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-   -   EF86 + SPICE = no noise contribution? (http://www.diyaudio.com/forums/tubes-valves/108941-ef86-spice-no-noise-contribution.html)

davygrvy 23rd September 2007 08:18 PM

EF86 + SPICE = no noise contribution?
 
Hi,

I've been playing around with SPICE working on a little microphone preamp and it's been loads of fun trying-out different topologies.

I got the EF86 model from http://www.duncanamps.com/spice/valves/ef86.inc

Now I'm trying to simulate noise with:

.noise V(out) V1 oct 4 20 20k

But the EF86 part doesn't have a contribution to the total. I doubt it is noiseless. I think I see why as the part is a .subckt who's behavior is defined by equations rather than a true model where you can set params such Af and Kf (flicker noise).

Assuming I put an EF86 in a test circuit and measure the noise behavior, in what manner could I add this to the EF86 .subckt? :confused:

davygrvy 23rd September 2007 08:24 PM

BTW, spice says EIN is -129.3dbu, which I doubt as theoretical is -130 (150 ohm source). I don't think I'm looking at a 0.7db over Johnson preamp ;)


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