As usual, I will post these photos one at a time. First, to show the original box that I purchased.

And a brief explanation of the purposes of the circuits/project. The controls that you see on the topside are 3 volume controls for volume. they are wired both in ladder and series connection to provide 36 steps of attenuation IIRC. The center control is the coarse volume adjustment with 6db steps for both channels. Each flanking control adjusts the L or right channel in 2db steps. This also works as a balance control to a degree. You will notice two tube sockets recessed into the top panel. A 7 pin 3S4 tube from the 50's is used for preamplification. They are directly heated triodes that perform admirably. There is only 6-7db of amplification available, which leads me to the next circuit. This circuit is called a line level BSC (Baffle Step Correction). Normally this is done in the speaker design phase, but in the case of single driver speakers, it can become useful for an adjustment of both bass and treble. A concept that Yamaha used in their earlier amplifiers at one time. The midrange is reduced a bit, allowing the bass and treble to sound louder by comparison. Of course, the volume must also be adjusted for any increase of all of the audio signal. The BSC circuit has a 4db insertion loss, and the pre-amp cuit has only a 6-7db gain, so the outcome is about the same as a buffer amp. I wouldn't say that this has limited value, or is only useful in certain systems. It probably is a try before you buy idea. And lastly, the pre-amp is likely to be battery powered. I may turn to conventional power supply. We'll see as things develop.

I'm feeling like a slacker - I've got projects stacked on top of projects, and yours are progressing well. Nice Work!

I know that feeling well...and I expect perfection of myself in everything.

Needless to say, I'm disappointed in my lack of perfection. LOL

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That's good advice my friend.

If I remember correctly, it will change the width of the usable window of attenuation. At one end you have full off, at the other you have full on - you're only getting 20% of the sweep between those two points.

But then we don't hear linearly but... logarithmically is it? So that 20% might be even less sweep (subjectively).

Of course, I could completely be talking out my arse - I was good at math, but never learned how to properly apply it to circuits - I was too busy chasing girls and being a rebel in school. (shrug)  I really need to take the time to (re) learn basic electronics.

Nice work 4krow, I'll be following this. I like your thought process.
Who wound your resistors ? I'm thinking of this for my ultimate Zen project in the works. I'll be having Dave Slagle wind them if I go in this direction.

Cheers,                CrazyBill

A bit of an update on the build. I have made a brass 'stand/mount' for the two ceramic solder lugs, and then proceeded to install ground wires to the ground bus that I placed on the Bakelite panel. The fine/coarse attenuator used here provides 66 steps by means of a ladder and series resistor arrangement designed by John Broskie. Very useful. It is going slow, but fortunately, this is not as complicated as it could be. I just want to get it right as possible.

Wow, so that's going to be actual DC voltage!

How many volts does the circuits need? I'm wondering if a rechargable Li-On or Li Po might work. (just curious and thinking about rechargeability and being able to run for long periods with more consistent voltage)

Rewind, rethink, redo. I picked another box that is smaller, but I can still fit all the needed stuff inside. I did have to make a top for it though.

As I try to get closer to the end of this project on the side, I found that the circuit will require 6 wires running from the battery box, not just 4. That allowed me to reconsider the arrangement that I have with the wiring and a switch, which is now removed.