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[Build] Dannysound - Cali Oscillator (258 clone)
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Author [Build] Dannysound - Cali Oscillator (258 clone)
Monobass




The Cali oscillator is a new and improved version of the classic Buchla 258 waveshaping linear FM oscillator with an additional pulsewidth modulated output.

Buy here - https://www.thonk.co.uk/product-category/manufacturer/dannysound/





The Cali Oscillator is Dannysound’s new and improved version of the legendary Buchla Model 258 VCO. The oscillator features the classic Sine to Square and Sine to Saw wave shaping with dedicated CV control.

The Cali Oscillator differs from previous versions of the 258 in that it has a 3-way position switch rather than 2-way. This new middle position features a bonus waveform that will shape from a pulse into a kind of triangular trapezoid shape. The shaping control is more unpredictable in this middle position – it can be thought of as an extra bonus waveform!

There are dedicated inputs for linear and logarithmic FM and the Cali also adds a Pulse output with it’s own width control and PWM CV input. The behaviour of the pulse output can be affected by the position of the waveform switch and wave shape control.

The module features Coarse and Fine frequency controls and an LFO mode, LFO range is accessed via an LED pushbutton that also acts as the LFO speed indicator – the button will light up when the waveform moves through its positive cycle.

Features:

    Sine to Saw/Square Waveform Output with CV over wave shaping
    Pulse output with voltage controlled PWM
    Linear FM with attenuator
    Logarithmic FM with attenuator
    Bonus ‘trapezoid’ output
    Coarse & Fine controls with LFO mode
    Genuine Rogan USA knobs (Hex keys included)
    All Through-hole build – no SMD components!
    Width: 12HP
    Depth: 42mm


Build Documents here - https://www.thonk.co.uk/documents/dannysound/

Schematics here - https://www.thonk.co.uk/documents/dannysound/Cali_Osc/schematics/

Buy here - https://www.thonk.co.uk/product-category/manufacturer/dannysound/

euromorcego
thumbs up

saw these at superbooth. totally looking forward to get more info!

Also: there were also drum modules based on the Radio Music ... any news on them?

I see the page is up: https://www.thonk.co.uk/shop/dannysound-cali-osc-kit/

Will there also be a pcb/panel option?

Also, the build guide seems to have 53M, maybe there is a possibility to shrink the file a bit?
Monobass
euromorcego wrote:

Also, the build guide seems to have 53M, maybe there is a possibility to shrink the file a bit?


just dropped it to 4.5mb.

We'll have panel/pcb in a few weeks. Will start a new thread on the drums soon, those aren't Dannysound.
CliffordMilk
These look and sound great. I'm thinking of building a few. How well do they track?
dannysound
The EN129 tracks very well.

The Cali oscillator has a slight dip in pitch around the middle frequencies but it's not too bad.

I've been using these oscillators in synthesisers for about 5 years now (They started life in these blue monosynths that I sold). The strange thing is, even though the Cali oscillator doesn't track as well as the EN129 I do find myself turning to the Cali for the musical lines. There's something about the timbre of the Cali that I really like, especially setting the waveshape to 30% ish, sounds more acoustic somehow.
Monobass
Build Documents and schematics here - https://www.thonk.co.uk/documents/dannysound/
jimi23
Monobass wrote:

We'll have panel/pcb in a few weeks. Will start a new thread on the drums soon, those aren't Dannysound.


Any chance of it being PCB/Panel/Rare parts?
Specifically SSM2220, CA3140, CA3080. Most people who bulk buy components would generally have everything else on hand, having a quick look at the schematic
Monobass
SSM2220 - the recommendation is to actually just use a pair of matched transistors instead, which we sell on Thonk or you can match yourself.

CA3140EZ - Easily available from Farnell, Mouser, TME, Digikey , RS, Future etc

CA3080 - We have a good supply of newly manufactured ones at Thonk which isn't going to dry up
igowen
finished building and calibrating one of these last night and it sounds wonderful. one question on the "bonus" wave shape (toggle switch in the middle position) -- the range on mine is pretty limited. it starts out as a sort of truncated sine, and then around 9 o'clock it goes into a sort of unstable glitchy wave shape and then rapidly changes to a triangle wave for the rest of the range of the pot. is this the expected functionality/range? the description in the build guide doesn't give one much to go on and i wanted to make sure i didn't make a mistake somewhere in the build.
rinta
igowen wrote:
finished building and calibrating one of these last night and it sounds wonderful. one question on the "bonus" wave shape (toggle switch in the middle position) -- the range on mine is pretty limited. it starts out as a sort of truncated sine, and then around 9 o'clock it goes into a sort of unstable glitchy wave shape and then rapidly changes to a triangle wave for the rest of the range of the pot. is this the expected functionality/range? the description in the build guide doesn't give one much to go on and i wanted to make sure i didn't make a mistake somewhere in the build.


