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 Forum index » DIY Hardware and Software » Jürgen Haible designs
Variable Slope Filter / Phaser
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interested?
yes
88%
 88%  [ 37 ]
no
11%
 11%  [ 5 ]
Total Votes : 42

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jhaible



Joined: May 25, 2007
Posts: 2014
Location: Germany
Audio files: 24

PostPosted: Mon Jan 11, 2010 10:11 am    Post subject: Reply with quote  Mark this post and the followings unread

JoeMorris wrote:
Just finished this, sounds great.
One question...
My LFO seems to run quite fast, with a minimum speed of around 20hz...
Is this right?
Joe


No.
Do you have the (manual) RATE pot connected?
Is C19 really 470nF ?

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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JoeMorris



Joined: Apr 26, 2009
Posts: 160
Location: Brighton

PostPosted: Mon Jan 25, 2010 4:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

hmm got the oscillators sorted but still not cracked this filter lfo....

c19 is 470nf, i replaced it with a new one too...
rate pot is fine...

ive tried to trace this to work out what is going on and ive swapped all the chips round but no joy in getting this thing to run slower!
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JoeMorris



Joined: Apr 26, 2009
Posts: 160
Location: Brighton

PostPosted: Mon Jan 25, 2010 5:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

swapped out q9 and q10, seems to work now....
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JoeMorris



Joined: Apr 26, 2009
Posts: 160
Location: Brighton

PostPosted: Wed Jan 27, 2010 6:18 am    Post subject: Reply with quote  Mark this post and the followings unread

...and again, sounds brilliant, especially with the living vcos.

This is my first foray into modulars, and it's a revelation. All my other synths sound like toys. I can see this being a dangerous development.
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TekniK



Joined: Aug 10, 2008
Posts: 1062

PostPosted: Wed Jan 27, 2010 1:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

JoeMorris wrote:
I can see this being a dangerous development.


very dangerous! specialy these fine JH hi quality designs..
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dingebre



Joined: Aug 10, 2008
Posts: 252
Location: Salt Lake City, UT USA

PostPosted: Mon Mar 01, 2010 10:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'm gearing up to build one or two for a Frac Rack system. So, here's my close to order FPD panel file for your consideration. It does not have mounting holes for the PCB yet. I like to use a pair of standoffs and mount the PCB vertically if i can. Anyway, this panel includes all the controls except a bypass switch. I figure I can unplug it if I don't want it. It also includes JH's Mix/Filter switch which is not on the schematics. It takes the mix pot out of the loop. JH used a Push/Pull type pot. I'm going to use a DPDT switch.

I've test fitted Alpha 12 mm pots, Swichcraft "tiny" jacks, and the small SPST switches and I think it is good to go. Bigger pots will probably not work especially on the top row.

This should translate well to a Euro size with little or no modifications. other than panel width and mounting holes.


Please let me know if I have missed something. I'll probably order the panel in a couple of weeks.

The name is in Bulgarian as are all my custom designs (long story) and reads, "JH Variable Slope Filter".

EDIT *****************************8

I made some small changes to the panel and added some mounting holes
on the right side. Also, note that the pot holes are 0.2813 inches which works great for the 12mm alpha pots.

I don't think the switches on the bottom are ideal, but i like to put labels on top and so this configuration worked best for me.

David


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_________________
David M. Ingebretsen, M.S., M.E.
Collision Forensics & Enginering, Inc.

dingebre@3dphysics.net
http://www.xmission.com/~dingebre/Synthasystem.html
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dingebre



Joined: Aug 10, 2008
Posts: 252
Location: Salt Lake City, UT USA

PostPosted: Mon Apr 05, 2010 6:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

Just finished the PCB. JH, I think you only missed one or two standard values of resistor between 220 ohms and 10 Meg Smile I've never seen so many different values of resistors on one PCB... Thank heaven Mouser packages their resistors separately and labels them.

David

_________________
David M. Ingebretsen, M.S., M.E.
Collision Forensics & Enginering, Inc.

dingebre@3dphysics.net
http://www.xmission.com/~dingebre/Synthasystem.html
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jhaible



Joined: May 25, 2007
Posts: 2014
Location: Germany
Audio files: 24

PostPosted: Tue Apr 06, 2010 12:09 am    Post subject: Reply with quote  Mark this post and the followings unread

dingebre wrote:
Just finished the PCB. JH, I think you only missed one or two standard values of resistor between 220 ohms and 10 Meg Smile I've never seen so many different values of resistors on one PCB... Thank heaven Mouser packages their resistors separately and labels them.

