[BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

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Monobass
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[BUILD] God's Box 'Humpback' - 8hp Eurorack Multimode VCF

Post by Monobass » Fri Jul 17, 2015 4:48 am

A full DIY kit for a 2-pole multimode filter reminiscent of the classic ‘SEM’ style state variable VCF.
Special features include a hot rodded resonance circuit and increased frequency range.

http://www.thonk.co.uk/shop/humpback/

BUILD DOC AND SCHEMATICS– http://thonk.co.uk/documents/gbox/humpback/

[video][/video]

Image

[video][/video]
Last edited by Monobass on Wed Aug 09, 2017 5:54 am, edited 3 times in total.
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Post by Monobass » Fri Jul 17, 2015 4:48 am

...
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talfred
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Post by talfred » Fri Jul 17, 2015 6:00 pm

Well, this sounds like a very good filter. Might just juild this one and sell my koma svf. Any more demos somewhere?

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Post by Monobass » Sat Jul 18, 2015 2:19 am

More demos coming this week, it sound great but we've been totally focussing on getting the kits ready! More soon.
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Post by Monobass » Wed Jul 22, 2015 4:33 pm

Build document now online - http://thonk.co.uk/documents/gbox/humpback/

Image
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LowOver
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Post by LowOver » Mon Jul 27, 2015 10:28 am

that sounds good , always wanted a sem style filter in my rack....and diy , great...will order if the full turing machine kids are avaiable again :yay:

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Post by Monobass » Mon Jul 27, 2015 10:38 am

Yep they will be this week :guinness:
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Post by Monobass » Wed Aug 19, 2015 8:45 am

I sold 50 kits and have an empty build thread, must be good news? :)
(touch wood)
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Post by Monobass » Wed Aug 19, 2015 8:46 am

nice vid on the Humpback from DivKid

[video][/video]
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Post by oberkorn » Thu Aug 20, 2015 1:30 pm

built it yesterday, sounds delightfully creamy good, even without calibration :party:

only issue, one of the IC sockets was bad, wouldn't allow one leg of the chip to go in,
only noticed this once it was soldered in, had to desolder it luckily without damaging the pads,
replaced it and one 220r resistor I damaged in the process with parts from the spares bin and everything was happy :)

you can get the most wonderful phaser-like effects by mixing the filter outputs, will try to do a demo over the weekend
this blank space left intentionally

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Post by Monobass » Thu Aug 20, 2015 1:45 pm

oh sorry about the socket! I think that's the first report I've ever had like that on an ic socket. Next time you place an order let me know and i'll replenish you :)

yeah I really like the phaser-like notch output, so much more interesting than a lot of notches out there I think!
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Post by Biotron345 » Sat Aug 22, 2015 12:54 am

How do I calibrate this little beast? :banana:

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Post by Monobass » Sat Aug 22, 2015 3:43 am

One of the main goals of the Humpback was for a filter which required as little trimming as possible, to this end the tracking trimmer makes such a subtle change that we have actually considered removing it in the next revision.

Or the short answer is I haven't actually trimmed the last two I built and haven't found it necessary.
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Post by starmandeluxe » Mon Aug 24, 2015 8:09 pm

I just built this and its sound is amazing! I love it. Maybe best DIY I've done. The only questionable thing is when I turn the resonance almost all the way up, it starts doing some strange things such as the signal cuts out almost completely and goes all crackly, and turning it past that the resonance gets SUPER loud, so it's almost unusable at the extremes. I know there's a jumper that can change this behavior but I haven't tried it yet. I do like the heavily distorted sound but I wish the level was consistent instead of jumping into armageddon-mode :hihi:

Hear it in action here! (Sequenced by my Turing Machine with Expanders!)

https://soundcloud.com/starmandeluxe/no ... lca-sample

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Post by Monobass » Tue Aug 25, 2015 2:16 am

Sounds great.