Similar behavior here with the switch in the middle position.

I also would like to confirm if the initial waveshape is triangle, not sine like on Suptnik Oscillator which I think is also based on the half of 258. How about yours?
igowen
rinta wrote:
igowen wrote:
finished building and calibrating one of these last night and it sounds wonderful. one question on the "bonus" wave shape (toggle switch in the middle position) -- the range on mine is pretty limited. it starts out as a sort of truncated sine, and then around 9 o'clock it goes into a sort of unstable glitchy wave shape and then rapidly changes to a triangle wave for the rest of the range of the pot. is this the expected functionality/range? the description in the build guide doesn't give one much to go on and i wanted to make sure i didn't make a mistake somewhere in the build.


Similar behavior here with the switch in the middle position.

I also would like to confirm if the initial waveshape is triangle, not sine like on Suptnik Oscillator which I think is also based on the half of 258. How about yours?


mine outputs a fairly clean sine wave with the wave shape pot at 0, but i followed the calibration steps in the build guide to achieve that. did you calibrate the wave shape on yours?
rinta
igowen wrote:
rinta wrote:
igowen wrote:
finished building and calibrating one of these last night and it sounds wonderful. one question on the "bonus" wave shape (toggle switch in the middle position) -- the range on mine is pretty limited. it starts out as a sort of truncated sine, and then around 9 o'clock it goes into a sort of unstable glitchy wave shape and then rapidly changes to a triangle wave for the rest of the range of the pot. is this the expected functionality/range? the description in the build guide doesn't give one much to go on and i wanted to make sure i didn't make a mistake somewhere in the build.


Similar behavior here with the switch in the middle position.

I also would like to confirm if the initial waveshape is triangle, not sine like on Suptnik Oscillator which I think is also based on the half of 258. How about yours?


mine outputs a fairly clean sine wave with the wave shape pot at 0, but i followed the calibration steps in the build guide to achieve that. did you calibrate the wave shape on yours?


Must have overlooked something. Will look into it again, very glad to know that it can do sine. Thanks!
rinta
rinta wrote:
igowen wrote:
rinta wrote:
igowen wrote:
finished building and calibrating one of these last night and it sounds wonderful. one question on the "bonus" wave shape (toggle switch in the middle position) -- the range on mine is pretty limited. it starts out as a sort of truncated sine, and then around 9 o'clock it goes into a sort of unstable glitchy wave shape and then rapidly changes to a triangle wave for the rest of the range of the pot. is this the expected functionality/range? the description in the build guide doesn't give one much to go on and i wanted to make sure i didn't make a mistake somewhere in the build.


Similar behavior here with the switch in the middle position.

I also would like to confirm if the initial waveshape is triangle, not sine like on Suptnik Oscillator which I think is also based on the half of 258. How about yours?


mine outputs a fairly clean sine wave with the wave shape pot at 0, but i followed the calibration steps in the build guide to achieve that. did you calibrate the wave shape on yours?


Must have overlooked something. Will look into it again, very glad to know that it can do sine. Thanks!


Turned out I had a mistake when calibrating waveshape. After following instructions in the manual again, I get a nice sine! Even the way it reacts to modulation became more beautiful with correct calibration.
schege
I'm very interested in the Cali oscillator (same for the EN129). But except the Superbooth video there are no sound examples/videos to find in the internet. Would be great if Danny or someone else could give some examples. Especially I'd like to hear how the EN129 reacts on linear FM and if the pitch of the tone is stabil when FMing. Also I'd like to know how ist the tracking of these osc. How many octaves do they track approximately. Thanks!
pugix
My Thonk full kit is on order! It will be fun to compare this with the J3RK 258J clones that I built in MOTM format. I'm happy this Dannysound design is now available for Eurorack.

http://pugix.com/synth/buchla-258j-vco/
pugix
I've been looking over the schematic. A nice feature is the LED monitors on the CV inputs, pre-attenuation. You can see what the CV on the input is doing (positive excursions only). Another nice feature on this and the TZO is power supply isolation using 9V regulators for the tuning pots.