David


It wasn't intentional, but ... the cheapest way for me to get resistors was buying them as a complete set of E24 values, 100 each, comlete with a rack of tiny drawers. Smile

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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TekniK



Joined: Aug 10, 2008
Posts: 1062

PostPosted: Wed Apr 07, 2010 12:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

i have to wire this one + another one to built
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jhaible



Joined: May 25, 2007
Posts: 2014
Location: Germany
Audio files: 24

PostPosted: Thu Apr 08, 2010 12:27 am    Post subject: Reply with quote  Mark this post and the followings unread

TekniK wrote:
i have to wire this one + another one to built


Looks so cool - love those knobs - concentric even!

Do you have a picture with more / all of your homebuilt modules / whole system?

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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TekniK



Joined: Aug 10, 2008
Posts: 1062

PostPosted: Thu Apr 08, 2010 12:53 am    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
TekniK wrote:
i have to wire this one + another one to built


Looks so cool - love those knobs - concentric even!

Do you have a picture with more / all of your homebuilt modules / whole system?

JH.


Yes ,its very dence but cool,my most expensive modulle i think due to all those concentrics.

Look in the Built 2010 pictures topic,i posted more recently including your Polymoog modulle.
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dcreatorx



Joined: Jun 02, 2009
Posts: 17
Location: Barcelona

PostPosted: Fri Apr 16, 2010 5:58 am    Post subject: front panel Reply with quote  Mark this post and the followings unread

Hello, my varislope is already built, but now I need a panel. Can somebody say where to get one or give another solution ?

Thank you all !
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guitarfool



Joined: Feb 26, 2007
Posts: 156
Location: Maryland
Audio files: 8

PostPosted: Tue May 11, 2010 5:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

Okay, I finally got my Variable Slope Filter/Phaser done. I did a full-up panel with all the options (except a Wave CV input, but I'm going to add that in), and I'm glad I did. The LFO section is really amazing - worth building this just for that.

Here's a crappy audio file using only JH modules, with the Vari-Slope LFO controlling. A drone from a Living VCO is the input, with the "LFO Wave" set somewhere between "S&H" and "Square". Varislop output goes straight into the mixer. The LFO output also feeds a Tau Phaser set just below self-resonance, whose output goes through a String Filter. That's the drum sound that comes in after the start. Halfway through I hit the "Color" switch on the Tau to change the drum pitch a bit. No other modules or effects were used!


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emdot_ambient



Joined: Nov 22, 2009
Posts: 669
Location: Frederick, MD

PostPosted: Thu May 13, 2010 3:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK, let me see if I get this straight...

If you build the Variable Slope Filter version (no modulation or phaser), you would be able to switch from 6dB up to 36dB in increments of 6dB...correct?

And if so, it should be pretty easy to switch between those with a 6P rotary switch.

Would it be easy to build it with the LFO and the Filter only? Always need more LFOs...just thinking.
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jhaible



Joined: May 25, 2007
Posts: 2014
Location: Germany
Audio files: 24

PostPosted: Thu May 13, 2010 9:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

emdot_ambient wrote:
OK, let me see if I get this straight...

If you build the Variable Slope Filter version (no modulation or phaser), you would be able to switch from 6dB up to 36dB in increments of 6dB...correct?

And if so, it should be pretty easy to switch between those with a 6P rotary switch.

Would it be easy to build it with the LFO and the Filter only? Always need more LFOs...just thinking.


The switches change the individual stages from LPF to APF, so if you think of the whole thing as a LPF, you can surely do what you describe, because every LPF stage contributes 6dB/8ve of slope, and an APF stage doesn't contribute. To be honest, I haven't even thought of that feature, because a mix of LPF and APF stages creates other interesting effects, especially when mixed with the straight (dry) signal. And the "advertised" Variable Slope function is a continuous pole spread (controlled by a potentiometer and/or a CV) which gradually shifts individual poles (basically: cutoff frequencies) out of the musically interesing range.

