Igor

Topic name says it all... Something to add? :)
« Last Edit: December 27, 2012, 09:16:10 PM by Igor »
http://www.ij-audio.com
(new site hopefully will be up in July)


flaheu

cool  8)
As MagnetoSound said:
"Sad lack of balls in today's bands, IMO"

Harpo

maybe additional switches to decrease filters frequency range (freq.x1 / x10) or increase frontpanel hight to 2HE so you can use bigger knobs for the frequency pots ?
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.  -Douglas Adams

abechap024

Looks great! :D
AC Sound - some DIY circuitboards

Igor

maybe additional switches to decrease filters frequency range (freq.x1 / x10) or increase frontpanel hight to 2HE so you can use bigger knobs for the frequency pots ?

Versatility and space saving EQ with lot of options is what I need for now.
(last time I need space saving due to racks overload :)

The goal is not building single channel Pultec in 2RU with huge knobs,
golden dragon tubes and alpha pots BUT nice front panel and talk to all friends "woa, big knobs, tube sound, maaan".

The goal is to have extremely versatile and powerful tool, which can be both precision, rough, gentle and aggressive, in small rack space.

It can do some real magic.

BTW, I will use this eq's filter with some tweakups as one of filters options in Uni-Q.

I can agree for decreasing frequency range (more precision)... but about x2 times.
Possible to do if freq pots replaced from 100k revlog to 47k revlogs.

If somebody need recallability for "my GF told me the mix is great, she heard it in a car, but she can't hear my bass guitar and I want bit more highs on ... CYMBALS!!!!!"
Well, I prefer not stack with this kinda people so no mix fixes, however, can agree with 2RU with stepped 21 pos switches.
Just solder them with wires....etc.

From the other side, Easy Active can be expanded to 5RU front panel and use 9mm Alpha pots.
Than, 8mm front panel; 45mm China copies of RCA knobs -  trust me, when they used on 9mm Alpha pots, the sound becomes huge.
(Well, reincarnation like this...deserves a nail into head).

I will use LME49740 (great quality/price value opamp, $6 for quad), they sound awesome at filters circuits.

From the point of builder... it not using hi-cost components, very easy to build, awesome sounding EQ.
Breadboarded, passed many hours with it, listening/tweaking at workshop, and found way useful.
I would prefer EA to Urei545, SSL channel EQ or Neumann 492 - IMHO they are really boring in comparison to Easy Active. YMMV.
« Last Edit: December 05, 2012, 08:45:13 PM by Igor »
http://www.ij-audio.com
(new site hopefully will be up in July)

druu

Interesting, keep to hear more on this.

JohnRoberts

I have long been a fan of parametric EQ for it's complete flexibility, and I did a similar parametric with shelving option in a (LOFT) console input strip back in the late 70s/early 80s. I also sold a simpler hifi parametric kit in Popular Electronics ( Sep 1979).   

Using a Paul Buff design (Valley People) is as good a starting point as any, while I think that brand is still being sold by somebody other than Paul.

From a quick glance at an old schematic I found on the WWW, the main thing I would have done differently is configured the variable frequency pots as potentiometers (dividers) instead of rheostats (variable resistors), for better accuracy, The bulk resistance tolerance of most screened pots is around 20%. (The better way to handle this has been discussed in other parametric threads here, but simply the accuracy of the taper is better than the accuracy of the resistance. Letting the divider go all the way to ground and shunting with a fixed resistor in parallel makes the LF end limit accuracy 1% or 5% vs. the 20% pot.).

For studio use accuracy and repeatability is always  nice, so reduced pot range with switched in capacitors for x10 or whatever will  improve control resolution and extend range.

JR

Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Igor

I have long been a fan of parametric EQ for it's complete flexibility, and I did a similar parametric with shelving option in a (LOFT) console input strip back in the late 70s/early 80s. I also sold a simpler hifi parametric kit in Popular Electronics ( Sep 1979).   

Using a Paul Buff design (Valley People) is as good a starting point as any, while I think that brand is still being sold by somebody other than Paul.