Something interesting is the normalizing of +3V to the V/OCT input. If you patch 0V to V/OCT, the pitch will drop three octaves. A similar design is seen in the TZO, but 3.8V.

Note that the schematic values for R222 and R227 are the same as labeled on the PC board. These two have been changed in the build guide.

Something a little odd I noted was the voltage divider on the pulse output: 1K/1K, which would make the pulse be quite hot at about +/-6V. On the EN129 TZO the square and pulse outs use a 1K8/1K5 divider, which makes for about a +/-5.5V output level. I'm thinking I will use 2K/1K5 on all of these, which would reduce the levels to about +/-5V. A minor detail, I know.
dannysound
pugix
Thanks very much for the nice compliments and the breakdown of the schematics. I think I forgot to mention about the power supply isolation!

The pulse wave on both the Cali and Thru zero are +/- 5v. On the Cali it's due to the TL072 not hitting the rails as it's an opamp (required for the summing stage) rather than a comparator.
It's also driven from the main output rather than a triangle wave so it's not a typical sounding pulse wave.

Cali video should be up soon, although I concentrated on demonstrating the pitch and wave shape aspects so there's no examples of the pulse output. I might see about doing another video for that in the future.
The EN129 video will follow shortly.
pugix
dannysound wrote:
pugix
The pulse wave on both the Cali and Thru zero are +/- 5v. On the Cali it's due to the TL072 not hitting the rails as it's an opamp (required for the summing stage) rather than a comparator.


IC201B is operating as a comparator with hysteresis. But I take your point about it not hitting the rails, especially with a 2K load. I'm happy to use your values. The precise amplitude of a pulse wave isn't all that important.
dannysound
pugix
I made the same calculations as you in the beginning, took me a while to figure out why I wasn't getting +/- 5V!
Monobass
Demo video

pugix
Monobass wrote:
Demo video



Thank you! Nice demo of the wave shapes from the main output. We could have listened more to the triangle wave seen with the switch in the middle position.

Please make another that demonstrates the linear FM and the Pulse output and PWM. Linear FM is my favorite feature of the J3RK version.
pugix
I have a question about R10, 220K. It sets the maximum sensitivity of the linear FM CV, as well as setting an initial current. Compare the schematic of Mark Verbos. Note that the other parts values in the Verbos schematic are identical to those used in the Cali Osc, except around the linear FM CV input.

http://pugix.com/synth/wp-content/uploads/2011/07/258mod.jpg

http://pugix.com/synth/buchla-258j-vco/

The other differences in the linear FM CV are that the Cali Osc puts a buffer (IC3C) between the CV input attenuator and the CA3140 and DC couples it. So there is a question as to why the Cali Osc linear FM is DC-coupled (atypical for linear FM).

Let's analyze this. In the Cali Osc, with no linear FM input, the node at pin 2 of the CA3140 and the collector of U1Q2Q1is biased at around -1.5V, given the voltage divider made by R9 and R10. Whereas in the Verbos schematic, there is no voltage divider, due to the capacitor, and we see just the 1.5M resistor to -15V.

So is the reason for the 220K value due to it being DC coupled? My only concern is that this doesn't compromise the depth of linear FM available. If I were to put a 1uf capacitor in series with a 39K resistor in place of R10, it would be exactly like what I have in my J3RK build.

Maybe you did this because of an interaction with the Tune (initial frequency) trimpot and the LFO feature. I'm curious.

Thanks,
dannysound
pugix
Hi there, I sent you a PM about this earlier as I was recovering from my sister's wedding and wasn't really too with it!
It's a very good question so I'll explain for anyone else interested.

The original buchla design used a discrete Lin fm input stage which required a cap to isolate the fm input from the dc offset of the discrete stage input. As this design (based on the verbos update) uses a CA3140 it meant Lin fm can operate down to dc so I thought that might be handy if you'd like to run v/oct or a slowly changing voltage into Lin fm. The inverting buffer is used so +ve input = increased frequency and vice versa.
The junction of R9 and R10 are summed at pin 2 (virtual ground) of the CA3140. You can lower R10 to whatever value you like to get the lin fm as you prefer. I set the value of 220k as that's what I prefer, I think the verbos schematic used 10k.

Thanks for highlighting this as it's definitely something people might want to experiment with.
pugix
dannysound wrote:
pugix
Hi there, I sent you a PM about this earlier as I was recovering from my sister's wedding and wasn't really too with it!
It's a very good question so I'll explain for anyone else interested.

