Alex designed this amp to have minimal overall distortion and did not engineer in any second harmonic distortion that some might prefer.

I have a feeling I know what this is in reference to... LOL.

These results look really promising. Can't wait to compare this side-by-side with the LL ver 1.
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Tari

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Re: Liquid Lightning Mk II
« Reply #2 on: March 15, 2013, 05:17:58 PM »
Very impressive.  Are there any slew rate measurements?
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AstralStorm

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Re: Liquid Lightning Mk II
« Reply #3 on: March 15, 2013, 06:37:10 PM »
I second the opinion about this measurement, very impressive.
What about IMD? (both ways, SMPTE and CCIF) Crosstalk?
I'd expect a very good result on both for this price...

Perhaps a GSM interference test too?
Also, why can't he measure with some real load, like SR 007s? Even electrostats aren't (near) pure capacitance.

Slew rate is way overrated - it's just a number, meaningless unless overshoot and damping is also given. ::) Small and large signal square wave please instead.
« Last Edit: March 15, 2013, 07:03:58 PM by AstralStorm »
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kevin gilmore

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Re: Liquid Lightning Mk II
« Reply #4 on: March 15, 2013, 11:58:02 PM »
140db signal to noise ratio on an amplifier with a voltage gain of 500?

Absolutely impossible at room temperature.
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dBel84

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Re: Liquid Lightning Mk II
« Reply #5 on: March 16, 2013, 01:11:53 AM »
why thank you for your enlightenment oh gracious one.


(edited my initial comment as i realised the fallacy of my conviction before such a great sauce of no-ledge)
« Last Edit: March 16, 2013, 03:36:25 AM by dBel84 »
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anetode

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Re: Liquid Lightning Mk II
« Reply #6 on: March 16, 2013, 03:05:32 AM »
Much better with the understated machined frontplate.
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n3rdling

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Re: Liquid Lightning Mk II
« Reply #7 on: March 16, 2013, 03:18:41 AM »
I agree it looks better now but I still hate that knob  :)p12
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AstralStorm

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Re: Liquid Lightning Mk II
« Reply #8 on: March 17, 2013, 10:18:31 AM »
Quote from: kevin gilmore on March 15, 2013, 11:58:02 PM
140db signal to noise ratio on an amplifier with a voltage gain of 500?

Absolutely impossible at room temperature.
That's 130 dB. You should use a harmonic/geometric average for noise levels.

And not necessarily gain 500. Maybe it's a very hot signal and it's just gain 10. (We only get info that dbR is 100 V RMS (~200 V), nothing about gain.)
Looks like the graph might've been smoothed or averaged, halving the noise, making this -124 dB. Still very, very respectable. Anything below -110 dB surely is.
Perhaps it's been cooled down some too... Maybe also driven from a super stable lab power supply. (Or maybe has one such built in? Plus heavy shielding.)

Many ways to cheat.

EDIT: Never mind, it's -13 dBV input signal (~0.5V RMS), not hot, but it's gain ~200, not 500. Very high. Something is fishy about this measurement.
Perhaps not as much fishy, as the role of this measurement was not to exhibit SNR, but THD, which doesn't change when averaged.

Also I was wrong about the impedance - it is 120 pF paralleled with 200 kOhm.
« Last Edit: March 17, 2013, 10:50:40 AM by AstralStorm »
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dBel84

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Re: Liquid Lightning Mk II
« Reply #9 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.
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