5-Band Fully Parametric EQ

[fuzzo]

really interesting stuff , and well done ! 

the "rack" type could by more appropriate for that project, no ? Plus, that kind of "effet" (isn't really one by the way) has no needs to be switch on/off in a song, it stays on all the time. So  why have you kept the "pedal" format ?

the project is maybe too big for me (a lot of knobs to place on a faceplate/box) but the three bands version could be really usefull !

[aziltz]

It's a pedal and not a rack for two reasons: A) its not for me, and B) i don't make racks (or at haven't tried).  I think to some degree certain players like the idea of bending over and adjusting all in one place.

Sure it might *fit* in a rack better, but what's the fun in that engineering?

Calling it a non-effect seems kind of harsh.  I think its pretty awesome in that you can drastically change the sound of the raw guitar, while having it still sound like a clean guitar.  Put it before an overdrive and it becomes an On-Off type effect.  It's all in how you use it.

It can do manual wah stuff too, in fact it can do 3 Manual Wahs.

[fuzzo]

Sure it might *fit* in a rack better, but what's the fun in that engineering?

Nothing different , just take less place on a setup (placed on the amp) whereas a big box pedal takes a lot of space on a pedalboard.

alling it a non-effect seems kind of harsh.  I think its pretty awesome in that you can drastically change the sound of the raw guitar, while having it still sound like a clean guitar.  Put it before an overdrive and it becomes an On-Off type effect.  It's all in how you use it.

It can do manual wah stuff too, in fact it can do 3 Manual Wahs.

Actually I depends of  how you use the EQ , like a filter for some specific part of a song or like a big tonal correction of amp's tone on ON all the time (I'm more in that case it's why I'm thinking about a "rack version" ) .

But Really nice job !

[jkokura]

I wouldn't want this in a rack. I don't have a rack in my system, and I'm not using one just cause I want an eq - I have a pedal board for that kind of stuff!

Not to mention, a rack effect usually gets used in an effects loop - not all amps have loops, and that limits where your eq is for most of us. I want my eq up from BEFORE my effects most of the time. The wiring from the guitar to the board, to a rack eq, back to the board to the amp, then sometimes potentially back to the board from the loop and then back to the amp....

Rack effects are not where it's at for small gigs.

Hopefully, if we can find ways to take this and make 2, 3 and 4 band parametric EQ's those of us not willing to give real estate to a DD for a full 5 band parametric EQ will be.
appeased

Jacob

[aziltz]

I think I will fit it into a 1590BB successfully.

[ianmgull]

Aziltz,

First of all excellent work, I'm impressed. I had a couple questions for you. In the interest of conserving space I was wondering how to leave off the input and output pots. If the pots were taken completely out, would this result in unity gain? Or is there some boost built into the design?

Second, is the buffered voltage reference a necessity? or did you do this as a result of having an extra op amp.

[punkin]

I've gotta ask...how does it sound? Any interest in making a few extra boards?

[aziltz]

Aziltz,

First of all excellent work, I'm impressed. I had a couple questions for you. In the interest of conserving space I was wondering how to leave off the input and output pots. If the pots were taken completely out, would this result in unity gain? Or is there some boost built into the design?

Second, is the buffered voltage reference a necessity? or did you do this as a result of having an extra op amp.

Thanks for the kind words.

The Input and Output Trims could certainly be left off, as could the first and last opamp stages.  This would require a new layout, which I am working.

However, I think the buffered voltage reference is generally a good idea.  With so many pieces going back to it, including a leg of each Frequency Trim/Pot I think its best to have a buffered there to prevent loading, or funny behavior. 

I've built one of these so far and its worked great.  I'm in the middle of another, but I'm also working on a v.2 layout with board mounted pots and less clutter.  Aiming for a 1590BB Box.  I should have it ready to share by mid-January.

I've gotta ask...how does it sound? Any interest in making a few extra boards?

I have a few transfers left, that I could probably make 1 or 2 of the original PCBs when I get back to Virginia in early January.  I think I will probably offer PCBs of the v.2 when I am ready as well, Madbean-Style.

The sound is nice and versatile.  Flat is FLAT and it boosts/cuts nicely for some nice tone shaping.  Best part is it can be adapted for more or less control depending on your needs.

Take care, and happy holidays.

-Austin Z.

[jkokura]

Hey man,

I was curious - how are you doing on layouts for the 3, 4 and 5 band versions? How did it go with the two versions you were building? Haven't seen much of an update lately, and I'd love to begin the process of building one of these for my Acoustic Guitar board!

