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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  Active Baxandall Tone Controls examples. 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: Active Baxandall Tone Controls examples.  (Read 11874 times)
ubaid88
Posts: 136

Muhammad Ubaid ur Rehman Khan


Active Baxandall Tone Controls examples.
« on: November 09, 2009, 04:48:21 PM »

Ok here 2 type of Baxandall Tone Controls from carvin amps.

Passive one

Active one


Check them, if there is anything wrong or missing in them. I will use the active one for my Dr Boogey. Also in active tonestack there is 10uf cap(non-pol), can it be replaced by polar or a smaller value of non-pol caps(1uf or below). 10uf is not available for me in non-polar.
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Derringer
Posts: 933



Re: Active Baxandall Tone Controls examples.
« Reply #1 on: November 09, 2009, 05:07:13 PM »

this may be a simpler route for you



The Baxandal is a wonderfully designed tonestack. If you want more bass, you turn up the bass. If you want more highs, you turn up the highs. If you want more mids, you lower the bass and treble and boost the volume.

So the way I look at it, as long as you have something to boost the volume to the degree you need ... then it's an active stack.
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ubaid88
Posts: 136

Muhammad Ubaid ur Rehman Khan


Re: Active Baxandall Tone Controls examples.
« Reply #2 on: November 09, 2009, 05:51:24 PM »

wat are the value of polarized caps??
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Derringer
Posts: 933



Re: Active Baxandall Tone Controls examples.
« Reply #3 on: November 09, 2009, 06:11:47 PM »

I think I used 2.2 uf because I have a ton of them

But 10 uf would be fine as well
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ubaid88
Posts: 136

Muhammad Ubaid ur Rehman Khan


Re: Active Baxandall Tone Controls examples.
« Reply #4 on: November 09, 2009, 07:31:43 PM »

can you suggest a 3 band one.
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aziltz
Posts: 1155


grad student


Re: Active Baxandall Tone Controls examples.
« Reply #5 on: November 09, 2009, 07:45:42 PM »

I've been told that the Catalinbread Silverkiss is a tweaked version of this 3-Band Active EQ.  I don't know that it's necessarily Baxandall, but I haven't looked into it yet.

http://freecircuitdiagram.com/wp-content/uploads/2008/11/3-band-graphic-equalizer-circuit.jpg

The Catalinbread Forum Reps told me so.
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caspercody
Posts: 562

Rob Schneider


Re: Active Baxandall Tone Controls examples.
« Reply #6 on: November 10, 2009, 10:55:21 AM »

Could you use a 11n at C28, and eliminate C47 and C57?

Why the three in parallel?
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head_spaz
Posts: 302


Re: Active Baxandall Tone Controls examples.
« Reply #7 on: November 10, 2009, 11:08:05 AM »

I recognize that circuit.... it's right out of the Carvin Quad-X
I gots me one of them, and the Tube100 Stereo poweramp to go with it.

The one that Derringer posted might be better as a stand-alone, because the Carvin one is inverting...
meaning that it is has a low impedance input.
If you're gonna use Carvin's Baxendall inbetween stages, it'd be ok.
The Quad-X uses a bunch of them since it's a four channel preamp. They work ok... but they can get
a little muddy sounding. To correct it, Carvin incorporates a mud_cutter stage ahead of the baxendall,
they call it a "Cloaking Filter"
« Last Edit: November 10, 2009, 11:26:25 AM by head_spaz » Logged

Deception does not exist in real life, it is only a figment of perception.
liquids
Posts: 1021


Matthew


Re: Active Baxandall Tone Controls examples.
« Reply #8 on: November 10, 2009, 11:48:33 AM »

Ubaid, hi again.  continuiation of the last thread.

You really need to breadboard these at this point.  The schematics you use should all work if you just 'like the concept' of what your doing - that is, replacing the dr. boogey first with cascode, now SRPP stages, etc., first a passive tone stack, now an active tone stack as I suggested...  But if you breadboard, you will verify, and better yet hear and compare the differences for yourself.  They are starting points for tweaking.  But no matter how many times you post, you can't get people to hear for you...  I encourage you to start tinkering and listening, then come back knowing what you do and don't like, if you don't know how to get what you do like.

Also, Derringers tone stack is not an active tone stack, it's a buffer, with a passive baxandall, plus a gain recovery stage.  That is not active.  Since it's passive, the controls are highly interactive.  Active tone stacks implement negative feedback and control a frequency range that has little to no interaction with the other tone control(s) unless it is so desired.  The 3 band is a good example.  

This is the active version of what derringer posted, and one I like a lot, even over the 'classic' active baxandall circuit, since you can actually change caps to boost a different (bass) frequency range than the frequency range you want to cut, if you mod it:  http://focus.ti.com/lit/an/sloa042/sloa042.pdf

Not sure how inverting phase and low input impedance are synonymous--maybe you can explain that, head_spaz.  

Good luck.
« Last Edit: November 10, 2009, 11:51:57 AM by liquids » Logged

Breadboard it!
liquids
Posts: 1021


Matthew


Re: Active Baxandall Tone Controls examples.
« Reply #9 on: November 10, 2009, 11:56:10 AM »

Also in active tonestack there is 10uf cap(non-pol), can it be replaced by polar or a smaller value of non-pol caps(1uf or below). 10uf is not available for me in non-polar.

Weather or not it is polarized doesn't matter in almost any case.   The schematic probably didn't intend to suggest it as non-polarized anyhow.  Use a 10uF polarized, or whatever you have, to start.  The bigger cap is there to pass as much bass as possible, to a point...not always good in every circuit...experimentation would really help you. 
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Breadboard it!
ubaid88
Posts: 136

Muhammad Ubaid ur Rehman Khan


Re: Active Baxandall Tone Controls examples.
« Reply #10 on: November 10, 2009, 01:19:06 PM »

Thanks again liquids.

Yeah definitely need a breadboard now. To experiment my design. And wat sounds best when they are all put together.
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