I'm looking for a reference for a simple active EQ design for audio. Basically I'd like one knob that when rotated counterclockwise, say, gives bass boost and treble cut, and when rotated clockwise gives treble boost and bass cut. Maybe done with just a couple op-amp sections...
Any suggestions?
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Dual-gang pot? ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
Maybe, but likely too bulky and too costly...
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Maybe two op amps configured as high pass, low pass filters, and then a single pot with output taken from the tap as like a balance control...
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Should really control the resistance of the feedback paths for true boost/cut. Just thinking out loud
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Fig. 10.14 in Douglas Self's book "Small Signal Audio Design" seems to have what I'm looking for, it apparently is called the "Ambler active tone control circuit"
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People used to call this a "tone control."
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Still two pots, no? You might think about something with switched cap filters.
George H.
The Ambler tilt control has only one pot.
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That's the word I was trying to remember... "tilt", as in a tilt equalizer. ...Jim Thompson
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| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
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The touchstone of liberalism is intolerance
Ahh.. shown here?
That's kinda cute.
George H.
How about this?
Or if you need higher resolution and sample rate add this,
-- Rick C
...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
Here's one of a vintage you'd probably appreciate... :^)
I suppose it's not active though. Does it have to be? Why does it matter?
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:
The active Baxandall tone control - with two pots - sounds very like what you are asking for. Put the two pots on the same shaft and you'd have what you ask for.
The Peter Baxandall involved is the same guy that invented the Baxandall class-D amplifier. He was an active member of the UK audio engineering mafia, and a good mate of Peter Walker the guy that set up Quad Electroacoustics.
-- Bill Sloman, Sydney
Huh, I don't really know tubes, but I can see how that works. Nice schematic. The other circuit has two poles... I'd have to make a bode plot. Mixing things with pots is kinda fun.
George H.
'Tone' is just treble cut.
NT
Google images for tone control circuit
There are lots of single-pot circuits, some of which do the nearly-ideal adjustable s-curve thing.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Everything is possible, but IRL 'tone' on a control knob means treble cut at least 99% of the time.
NT
Google it.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
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