NYD eq finished! ## PICS ##

[MikoKensington]

Hey Jaakko, was there a particular reason for the combination of toroids and tubular axials? Or was it just the only way to get all the values from wilco?

 

[Viitalahde]

[quote author="MikoKensington"]Hey Jaakko, was there a particular reason for the combination of toroids and tubular axials?[/quote]

Actually there was. The toroids are of a lower DC resistance, allowing me to make the lowest bands even tighter. I'm using toroids up to, say, 260Hz.

They also sounded better there.. And can probably handle a bit higher levels. Pain in the ass to mount. :?

 

[tardishead]

can anyone point me to the right mathematics

how do you calculate resistor values to make a +15 -15db CUT BOOST?
Also do you guys recommend the UTC inductors - VIC variable style?

 

[Bauman]

NICE ONE JAAKKO!!!!!

:sam: :sam: :sam:
Fabio

 

[NewYorkDave]

Tardis,

The resistor ladder in the EQ is just a voltage divider, with the load impedance (~500 ohms) acting as the lower leg of the divider. In "boost" mode, a reactive element shunts across (bypasses) the series arm, reducing the attenuation around a certain band of frequencies. In "cut" mode, the reactive element shunts across the load impedance, increasing attenuation in that frequency range.

You can find the values you need by converting the decibel values to "K" values and using voltage divider calculations. You have to do this for every step of attenuation. It's a tedious exercise, which is why I'm not going to do it again right now :wink:. I haven't tried them, but there are Javascript voltage divider calculators on the web, which should speed up the work somewhat. A Google search on "voltage divider calculator" turns up several. And there are also decibel calculators to give you the "K" values.

Please note that the series resistances of the inductors limit the amount of cut available; 15dB will not be easy to achieve in the low bands unless you find inductors of suitable value with extraordinarily low DCR.

 

[Viitalahde]

[quote author="NewYorkDave"]You can find the values you need by converting the decibel values to "K" values and using voltage divider calculations.[/quote]

For the -1dB point I made, the Audio Cyclopedia was priceless when the starting point for me was "how am I supposed to do this?" :wink:

 

[NewYorkDave]

Hey, I finished my quickie ghetto prototype yesterday. I tested it with discrete tones and an AC millivoltmeter calibrated in dB, then I did a listening test with mixed program material.

The high and low bands work great. The mid band only gave about +/-6dB of range--but I determined quickly that it was due to the shitty (improvised) tapped inductor I used, not a fault in the circuit or the wiring. I'll test again later with better (Wilco) inductors in there. The high band uses Fastron plug-ins and they're working just fine there.

 

[NewYorkDave]

All right, I dug the Wilcos I need out of storage and I'll put them in tomorrow. I've already started labelling the front panel--with Dymo, of course!

Jaakko, did you run sweeps on your unit, or did you just do an "ear test?"

 

[Viitalahde]

Dave, I'm waiting to see that one! :wink:

[quote author="NewYorkDave"]Jaakko, did you run sweeps on your unit, or did you just do an "ear test?"[/quote]

Ears first but I did run lots of sweeps through it, too. The curves look good and the L/R match is very good. I matched the inductors in a very unscientific way: hooked up the inductor in the circuit, took a dB loss from a chosen frequency and compared to that. Works fine!

Oh, distortion does obviously add up when you equalize using the coils.. which is not a bad thing of course. I do run it at pretty low levels.

Tuesday & Wednesday were the ultimate tests: mastered two 7-track CD's (punkish stuff) and this EQ came in use for softening the bass a tad and especially bringing the high end up. Once or twice I also added a dB or two in the lower midrange. Very nice and the customers were happy. :thumb:

 

[clintrubber]

[quote author="Viitalahde"]Oh, distortion does obviously add up when you equalize using the coils.. which is not a bad thing of course. I do run it at pretty low levels.[/quote]
This is what kind of surprised me for 'the' Pultec-EQ when seeing the schematic: for something having heard being praised as an LCR-EQ and all the associated 'magic' there's obviously not much coil going on - just the hi-boost as we all know.
So when not using that band it's 'just' a passive RC-EQ, sounds immediately less glamorous :wink:

So the NYD-EQ should be better :thumb:

 

[NewYorkDave]

The ghetto-style prototype is done and sounding grrrrreeeat. More details later, in a new thread.

 

[analag]

Yes I like the look of this, and I also take note of the Mastering Engineer's choice of frequency, since this EQ will be living in my buss insert rack. Definately my next project (at some point in the future) after I finish this mic.

Analag

 

[Viitalahde]

[quote author="analag"]I also take note of the Mastering Engineer's choice of frequency[/quote]

Now that I've used it more, it seems like I most often use the 140hz bass shelf (often just 1dB) with 135Hz dip (also 1dB), and either the 10k or 20k bell, anything from +1dB to +3dB.

I'll probably add some series resistance to the highest band in the next few days.

Yesterday I was working on some heavy metal material and the highs of this thing were too sweet for the type of music, my Sontec was just better. The previous project.. NYD EQ rocked! :thumb:

 

[Svart]

Man I wanna build one of these too.. :? anyone have the schemos? all the info is GONE!