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
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
For values, get Duncanamps' TSC. Putz around until you get impedances, frequencies and ranges as needed.
Tim
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.
Stick to fender/vox/marshall circuit.
skyraider said:
Well gee, that's just a matter of tweaking the values, which will have to be done anyway.
Tim
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?
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
--
Danny
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.
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!
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.
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.
Hey thanks alot, I thought that I could just change some values to modify it for tone. I stil have some work to do on the4 amp before I actually hook the circuit up. I have a Bogen CHB20A 20 watt PA that I am convertting to a guitr amp. I will look into it and let you know how it went.
Just as a matter of interest,
...do you guitar players out there twiddle with the tone controls a lot, or do you find a sound you like & stick with the same settings?
(my amp has only a volume control, so I don't have any choice....must get around to that pre-amp some day...when I do it'll probably only have Treble boost & overdrive...)
Pete McK
...do you guitar players out there twiddle with the tone controls a lot, or do you find a sound you like & stick with the same settings?
(my amp has only a volume control, so I don't have any choice....must get around to that pre-amp some day...when I do it'll probably only have Treble boost & overdrive...)
Pete McK
Re: Just as a matter of interest,
I personally twiddle quite often, at home I tend to leave it, but when giging I twiddle for (hopefully) obvious reasons.
I also use a Baxandall tone stack in the clean channel in my main amp. Mind you I'm mostly playing jazz and a good jazz tone tends to use a fairly different aproach to most other styles, you just have to hear the charachteristic sound of a good jazz pickup and compare it with most other pickups to tell. In the dirsty channel I use a fvm tone stack (based more on a Marshall, but modified a bit) to provide the basic tone, but in one of the following stages I placed a baxandall tone stack for more control. I've found this set up, while inefficient, gives extremely good results.
Connecting your ground leads to the chassis should hopefully work fine... if it doesn't then you need to do something about grounding the chassis asap... 😉
PeteMcK said:
I personally twiddle quite often, at home I tend to leave it, but when giging I twiddle for (hopefully) obvious reasons.
I also use a Baxandall tone stack in the clean channel in my main amp. Mind you I'm mostly playing jazz and a good jazz tone tends to use a fairly different aproach to most other styles, you just have to hear the charachteristic sound of a good jazz pickup and compare it with most other pickups to tell. In the dirsty channel I use a fvm tone stack (based more on a Marshall, but modified a bit) to provide the basic tone, but in one of the following stages I placed a baxandall tone stack for more control. I've found this set up, while inefficient, gives extremely good results.
Connecting your ground leads to the chassis should hopefully work fine... if it doesn't then you need to do something about grounding the chassis asap... 😉
Re: Re: Just as a matter of interest,
Personally I dont tend to mess around a lot, I just "set it and forget it" to quote Ron Popeille. I want the circuit to be efficient, I dont want to drill more holes in the control panel of the amps chassis (so the fewer knobs the better), and I would like more control over the tone. This is why I wanted the baxandall... I am leaning towards the baxandall again, but I still have some time before I start the process of installing it, so keep the messages coming.
Personally I dont tend to mess around a lot, I just "set it and forget it" to quote Ron Popeille. I want the circuit to be efficient, I dont want to drill more holes in the control panel of the amps chassis (so the fewer knobs the better), and I would like more control over the tone. This is why I wanted the baxandall... I am leaning towards the baxandall again, but I still have some time before I start the process of installing it, so keep the messages coming.
Hey, for anyone who has any experience with tone stacks...I love hendrix clean tone, hendrix nasty tone, and friedman metal "tone", I will be playing a strat for the most part. What stack do you recommend that can be effective for adjustments in thosesound styles? any and all comments will help.
This thread looks like it's pretty well played out, but here's my take on the two tonestacks.
First, all stacks have an insertion loss. Any boost or cut is measured against the insertion loss, generally when the controls are set to flat response.
Having said this, the Fender stack is a boost only stack. That is, when treble and bass are set to minimum, the response is basically flat. You can only boost them from there. This leaves a midrange notch. The midrange control changes the depth of this notch.
The frequency of the notch is typcally set around 400Hz (if I remember right) because this seems to work with the spectrum of the guitar sound.
