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Bernhard 16th March 2009 01:17 PM

Does that qualify as "X" ?
I'm just curious, does that circlotron qualify as X ?

X resistor is marked with red X.

Bernhard 16th March 2009 11:13 PM

Nobody ?

For a +/- 20V swing into 8 ohms I was able to tune a slightly modified circuit's harmonics from initial -60 dB down to -85 dB without the X.

With X added down to -105 dB and for a +/- 2V swing down to -140 dB.

In virtual reality ;)

Bernhard 17th March 2009 01:07 PM

I found that the boost from -85dB to -105 dB happened only after the modification of adding additional feedback & X connections.
The X resistors are becoming very value sensitive with a +20 dB performance peak at a certain point, while with only one X connection the values seem to be not very important.

There are now high impedance feedback connections from the output stage to every arm of the differential input amps, and low impedance feedback connections to every leg of the differential input amps.

The X connections may be like in the schematic or also crossed between the legs.

However, I'm not sure what will happen in the real world. :rolleyes:

Bernhard 17th March 2009 01:34 PM

Now... is that an X ? :clown:

EUVL 17th March 2009 05:13 PM

Here is a simplier X-Circlotron :

Built multiple versions with Toshiba & IRF MOSFETs. Sounds great.
(My usual bias !!)



Bernhard 24th March 2009 12:54 AM

Schematic in #1 updated.

All perform more or less equal.

Any comment ? :confused:

Bernhard 24th March 2009 02:02 PM

Ok, so I think this is not "X" because I have at least three feedback connections on each side.

Nelson Pass 24th March 2009 07:55 PM

I don't know - it doesn't fit on my screen, and anyway
its got more than three parts in it.


Bernhard 25th March 2009 02:04 PM


Originally posted by Nelson Pass
I don't know - it doesn't fit on my screen, and anyway
its got more than three parts in it.


Master, I hear your voice.

My circuit is to complicated.*

Just removed the VAS. :)

*less is more

Bernhard 25th March 2009 08:50 PM

Schematic in post #1 updated, with VAS removed.

I will try also with only one differential input amp again.

Any suggestions ?

Cascodes ?

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