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9am53 7th March 2005 03:20 PM

baxandall tone control
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 8th March 2005 04:55 AM

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

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


skyraider 8th March 2005 08:47 AM

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 8th March 2005 10:35 AM


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.


9am53 8th March 2005 04:31 PM

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 8th March 2005 06:15 PM

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.

9am53 8th March 2005 06:42 PM

thanks azira, interesting insight

Enzo 9th March 2005 05:36 AM

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 9th March 2005 04:25 PM

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 12th March 2005 03:54 PM

There's a good discussion of tone stacks here:

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.

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