But you're right: In addition to this continous effect, you also have stepped slope switching, as you described. I should have advertised this as an additional feature! Smile

[Addendum] About a rotary switch instead of 6 individual switches:
a) That switch would have to close more and more contacts as you turn it, like pos 1 = no contact, pos 2 = 1st contact closed, pos 3 = 1st *and* 2nd contact closed, pos 4 = 1st, 2nd and 3rd contact closed, ans so on. Should be possible with diodes and electronic switching.
b) With the pole spread function, it's *not* the same whether the 1st or the 6th stage is switched to APF. So with a 6-pos rotary switch, you give up some of the flexibility.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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emdot_ambient



Joined: Nov 22, 2009
Posts: 669
Location: Frederick, MD

PostPosted: Fri May 14, 2010 4:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the reply. I was thinking of a couple different uses for this project and one of them would purposefully be more limited, thus the rotary switch idea.

But these seem awesomely flexible and powerful...so I ordered 2. Hopefully you got my email.
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dingebre



Joined: Aug 10, 2008
Posts: 252
Location: Salt Lake City, UT USA

PostPosted: Fri May 14, 2010 11:51 pm    Post subject: FLAMES!!!!! Reply with quote  Mark this post and the followings unread

I hate to display my ignorance, but this was too good not to share.

I was finally able to make time to start calibrating the filter. I finished it a week or more ago but had not plugged it in.

I'm holding the module in my lap, plug in the power... and FLAMES!!!! The rate pot was actually on fire! It "popped" and a tiny jet of flame was coming out of the pot. I just stared at it. It was so out of context, it took me a full 5 or 10 seconds to realize I might start my pants on fire!

I've exploded electrolytic caps, wired things backwards and seen the magic smoke, but not an honest to goodness flame. This is a whole new level of "DUH!" for me.

The pot was mis-wired. I had ground to the wiper so when I rotated the pot, it shorted out to -v.

I will not confirm that I wired the replacement pot the same way and fried it, too before I realized what I had done Smile

David

(The module is fine, just smells a bit like a campfire.)

_________________
David M. Ingebretsen, M.S., M.E.
Collision Forensics & Enginering, Inc.

dingebre@3dphysics.net
http://www.xmission.com/~dingebre/Synthasystem.html
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jhaible



Joined: May 25, 2007
Posts: 2014
Location: Germany
Audio files: 24

PostPosted: Sat May 15, 2010 1:10 am    Post subject: Re: FLAMES!!!!! Reply with quote  Mark this post and the followings unread

dingebre wrote:
The pot was mis-wired. I had ground to the wiper so when I rotated the pot, it shorted out to -v.


If this is of any consolation, I've burnt a couple of pots that way, too.
Especially when testing with alligator clips. I have some pots with wires soldered-on, and tiny clips on the other end, for testing. I *do* colour-code the wires, but sometimes ...
The effect is particularly funny when you power it up with the wiper *not* near the end position, waiting silently for the big event. Smile

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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jhaible



Joined: May 25, 2007
Posts: 2014
Location: Germany
Audio files: 24

PostPosted: Sat May 15, 2010 1:19 am    Post subject: Reply with quote  Mark this post and the followings unread

emdot_ambient wrote:

But these seem awesomely flexible and powerful...so I ordered 2. Hopefully you got my email.


Normally I send an invoice mail with payment directions right after receiving an order. If you haven't got this mail, either your mail or my mail was lost.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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dingebre



Joined: Aug 10, 2008
Posts: 252
Location: Salt Lake City, UT USA

PostPosted: Sat May 15, 2010 9:32 am    Post subject: Re: FLAMES!!!!! Reply with quote  Mark this post and the followings unread

jhaible wrote:
dingebre wrote:
The pot was mis-wired. I had ground to the wiper so when I rotated the pot, it shorted out to -v.


If this is of any consolation, I've burnt a couple of pots that way, too.
Especially when testing with alligator clips. I have some pots with wires soldered-on, and tiny clips on the other end, for testing. I *do* colour-code the wires, but sometimes ...
The effect is particularly funny when you power it up with the wiper *not* near the end position, waiting silently for the big event. Smile

JH.


It actually is consoling to know I'm not alone Smile Thanks JH.

Very, very cool module by the way. Even without calibration it is amazing.

David

_________________
David M. Ingebretsen, M.S., M.E.
Collision Forensics & Enginering, Inc.

dingebre@3dphysics.net
http://www.xmission.com/~dingebre/Synthasystem.html
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MR-808



Joined: Sep 30, 2010
Posts: 28
Location: Portland, OR

PostPosted: Sun Oct 24, 2010 11:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
Theoretically that HPF should come as MOTM module some day, so I was reluctant put a HPF mode into this PCB project.