The original buchla design used a discrete Lin fm input stage which required a cap to isolate the fm input from the dc offset of the discrete stage input. As this design (based on the verbos update) uses a CA3140 it meant Lin fm can operate down to dc so I thought that might be handy if you'd like to run v/oct or a slowly changing voltage into Lin fm. The inverting buffer is used so +ve input = increased frequency and vice versa.
The junction of R9 and R10 are summed at pin 2 (virtual ground) of the CA3140. You can lower R10 to whatever value you like to get the lin fm as you prefer. I set the value of 220k as that's what I prefer, I think the verbos schematic used 10k.

Thanks for highlighting this as it's definitely something people might want to experiment with.


Thanks very much for this clarification. I'm going to experiment with a lower value for R10.
pugix
I just finished assembling the Cali Osc. I will test and calibrate it tomorrow. I want to point out something about the panel assembly. The jacks are not supposed to sit flush against the PC board! You can verify this from the picture at the end of the build doc. The coarse frequency pot and the waveform switch are the two mechanical support points and establish the board-to-panel spacing to be 12mm. But the jacks are meant for 11mm spacing. This is not made clear in the doc, which tells you "Solder one pin on each of the four outer jack sockets then add nuts to keep panel in place." If you happened to solder the jacks along the bottom flush to the PC board and then tightened their nuts, the panel would flex, putting stress on the pot and switch. Don't do that! What you need to do is before soldering first snug the jack nuts, so the jacks are flush with the panel. The panel at this point is cantilevered out over the bottom, being affixed by the pot and switch (which should be soldered at this point). You will note a bit of flex. Measure 12mm spacing and solder a ground leg on each of the two outer jacks. That will hold the board at the proper spacing. You want the board and the panel to be parallel. Now you can finish soldering the rest of the jack lugs, the pots, and the lighted switch.

I'll be posting my full write-up soon.
pugix
Here is my writeup with demo recordings. Great VCO!

http://pugix.com/synth/dannysound-california-oscillator/
Brunstein
Hiya, I've just built one, and have an issue. I wondered if you might know where to locate the problem, dannysound, and if you might have some ideas for solving it?

I must have done something wrong, as when I'm trying to calibrate the waveshape, the "sine shape" trimmer raises the pitch and doesn't really affect the waveshape.. I'm not getting a triangle or sine out of it.. I've attached a screenshot of the waveshape I'm seeing. Any ideas on what I've done incorrectly, and how I could rectify it?

It tracks really well, and can tell it's going to be great.. I just need to solve this issue somehow!

Thanks,

David
dannysound
Brunstein
Hi there, try checking Q2 2N5458 is correctly installed also check D1, D2, R24, R40, R41 and R42 are also correct. Also make sure the wave shape toggle switch is not in the middle position when calibrating the sine wave! :)
Brunstein
Hey Danny – sorted I think. I feel like an idiot, but I think the problem was the signal clipping on the way into my computer, rather than anything to do with the build! Getting on with your other oscillator now, and will test properly later. Thanks for your help!

David

dannysound wrote:
Brunstein
Hi there, try checking Q2 2N5458 is correctly installed also check D1, D2, R24, R40, R41 and R42 are also correct. Also make sure the wave shape toggle switch is not in the middle position when calibrating the sine wave! smile
breadman
Excited to grab a few panel/pcb sets and get these in my rack. Already have a couple Feedback Two59s which I love--nothing else sounds like a good Buchla osc!
dannysound
Brunstein
No worries that sort of thing happens to me all the time! Hope all goes well with the EN129, let me know if you have any difficulties.
Monobass
new video demo from DivKid

pugix
Monobass wrote:
new video demo from DivKid



Great tip on patching the pulse out to the wave shape CV in. I look forward to the demo of the Cali and the EN129 together.

Remember, as I noted in my blog post, the linear FM max depth can be increased by changing one resistor, if you like seriously deep linear FM.
efluon
Just soldered two of these.

Unfortunately on one I flipped one of the 2n3904's (I2). Now I turned that right, the led still only lights up when in square-shaper mode. And the shaper does not seem to work, there is only the triangle. Have I fried the transistor? Can I replace with a bc548 (which I have)?

