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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 #20 on: March 17, 2013, 09:38:50 PM »
Only -80 you can do better than that

Pretty sure Justin says the thd on the bhse is
Less than .1 %

So obviously the LL2 is 100 times moar better
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ultrabike

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Re: Liquid Lightning Mk II
« Reply #21 on: March 17, 2013, 09:43:30 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.

Thanks, it's been a while...

That means that by having 200 kohms in parallel with 120 pF we get:

63 kohms magnitude (instead of 50 kohm,) or 20k - j60k ohms at 20 kHz.
110 kohm magnitude (instead of  80 kohm) or 61k - j91k ohms at 10 kHz.

So are those impedances not even close to what the load of the headphone is?
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dBel84

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Re: Liquid Lightning Mk II
« Reply #22 on: March 17, 2013, 09:59:48 PM »
I see this thread is being derailed into a "how great I art" soapbox for the mafioso kingpin. I find it hard to believe that you , Kevin, think Alex doesn't understand the complexities involved. If you were less of a narcissist and at all trust worthy, there could have been a lot more collaboration in truly measuring these amps. As it stands , Alex followed the standards used by STAX as they are the only ones who have publicly available data. People have been asking for data for the longest time and when he finally does put his money where his mouth is and sends it off to be measured, you have to come forward to discredit the measurements themselves. Are they perfect ? No , do they represent current industry standard ? Yes. 

He gets the difficulties and problems involved with measuring estat amps, we have discussed this amongst ourselves innumerable times.


As for the negative karma , i didn't have the will to  impart even this level of recognition on you. Why not just face facts, Alex knows what he is doing, has designed an excellent amplifier and people who have heard it seem to enjoy using it. He has never spoken ill of you , in fact I have heard him complement the KGSSHV design. If you feel the LL is 100x better than the BHSE , you should tell him. I for one am surprised that you feel this way.

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kevin gilmore

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Re: Liquid Lightning Mk II
« Reply #23 on: March 18, 2013, 02:11:10 AM »
Quote (selected)
That means that by having 200 kohms in parallel with 120 pF we get:

63 kohms magnitude (instead of 50 kohm,) or 20k - j60k ohms at 20 kHz.
110 kohm magnitude (instead of  80 kohm) or 61k - j91k ohms at 10 kHz.

So are those impedances not even close to what the load of the headphone is?

The real headphones are going to be almost pure capacitive, so something like 5M - j220k at 20hz

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eggil

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Re: Liquid Lightning Mk II
« Reply #24 on: March 18, 2013, 06:23:17 AM »
Quote from: dBel84 on March 17, 2013, 09:59:48 PM
I see this thread is being derailed into a "how great I art" soapbox for the mafioso kingpin. I find it hard to believe that you , Kevin, think Alex doesn't understand the complexities involved. If you were less of a narcissist and at all trust worthy, there could have been a lot more collaboration in truly measuring these amps. As it stands , Alex followed the standards used by STAX as they are the only ones who have publicly available data. People have been asking for data for the longest time and when he finally does put his money where his mouth is and sends it off to be measured, you have to come forward to discredit the measurements themselves. Are they perfect ? No , do they represent current industry standard ? Yes. 

He gets the difficulties and problems involved with measuring estat amps, we have discussed this amongst ourselves innumerable times.


As for the negative karma , i didn't have the will to  impart even this level of recognition on you. Why not just face facts, Alex knows what he is doing, has designed an excellent amplifier and people who have heard it seem to enjoy using it. He has never spoken ill of you , in fact I have heard him complement the KGSSHV design. If you feel the LL is 100x better than the BHSE , you should tell him. I for one am surprised that you feel this way.

I guess is not OK to disagree or offer different points of view but calling names is fine?
You'd do a  better service by offering a counter argument.

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ultrabike

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Re: Liquid Lightning Mk II
« Reply #25 on: March 18, 2013, 06:46:27 AM »
Quote from: kevin gilmore on March 18, 2013, 02:11:10 AM
Quote (selected)
That means that by having 200 kohms in parallel with 120 pF we get:

63 kohms magnitude (instead of 50 kohm,) or 20k - j60k ohms at 20 kHz.
110 kohm magnitude (instead of  80 kohm) or 61k - j91k ohms at 10 kHz.

So are those impedances not even close to what the load of the headphone is?

The real headphones are going to be almost pure capacitive, so something like 5M - j220k at 20hz

The 5M series resistance seems to make the impedance almost purely resistive (~5M magnitude) above 20 Hz, correct?

Also, the 220k at 20 Hz seems to imply a 36nF cap. I have seen numbers in the pF thrown around (150pF, 80pF, 100pF...). If you meant 220k at 20kHz that would put the cap at around 36pF, which seems a little small, but more in range with what little I've read.

