Roland SH5 bandpass filter

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kragg
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Post by kragg » Sat Sep 22, 2018 7:48 am

Hello !
It's been a little while, but i managed to find some time to rebuild the filter, using the new layout, and it worked fine since the first attempt :bananaguitar:
I find the new layout much improved, very easy to read, with enough space between components while being more compact, it's great to work with !
In order to be able to troubleshoot it more easily (in case it hadn't worked), i built it using the original component values (dual gang pot, default value for the resonance, external 15V power supply -no charge pump on a daughter board-), which might have helped if it hadn't [/img]work as expected :)

The filter sounds great, very "liquid" and clean (well, it's a Roland design), and i am quite impressed with the sweep range : it goes from very low to very high, which is a good surprise.
The resonance is quite onthe gentle side, which is fine (it sounds "classy", rather polite), but i might end up ading a switch to swap between "stock value" and "increased resonance" when it's needed.
Pushed to the max, there is a little drop in volume, but that's subtle (unlike on a Pro-One, for instance), and not an issue at all, just that kind of design.

One mod i might try to add is a CV input (i can't remember if i had find a layout, or a way to do this ?).
[edit : I think i remember i had read that it was not designed to be cv-modulated. Nevermind, still, it sounds great :) ]

Thank you very much everyone for the help, to the fellow wigglers watching the topic, do not hesitate to build it ! :tu:

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Starspawn
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Post by Starspawn » Sun Sep 23, 2018 1:50 pm

Wheres the updated layout?

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kragg
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Post by kragg » Sun Sep 23, 2018 2:15 pm

Here :
Image
It's much more compact, and easier to build.

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Post by ashleym » Sun Sep 23, 2018 4:25 pm

Thanks for that. This is just the excuse I needed to make something from scratch myself. Even typing this I’m thinking of putting a couple or so together, then I’m thinking of looking at the frequencies involved to do a sort of vowel filter.......

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kragg
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Post by kragg » Sun Sep 23, 2018 6:00 pm

The "original" module from Ken Stone used 3 together to make a filterbank.
(Unfortunately, it seems that the website isn't available anymore)
http://www.effectsdatabase.com/diy/kens ... ular/cgs30

guitargodmiles
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12v?

Post by guitargodmiles » Fri May 24, 2019 8:25 pm

Will this work on eurorack 12v as is?

Thanks

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wackelpeter
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Re: 12v?

Post by wackelpeter » Sat May 25, 2019 1:17 am

guitargodmiles wrote:Will this work on eurorack 12v as is?

Thanks
If you meant the CGS30 BPF it says that it should work on +/- 12V too, but untested...

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Re: 12v?

Post by ringroad1 » Sat May 25, 2019 2:16 am

guitargodmiles wrote:Will this work on eurorack 12v as is?
I've got a couple running in my +/-12V box, don't think I made any changes, works fine

pufffin2001
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soldering direction

Post by pufffin2001 » Sun Oct 20, 2019 2:51 am

hello,

First of all, amazing thread, and thank you for your
generosity in showing how this amazing filter is made!
i am a complete beginner when it comes to electronics.
i managed to get all the components necessary for this build,
but do not understand veroboards very well. do you have a picture
of the soldering side? thank you very much for your help!

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wackelpeter
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Post by wackelpeter » Sun Oct 20, 2019 4:06 am

If you mean a picture of the above posted layout by kragg, you don't need it.

The red dots indicate, where you have to cut the trace of the stripboard. Best use a 3,5mm or 4mm drill for that only peeling the copper off, you can do that drilling by hand or carefully with a machine... not too much because you may want to solder something next to the drilled part and the solder leg would be happy if there is some copper left on the hole.

You just need a drill, some sharp cutting tool to scratch off remains of copper that may be loose or in contact with a neighbouring trace and an old tootbrush to clean it a bit. And a magnifier is always useful..

Otherwise there is nothing else except that as usual i repeat the mantra, use sockets for the IC's and have fun.

ahh yes, as i was wondering that the upper IC seemed not to have +15V and gnd... it's shown there as connected underneath the IC's i would prefer to do that as you place any other component on top, this would cost you only two or three additional rows on the boards but i think it has the advantage that you have all your connections visible and not eventually some short hidden underneath an IC socket...

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Post by pufffin2001 » Sun Oct 20, 2019 4:31 am

so i only need to solder where 2 components meet?
this is where i get confused. thanks for your help, nice track btw!