Jacob

[aziltz]

Hey Jacob,

I'm finishing up the 2nd one this week.  I had some set backs over my break that kept me from finishing it earlier.  It's coming along nicely.

In other news, I'm working on a v2.0 that changes the bass and treble to a Baxandall-Type Shelf, with the three middle bands fully/semi parametric.  I've simulated the circuit and I'm liking how it works, but I haven't designed the layout yet.

Do you know where I can find an eagle package for pc board mounted pots?

Remind me again, what features/bands were you interested in a layout for?  I could work on it a bit over the weekend...

Take care,

-Austin

[jkokura]

I don't know about the eagle parts - I dabbled in learning that program for a week or two back in October, but truth told it's not really something I feel confident about. I don't know if I'll ever make my own PCB's. I'm learning to use perf right now.

Anyway, I can see me using 2, 3, 4 and 5 band fully parametric EQ's in the future. I knew you were developing the 5 band parametric eq board still, but you had said you'd perhaps work on a 3 band fully parametric version. If it's easy to do, I can see a use for a 2 band and a 4 band, but the 3 and 5 band versions would probably be enough.

Keep us updated, and I hope you're life is going smoother these days.

Jacob

[aziltz]

Here's what the 2nd one ended up as.  I forgot to take a gut shot, I'll try to do that in the morning.

[jkokura]

Dude that looks great. I love how the Input and output are on the 'top' of the box.

How's it sound? Is it dead quiet, little noisy? Fizzy or just transparent?

How are the knobs reacting? Have we got both cut and boost for the individual bands? Does the Q seem valuable to have a knob on? Do the frequency knobs interact with each other or are the bands well seperated?

I'm really impressed by these man.

Jacob

[aziltz]

impressed?  wait till you see the wiring, best job ever!

There is a tiny little white noise floor... I'm not exactly sure how to go about minimizing it.  I'm sure it has to do with the PCB layout though.

Boost/Cut on each band.  I used Center Detents so when its off its really off.  Q is really nice to have on the 3 middle bands, because you can take it from subtle to honk to full on static wah.  I'm rearranging the design slowly to have a baxandall-type shelf response on the highs and lows.  5 Bands its a bit overkill for regular guitar.  the 3 middle bands easily cover the main frequencies, but the high shelf is nice to tame the sheen on an acoustic.

The Bands all overlap slightly.  The Bass band can get up to the low E string on a guitar, and the Low Band can get down to the low E on a Bass Guitar.

I think for guitar, the optimum thing would be 3-4 bands for electric and definitely 4 for acoustic.  5 is kind of overkill, but hey, some may want it.

...still working on the layouts, sorry for all the delays.

[jkokura]

Don't apologize for the delays - that's a different type of pedal and not your fault if they're not designed right...







er.... oh. You mean taking longer than you intended...

And thanks for the report. That's what I imagined. Where'd you source the centre detent pots?

Jacob

[aziltz]

And thanks for the report. That's what I imagined. Where'd you source the centre detent pots?

Jacob

mouser is your friend for anything over 10-15ct...

http://www.mouser.com/Search/ProductDetail.aspx?R=RV16AF-10-15R1-B10K-0Cvirtualkey14860000virtualkey313-2000F-10K

i also got my trimpots there as well,

http://www.mouser.com/Search/ProductDetail.aspx?R=T73YP103KT20virtualkey61330000virtualkey72-T70YP-10K

[aziltz]

I've been silent for too long regarding this.  Apologies to all who were interested.  Here's the current circuit I'm working with.  High and Low Bands have been changed to Bax-type Shelf, with variable shelf roll off in the treble.  No board yet, but when its done I'll be offering to make a few.

I've eliminated the input and output gain stages and trimmers.  Headroom has been increased to 18v and I've hopefully simplified the operation a bit.

[jkokura]

I will take 2 of the 3 band boards.

I'm not sure if I've asked - how quiet is it? I want to use it with my acoustic guitar setup, but need it to be hissless.

Jacob

[aziltz]

I haven't built this version yet, but I eliminated the input and output stages because I think they were causing a hint of white noise.  The Frequency pots crackle a tiny bit, but that's just part of the circuit.

I think, in this current state, it's probably best to just make one board layout, and the builder can just leave off what they don't need.  I can make details on that.  Do you have any thoughts on that idea?

[Taylor]

Hey Austin, I'm glad I ran across this. I was thinking about building something based on RG's parametric article, then I saw this.

When you say you're going to offer boards, are you going to get them fabbed or will these be home etched boards? I'll be interested to see how your layout ends up. I'd probably buy a board. But I hate off board wiring so hopefully all those pots will be board-mountable...