The module does allow you to keep increasing the resonance level until it vastly dwarfs the input signal and starts clipping the module internally, the answer is just backing off on the dial :)

But do you have the jumper on or off at the moment?
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Post by starmandeluxe » Thu Aug 27, 2015 12:10 am

Monobass wrote:Sounds great.

The module does allow you to keep increasing the resonance level until it vastly dwarfs the input signal and starts clipping the module internally, the answer is just backing off on the dial :)

But do you have the jumper on or off at the moment?
The jumper was on. I actually tried taking it off yesterday just to see what the alternative is like, and I decided to put it back on 8-)

Thanks for a wonderful filter!

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Post by megaohm » Thu Aug 27, 2015 1:10 am

Schematic missing from build doc.
Is this posted anywhere?
www.MegaOhmAudio.com

Will work for pistachios

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Post by mpTRONIX » Thu Aug 27, 2015 3:11 am

Schematic = i Need too. :despair: :hmm: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :help: :cry:

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Post by thorncore » Tue Sep 01, 2015 10:16 am

any plans for a PCB only option?

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Post by lowacid » Sat Sep 26, 2015 5:00 am

megaohm wrote:Schematic missing from build doc.
Is this posted anywhere?
i'd like it too. i find it a little too harsh with resonance (even with jumper off) on the second i have made.

i'd like to recalibrate it a little less "savage" héhé. At least in sem classic mode.
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Post by johyde » Sat Sep 26, 2015 6:58 am

I've just finished this kit - enjoyable build!

I have unfortunately got some problems with it. The high pass and band pass outputs sound exactly as I'd expect, but the low pass and notch produce some strange results - the response as I sweep the cutoff knob is completely non-linear, with reasonably expected sound in places, no sound in some others, and distortion/clicks in others. This varies when I tweak the input and resonance, but always exhibits this behaviour.

The only mistake I made is that when I first tried it I took the patch cables going through another filter and just swapped them in on this one. Unfortunately I did them the wrong way round, so the output was connected to the input and vice versa. So I had a triangle-wave from a Make Noise DPO plugged into the LP out. I know this isn't a good idea, but I'm sure I will have made similar mistakes before and it's not caused me to blow anything. Can anyone tell me if this is a likely cause. Otherwise I'll just keep looking for any mistakes I might have made.

Love the filter anyway. the BP and HP sound lovely, and I actually got some quite nice stuff out of the funky LP, which sounds kinda cool even if not what I expected.

I have tried with the jumper on and off, and I've also fiddled with the trimpot , which didn't seem to make much difference. What does that do anyway?
Last edited by johyde on Sun Sep 27, 2015 7:18 am, edited 1 time in total.

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Post by LektroiD » Sat Sep 26, 2015 11:18 pm

thorncore wrote:any plans for a PCB only option?
Or PCB/Panel. Seems a lot of extra money to spend on jellybean parts.

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Post by johyde » Sun Sep 27, 2015 3:43 pm

Hmm.. still having a few issues. I swapped out the TL072s as I had some knocking around, and that seems to have somehow sorted that intermittent problem. However, now I'm finding the resonance way too strong - this seems to strike a chord with what lowacid said. Even with the resonance knob turned right down, the lower half of a sweep sounds quite nice (though with definite pronounced resonance), but in the higher frequencies it goes completely into self oscillation. Removing the jumper seems to make a small amount of difference, but not much. Again, I'm getting some useable sounds out of it, but it would be more versatile if I could have a bit more control over that resonance..

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Post by seank » Sun Sep 27, 2015 5:23 pm

just finished mine and it's self oscillating even with the res turned all the way down and the jumper removed. i can barely hear the input passing through. any tips?

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Post by lowacid » Mon Sep 28, 2015 4:26 am

seank wrote:just finished mine and it's self oscillating even with the res turned all the way down and the jumper removed. i can barely hear the input passing through. any tips?
Could you make some pictures of your builds ? that would be helpfull to help
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