Pan between out of phase filters: flat and mids cut/boost!

[bioroids]

Hi!

I posted a Tone control, based on the panning between 2 filters idea (thanks Mark Hammer!).

The idea is that one of the filters gets an inverted signal. The non-inverted goes to a Wein network for a mid-boost, and the inverted gets a full range signal. When you mix both, interesting things happen

The problem is the level variation between different settings of the pot. I think the cause is the broad action of the Wein network. Is there some way of raising its Q-factor? Maybe bootstraping it?

Well I hope it is usefull for someone! I posted the circuit details and some plot graphs at http://www.dedalofx.com/bioroids

Luck

Miguel

[StephenGiles]

Miguel - buenos tardes! Can we voltage control this I wonder? It might be a good effect with an LFO.
Stephen

[bioroids]

Buenas tardes!!

Can we voltage control this I wonder? It might be a good effect with an LFO.
Stephen

Why not!? Now that you mention it, it looks a little like a strange phaser stage.

This can be improved a lot. I just "discovered" that using a bridge-T on one side and the wein on the other it's much better than the posted schematic, and you have equal level at all settings! Still I'd like to make it a little sharper.

For voltage control, the simplest would be replace the pot by some kind of dual led/ldr combo. With higher resistance between the filters the interact much less (maybe requiring to alter the values)

Luck!

Miguel

[Mark Hammer]

Thanks for the nod and taking the idea further.  Very clever, and maybe a nice thing to insert into a BMP variation instead of the traditional woolly-to-whiney tone control.

Question: Hard to tell from the posted graphs, but is the boost position audibly louder than the cut position, and if so how much?

I'm not saying that absolutely equal loudness is the ideal to be necessarily pursued, but it does have implications for what sort of changes to the circuit you may want to make.  For instance, the overall drawn amplitude seems lower, yet the bass and treble seem to have higher amplitude in the scoop trace.  With that change, I ask myself how audibly different are the two extremes in *perceived* loudness.

[bioroids]

hi!

The difference is pretty audible, though is hard to tell from the graphs  :? . The problem seems to be that the cut is too broad.

I'm about to post a better version I've been trying, involving a Bridged T on one side and a Wein on the other. This can be balanced to get flat response at the middle of the pot, and then mids cut/boost at either side. It works much better, though the amplitude is not yet consistent. But it is usable in fact  

Thanks and luck!

Miguel

[bioroids]

Posted the new version. Much better!!

http://www.dedalofx.com/bioroids

Still i'd like it to be a sharper notch, but it' s pretty usefull as it is.

Luck!

Miguel

[Arn C.]

Miguel,
    Do you use a linear or log pot for the tone pot?

Thanks!
Arn C.

ps  Nice job by the way!

[bioroids]

Oh, I forgot to say that!  :oops:

I used a Linear Pot (normal B taper) and works pretty nice.

Luck

Miguel

[Arn C.]

Thanks!  I will give this a go!

Peace!
Arn C.

[bioroids]

Let me know how it goes!

I wonder, is this how some "contour" controls work?

Luck

Miguel

[Processaurus]

Thanks a lot for posting your work, Miguel.  Coincidently this last week I was also trying Mark's panning tone control, and some BMP variations and have been impressed with how radically an EQ can change the character of fuzzy, full-bandwidth sounds.  I really like the look of what you're developing; a tone knob with several distinct, usable sounds throughout.

PS I was looking up Wein filterss, and couldn't find anything, is that type of filter spelled Wien?

[bioroids]

PS I was looking up Wein filterss, and couldn't find anything, is that type of filter spelled Wien?

You know, I'm a dumbass.  :oops:
It's Wien as you note, not Wein he he. In spanish the term "Wien" doesn't make a lot of sense, so I always mix it up...

Thanks for correcting me. I could edit my previous posts, but it'll feel a little like "obliterating the past" (as in 1984)

If you search the forum with the word "contour" there are variuos thoughts about this kind of controls, it seems. I'm reading them now.

Luck!

Miguel

[ExpAnonColin]

Perhaps a series resistance would help fix the 25% problem.

-Colin