NYD's passive EQ, ghetto edition

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Hey Dave Would I need to use the toko inductors or would the damn fastrons work also?

Just kidding

Dave, Id say go for it. I wish you good luck in any future indeaver you may persue.

John D
 
Since you mentioned it, I used Wilco for the low and mid bands, Fastron for the high :grin:. Wilco would work great for the high band as well, but resistance might have to be added to keep the curves from being too sharp to be useful. The DCR of the Wilcos is very low.

Analag, the curves I posted on page 5 are actual measurements of the "ghetto prototype", not simulations. I'm glad you think they look better than the Pultec, but that's certainly in the ear of the listener. The Pultec has been well-loved for a very long time, so it must have something going for it :wink:.

All: thanks for the words of encouragement and the suggestions. They're all good ideas; I particularly like Paul's idea of creating a "feedback pair" PCB. It'd certainly be a versatile product for many applications if it conformed to his recommendations. I'm thinking it'd be cool to make it narrow enough to mount on its side in a 1RU enclosure. I've never taken the time to learn any PCB layout software, but I'll mess around with some hand-drawn layouts just to get a general idea of how I'd do it.

As for the passive EQ, it's been one heck of a journey. It all started almost exactly two years ago when I looked at the Langevin EQ251A and the Cinema 4031B and thought, "how can I build something like that with fewer parts and no hard-to-get switches?" Within days, I had drawn up a workable idea. This was followed by two years of very sporadic tweaking on-paper--the design was put on the back burner more times than I could count, as I lost interest and then regained it again.

Recently, inspired by seeing Jaakko's completed version, I decided to stop putting it off and build some sort of prototype, even a junky-looking one, just so I could feel like I'd accomplished something with the design. I fully intended to post the latest version of the schematic here, as I always do. And that was still my intention when I started this thread.

But with a working unit--and one that works well, at that--in hand, a bunch of realizations came flooding into my mind. I don't believe there's any passive EQ out there right now (for studio use) that's not a Pultec clone of some sort. And I'm pretty sure that nobody is offering a completely passive EQ (in the general style of the Langevin, Cinema and other old-school "program equalizers") with no built-in amplifiers, allowing the operator to use the amplifier of his choice for gain makeup.

Although the principles of L-C filters are well-known--and I certainly hadn't invented a whole new type of filter or anything like that--I had hacked together an implementation that was different from any commercial program EQ I've ever seen. And it uses about half the number of parts of the old classics. In other words, it's definitely not a clone of any product I'm aware of.

For whatever reason, many people seem in love with the idea of passive equalization these days, and I had here a circuit made of available, non-exotic parts, that could be built at a reasonable cost, which could fill a unique niche in the market. And that's when I realized at last that I'd be an idiot if I just put it out there for anybody else to exploit. I spent many hours over the course of two years refining this simple circuit to be "just so", and nobody is going to make me feel guilty for wanting to try to get some sort of return on my time and effort.
 
Just an idea :
clik on
newyorkdaveeq8vs.jpg
 
well fotis, i dont think ive seen you post any circuits around here. who are you to criticise? the guy doesnt owe you anything!

That's the advantage of freedom. Isn't??
fotis
 
[quote author="NewYorkDave"]Mik, that looks really cool. What did you use to draw that?

(And I like Kruz's "Dymo mod" as well! :green:).[/quote]

That Dymo style is the way to go. It really stands out. Do all the lettering that way.
I guess you found yerself a "corporate design" thanks to Jaakko.
 
[quote author="NewYorkDave"]Mik, that looks really cool. What did you use to draw that?

(And I like Kruz's "Dymo mod" as well! :green:).[/quote]

I have used Osmond PCB in a strange manner, I will onorend if you'll want to use it.

M. :thumb:
 
Excellent Job! Which knobs do you have in minds?
You should try Illustrator or another vector based design software, that should increase your design potential which is already high. Just an idea. :wink:
 
[quote author="laitue5"]Excellent Job! Which knobs do you have in minds?
You should try Illustrator or another vector based design software, that should increase your design potential which is already high. Just an idea. :wink:[/quote]
I know, but I don't have any time to learn this cound Of programs that I still got in my computer, anyway, Knob are : the Big one is fron OKW
http://www.okwenclosures.com/products/okw/tuning-knobs.htm
the other one is European from Mentor, both got 6mm shaft hole
http://www.mentor-components.com/products.phtml?cat=47&sa=20&sb=10
M.
 
Hi Peeps

I'm new here, been lurking for a couple of days (caught a link to you from www.diyaudio.com). I just saw your post in time to download the PassiveEQ1.pdf, looks like a very nice simple circuit. I'm hoping to become a 'useful' member (I have a good source of older studio manuals and circuit diagrams, Neve, AMS, Studer A80s etc).

As for profiting for you circuits NYDave, I would suggest you do a pay to view system from a website:

$XX for the circuit diagram
$XX for the circuit board and say a digikey parts list
$XX for a built up board
$XX for a completed tested and working unit

Have a look at the ESP website if you want to see a successful DIY audio site. http://sound.westhost.com/

I know I've got circuits befor off the net and built them on Vero Board but after doing a couple of projects like this I now always but a proper PCB for the project wherever possible, Veroboard is fine for testing/learning about a circuit, but if you want something that is actually a useable piece of reliable equipment, then a PCB is definitely the way to go.

Just my opinion but I think you could certainly make something of this.
 
Well, it looks like the dream is dead unless I can find a supplier of high-L, high-Q inductors in small quantities. I got a quote from Wilco today, and there is no way I can meet their minimums without taking out a bank loan. :sad:
 
I really only need three large values that are hard to get. For the smaller values in the high freq. band, the Fastrons work just fine.

Maybe I should learn how to wind the f*cking things myself; I could make one tapped inductor each for the low and mid band instead of using separates. It looks like "75" ferrite material might work, nice high AL value... But even then, I'm still looking at several hundred turns. :mad:
 

Latest posts

Back
Top