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)
Joined: Aug 10, 2008 Posts: 270 Location: Salt Lake City, UT USA
Posted: Mon Mar 01, 2010 10:56 pm Post subject:
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
Frac Vari Slope.jpg
Description:
Filesize:
85.39 KB
Viewed:
1083 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.
Joined: Aug 10, 2008 Posts: 270 Location: Salt Lake City, UT USA
Posted: Mon Apr 05, 2010 6:12 pm Post subject:
Just finished the PCB. JH, I think you only missed one or two standard values of resistor between 220 ohms and 10 Meg 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.
Just finished the PCB. JH, I think you only missed one or two standard values of resistor between 220 ohms and 10 Meg 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.
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)
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)
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!
Joined: Nov 22, 2009 Posts: 667 Location: Frederick, MD
Posted: Thu May 13, 2010 3:35 pm Post subject:
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.
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!
[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)
Joined: Nov 22, 2009 Posts: 667 Location: Frederick, MD
Posted: Fri May 14, 2010 4:27 pm Post subject:
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.
Joined: Aug 10, 2008 Posts: 270 Location: Salt Lake City, UT USA
Posted: Fri May 14, 2010 11:51 pm Post subject:
FLAMES!!!!!
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
David
(The module is fine, just smells a bit like a campfire.) _________________ David M. Ingebretsen, M.S., M.E.
Collision Forensics & Enginering, Inc.
Posted: Sat May 15, 2010 1:10 am Post subject:
Re: FLAMES!!!!!
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.
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)
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)
Joined: Aug 10, 2008 Posts: 270 Location: Salt Lake City, UT USA
Posted: Sat May 15, 2010 9:32 am Post subject:
Re: FLAMES!!!!!
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.
JH.
It actually is consoling to know I'm not alone 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.
(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. )
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!
varislope_varistate.PNG
Description:
Filesize:
48.89 KB
Viewed:
2456 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.
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)
Joined: Aug 16, 2006 Posts: 477 Location: new york city
Posted: Sun Jan 23, 2011 8:41 am Post subject:
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.
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)
Joined: Aug 16, 2006 Posts: 477 Location: new york city
Posted: Sun Jan 23, 2011 11:08 am Post subject:
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!!
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You can download files in this forum
Forum index » DIY Hardware and Software » Jürgen Haible designs
FAQ
Calendar
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
Chat Room
I've never seen so many different values of resistors on one PCB... Thank heaven Mouser packages their resistors separately and labels them.
