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4 hours ago, paul_5 said:

Easiest way would be to gear a multimeter across to measure continuity.

second easiest is to flip the board over and see which one goes to a 10nf capacitor (with a 2.2M to ground), then a 10k resistor into an IC - that’s the input.

the output of that circuit has a 100k resistor to ground on it.
 

09B93219-548F-4F4C-A2D4-376F82FD9035.png.f0203ef37a7466760b755c464dad34b9.png

Thanks for the nudge in the right direction, from tracing the PCB, I think I’ve discerned the following:

Grey (input?) -> 22nf -> 10k - 470k etc

White (ground?)-> 10uf cap -> 22k res & IC

Black (output?)-> vol pot middle lug -> other lugs going to IC & diodes etc

The input cap value threw me a bit as it’s a different value to that schem (10nf), this cap is a 2A223J, so pretty sure it’s 22nf

Any further thoughts @paul_5 ?

Cheers
Si

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Posted (edited)

I think you’re right - 10uf is too large to be anything but a power filtering capacitor, so that’s the one going to ground.

the lead coming off the volume pot is the output, and that can only mean that the signal input is the grey one.


edit: hopefully this will be of some use to you:

Wiring-Up-A-3PDT.thumb.jpg.d94327f8e2901dc76328b8d325527857.jpg

 

Edited by paul_5

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Posted (edited)
1 hour ago, paul_5 said:

I think you’re right - 10uf is too large to be anything but a power filtering capacitor, so that’s the one going to ground.

the lead coming off the volume pot is the output, and that can only mean that the signal input is the grey one.


edit: hopefully this will be of some use to you:

Wiring-Up-A-3PDT.thumb.jpg.d94327f8e2901dc76328b8d325527857.jpg

 

Brilliant, thanks for your help.
Yeah I’m fine rewiring the 3PDT in whatever config (there’s a few variations it seems), it was just making sure I had the PCB going to the right places ☺️.

Cheers

Si

Edited by Sibob

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Just built the Omnilooper:

https://schalltechnik04.de/en/instructions/omnilooper

Mainly to try with various oldschool envelope follower pedals - very nice with the mutron clone - phase shift required! The impedence button makes a big difference too.  Really useful for integrating those pedals that remove all the body.

The only problem I'm having, which I've noticed in some of his other designs, is that it can stop passing signal when the power supply fluctuates - e.g. a cable gets unseated and then comes back straightaway - the light is on but the circuit doesn't work until you turn it off and on again, which can be confusing on stage with bad power!

That and although it is satisfying to have it was a bit build by numbers getting the whole kit from Julian - but the thought of trying to drill the little button holes so the caps didn't stick gave me the heebie jeebies!

IMG_2749.thumb.jpg.801be208ec723f1c9d217857e4280389.jpg

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Has anyone got a good source of the right angled PCB pin 16mm pots? I never buy huge quantities so I usually just get them from bitsbox but I'm looking to stock up. They're cheap at rapid but they only have half the values I need. Can anyone vouch for an ebay seller? 

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Worth trying Farnell? I find it really hard to keep track of ebay sellers and end up buying 12 things from 12 sellers at £1.50 each (plus postage of course - the kicker!)

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1 hour ago, bloke_zero said:

Worth trying Farnell? I find it really hard to keep track of ebay sellers and end up buying 12 things from 12 sellers at £1.50 each (plus postage of course - the kicker!)

Farnell don't stock a big range of the right angle PCB pin ones unfortunately - a point of contention I raised with the guy responsible for them when I worked there, but to no avail... 

They're mainly of interest to the hobbyist (pedal hobbyists specifically) so they're hard to find at the big boys. 

 

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2 hours ago, bloke_zero said:

Worth trying Farnell? I find it really hard to keep track of ebay sellers and end up buying 12 things from 12 sellers at £1.50 each (plus postage of course - the kicker!)

Always check CPC as well as Farnell - same group, but CPC is focused on smaller customers so their MOQ is often lower and their prices for small quantities are often better.

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33 minutes ago, Chienmortbb said:

I just bought some from Tayda. They take a couple of weeks to arrive but AVE a fair selection https://www.taydaelectronics.com/potentiometer-variable-resistors/rotary-potentiometer.html?p=4

I've used them a lot in the past on modular synth builds - they are good and cheap. Sometimes you get hit with additional import charges and sometimes not - I used to get their deliveries at work and it drove goods-in crazy 🙂

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Anybody know a diy option for an alembic/wal style onboard preamp?

Basically (as I understand it!) they are a lowpass and high pass filter in series with a Q bump switch, which presumably adds some resonance to the low pass to bring out the tops.

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2 hours ago, bloke_zero said:

Anybody know a diy option for an alembic/wal style onboard preamp?

Basically (as I understand it!) they are a lowpass and high pass filter in series with a Q bump switch, which presumably adds some resonance to the low pass to bring out the tops.

@Passinwindhas a design and I have some PCBs for it but I don’t know how close it is to the Alembic/Wal. You can get three PCBs from OSHPark or I have a spare one. You can find details over on the other place https://www.talkbass.com/wiki/pw3b-lpf-open-source-onboard-preamp/

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15 hours ago, Chienmortbb said:

@Passinwindhas a design and I have some PCBs for it but I don’t know how close it is to the Alembic/Wal. You can get three PCBs from OSHPark or I have a spare one. You can find details over on the other place https://www.talkbass.com/wiki/pw3b-lpf-open-source-onboard-preamp/

Thanks - sounds interesting!  I have no idea really what the Wal one sounds like - I just love low pass filters and would love to build something for a bass build I'm working on. I'll message you about the pcb.