If we neglect the 5M series resistance (otherwise everything will measure ~5M as it should), lets see the effects of a 200kohm (resistive) probe on the following capacitances at 10 kHz:

C = 36nF ->  442 ohm (1 - j442)
C = 150pF -> 93 kohm (44k - j83k)
C = 120pF -> 110 kohm (61k - j92k)
C = 110pF -> 117 kohm (69k - j95k)
C = 100pF -> 125 kohm (77k - j97k)
C = 80pF -> 141 kohm (99k - j100k)
C = 36pF -> 182 kohm (166k - j75k)

If we neglect the 5M series resistance, lets see the effects of a 100M (resistive) probe on the following capacitances at 10 kHz:

C = 36nF ->  442 ohm (40u - j442)
C = 150pF -> 106 kohm (2 - j106k)
C = 120pF -> 133 kohm (4 - j133k)
C = 110pF -> 145 kohm (4 - j145k)
C = 100pF -> 159 kohm (5 - j159k)
C = 80pF -> 199 kohm (8 - j199k)
C = 36pF -> 442 kohm (40 - j442k)

In all cases obviously the 100M probe yields more reactive impedances, but somewhat close in magnitude to the 200k probe results, with the exception of the 36pF case of course.

Like dBel84 said, not perfect, but so far IMO, not necessarily unreasonable.

(EDIT: fixed the Headwize linky)

(EDIT: Note that if going by 36 pF, at 20 Hz the impedance with the 5M would be 5M - j0.2M, and therefore things would still be almost fully resistive above 20 Hz)
« Last Edit: March 18, 2013, 09:07:42 AM by ultrabike »
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Solderdude

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Re: Liquid Lightning Mk II
« Reply #26 on: March 18, 2013, 07:31:42 AM »
Loading an amp with a pure capacitive load WILL simply give different measurements compared to the same amp loaded with an extra resistance, certainly when signals with sharp rise/fall times are used instead of sine waves.
The 'severity' would depend on the feedback topology used and the output stage's configuration (output R).

On the other hand IF you want this amp to perform as it does in the distortion plot all you have to do is load it with an extra 200k resistor over the driver contacts wouldn't it... ?
easily done at the socket itself.... but IMO not really needed....because...

IF the feedback resistor(s) used already supply such a resistive load it isn't even an issue anyway (if the output is relatively lowZ ) as a similar load is already there in the form of that feedback R.
The R from the neg input to ground needs to be low R anyway to achieve a good SN ratio which implies a rather low feedback R (in most designs).

That extra 200k load isn't going to affect the shown measurements with sinewaves in this case.

as you were... just enjoy the amps regardless who manufactured them.
« Last Edit: March 18, 2013, 07:37:57 AM by Solderdude »
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kevin gilmore

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Re: Liquid Lightning Mk II
« Reply #27 on: March 18, 2013, 10:02:40 AM »
lets try that again

the impedance of 120pf at 20hz is 6.6M
the impedance of 120pf at 1khz is 1.3M
the impedance of 120pf at 10khz is 132k
the impedance of 120pf at 20khz is 66k

I should not try to post when watching animation domination
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ultrabike

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Re: Liquid Lightning Mk II
« Reply #28 on: March 18, 2013, 06:39:18 PM »
:)p13 Thanks, those numbers make more sense. The 200k probe would cap the impedance to ~200k. A pure 120pF cap will get to 200k at around 6.6 kHz and will jump to 400k at around 3.3 kHz. If we define "being in the ball park" as 2x the probe load, then

for the 200k probe that would be around 3.3 kHz (pure cap would be 400k, while cap||200k would be ~180k).
for the 1M probe that would be around 663 Hz (pure cap would be 2M, while cap||1M would be ~895k).
for the 5M probe that would be around 132 Hz (pure cap would be 10M, while cap||5M would be ~4.48M).
for the 100M probe that would be around 6.6 Hz (pure cap would be 200M, while cap||100M would be ~89.5M) .

You mentioned that the THD of the BHSE  is less than 0.1% according to Justin. Do you know what load (including probe), frequency and voltage was used to arrive to this number. I know Stax SRM-727 claims 0.01% THD / 1 kHz 100 Vrms. Is there any way to compare apples to apples here using a load for the BHSE similar to what was used for the LL2?
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MuppetFace

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Re: Liquid Lightning Mk II
« Reply #29 on: March 19, 2013, 06:53:29 AM »
Quote from: eggil on March 18, 2013, 06:23:17 AM
I guess is not OK to disagree or offer different points of view but calling names is fine?
You'd do a  better service by offering a counter argument.

The post you're quoting has a counter-argument: "the tests were done to Stax's current standards; Alex isn't a novice and it's reasonable to assume he knows what he's doing."

A lot of what's going on in this thread is an extension of drama that has been in the works for a while now. You want name calling? Visit the thread on a certain other forum where everyone decides to drag Alex's name through the mud. I guarantee you if I posted my "alternate point of view" about the LL and Alex there I'd be hazed mercilessly.
« Last Edit: March 19, 2013, 07:13:38 AM by MuppetFace »
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