no more tone stacks for me..

[Kipper4]

>Have you considered rgs parametric eq

prametric eqs are so cool. I built and modified a pq-4 and loved it. I haven't tried rg's though. also I'm not op.

not hjacking but do you have a link to a schemo for that please MrBinns

[Transmogrifox]

not hjacking but do you have a link to a schemo for that please MrBinns

Well I'm not MrBinns, but here's the link with a mighty nice read to go along with it.
http://www.geofex.com/article_folders/eqs/paramet.htm

[MrBinns]

>Have you considered rgs parametric eq

prametric eqs are so cool. I built and modified a pq-4 and loved it. I haven't tried rg's though. also I'm not op.

not hjacking but do you have a link to a schemo for that please MrBinns

The pq-4 is from here: http://www.synthdiy.com/files/2007/boss_pq-4.png

I used TL074's for the op amps

To modify it, I took out the low section at the bottom and the presence section. I added another state variable filter for the bass section w/ .15uF caps. I was going to add a forth op amp to each section to control the q value. I need to re-bread board it.

I found the page(page 47): https://books.google.com/books?id=N7QgBQAAQBAJ&pg=PA48&lpg=PA48&dq=4+stage+state+variable+filter+with+q&source=bl&ots=FYNRNrk9ac&sig=7q7LzLuQz-HGkXXCBFVGTJQfG0E&hl=en&sa=X&ei=CMUZVfDVOdGKyAS4z4GYDg&ved=0CEkQ6AEwBw#v=onepage&q=4%20stage%20state%20variable%20filter%20with%20q&f=false

The three right most resistors I 'have' as 5K. The bottom three resistors from left to right I 'have' as 18K, 12K, and, 6K with a 100K lin pot in series with the 6K. After the 5K resistor, Vout, I have a 1uF(10uF)[20uF]cap to 500(500)[400]resistor to 100Kpot for highs(mids)[lows] sections. It's wired like the pq-4 C5, R9, pot, but moved over and with different values. I hope that makes sense. I drew it in a notebook so can't really upload it.

[Kipper4]

Thanks Mr B

[deadastronaut]

Oooh that pq4...yum...

nice...

[MrBinns]

Thanks Mr B

o and I want to say the q values I chose were 1/3-3octaves

it looks like it's closer to 1/6th and 2.5octaves. idk if those are good values or not. I haven't tried it out yet.

[anotherjim]

PQ-4 has some tapped (4 terminal) pots? Centre tap I guess, although drawn offset?

[MrBinns]

PQ-4 has some tapped (4 terminal) pots? Centre tap I guess, although drawn offset?

Is that what the part means? I just assumed it meant to ground the back of the pot or something.

They do have fancy pots though. dual gang 50K c taper, stacked with a 100K w taper, 9mm concentric pot.

I feel bad for hijacking this post. Should we move?

[tca]

Quote from: MrBinns on Today at 10:30:43 AM

feel bad for hijacking this post. Should we move?

I guess so... is not easy to keep up with 2 topics in a linear medium.

Cheers.

[Rob Strand]

This parametric has far less components than other options.  You can put these in series as mentioned in the original thread to get more bands.   
http://www.diystompboxes.com/smfforum/index.php?topic=95483.0;nowap

[Rob Strand]

PQ-4 has some tapped (4 terminal) pots? Centre tap I guess,

I suspect the tapped pots are real.  You see these used time to time on professional Equalizers.   The centre tap stops the bands interacting with each other.  It tends to be a good thing.  Put it this way:  if you use non centre-tapped pots on a parametric circuit which was designed  for centre-tapped pots the result is no better or worse than any other circuit that doesn't use centre-tapped pots.  For a graphic EQ it would be a different matter.

[MrBinns]

I made a pq-4 thread.

http://www.diystompboxes.com/smfforum/index.php?topic=111458.0

[deadastronaut]

Just got back from camping, great weekend...and now have my la3600 ic..

should get it breaded later..

[deadastronaut]

Well i have it on breadboard, all working fine..

i stuck a buffer in front to lift it up a bit and tweaked to get better unity..

i'll use an opamp for the buffer and have a volume on it too..but for now this is how it stands

a bit of tweaking on cap values i think too.....thoughts?..suggestions?..

i have no idea of the ''actual'' freq's ...but its sounding pretty good so far

[tca]

Nice!

What values for the caps? That C9=470u cap can not be right (missprint)?

Cheers.

[deadastronaut]

oops!  470n..

[tca]

ah, ok!

The cap values are not "exactly" the ones I've calculated... but it could work nicely, it is all about compromise!

Any first impressions? Control, responce...?

[deadastronaut]

responds nicely..proper seperation etc..

once i swap the bjt for an opamp, i'll have a nice vol for 'make up' when scooping etc..

i just used that to get it going for now (nearest to hand bits )

but yeah pretty cool so far..

[deadastronaut]

any suggestions for other/better values while i have it on bread..

heres what i have so far..

47n     10n     3.3n    1n    220p

1uf     470n    100n   68n   10n

[tca]

> heres what i have so far...

47n     10n     3.3n    1n    220p

1uf     470n    100n   68n   10n

---------------------------------------

My take on values:

30n  10n  3n   1n   360p

1.5u 470n 150n 6.8n 22n

Not much of a difference...