baxandall tone control

[9am53]

I get the gist that the baxandall tone circuit is superior to the fender/vox/marshall cicuit, and it looks simple to hook up. I have two problems though, how do I choose r/c values for my amp (Bogen CHB20A)? The second will undoubtedly illicit many groans...where do I connect the leads going to ground? My naive intuition says somewhere on the chassis; but my intuition tends to be very wrong! Thank you for your help

[Sch3mat1c]

Whatever the circuit ground is. If it isn't the chassis, it's what all the cathodes eventually drain into.

For values, get Duncanamps' TSC. Putz around until you get impedances, frequencies and ranges as needed.

Tim

[skyraider]

Baxandal is not optimised for a guitar tone, thats why you dont find it in guitar amps in the first place. Try plugging a guitar into a classic integrated amp and try to get the sound 'correct'. it wont happen because the bass/treble boost is not in the correct frequency.
Stick to fender/vox/marshall circuit.

[Sch3mat1c]

Originally posted by skyraider
it wont happen because the bass/treble boost is not in the correct frequency.

Well gee, that's just a matter of tweaking the values, which will have to be done anyway.

Tim

[9am53]

The reason I dont want to use the f/v/m circuit is because apparently allthought the baxandall circuit has only two knobs it can apparently give you more mid boost. I thought I could tweak it to be good with guitar just with cap and resistor values. What do you guys think?

[azira]

Guitar pickups don't have a flat response. They actually have a very pronounced midrange response. The baxandall circuit is for hi-fi audio purposes while the F/M/V circuit is meant for guitars to balance it's output. If you turn the bass and treble all the way down on your guitar and play a few chords you'll hear what your guitar pickup actually sounds like.
--
Danny

[9am53]

thanks azira, interesting insight

[Enzo]

And remember that all these passive circuits are really cut only, nothing "boosts" the midrange. All you can do is cut the highs and lows around it.

[9am53]

Thanks a lot guys, I am going to use the old f/v/m circuit, now I just have to figure out how the rest of the amp works!

[mlabbee]

There's a good discussion of tone stacks here: http://amps.zugster.net/articles/tonestacks/index.html

He gives a schem for a Baxandall set up for guitar and I have used it - it works very well.

Disregard the comments about guitar tone above. They are right, but there is nothing inherently midrangey about a Baxandall circuit - you can set it up to have virtually any response you want (see the midrange boost example given in the above link - add a cap, dramatically change the profile). The advantage the Baxandall circuit has is that it provides a great deal more variation in tone with only two knobs vs. less variation in tone with the 3 knob f/v/m circuits.

Baxandall is worth playing with - I've heard they are best for low popwer amps, which is mostly what I build, so I don't know how well it will work in a high power amp.