From a quick glance at an old schematic I found on the WWW, the main thing I would have done differently is configured the variable frequency pots as potentiometers (dividers) instead of rheostats (variable resistors), for better accuracy, The bulk resistance tolerance of most screened pots is around 20%. (The better way to handle this has been discussed in other parametric threads here, but simply the accuracy of the taper is better than the accuracy of the resistance. Letting the divider go all the way to ground and shunting with a fixed resistor in parallel makes the LF end limit accuracy 1% or 5% vs. the 20% pot.).

For studio use accuracy and repeatability is always  nice, so reduced pot range with switched in capacitors for x10 or whatever will  improve control resolution and extend range.

JR



Hi John, thanx for your reply!

I agree about divider configuration, and did some tests with it. Limitation is, on ranges over x30 (band range kinda 30hz - 1khz) filter becomes bit weak.
However, the divider configuration is dead stable on x10-x15 ranges.

To have less range on potentiometers but more precision, and use dual 10k lin pot instead of dual 100K revlogs, it can be great point.

Focusrite 430, UREI 545 (but not 546) and Barry Porter EQ came to mind immediately.

Possible to use x3 or x10 switch with adding pair of capacitors to integrator's capacitors. In 1RU, there is no much space for this switch.

If it is still possible to have say 30Hz - 600hz stable range (x20) for lows, 500hz - 10khz for mid and 1kHz - 20kHz for highs, would be fine for me.

I going to think about this. Rev.1 PCB's are already ordered, but I will try your idea and compare how it feels.

To summarize: make option to have less range and more precision with regular 10K OR to have more range but less precision with 100k revlogs.

Put in TODO list.

People: what is more important for you in EQ like this: range or precision?
« Last Edit: December 06, 2012, 08:49:17 PM by Igor »
http://www.ij-audio.com
(new site hopefully will be up in July)

Igor

Her we go... The PCB design for one channel with some fixes.
There will be 2 pcbs (L and R) at front panel and single input/output/power supply at back.
Wiring/assembly done for really lazy people.

Stay tuned! ;)
http://www.ij-audio.com
(new site hopefully will be up in July)

Igor

And here is the schematic of one channel EQ front panel PCB
(the rest like power supply, input/output THAT chips, relays, XLR's, even the mains fuse etc are located at back PCB)
http://www.ij-audio.com
(new site hopefully will be up in July)


Igor

Re: Easy Active. SVF EQ, tweaked up Valley People Maxi-Q, pair in 1RU. Soon!
« Reply #10 on: December 08, 2012, 02:15:18 PM »
Input/output PCB:
http://www.ij-audio.com
(new site hopefully will be up in July)

flaheu

Re: Easy Active. SVF EQ, tweaked up Valley People Maxi-Q, pair in 1RU. Soon!
« Reply #11 on: December 10, 2012, 04:28:09 AM »
cool project  8)

when will it be available ?

I've got some w492 and altough they are nice I'm not so impressed, but these seems to be what I need.  :o
As MagnetoSound said:
"Sad lack of balls in today's bands, IMO"

Igor

Re: Easy Active. SVF EQ, tweaked up Valley People Maxi-Q, pair in 1RU. Soon!
« Reply #12 on: December 13, 2012, 11:56:02 AM »
cool project  8)

when will it be available ?

I've got some w492 and altough they are nice I'm not so impressed, but these seems to be what I need.  :o

In 2012 yet, if everything will go flawless.
W492 is really boring EQ IMHO - some years ago I did tweaks to 4 original modules (recap, fast opamps, etc).
If I building SVF-based eq, why not use main benefits of this design - functionality and flexibility?
Otherwice, I can build every fixed Q midrange band with 1 opamp for both gain and variable frequency...
http://www.ij-audio.com
(new site hopefully will be up in July)

druu

Re: Easy Active. SVF EQ, tweaked up Valley People Maxi-Q, pair in 1RU. Soon!
« Reply #13 on: December 19, 2012, 08:35:48 PM »
Bump! :D

Igor

Re: Easy Active. SVF EQ, tweaked up Valley People Maxi-Q, pair in 1RU. Soon!
« Reply #14 on: December 21, 2012, 03:16:27 AM »
Bump! :D

Received the PCB's. Will update very soon.
http://www.ij-audio.com
(new site hopefully will be up in July)

Sylvain D.