But you can easily hack the circuit to get a HPF:

http://www.jhaible.de/varislope_filter_phaser/varislope_filter_phaser_sch1.pdf

(1) Remove R7, R15, R20, R26, R31, R36.

(2) Omit all DG419 chips and connect Pin1 to Pin2 on each DG419 footprint.

Not tested by me, but it should work!

(Please report back if you have tried it. Smile )

JH.


If I'm reading the schematic correctly, then it should be fairly simple to add a DG419 for each stage and use DPDT on-none-on switches to select high pass, all pass, & low pass for each stage. I've modified Jürgen's schematic to show this for a single stage.

Time for another parts order!


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jhaible



Joined: May 25, 2007
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PostPosted: Mon Oct 25, 2010 12:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Sure, you can disconnect the path from the previous stage to the OTA input, while leaving the capacitor connected to the previous stage, thus forming a HPF function. Just like this old Emu patent, and the SSM2040 data sheet, show. And with the voltage controlled pole spread circuitry on that board, you get a Variable Slope HPF.

The reason why I had not implemented this on the board right from the start is simple: I have contributed a Variable Slope HPF, using this technology, to become a MOTM module. But that was many years ago, and I haven't seen it seeing the light of day, so yes: it's a good thing to modify the circuit like this.

Just a little hint: Instead of packing another six DG switches somewhere on the solder side (?), build a second board and hard-wire it to HPF function. Omit the DG's altogether, wire the caps to the previous stage, and omit the 100k resistors from previous stage to OTA inputs. You may even omit the whole LFO stuff on that HPF board. Then, connect two of the filter boards in series (speaking of signal path), and enjoy a varible slope HPF - LPF configuration. You may find an unused opamp on the HPF board to make a CV inverter, and route some Voltage Controled Bandwidth function for the resulting BPF filter. (I think Buchla or Serge had something like that, but certainly not in 12-pole configuration, and probably not Variable Slope, either.)

How about that?

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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numbernone



Joined: Aug 16, 2006
Posts: 477
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PostPosted: Sun Jan 23, 2011 8:41 am    Post subject: Reply with quote  Mark this post and the followings unread

After scraping up enough 13700s that were lying around, I did final assembly, and hooked the filter up to my test supply.

This brings me to the strangest problem I have ever encountered which is preventing any further troubleshooting/enjoyment.

On power up the -V rail enters the circuit at -15v. Ground connection is noce throughout. However the +V rail is pulled down to near 0 at the supply. Power down, power up same deal. Unhook supply and rail returns to 15v, test with other modules...fine. Rehook to filter, +V rail takes a dive again.

No smoke, no spark, no heat, no nothing.

What the hell am I missing here??

thanks.
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jhaible



Joined: May 25, 2007
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Location: Germany
Audio files: 24

PostPosted: Sun Jan 23, 2011 8:58 am    Post subject: Reply with quote  Mark this post and the followings unread

numbernone wrote:
After scraping up enough 13700s that were lying around, I did final assembly, and hooked the filter up to my test supply.

This brings me to the strangest problem I have ever encountered which is preventing any further troubleshooting/enjoyment.

On power up the -V rail enters the circuit at -15v. Ground connection is noce throughout. However the +V rail is pulled down to near 0 at the supply. Power down, power up same deal. Unhook supply and rail returns to 15v, test with other modules...fine. Rehook to filter, +V rail takes a dive again.

No smoke, no spark, no heat, no nothing.

What the hell am I missing here??

thanks.


Sounds like a short between +V rail and GND on the board, and a good PSU that can handle a short without destroying itself.

Check for electrolytics soldered in with reverse polarity, or solder bridges etc.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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numbernone



Joined: Aug 16, 2006
Posts: 477
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PostPosted: Sun Jan 23, 2011 11:08 am    Post subject: Reply with quote  Mark this post and the followings unread

Getting there now, seems I had not read the docs in quite sometime. I assume my use of physical switches AND the DG419s was causing some problems? With the DGs pulled, I am getting some action happening, seems it will need some serious trimming, as it is not at all acting as I would expect. Self oscillation only at high frequencies, switches have no effect. LFO is AWESOME!!

More questions later if I cant arrive solo.
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