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[Order] Raging Bull (Taurus I VCF/VCA) PCBs/panels
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page 1, 2, 3, 4  Next [all]
Author [Order] Raging Bull (Taurus I VCF/VCA) PCBs/panels
frequencycentral
Raging Bull is based on the legendary Moog Taurus Mk I VCF and VCA. It has a lovely, thick Moog-like quality, which is further enhanced by the drive you can get out of its VCA at higher settings.



A big part of the sound of the Taurus was the way in which the VCF interfaced with the VCA, so on Raging Bull the VCA is always in the audio path. A toggle switch allows you to select ‘always open’ or CV control of the VCA from CV input 1.



My good buddy Matt Preston (matttech) has kindly done a suite of demos of this module, which can be found here:

http://matttechmodulardemos.bandcamp.com/album/frequency-central-ragin g-bull-moog-taurus-vca-vcf-clone



Build doc: http://www.frequencycentral.co.uk/wp-content/uploads/2014/04/Raging-Bu ll-Build-Doc.pdf

Raging Bull PCB: £15 GBP
Raging Bull (10HP): £15 GBP


order via PM or email from my website
Maco
One PCB for meeee
frequencycentral
Build doc added: http://www.frequencycentral.co.uk/wp-content/uploads/2014/04/Raging-Bu ll-Build-Doc.pdf
Barcode
On my want list!
Jarno
+1

Do the transistors need to be matched?
frequencycentral
No need to match, uses CA3046 for bottom and top rungs of the ladder, so half the work is done for you. Other than this, Moog were known not to match theirs.
nikmis
I am starting to get to the point where I have too many filters, but now I want this. Mainly because of the demos, especially the slow sweeps at high gain and mid resonance.
Reality Checkpoint
A great sounding filter.

PM on way!
Jarno
Tried to find rev log PC mount pots recently but couldn't find them. So I used non-pc mount ones and hooked them up using 1mm solid core wire.
But did anyone try log faking? Add a resistor from top to wiper.
See "the secret life of pots" by rg keen.
frequencycentral
50k rev log @ Tayda: http://www.taydaelectronics.com/potentiometer-variable-resistors/50k-o hm-c50k-50kc-anti-log-taper-potentiometer.html
seancostello
A favor to ask: Could someone try replacing the resonance coupling capacitor (C509 in the original schematic) with a much SMALLER value? I'm not sure what value would be needed to simulate the highpass filters in the Minimoog resonance path, but it might add even more bass oompf to the sound of the Raging Bull when the resonance is turned up. It will also raise the cutoff frequency at which self oscillation is possible, but this is also true of the Minimoog and Moog Modular.

Thanks,

Sean Costello
widdly
Why are schematics not included for this? How do people debug Frequency Central builds without schematics?
frequencycentral
widdly wrote:
Why are schematics not included for this? How do people debug Frequency Central builds without schematics?


http://www.frequencycentral.co.uk/wp-content/uploads/2014/04/Raging-Bu ll-Schematic.pdf
widdly
Nice one, thanks
emdot_ambient
Sounds great...but the PCB's got no mounting holes. Can't really see how it could be mounted other than via the pots.

Oh well, my backlog is too big as it is lol
Jarno
OT, but I sometimes use thick silverplated copperwire to mount small PCB's (and these are very small). Either just on the pots, or on a few pots and one or two jacks so the wires form a triangle, pretty stiff mount.
raveboyy
Hi,

what are theese holes for??

2 holes in the corner of LF351
4 holes besides the `Rev 1.1` and `Jan 2014` prints

Quote:

A favor to ask: Could someone try replacing the resonance coupling capacitor (C509 in the original schematic) with a much SMALLER value? I'm not sure what value would be needed to simulate the highpass filters in the Minimoog resonance path, but it might add even more bass oompf to the sound of the Raging Bull when the resonance is turned up. It will also raise the cutoff frequency at which self oscillation is possible, but this is also true of the Minimoog and Moog Modular.


This sounds interresting...[/quote]
frequencycentral
Those are vias. They take traces from one side of the PCB to the other. Just leave them.
raveboyy
Thanks Rick,

and something more I need help with.

Do all the resistors have to be 1-5% 1/4W ? I ordered them and some of them (100K, 470K, 2M2) are I think 1% 2W...does it matter? Should i buy the common ones instead?

And the caps must be the polyester ones? I bought some of them ceramic...should I buy the polyester ones instead?


Thanks a lot
rockwoofstone
Finished building mine this weekend, and have some issues which have me stumped.

Generally speaking, everything is doing something like it should. VCA thump is completely trimmed out, and all things VCA seem to be working perfectly. However, there are issues which I can't get my head around with the filter itself, so wondering if anyone has any suggestions...

1. I don't get any resonance when the cutoff is set to anything approaching a lower frequency (self resonating). Even with the resonance pot all the way up, and the trimmer also at the maximum position (all to maximise resonance), I still get the resonance cutting out for anything lower than around 800Hz cut-off. Net result in normal use is as if there's no resonance of note when doing classic Taurus ranges of filtering on bass notes.

2. Possibly related to the above, but there seems to be some slewing of the resonance frequency, even when not being changed, more noticeable at frequencies lower to the point at which the resonance cuts out as described above. Additionally, these first two issues result in it being nigh on impossible to trim the scale to be 1V/Oct for useful frequencies, as the resonant frequency struggles to be stable at the lower end.

3. I get a pretty substantial click when I feed any cut-off CV in with a fast attack (VCA open, CV input into input 1 or 2). I see this even with no audio input, and resonance all the way down. If I increase the initial cut-off frequency (from the pot) to something above the minimum (e.g. ~100Hz), then the click goes away.

4. When sweeping the cutoff all the way down to minimum when feeding in a lowish audio note (say, ~100Hz), I get a drop off on out put frequency just for a fraction of a second before the audio is filtered out. It's enough to be audible, and gives the impression that I'm pitch bending the note down by about half a semi-tone in the final few 10ths of a second before the note is completely filtered out.

Sorry about the large list of issues - I suspect in the end they're all related, but I've had the scope on a few parts of the circuit, and nothing seems out of the ordinary. No shorts, no dry joints, etc, and stumped as to what it could be! seriously, i just don't get it

Any suggestions would be most welcome! thumbs up
rockwoofstone
Spent the evening on the problems above, and everything I examined looked OK, but the problems persisted. very frustrating

In the end, I pulled the 3 pairs of BC547s and replaced them with matched pairs, and everything now works absolutely fine. May be worth adding a comment to this effect to the build instructions in case someone else has a similar issue.

Anyway - all good now! thumbs up
raveboyy
Just finished mine today:) sounds very good hyper

Just one little thing is when I rise the resonance, the volume drops quite a bit.

I adjusted all the trimmers to the taste, tried with different sounds but can`t get the resonance vs volume right... any suggestions?
Maco
Anyone with a mouser bom?
the trimmer are those like rectangle boxes or the rounded ones?

Any picture of the front populated please?


Thanks
raveboyy
Maco wrote:
Anyone with a mouser bom?
the trimmer are those like rectangle boxes or the rounded ones?

Any picture of the front populated please?


Thanks


Something like this one


Pins on the bottom, wheel on the top.. so you can reach it then with screwdriver when other components are soldered around it..

Can be even the box but watch the dimensions, so it can fit on the PCB..important is the size ..pins should be 5 or 6 mm far from each other...and the right resistance value of course

Do you have a source of the CA3046 IC or a equivalent??
Maco
thanks rave boy i found the trimmers and ca3046 at tayda will get it
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