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transient test - Part II

Hi,

Been looking at differences between a simple cathode follower and
a skiklai follower, trying to understand them.

Input uses bandlimited (27th harmonic) square wave of
1050Hz at 7V peak combined with 5Khz 1v peak sine wave.

This is slightly smaller than the 8v peak square wave used before
which was overloading slightly.

Looked at IM components...Here are two graphs, one for each circuit.
(Cut and Paste into your browser)

http://img.audioasylum.com/cgi/i.pl?u=users/8660&f=LogSimple10ohm_load7v1050square_1v5Khzsine.JPG


http://img.audioasylum.com/cgi/i.pl?u=users/8660&f=LogSziklaiUnComp10ohm_load7v1050square_1v5Khzsine.JPG

The simple circuit goes up to 10mV fullscale, while the sziklai
goes up to only 1mV. The slice of the spectrun
shows the same IM components:

13650 = 13f1
13900 = 18f1 - f2
13950 = 3f2 - f1
14150 = 23f1 - 2f2
14200 = 2f2 + 4f1
14400 = 28f1 - 3f2
14450 = f2 + 9f1
14700 = 14f1
14950 = 19f1 - f2
15000 = 3f2

The sziklai is *much* more linear. For instance 14450(f2 + 9f1)
is about 5mV on the simple and 100uV on the Sziklai. The simple
circuit has a much higher floor of harmonics (about 80nV compared
to about 2nV (not shown)) then the sziklai.

Now looking at harmonics of the 1v sine wave for both circuits:




Harmonic Sziklai Simple
Fundamental
(dB) 		0.00 0.00
2nd -86.55 -55.49
3rd -100.38 -89.40
4th -113.45 -111.52
5th -125.14 -129.77
6th -135.24 -130.94
7th -146.01 -133.78
8th -161.81 -142.09
9th -150.18 -137.41
10th -152.95 -134.77
11th -155.87 -154.48
12th -155.32 -155.86
13th -155.67 -135.01

The simple circuit has higher 2nd. This may ultimately be why
the simpler circuit may sound better. Its harmonic pattern matches
a Cheever/Hiraga type of pattern better.

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Topic - transient test - Part II - mfc 21:52:14 07/30/03 (83)
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