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wackelpeter
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Post by wackelpeter » Sun Oct 20, 2019 5:03 am

Don't know what kind of board you will use... If it's a stripboard as shown in the picture (those that have vertical copper lines) then you just stick in the components as shown, solder their legs and cut the trace where marked...

If it's a perfboard or veroboard... don't know which is the correct description, i mean those with single copper dots (soldering points), then of course you have to connect those dots/points as needed... for example you had to connect pin 2 of the upper IC with the 2 legs of the 47k resistors that are sitting on the line marked with E...

That's why i prefer stripboard as you don't have to make interconnecting traces, they are already there and you only have to cut them where you don't need them or where they should be interrupted.

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Post by pufffin2001 » Sun Oct 20, 2019 5:13 am

thanks wackelpeter! i am using a stripboard.
yes i cut the traces, but am finding it it hard to nest the
links under the IC sockets!

so i don't have to worry about the connections and just
solder the legs.cool. this cleared things up for me!

i found a +/-12V powersupply from an old akai sampler
which i'm trying to figure out how to implement.

danke sehr for your help!

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Post by wackelpeter » Sun Oct 20, 2019 6:06 am

pufffin2001 wrote: but am finding it it hard to nest the
links under the IC sockets
danke sehr for your help!
that's why i wrote i prefer to keep those connections one or a few rows next to the IC's... ;)

It doesn't really matter if it connected 3 or 5 rows next to the input it should reach (at least for gnd and supply voltages) as long as it connects to them... also usually you would add a 100nF cap (this should be as close as possible to pin 4 and 8 of for example a TL072 IC and connect the other pin to gnd... those bypass caps are for providing more stability to the power of the IC.

These act as little buffers for the power supply, they do the same as the 10uF electrolytes at the power input, but only are closer to the IC and so provide more stability...

The other rule is to keep singal path connections (all audio signals) as short as possible... keep traces connecting to caps as short as possible (this in reference to the audio part specifically)...

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wackelpeter
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Post by wackelpeter » Sun Oct 20, 2019 6:16 am

As i see it now the electrolytic cap that connects to pin 8 of the lower IC should connect on the other side to gnd and not -15V or -12V...

usually you place a small resistor before them (10 to 15 ohms) acting as a kind of lpf together with the caps and also acting as protection for your circuit... because in case of a short you just roast the resistor and not all IC's...


15+ *10ohm * *capNo1/10uF+*
gnd *capNo1/10uF-**capNo2/10uF+*
15- *10ohm * *cap No2/10uF-*

don't know if it's formatted properly, but the asterisk marks the legs of the components and you had to cut the trace underneath the 10ohm resistor, the + pole of the first cap goes to +15 after the resistor and the - pole to gnd, while the + pole of the second cap goes to gnd too and it's - pole to -15 after the other 10ohm resistor...

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Post by wackelpeter » Sun Oct 20, 2019 6:37 am

had to look a little bit, here is a stripboard layout for another roland VCF i made some time ago...

http://electro-music.com/forum/phpbb-fi ... cf_676.png

it's just an example to show how to place/connect the resistors/caps i above wrote about... it's just an idea, you can place them however you want if you follow the signal flow and schematic.

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Post by pufffin2001 » Sun Oct 20, 2019 7:14 am

thanks man!

i thought everything had to be in the right place,
didn't know about the flexibility in laying out resistors and caps, etc.

so as long as IC pin connections are in the right place, other
components could be moved around, no?

thanks for pointing out the right direction!
i used to own an SH 5 which i got bored of and threw out the window,
(WTF?)
i liked the BPF alot and i stumble upon DIY,

no way i can afford another SH5............

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Post by wackelpeter » Sun Oct 20, 2019 7:26 am

Yes somehow it's some kind of free-form soldering... :D

but i tend to keep it at least a bit systematic, because when i watch some years later on a board, i think it would be cool if there would be systematic order and me not having to dive into a chaos of components... and well of course the components should be connected according to the schematics... Not the layout of a stripboard is the 100% accurate or correct building guide, but the schematics fro that circuit are... and you should be somehow able at least a bit to follow the schematics and have a rough understadning of what happens or how the signal flow works, etc. ...this may come or get better within time, so usually it's best to start with simpler and less difficult circuits and the knowledge grows with exeperience...

for example use always the same colours for gnd, + and - supply voltages, then i usually tend to have a gnd trace on top and on the bottom of each IC, to connect the bypass caps as short as possible to the IC and also other components that are connected to gnd... etc...

