Nova/Groove Tubes/Sterling mod questions

[Amled87]

For the most part, yeah

Not sure that 500pF-larger-than-stock input capacitance REALLY works as you might expect, though. Confirmation bias is a fickle mistress...

1nF into 1G gives a cutoff frequency of 0.16Hz - that's zero-point-sixteen Hertz, waaaaaaaaay below what you can expect to hear (not to mention, what you might want to pick up / record).

1.5nF into 1G pushes that even further down, to 0.106Hz. If you claim you can hear THAT difference, you're the most advanced whale / elephant (what other animals deal with infrasound / subsonic frequencies?) i've heard of And "golden ears" like that belong to "audiophool" environments anyway, not in this blue-collar world But i merely jest...

Jokes aside though, you'll also want to add a 100-200k resistor between the C2 "free end", and ground, and probe the signal at the connection between those two (in order to also see the effect of that output capacitor has on the low frequencies, and the load that a preamp that you would plug this mic into, would have on the circuit).

Other than that, yeah, looks about right indeed And if you click on the name of the signal, in the plot window, you get a cursor you can grab the vertical line of, and drag side to side & see a detailed readout of the signal level at the respective frequency.

Although you might want to consider a JFET there, if that's what your real circuit is using..? Or rather, do indeed recreate THE actual circuit you're trying to analyze? But i do understand if / that this was a sanity-check first-attempt, just to make sure the "protocol" is right

The added 500pf is there on the input because I liked what it did to the sound (the original 1n is a cheap polyester cap and I added a silver mica of 500pf) I'll swap the npn transistor out for a jfet which is what is in the circuit lol. Quick run through so just grabbed components from the list lol

 

[Khron]

I liked what it did to the sound

https://en.wikipedia.org/wiki/Confirmation_bias

Just saying...

If you expect a difference, you WILL hear a difference.

 

[Amled87]

https://en.wikipedia.org/wiki/Confirmation_bias

Just saying...

If you expect a difference, you WILL hear a difference.

Hmm, I can't explain it to be honest. It just seemed like a good idea at the time (before making these new changes, I added the silver mica cap to the input and also added a 0.1uF wima polypropylene to the 10uF output electrolytic cap). I've since changed the the capsule coupling cap, output cap to both philips polyester caps though. I'll remove the 500pF because mathematically it's not doing anything as you stated, because no one can hear where it extends the low-end. Perhaps replace the capsule coupling cap with something better all together of same value if I'm going to do anything there.

Quick question, on this simulation should I put the capsule coupling cap between the two 1G as in the schematic or before/after it. Also, should I be adding the 57pF of the capsule capacitance to the input as well? I measured it out of circuit with a meter.