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6SN7 Distortion Canceling in Amp

sleiven

Member
2007-05-05 9:28 pm
uTracer? Ronald's electronic project site

I built one to do just that, so I can model the actual tubes I will be using. It's a quick and easy way of generating models. If you use the Derk Reefman's "Extractmodel" you get Koren & Derk parameters for your tube. You can also chose the measurement range to get a best fit for your tube operating conditions so you can do some optimisation that way.

I have done some parameter extraction for folks who have sent me tubes to measure, it's not a "service" but I am happy to do it FOC because that way I get to learn more about tubes



In my amplifier all the 6 Tung Sol reissue 6SN7 I have gives much lower distorion in my amp than any other 6SN7 I got. I think the difference should be visible also when tracing the indiviual tube curves..and comparing . Something is special with the TS 6SN7..
367065d1456038832-6sn7-ra-r-spa-rsma-l-capture.jpg


Best regards Balle
 

sleiven

Member
2007-05-05 9:28 pm
Reducing the power from 4.5wat to 1.1Watt gives the same trend, but quite horrific distortion for some non-Tungsol tubes.
367122d1456062470-6sn7-ra-r-spa-rsma-l-capture.jpg



With this 6SN7 model I get 0.67 %THD at 1.1 Watt
* 6SN7 sylvanie LTSpice model
* Modified Koren model (8 parameters):
* Traced by erik 25/12/2013 using Curve Captor v0.9.1
* from datasheet tracer
*
* 6SN7WGTk8 LTSpice model
.subckt 6SN7WGTk8 P G K
Bp P K I=(0.02170661176m)*uramp(V(P,K)*ln(1.0+(-0.1418880099)+exp((5.336202785)+(5.336202785)*((22.20702463)+(-20.28905564m)*V(G,K))*V(G,K)/sqrt((-0.0001481184562)**2+(V(P,K)-(-11.62245799))**2)))/(5.336202785))**(1.347919701)
Cgk G K 2.4p ; 0.2p added
Cpk P K 1.2p ; 0.5p added
Cgp G P 4.2p ; 0.5p added
Rpk P K 1G ; to avoid floating nodes
d3 G K dx1
.model dx1 d(is=1n rs=2k cjo=1pf N=1.5 tt=1n)
.ends
 
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