Interesting little EQ i came up with...Equalite

[Kipper4]

yep this

[rankot]

I will definitely try this one! Is it noisy like gyrator based op amp EQs?

[dschwartz]

C taper?
it will work but it will not be 0dB at the center..

[Kipper4]

True that about the C taper. It was just to try it.

No it's not noisy like a gyrator. The Q pot I added does make it noisy because of the added q in the highs though.
I tried a 10k Q pot it didn't work through all the range. Plus the 5k pot needs a stopper R.
The high gain is a bonus but probably to much for most applications imo.
A very good low parts low pots Eq.
Sterling job Daniel.

[dschwartz]

True that about the C taper. It was just to try it.

No it's not noisy like a gyrator. The Q pot I added does make it noisy because of the added q in the highs though.
I tried a 10k Q pot it didn't work through all the range. Plus the 5k pot needs a stopper R.
The high gain is a bonus but probably to much for most applications imo.
A very good low parts low pots Eq.
Sterling job Daniel.

nice shem!
you need to add the dc blocking cap at the input
changing the frequency via the ground resistor is a PITA..it changes the Q too much and has limited range..i´m sure there´s a way to do it but i tried and failed..

[Kipper4]

Yer I'm not sure the extra 5k pot is worth it. Maybe if one where to make a 6x stage maybe one extra pot might make sense.
Oops forgot the input cap. I used 100nf.
A useful addition to the thread would be the calcs for freqauncy.

[ElectricDruid]

That's a really neat, elegant little circuit. I like it a lot.

Well done, and nice work Daniel.

Tom

[dschwartz]

Yer I'm not sure the extra 5k pot is worth it. Maybe if one where to make a 6x stage maybe one extra pot might make sense.
Oops forgot the input cap. I used 100nf.
A useful addition to the thread would be the calcs for freqauncy.

i used this formula to calculate the center freqs:


R1 is the big resistor, and R3 the smaller.

where C2=C3  and R2=0 (use the bottom formula for bridged T)
The Q is given by the relation between R3 and R1 i don´t have a formula for that but it is sort of R1/R3 dB´s

[jonathanfdean]

So, an updated Purple Peaked, sort of

Sent from my XT1032 using Tapatalk

[dschwartz]

So, an updated Purple Peaked, sort of

Sent from my XT1032 using Tapatalk

Well, the use of T filters at the feedback is a common practice for frequency boost. The novelty is that my configuration let's you boost or cut the frequency with the same T filter..similar to a baxandall mid control..but you can get extreme boost or cut.

[Kipper4]

Thanks for the info Daniel.

[GibsonGM]

This looks really neat, Daniel. I want to check it out, but only have TL072s...yes, I could just use them, but what fun would THAT be?   

Do you suppose this would work well with TL064's?  I still have a few from an Easyvibe build, this might be a good way to use them!  I am not sure they are as quiet as the 74's, etc.

Thx.

[dschwartz]

It should work fine on any opamp.. in this case, the opamp is just making the operation it should do..
But feel free to try different ones while boosting the hell out of frequencies..maybe there's an interesting distortion pedal hiding there

[DDD]

I've spent some time playing with EQ with W-shape response.
Well, it's very interesting and can produce a lot of useful tones.

[derationalize]

Sorry about the necro, but I've been messing with this circuit a lot and I can't quite get it working correctly. Version 1 with the resistor to ground works great, but the dual pot version is acting weird. I keep rebuilding the circuit and it keeps ending up with the same problem. There is only output when both the gain pot and the dual gang are roughly in the same area of rotation. Example; gain pot at 0-10% then parametric control works from about 0-15% then cuts off the output. If gain pot is around 90-100%, then I only get output when the dual gang is somewhere around 85-100%. I have a 100k dual gang pot and I've tried 500k, 200k, and 100k for the gain pot and I keep getting the same result. I'm using all the values from the 600 Hz section and I have the last buffering stage afterwards as well. Turning the gain pot all the way one way gives a nice peaky Q to sweep, but the other way produces no notch.

Anyone have any ideas? Do I have my dual gang pot wired up wrong? Should I add a buffer before the input?