Tube mixer design

[rafafredd]

Hi.

I´ve been looking for a tube mixer project for a long time. I came to find an article at tubecad journal about the subject, so, I got this project and moded it for my needs, but as I´m very new to eletronics, I would like you to see the circuit and tell me if it´s all right. The original was a 4x1 mixer. I tried to make it a 8x2 mixer by adding more channels and some 10k panpots, so that it suit my needs. I added a BChannel section to, that is just identical to the channel A for stereo. Here are the links to the original one and the moded one:

You can see the original article here:

http://www.tubecad.com/april_may2001/page22.html

And the moded version

http://www.geocities.com/rafafreddy/index.html

go on tube mixer

I really don´t know if it will work, so let me know if I´m just dreaming...

Also, R32 and C2 needs some values!
Someone said me that a couple of kohms would do for R32, and 47uf/250V would do for C2.

Is it allright?

Thanks

 

[Prior]

Well, you certainly are new to electronics. This is not the way a
panorama-circuit gets implemented. As you did it, your A-channel would maintain the same volume, while you'd fade away your B-channel turning the pan-knob. I saw you've drawn some kind of tube-cascode as the apply it in old FM-receivers. It has a good noise figure and broad bandwith, but I would not think it is suited for audio anyway. There is no way you can design with tubes if you haven't read a pile of books about them. Why wouldn't you just start with the beginning and collect a lot of mixer-designs. You might even decide not to make a tube-mixer. Tubes do indeed have their charmes, but a decent design with modern opamps is way better than a three-tube stereo-mixer design. Designing your own mixer is not done by a biginner anyway. I don't mean to upset you, I just want to prevent you from a disappointment. Electronics really is a exciting hobby, but does need a lot of gathering knowledge. So get yourself some books from the library, and concerning te mixer, take an existing design. I hope you'll enjoy it as we all do.

 

[Joel]

Rafa,

There is a very simple, sturdy design in the back of the RCA tube manual which is a 2 input-1 output mixer with two level controls. In the 1947 manual it uses 6SC7 octal dual triodes; in the 1963 and later additions it uses 6EU7 miniatures.
You could of course put two such circuits in the same chassis to make a 4-to-2 mixer.

I would think that's a good place to start. I'm actually planning on throwing one together myself.