Parametric EQ?

[Svart]

ok Omeg can make the triple 47k revlog for 3.34 pounds for quantities of 10.

they do not do center taps anymore so the 22k pots are a no go.

Alpha called me the other day but I was away so we'll see what they'll do.

 

[PRR]

> parametric EQs ... compact enough to use in an existing channel strip.

I mostly agree with TedF. You want one good parametric EQ in the studio to fix big problems, but putting one on every channel should not be necessary (except for sales), costs a fortune (especially at 1-off or even 8-of prices), and invites abuse and an ugly mix.

It is also a tool for filter-geeks, not musicians. Falling in love with beautiful filter curves does not improve the music.

Yes, I know the ParaEQ was developed by an excellent audio producer. It is possible to not abuse one, even make music with it, sure. But on the list of things that I "must" DIY, ParaEQ falls far-far down the list. Lower even than Graphic EQ, which is a nightmare.

> simple 'Baxendall' shelving curves, with possibly some low 'Q' mids added.

Right. Maybe a 3-position switch to change the cap in each band.

 

[Svart]

hmm reviewing the barely readable prints it specifies a 47k revlog triple pot but I am counting 4 pots with the same designation.. :?:

still trying to find someone who can make centertapped pots.

 

[Svart]

thanks PRR, I understand your position and appreciate the insight.

However, I might be able to obtain some of the crazy pots needed to do a pair of 9k modules, I found some multi ganged modules on Eb@y and some others with the correct tapers and values that I could possibly hack together to get what I need. I also have a number of pot manufacturers working on quotes for small orders.

The hard part is the center taps.. If i could find a way to add the centertap myself it would be easy..

:shock:


uh oh here come the ideas..

conductive ink pens... I have some pots I can experiment with.. I'll get a conductive ink pen and give it a try! I don't think the ink will be good enough but it might be good enough for a filter..


This has become more of a "I'm going to do it" rather than a "do i need it".
:thumb:

 

[Svart]

outstanding! centertapped pots are easy! first you MUST find a pot with the element deposited on the same PCB as the pins and it MUST be PCB not phenolic. The cheap alpha pots from mouser are the easiest to do so far.

here's the scoop.

take the pot apart.

see the wiper element and notice that it has multiple wiper fingers.

I clipped two sets of the 4 away so there would be more room on the edge of the element.

I drilled a SMALL hole between the element and the edge of the PCB. I used a hole for a 2mm/#0 screw.

i took the edge of my model knife and lightly roughed up the very edge of the carbon track, and then roughed up the pcb in a line to the hole and around the hole.

make sure your conductive ink pen is completely shaken up and ready to use.

now make a nice track from the carbon to surrounding the hole.

let this stuff dry completely. if you try to mess with it while it's wet it'll really make a mess and/or not conduct properly. 15 minutes did the trick.

Now i used little brass screws so that I could solder a wire to them first and then insert, however you want to do it should work, just remember that you cannot heat the ink up or it melts away instantly.

insert your screw or whatever you plan to use into the hole and tighten but tighten the nut, don't turn the screw or you will scratch your ink right off the PCB.

voila! centertapped pots.

I used Silver ink, with a resistance of .02 per MM. YMMV.

now I am going to experiment with ganged pots and getting the tapers that I want. ultimately leading up to a pair of ssl9k EQ sections.

 

[Andy Millar]

With the 9k EQ I was trying to make something that could be switched between E and G types, that's partly why the pots are so weird. If you stick to the one you like things get much simpler.

In particular the E type eq doesn't need anything too fancy (now that you can find antilog pots reasonably easily), and has a much more natural tone. Although the G is fun, particularly on bass and vocals. (And believe me, we did try to use sensible pots on it!) Personally if I had a large desk I'd have mostly Es with just a few Gs to play with.

Having built a few E type circuits for myself since leaving I haven't bothered with centre tapped pots, although you might then want a 'defeat' switch for each section.

 

[tony dB]

could we place a group buy at S S L for pots?

 

[Svart]

doesn't look like it.. i think someone already tried and they won't sell them. I am trying another avenue so hold tight, but it looks like making our own pots would be the way to go. Centertapping is easy and we can fudge a little and make rev log pots from linears but i am not sure how the rest of the circuit would act just yet.

 

[Andy Millar]

I'm not surprised that SSL won't sell them (from their point of view why should they?) but has anyone tried approaching Clarostat who supply SSL?

 

[tony dB]

good thinking, do you happen to know people overthere?

 

[Svart]

yes, clarostat won't make pots unless you buy 10K+ at least that is what I got from them.

 

[chrissugar]

It wouldn't be easyer to make only the SSL E series eq?
As Andy said, it is the musical one and do not need special pots.

chrissugar

 

[Svart]

do you have a link to the schematic?