John Curl's Blowtorch preamplifier part II

[john curl]

Please look again, Jan. What you thought was 4.56K is really 4.99K. Just look at the graph, not just Jan, but everybody! Can't you see that it is NOT 4.56K? You made an oversight, Jan. Look again, blow up the graph, if necessary, look at Gerhard's work for comparison. However, please realize that an error has been made in where these frequencies come from.

[PMA]

I'll give you a hand, if we speak about this image:

[BV]

2f2-9f1..

[PMA]

Originally Posted by bv

2f2-9f1..

30 - 28.62 = 1.38

??

[BV]

1.38 exactly. Look in post 1076 with frequencies 3200 and 15000.Other products are below range, i can post picture with 140dB range.

[matejS]

I haven't read all the posts.... so, just a simple idea.

Create signal in some mathematical package and run FFT over it. This will give you what is expected. Now compare it to measurements. If not equal, opamp is not "prefect".

Matej

[brianco]

Originally Posted by Wavebourn

Really?
"You are dork! We did all that of this and that 40 years ago!"

Can you show me please something revolutionary that John did, or demonstrated, during the life of this particular thread, except empty statements about how progressive he and his friends are, and how badly we oppose him?

What John tries to suggest, only that on the picture made 30 years ago he sees presence of PIM, and this presence is signified by non-harmonic sidebands

If it is a New Word in The Progressive Science, I am The Pope.

Firstly I must apologise for not including you with PMA. I do feel that you are one of the few who is well qualified and has a zeal to get it right - in the real listening world.

Living over here on the edge of Europe and a long way from showrooms etc. I have no idea of how JC's designs sound. What is obvious though is that he is attempting to shake some people out of the ruts in which their thinking takes place. I also think that he may have his tongue in his cheek and that he is rattling a few cages for fun! If I am right in this, then he is indeed very successful.

[bohrok2610]

Originally Posted by PMA

I'll give you a hand, if we speak about this image:

The circled blips seem to be:
|2f2-9f1|=1380
|2f2-11f1|=4980
|2f2-7f1|=7740
|2f2-13f1|=11340
|2f2-5f1|=14100
...
which is to be expected since f1 is a square wave (odd harmonics). 2f2-8f1 is below range.

Martti

[PMA]

This would make sense, as the uA741 worked most probably in a slew rate limited mode, so very high order products might be expected.

[BV]

This is simple diode limiter with "DIM100" signal (3200sq+15000sin)so no SR limitations, only nonlinearity..The same "footprint".