Synth Module questions

[teej212]

Im looking to build the Steiner VCF and was wondering two things
1. will the guitars output be able to supply a level loud enough to work with the filter or would i need some sort of boost circuit in front of the filter?
2. is there any way to get +/- 15 volts from a 9v source?

thanks! heres a link to the schematic by the way

http://www.cgs.synth.net/modules/pic/schem_cgs35v1-3_syntha_vcf.gif

[DavenPaget]

Im looking to build the Steiner VCF and was wondering two things
1. will the guitars output be able to supply a level loud enough to work with the filter or would i need some sort of boost circuit in front of the filter?
2. is there any way to get +/- 15 volts from a 9v source?

thanks! heres a link to the schematic by the way

http://www.cgs.synth.net/modules/pic/schem_cgs35v1-3_syntha_vcf.gif

http://www.geofex.com/circuits/+9_to_33.htm
no 15 , but you can always get two circuits of these , just simply get a +18 and -18  ( i'm quite confused now O_O )
And use a 7815 and a 7915 ... I found something

You'll have to use 7815 and a 7915 ( you have no choice but to use the normal series unless you want a LDO because there's no 79L15 ) , you can 1N5818 schottky diodes if you need a lower dropout , that way you can get 18V±550mV @1A or much less ... ±200mV below 1A , impressive , better then those massive bags of BAT42/85 i have  
I believe my recommendation should work . You might need a larger enclosure , and please use 470uf for the filtering on the 7815 and 7915 .
If the MAX1044 is too expensive for you , the microchip TC1044 is much cheaper , according to what i find on E14/Farnell/Newark

[slacker]

You can make the Steiner VCF work on 9 volts, it doesn't sound quite the same as at higher voltages, the resonance won't go as high but it works Ok. http://www.diystompboxes.com/smfforum/index.php?topic=45148.0

If you're building Ken's version for guitar you want to boost the guitar up to synth levels, if you don't it works but because the guitar signal is so low it's noisy and you can get a lot of bleed through from the control voltages.

[teej212]

thats a cool project.  The LFO idea is intriguing, i dont understand how you have that hooked up to the cutoff frequency control though, can you explain that configuration?

[teej212]

after doing some more research I came across two simple lowpass filters- the Wilson low pass filter and time escobedo's Q&D vcf.  These would be the optimal choice for the project im working on seeing as they are extremely simple.  My question is about the cutoff- im looking for a pretty dramatic sweep, can either of these give me that? Also, if these clip i dont mind because i was planning on using my LPF mostly with distortion.

[slacker]

thats a cool project.  The LFO idea is intriguing,

Thanks, yeah the LFO is nice. Gives you nice random sounding patterns without the problems you can have building a sample and hold.

i dont understand how you have that hooked up to the cutoff frequency control though, can you explain that configuration?

The LFO and the envelope follower sweep the frequency range. The diodes are in there to try and stop the depth controls interacting with the Frequency control, it works Ok but it could be better. To be honest when I built it I didn't really know what I was doing, I just played around until I got it to work. Looking at it now I don't know why I did it like that, I should have just kept that part the same as the original schematic and used the CV input.

[teej212]

i think im just going to do the original version and add an lfo to the CV input.  Its gonna be a pain to make the power supplies but it should be worth it.  As long as the components are rated for 17 V you think there would be any problems to using that power supply above? Ive heard raising the voltage to lpf's can cause some whackiness with the resonance filter.

[newperson]

you can make one of ray's (mfos) power supplies for the +- very easy.  the older version has a lower part count and you really only need one set of filter caps if you only going to use it for one item.

[DavenPaget]

you can make one of ray's (mfos) power supplies for the +- very easy.  the older version has a lower part count and you really only need one set of filter caps if you only going to use it for one item.

He needs 15V not 9V .

[newperson]

yes, you can make them +-9, +-12, +-15, +-18 volts.  really whatever you need the voltages to be.  i have made many of them and they work fine for the different voltages.  

[teej212]

can you explain how you can regulate the 17v to 12v?

[Mark Hammer]

Just feed it to a 3-pin regulator.  They're usually good for input voltages a fair bit higher than the output voltage.

[Mick Bailey]

Some years ago I built a WP-20 synth and the filter is very good as well as simple. Sweep has a real growl and lower cutoff completely cuts off.

http://www.musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&VPW=1280&VPH=774

I modified it later to add a vactrol to get even more extreme effects with the AR generator, as well as a sub-octave generator and sequencer. I still have the synth and fired it up a couple of days ago - I'd forgot how effective the modules are, but it doesn't do 1v/oct.

[teej212]

so the 12 volt regulators going to work on the -17v? Is it the same principle for positive voltage and negative voltage?

[R.G.]

For some background, read "Power Supplies Basics" at geofex.com.