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On 13/10/2020 at 17:53, Chienmortbb said:

@Passinwindhas a design and I have some PCBs for it but I don’t know how close it is to the Alembic/Wal. You can get three PCBs from OSHPark or I have a spare one. You can find details over on the other place https://www.talkbass.com/wiki/pw3b-lpf-open-source-onboard-preamp/

If he doesn't want it I would!

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On 13/10/2020 at 09:53, Chienmortbb said:

@Passinwindhas a design and I have some PCBs for it but I don’t know how close it is to the Alembic/Wal. You can get three PCBs from OSHPark or I have a spare one. You can find details over on the other place https://www.talkbass.com/wiki/pw3b-lpf-open-source-onboard-preamp/

FWIW, I went out of my way not to do an overt clone of any of the existing designs I'm aware of, including the Alembic, Wal, ACG, Bartolini, and Craig Anderton ones. The long thread you linked to will explain my design intent much more thoroughly than I could manage here. 😎

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2 hours ago, Passinwind said:

FWIW, I went out of my way not to do an overt clone of any of the existing designs I'm aware of, including the Alembic, Wal, ACG, Bartolini, and Craig Anderton ones. The long thread you linked to will explain my design intent much more thoroughly than I could manage here. 😎

I had a good look through that - thank you!  I find the whole area fascinating and I've built a lot of different filters and I know that EQ similarly has a lot of different topologies (is that the right word?) and I'm really interested in trying out something that combines the two approaches.  I know that in a real sense EQ is just filter but I like that this has control over the resonance. And I love a DIY project and really appreciate the people who spend time putting them together so that people like me can build them - cheers!

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I’m putting together a modded DOD 250 for a friend, got all the relevant parts and kits etc, but what do you think to the following signal path?

3098953E-E824-4332-A16F-801C1F258323.thumb.jpeg.6ecc20aee3f4de56c05a38bcaa3ae454.jpeg
The output boost/volume is purely to give a global volume control.

Anything I’m missing? There’s no real reason why you’d have the Pre-gain boost after the blend is there?

Cheers

Si

Edited by Sibob

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Don't know if I'm late to the party with this, but I've found this guy's fleabay shop while I was scouting for knobs (stop sniggering at the back there). He seems to have a pretty wide range of PCBs available, if I didn't already have a Rat one waiting I'd have a punt at his.

https://www.ebay.co.uk/sch/m.html?item=363061238396&_ssn=dfx_parts&_ipg=100&rt=nc

 

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On 20/10/2020 at 13:03, Sibob said:

I’m putting together a modded DOD 250 for a friend, got all the relevant parts and kits etc, but what do you think to the following signal path?

3098953E-E824-4332-A16F-801C1F258323.thumb.jpeg.6ecc20aee3f4de56c05a38bcaa3ae454.jpeg
The output boost/volume is purely to give a global volume control.

Anything I’m missing? There’s no real reason why you’d have the Pre-gain boost after the blend is there?

Cheers

Si

Forgive me if I'm being a bit thick/noob -- I'm not all that au fait with FX in general -- but what does the 'clean blend' do?

 

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4 minutes ago, Rich said:

Forgive me if I'm being a bit thick/noob -- I'm not all that au fait with FX in general -- but what does the 'clean blend' do?

Lots of distortion or overdrive lose bass frequencies along the way so it's useful to have a way to blend in the original signal with the bass intact. I think this is essental for a lot of bass effects and can transform flange, filter FX as well.  But really useful with distortion and basses or synths where you'd loose a lot of the power in the lower frequencies.

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On 26/08/2020 at 08:17, Sibob said:

Thanks for the nudge in the right direction, from tracing the PCB, I think I’ve discerned the following:

Grey (input?) -> 22nf -> 10k - 470k etc

White (ground?)-> 10uf cap -> 22k res & IC

Black (output?)-> vol pot middle lug -> other lugs going to IC & diodes etc

The input cap value threw me a bit as it’s a different value to that schem (10nf), this cap is a 2A223J, so pretty sure it’s 22nf

Any further thoughts @paul_5 ?

Cheers
Si

What difference does it make to the sound if you have symetric diodes rather than the asymetric ones in this circuit?

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1 hour ago, Chienmortbb said:

What difference does it make to the sound if you have symetric diodes rather than the asymetric ones in this circuit?

Que?

Si

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2 hours ago, Chienmortbb said:

What difference does it make to the sound if you have symetric diodes rather than the asymetric ones in this circuit?

Asymmetric clipping produces more odd harmonics, creating a slightly harsher, more dissonant tone. Symmetric will produce more even harmonics, not necceassirly smoother, but a more pleasent sound. In pratcice the difference can be kind of hard to notice when you´re doing hard clipping like here (diodes directly on the op-amp output). It´s more noticeable in soft clipping setups (in the feedback loop of the op-amp) like the tubescreamer.

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I have built step attenuators to my basses every now and then. Today I happened to find two from my garage. How on earth did they got there?

20201029_131312.jpg

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