You're welcome, I hope you get it all sorted out without too much more bother.
You've had a lot of work to do, too, what with having to re-do everything multiple times. But that's the way it usually goes when we're learning something new!
Are the glass envelopes partly sticking out of the cab, unprotected? What happens if your niece bumps her guitar against them? There will be broken glass and sharp metal valve electrodes coated in toxic chemicals trying to lacerate her delicate little-girl skin. 😱
I've seen many DIY valve projects on the 'Web with tubes sticking out of the enclosure, but IMO this is a terrible idea. Even more so when the product is intended for a child.
-Gnobuddy
I've been thinking the same thing, I will likely find a perspex dome or similar to bolt to the top of the amp and cover the tubes while still keeping them free in the rubber while away from knocks etc and still visible. I just have to find the right thing to use!
Haven't been able to get to the amp this weekend at all! I was helping a friend with that ECU project. I got my alpha and CTS pots with all log taper and different values from 1M to 10k. I am going to do some testing in tone stack calculator and possible swap some parts on that tone stack, but I think I have a good handle on the resistor/cap relationship and the cutoff frequency. (1/RC it turns out!) so I have a better place to start from and might even end up making my own tone stack in future once I get a few more parts and can actually build a variable one to actually listen to and see what I like.
Once again, you have been a great help and I thank you! I am off to put some parts in the box and see if I can get an actual test going by dinner time tonight! XD
I'll try to remember to take photos of everything before I cover it all up.
For a single resistor and a single capacitor, cutoff frequency is 1/(2 pi R C) where pi = 3.1416 more or less.
But in a tone control circuit things are considerably more complicated, because there are a slew of resistors and a slew of caps, and particularly at some midrange frequencies, there's lot of interaction between the "bass" components, and the "treble" components.
TSC should help a lot in this regard, as long as you stick with one of the circuits it includes. If you ever want to go beyond the limitations of TSC, LTSpice is free, and extremely powerful, but there is a longer and steeper learning curve. There are many excellent free tutorials on the 'Web, though.
The people who came up with some of the more complex original tone control designs in the early twentieth century amaze me. They had to imagine the thing in their heads first, then design it with a blend of intuition and mathematics. Back then, without computers or even electronic calculators, it was hours of hard work to calculate the frequency response of a tone control once it had been designed.
And once you'd calculated a frequency response, you had to measure it, and even that was slow and tedious - you had to measure at a couple of dozen frequencies, pull out your book of logarithm tables, do lots of tedious arithmetic, and finally plot the curves by hand on graph paper.
We are so lucky to have tools like TSC and LTSpice, and affordable computers to run them on!
-Gnobuddy
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