Re: Easy Active. SVF EQ, tweaked up Valley People Maxi-Q, pair in 1RU. Soon!
« Reply #15 on: December 25, 2012, 09:25:38 PM »
Very cool Igor! (you obviously never sleep  ;D)

I have owned a pair of Maxi-Q since about 1996 and I love these EQs.

Lately I have thought of re-racking them with switches...(mastering version)
This may save me lots of work.



Igor

Re: Easy Active. Ultimate flexibility/sound EQ. First in White PCB Series!
« Reply #16 on: December 27, 2012, 08:34:40 PM »
Sylvain: yep, these are awesome EQ's. May need some upgrade to better FET switches and opamps.... in any case, very musical.
For the mastering version, it will be easier to go with White PCB series :)

OK, some updates on the progress.

First, Easy Active took many steps forward from Maxi-Q which was the inspiration. Faster, cleaner, more precision gain/Q controls.
FREQ controls range can be done in x100 or x15 range. I liked more x100 range option here, being tired of slow stepped precision controls ;)

The purpose was to get extremely versatile and great sounding EQ.
After many hours passed on lining up and fixing the proto, checking/testing, I heard it.
I expected less for this budget, really, and result overcame my best expectations.
Compared to Sontec, two different animals, but I really can put them at the same raw.
EA has more 'sound' because it is build on VSF design, but in a good sence.
I was able to compare to Filtec (BFE) MK3a which sounded sad against impudent EA,
well, steps....can be implemented in EA easy without cutting PCB's like you guys did with Sontec ;)

EA have lot of flexibility with only 3 bands; for bells,
cuts can be extremely agressive, gentle and very surgical at the same time;
boost is very sweet; and shelves with high or mid Q settings are very useful IMO at mild boost/cut settings.

Cool... some pictures.

Don't ask me what I was thinking about when testing the proto, but it came natural way:



The freqs on x100 range with 100k dual revlogs ($4 pair on Evilbay):



Easiest build with almost no wiring:







I/O PCB - will be offered in White PCB Series too, gyus at the factory messed the mask color:



And... some curves. Most taken from midrange band. Fast settings - 1/6 oct, cheap soundcard (noticeable rolloff at the edges).
The EQ performs waaay better than soundcard, well, have to get National, GPIB card and mod my spare HP8903B for this...

I hate soundcard based analysers even more from now,
it takes so much time to do what is easy with oscillator, scope and hardware analyser just to make some graphs!

Well... midrange band at medium Q:



High shelve:





Some extreme:





Some bla bla curves:



And the picture which came out soooo naturally.... I laughed my ass out!

« Last Edit: December 27, 2012, 09:21:05 PM by Igor »
http://www.ij-audio.com
(new site hopefully will be up in July)

Sylvain D.

Re: Easy Active. Ultimate flexibility/sound EQ. First in White PCB Series!
« Reply #17 on: December 27, 2012, 09:28:01 PM »
...and the picture that "came out... naturally"... ;D ;D

mulletchuck

Re: Easy Active. Ultimate flexibility/sound EQ. First in White PCB Series!
« Reply #18 on: December 27, 2012, 09:37:03 PM »
how about a 2-slot 51X version??
www.youtube.com/mulletchuck for all my recordings

Igor

Re: Easy Active. Ultimate flexibility/sound EQ. First in White PCB Series!
« Reply #19 on: December 27, 2012, 09:50:26 PM »
...and the picture that "came out... naturally"... ;D ;D

Well, I'm Addams :)

how about a 2-slot 51X version??

I doing this with quad pots for stereo control too. Will post pics some days later.
http://www.ij-audio.com
(new site hopefully will be up in July)


 

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