NewYorkDave Style Passive EQ

EDIT:

I'd like people to know I've since changed some values in the high end. I've configured the Q switch to provide a shelf option. I just found this post again and I changed the values a while ago so I don't know what the exact values of the changes were.

What I'm trying to say is if you take on this project I suggest you be prepared to experiment a bit as far as what frequencys and Q settings sound good to you.

in other words season to taste... :grin:




Hello all,
Just got back from three months of touring. I'm happy to be back and happy TT survived the madness. Its really good to see all of you here.

Touring was alot harder than expected and I'm sorry I couldn't keep you all informed and stay up to date in the forum. I did manage to meet one tech talker on the road and had alot of fun hanging out. wish I could have met more of you. maybe next time.

ANYHOW,

I had one week off during the three months and I managed to complete the passive eq I was working on that was based on NewYorkDaves design.
here it is:



http://www.onthespeakers.com/TEC/eqfront.JPG

http://www.onthespeakers.com/TEC/eqtop.JPG

http://www.onthespeakers.com/TEC/eqcap.JPG

http://www.onthespeakers.com/TEC/NYDEQ.JPG



I put SIX of these in one box and it just about drove me crazy!!!! I think Jaakko can feel me here...ALOT of wiring.

I used the SRPP stage found in the Gyraf pultec eq for gain make up.
I used paper and oil caps through out most of the high freqs. even some Vitamin Q's. All the inductors are high Q UTC's.

This thing sounds REALLY good. I have not been able to really give it a good tryout on a real recording, but everything works perfectly and just running some stereo songs through it makes me very excited.

I want to thank everyone here for making this possible especialy NewYorkDave and Jakob for thier designs...

and whoever is responsible for this forum (Ethan?) YOU ROCK.

good to be back,
Ian

Man, your poit to point wiring looks GREAT!

Really I just LOVE to see things like this!

It rocks.

Welcome back and congratulations for your nice looking EQ!

:shock: :shock: :shock: :shock: :shock:

..It looks TIGHT in there!

...tighter than a camel's ass in a sandstorm! :roll:

--It works? -It's quiet? -It sounds good?

-If so, take a pat on the back, O Mike Scott look-alike! :wink:

..oh, and have a beer on me! :guinness:

Welcome back!!!

Keith

front panel looks pretty dense control wise

if you could do it again is there anything you would have done different?

[quote author="bluebird"]...I put SIX of these in one box and it just about drove me crazy!!!![/quote]I bet! I'm suprised you're not mad as a hatter! I get cross-eyed just looking at it. :wink: It really looks good, though. Glad it works.

Where did you get those inductors?

thank god it works... right? sheesh trouble shooting could be a nightmare

Holy smokes! What a job! And I had a hard time fitting two 312 cards in one box. Did you pack the truck?

Man, that looks just plain crazy! Great job on it!

If it sounds good, though, I may find myself building a couple of channels. Note, that would be two in a box, not fifty, like Bluebird seems fond of doing. :green:

I seem to recall there being some limitations concerning the output impedance of the previous device in the chain with this EQ design. Can someone elaborate on that?

Thanks for the comments...

I think its a bit messy. I started out very clean but then I started rushing and just packing things in where ever they fit.

Hmmm things I would have done differently. Well I obviously should have had some kind of graphics. I like to think its better beacause you have to just use your ears...or the force. but its not. and yes the controls are cramped and a bit hard to use. but hey I got SIX of em'!!!

Yea it works perfectly and is very quiet...well there is a very small hum. it gets a little louder when I cut or boost the low. I'm using AC 6.3v for the heaters. Jakob warned me about this but I was to lazy to do DC. I balanced the heaters with two 100 ohm resistors and it helped so I really think it has to do with the heaters. its an SRPP gain makeup so I think I have to inject some B+ into the heater winding. I'm thinking +15 to 20 volts. Any advice on this?

I got the inductors at APEX, this crazy electronics surplus store near where I live, in Burbank CA. I pretty much cleaned them out of these values of UTC.

I want to use this mainly for mixing. So on to the passive mixer!!!!!

The bottle of Squirt shows distinguished taste, by the way. :green:

:shock: :wink:

That's amazing. Got everything packed in there pretty well. But touring makes you a master of space managing. Welcome back.

Ian--
The eq looks truly amazing! It was great meeting you at your Atlanta show--good to see you back on the list.


Tom

By the way It does sound really good, but thats just my opinion. and like I said I havent really been able to try it out and individual tracks.

the only thing some one might have a problem with is a few of the very high and very low freqs dont boost quite as much as the rest. for me its plenty.

adding Q pots would be good. I just ran out of space so I used switches beacause they fit.

The only way to really hear it its to make one and form your own opinion.

I don't consider myself a good enough engineer to promise anything.

:grin:

great job, greater wiring :shock: impressive!
Compared already to one of the big boys in the league?

:thumb: :thumb: :thumb:
:sam: :sam: :sam:

tdB

PS touring can suck BIG donkey balls, so do long studiosessions btw

what's the weight of this?
must be a lot :wink:

WOW, The winner of how to keep the cost of metal work down :grin:
Great work, I want to build this eq myself..two channels for a start.
jo

Holy shit, dude. I'm impressed! I'm glad that I was able to provide inspiration for such a monumental project.

For those of you who missed it the first time, here's my modest little circuit that took on a life of its own in Bluebird's lab:



Note that my version is designed for a nominal impedance of 600 ohms, and Bluebird built a 1kOhm version.

The L-C values in my chart give fairly broad curves that should be "musically useful" in most situations. I was trying to emulate the curves of the Langevin EQ251A or the Cinema Engineering 4031B, but with a simpler "inverted-L" type circuit. Sharper peaking curves can be obtained by using a higher L-to-C ratio.

The circuit can be scaled to any desired nominal impedance, but the limiting factor is that high values of inductors with a reasonably high "Q" are difficult to find and expensive. If an extra 12dB of insertion loss can be tolerated, one reasonable option is to build the 600-ohm circuit and precede it with a 10K:600 input transformer. This will keep the input impedance high enough to keep most devices happy, and will also ensure that the EQ circuit is driven from a low source impedance, which is crucial to correct operation. Notice that on my drawing, I specify a source impedance of 60 ohms or less. Once you get to 100 ohms or more, the amount of boost becomes very restricted.

The circuit has non-constant input and output impedances, which is the penalty for using a simple inverted-L circuit rather than the more complex constant-loss bridged-T type found in the Langevin and Cinema units. The constant-loss bridged-T type requires four times as many switch contacts and twice as many inductors and capacitors.

What is the circuitry of the "Z" module?

[quote author="owel"]What is the circuitry of the "Z" module?[/quote]

An inductor for low shelving, a capacitor for high shelving, or an inductor and capacitor in series for peaking. See the chart for suggested values. For peaking circuits, additional resistance can be added in series to broaden the "Q" (although this will reduce the amount of maximum cut/boost as well).