the whole system you can see below in my soundcloud link consists of only stripboard modules i've made in the last couple of years...

the only downside is that it's more work to solder and connect anything as on a etched PCB and you have plenty of cabling when the pots and sockets aren't soldered to the PCB directly... But anyway it's fun, i thought i'm finished but last weeks i made a spring reverb and a phaser, both waiting for an housing and recently being in the midst of finishing 2 CGS serge programmers... :)

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Post by pufffin2001 » Mon Oct 28, 2019 6:25 am

:nana: :nana: :nana: :nana: :nana: :nana:

Thank you wackelpeter and everyone in this thread for your kindness
in sharing this wonderful filter build info!

after many deliberations i was able to nail the sound,
how sweet it is!

:banana: :banana: :banana: :banana: :banana: :banana:

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Post by wackelpeter » Mon Oct 28, 2019 10:04 am

glad you got it working... and no probs, that's the main reason for this forum, to share experience, provide help and give other perspectives if looking at things...

btw. the stripboard layout on top wasn't mine... i only made the one in my post, but that's the only one i ever made... i'm more into freestyle soldering and planning occurs within the build process, except the panel mount components...

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Re: Roland SH5 bandpass filter

Post by Varin » Sun Oct 25, 2020 2:40 am

Ah... I have everything apart from 50K pot. What difference would 100K pot in its place make?

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Re: Roland SH5 bandpass filter

Post by KSS » Sun Oct 25, 2020 7:54 am

@wackelpeter
In the 121 layout you shared, the ICs are opaque. Is it safe to assume all ICs hav a complete column of holes-strip breaks?
That none have horizontal pin to pin connections?

Yes, I can figure it out. But for those who may not be able to, it would help if those inder IC breaks were expressly shown.

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Re:

Post by Varin » Sun Oct 25, 2020 5:16 pm

wackelpeter wrote:
Sun Oct 20, 2019 6:16 am
As i see it now the electrolytic cap that connects to pin 8 of the lower IC should connect on the other side to gnd and not -15V or -12V...

usually you place a small resistor before them (10 to 15 ohms) acting as a kind of lpf together with the caps and also acting as protection for your circuit... because in case of a short you just roast the resistor and not all IC's...


15+ *10ohm * *capNo1/10uF+*
gnd *capNo1/10uF-**capNo2/10uF+*
15- *10ohm * *cap No2/10uF-*

don't know if it's formatted properly, but the asterisk marks the legs of the components and you had to cut the trace underneath the 10ohm resistor, the + pole of the first cap goes to +15 after the resistor and the - pole to gnd, while the + pole of the second cap goes to gnd too and it's - pole to -15 after the other 10ohm resistor...
So the stripboard layout above is incorrect? Is the main issue that one electrolytic cap which should go from pin 8 of lower IC to ground rather than -12v?
kragg wrote:
Sat Sep 22, 2018 7:48 am
Hello !
Hi Kragg, can you confirm that electrolytic cap issue please? Also - why one dual pot rather than 2 separate pots?

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Re: Roland SH5 bandpass filter

Post by KSS » Mon Oct 26, 2020 1:49 am

You could use two pots. Just join thier shafts with a wide rubber band -old school trick!- or gears so they turn at the same time. ;)

The resistor in most synth filters is easier to change than the capacitor, so we use pots when we want an adjustable filter. This filter design needs a resistor for each pole, and we typically want both filter poles to move at the same time, so a double pot is called for.

In most voltage controlled filters each pole's pot is replaced by a gain element-VCA which acts as the variable resistance. OTAs and FETs are typically used as the VCA element. The difference in the ways these repsond is much of the difference we hear in VCFs.
These OTAs and FETs are easy to control with a single voltage, even when there are as many a 6 different poles-VCAs. Just run the same voltage to each one, and the filter's cutoff frequency changes for at the same rate, at the same time.

Since we can't do that with this non-voltage controlled filter, a dual pot is used.

But like I said up top, you *can* use two singles. In fact, you might best answer your question -and learn a great deal about filters- by doing so! You'll see how each pot alone affects the filter response, and how moving them in different ways -directions and speed- also affects its output. You may even decide to keep them. But if you're after the normal and expected results from a filter like this, use a dual pot, or mechanically connect the shafts.

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kragg
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Re: Roland SH5 bandpass filter

Post by kragg » Mon Oct 26, 2020 4:45 am

Hi, Sorry, it was two years ago, i can't remember about the capacitor....

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