The Baxandall (or really, I think what most people mean is the James) stack, can boost and cut the treble with respect to the flat response. Boost leaves the notch and cut leaves a peak at the midrange.
The midpoint in this stack is typically set around 1KHz because this seems to suit audio listening best.
Based on what I know, you can't make the Fender stack cut bass and treble, although you can play with the midpoint frequency.
The James stack can be configured in alot of ways, some with lots of boost/cut, some with much smaller amounts.
First, all stacks have an insertion loss. Any boost or cut is measured against the insertion loss, generally when the controls are set to flat response.
Having said this, the Fender stack is a boost only stack. That is, when treble and bass are set to minimum, the response is basically flat. You can only boost them from there. This leaves a midrange notch. The midrange control changes the depth of this notch.
The frequency of the notch is typcally set around 400Hz (if I remember right) because this seems to work with the spectrum of the guitar sound.
The Baxandall (or really, I think what most people mean is the James) stack, can boost and cut the treble with respect to the flat response. Boost leaves the notch and cut leaves a peak at the midrange.
The midpoint in this stack is typically set around 1KHz because this seems to suit audio listening best.
Based on what I know, you can't make the Fender stack cut bass and treble, although you can play with the midpoint frequency.
The James stack can be configured in alot of ways, some with lots of boost/cut, some with much smaller amounts.
A small wording correction:
The Baxandall (or really, I think what most people mean is the James) stack, can boost and cut the bass/treble with respect to the flat response.
The Baxandall (or really, I think what most people mean is the James) stack, can boost and cut the bass/treble with respect to the flat response.
Absolutely riveted by you guys and the dynamics of the posts. I'm a newey, ( signed on 2014/09/20 ) and I'm installing an active circuit in my custom Strat using a TL072 to isolate the inductive pups from the capacitive cable between amp and guitar. I am considering re configuring the three Pots as Volume treble and bass. With the pups looking into infinity and negligable loading it should liberate top end harmonics, I will use a baxendall tone stack to start with because all I need is a flat response with pots set central and the option of +/- 10dB of swing either way. Those of a more erudite persuasion might like to comment, if so please do. Lyford
Just in passing, and not commenting on relative merit, but I am a little surprised that there could be a misunderstanding between "James" and "Baxandall" topologies.
The "James" is clearly a passive circuit (only) needing log law controls, as distinct from the "Baxandall" is the feedback version round a tube (only), using linear controls. Characteristics of boosting, attenuation, slope etc. can be chosen to suit and is not a particular feature of either. The only slight advantage of the Baxandall is in stereo amplifiers, because in practice linear controls usually track more accurately than log ones.
As said I am not arguing for specific tonal characteristics preferred by guitarists, those are the preference of the instrumentalist. I simply suggest that the correct name be used.
Tone controls
Hi. Enzo is also right. There is nothing bad about baxandall. I have used many of these, and from the two transistor baxandall ckt as given in the Philips audi book, to even the one transistor versions. Yes that brings up another point. The first transistor buffer is vital, other wise it changes volume when you use the Bass or Treble controls. There are other interesting baxandal circuits also, which work very well. Like the ones using LF 351, 353, 356 high slew rate amplifiers. These are found in Nat Semi application book. They have a third pot with midrange, and that also works well. remember, for simplicity they have not shown the preceding transistor buffer, but include it. it is a simple emitter follower. if you use the op amps, the slew rate is important. minimum 10V/ uS. if using transistors, use the correct specced ones. Hope this helps. 😀
Hi. Enzo is also right. There is nothing bad about baxandall. I have used many of these, and from the two transistor baxandall ckt as given in the Philips audi book, to even the one transistor versions. Yes that brings up another point. The first transistor buffer is vital, other wise it changes volume when you use the Bass or Treble controls. There are other interesting baxandal circuits also, which work very well. Like the ones using LF 351, 353, 356 high slew rate amplifiers. These are found in Nat Semi application book. They have a third pot with midrange, and that also works well. remember, for simplicity they have not shown the preceding transistor buffer, but include it. it is a simple emitter follower. if you use the op amps, the slew rate is important. minimum 10V/ uS. if using transistors, use the correct specced ones. Hope this helps. 😀