NewYorkDave's Passive Equalizer

Hello. It's been a long time, hasn't it?

I'm pretty much out of the game now but it's come to my attention that some of the little circuits I drafted years ago are still being built and used by various musicians, engineers and hobbyists around the world. I find this most gratifying.

Some of you may remember one circuit that generated a lot of interest in its preliminary form but which I chose not to "publish" in the end because I had a notion to develop it into a commercial product. Instead, I put it away and forgot about it for five years. I've since come to realize that life is very short and much of its value comes from what we give of ourselves to the world - our love, our time, our help and concern for others, a thoughtfully-prepared meal, a song, a poem, or even an imperfect little circuit. With that in mind, I have returned to give my regards and one more humble contribution to this wonderful community of DIYers.

NYD-EQ1

Essentially, it's a stepped L-pad shunted by series-resonant circuits. Technically, there are "better" ways to build a passive equalizer (e.g., using constant-impedance bridged-T networks) and I don't claim there's anything particularly clever or elegant about this circuit, but it did fulfill my design goal of a usable 3-band passive equalizer with a minimum of parts. The prototype worked quite satisfactorily for me.

Really, the merits of a passive equalizer are highly debatable in this day and age but at the time of design, there was a lot of interest in such things and I was merely responding to that. I don't know if this is still the case; I haven't really kept up with things.

As with all my circuits, I offer this for non-commercial, hobbyist use only and reserve any and all commercial rights for myself. May it serve you well.

- Dave

HI NYD,

Thanks for sharing.

Cheers

Ian

Great to have you back and thank you for sharing it.

You're a STAR Dave...Great to see you posting again.
..and yes, both your "one-bottle" and "passive mixer" has been great and gets much use in my little "home studio"
J

NYDave,
hope all is well with you.  thank you very much for all your contributions and for this little gem as well. 
my 2 channel MILA and reamp box are great and your attenuation circuits have served me well and continue to do so.  your designs are practical, elegant (even if you may not think so) and very approachable for a diy'er in cost, function and usability.  your design notes and advice on diy'ing have always been a source of inspiration for many.
we have missed your presence here and the forum must look very different from when you last were here, but i believe the spirit and community of the forum is still mostly intact.  hopefully you will find your way back here as your life permits and grace us with more of your "lunch break circuit ideas".  no virtual beers now (whatever happened to them ethan?), but you deserve one for this little circuit.
kindest regards,
grant

Hi- hope you and yours are well..

JR

How funny is that... or rather mysterious. Just today I thought about your circuit you posted back in the day and hacked it into the simulator to check for values and adjust the frequencies and Qs to my taste. Really looking forward to build it.

Thanks for posting!

Thanks for great inspiration, NewYorkDave !

Just found this:

Welcome back, Dave.

We should really have a New York Dave META with all of his projects in there! I myself would like to try the One-Bottle.

quick, someone go get Analag into this thread! One of the Greats is back!

Thanks, guys. It's good to see you again.

Here's a picture of the prototype (built inside an old Shure mixer chassis).



Here's one set of measured curves. I had more but I can't find them now.



Notice that the 40Hz band doesn't quite make the nominal cut/boost spec. If you can find higher-Q (lower DCR) inductors than what I had, use them. You can always add a little resistance if you want to broaden the curves.

You can use any preamp or line amp of adequate gain and input impedance after the EQ but if you're so inclined, here's a sketch of a dedicated tube output amplifier. I didn't prototype it but it should work fine, with just enough gain to compensate for the insertion losses of the EQ and input matching circuit. The 200V B+ is just a ballpark figure. You can go a bit lower or higher and it won't make a big difference.



That's all I've got. Have fun and be well.

- Dave

Times are really changing... Xmas is now officially the 24th of August!!

Axel

hope you are doing well. missed your nostolgic posts  (christmas,woolworths , coney island) early 60s!!!
hope you stick around for a while
8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8) 8)

Rochey said:

quick, someone go get Analag into this thread! One of the Greats is back!

Click to expand...

Ahem...I'm here. Never left really.
Stick around brother, won't you?

Glad to finally have the opportunity to thank you for all the incredible designs you've posted here.  I made my first project a 6SN7 One Bottle, and I couldn't be happier with it.  Thank you!

millzners said:

Glad to finally have the opportunity to thank you for all the incredible designs you've posted here.

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x2

Welcome back, Dave! You just made my day. Please do stay a little longer, as you see you're not forgotten.

WOW!!

CJ AND NYD in the same week.

Made my month.