On the other one during calibration I do not see a way to tune ws_trim to change the voltage to -12V. Maybe I misunderstood that step? It works fine otherwise.
dannysound
efluon
BC548 will probably work, make sure you check the pinout first though.
To set the WS_Trim, make sure waveform switch is in middle position and waveshape control is at 0 then adjust the trimmer so the output stops oscillating.
efluon
dannysound wrote:
efluon
BC548 will probably work, make sure you check the pinout first though.
To set the WS_Trim, make sure waveform switch is in middle position and waveshape control is at 0 then adjust the trimmer so the output stops oscillating.


Thanks!@

Just looked fresh at it and - d'oh! forgot to solder the wire-bridge on that one. Now it works fine. oops

WS_Trim calibration is same as with the other: After trimming the sine in saw position to just below the kink on the sine bottom, then switching to middle position, output voltage flatlines at about -10.4, which sounds ok to me (given that -12V is the lower rail voltage). In the build manual -12V is stated, so that is a remnant of another format?
dannysound
efluon wrote:
[In the build manual -12V is stated, so that is a remnant of another format?


Not really, the opamp output basically hits the rail (-12V) but in reality the output won’t go down that far. As long as it stops oscillating that’s the main thing.
Originally this test wasn’t included but I realised after watching the divkid video that the WS trim needs a few extra turns to get the most out of the middle waveshape and it’s probably the easiest way to set this trimmer.
efluon
[quote="dannysound"]
efluon wrote:
the opamp output basically hits the rail (-12V) but in reality the output won’t go down that far. As long as it stops oscillating that’s the main thing.


Ok, cool! Took them for a spin yesterday, they feel really nice!

The PCB's are so nice also, layout and quality, and altogether these are the best quality complete kits I have soldered yet.

If you get around to another build-tut-revision, I think it would be good to integrate some of pugix' suggestions
- less pictures. the component bags are very conveniently packed and suggestive (different to the instructions)
- shrink-wrapping transistors+tempco
- panel mounting. i did it similar to the way in the manual, which works as well, even though the panel and the pcb are angled afterwards but a word about that would have helped.
All these are obviously just construcive suggestions, it has been a very easy and satisfying build, even with my dumb late-night errors.

dannysound
efluon
Thanks for the kind words and I’ll bear those suggestions in mind.
I’ve just finished the build guides for the Timbre and VCA modules, for some reason it always seems to be an absolute pain getting them done. This time the formatting went all wrong so I’ve basically done them twice!
I have a load more modules that I need to finalise and get ready for release then I’ll see about updating those build guides.
Hope you have fun with the oscillators, Buchla designs are always interesting both sonically and electronically. In that regard I don’t mind saying I’m just as much a fan of these oscillators as everyone else!
Monobass
A reminder that Dannysound publish schematics for all their designs, the Cali is here - https://www.thonk.co.uk/documents/dannysound/Cali_Osc/schematics/
oldsoulsound
Anyone have power specs for this Oscillator? There are no specs on Modular Grid.
dannysound
oldsoulsound
Oh yes sorry meant to do this a while ago.

-12v is 35mA
+12 is 41mA
oldsoulsound
I had a question about the wave shape pot. Mine seems to go from sine to triangle or square depending on switch at about the 1 o'clock position and then doesn't seem to vary very much after that. Is that normal? By the way I am loving the sound of this oscillator. So interesting, a little quirky, and full of such rich tones. Loving it. Want to build another. Here are some screen shots of what I'm getting.




dannysound
oldsoulsound
It could be that the WS_TRIM pot needs a few more turns. Try monitoring the output with the switch in the middle position and adjust WS_TRIM until the oscillator cuts out that’s the correct setting. If the wave shape pot still seems a little too sensitive let us know!
oldsoulsound
Adjusted the WS Trim pot while in the middle position until the sound cut out. Also measured these voltages in circuit.
Try checking
R47 = 150k
R46 = only measured 50K
R36 = 106r
R34 = 0r (wire link)

I'm still finding that the wave shape adjusts at about 1oclock and doesn't change at all after.

When in the middle position the wave shape changes to a triangle at about 10oclock and doesn't alter at all after.
dannysound
oldsoulsound

I’ve checked against the ones we have here and they all work like that, so everything is correct.
The tolerance of the transistor that controls the waveshape varies so the range of adjustment accounts for that.

If you want to really fine tune the control you could try changing R1 from 150k to 130k or 120k but that’s splitting hairs really as it won’t make much difference in operation.
oldsoulsound
Thats what I have been suspecting. Thank you for all your help. Everything sounds fantastic. One last question for you. After adjusting the WS Trim so the sound cuts out in the middle position. I noticed my sine waves have a little kink at the bottom of the trough. Does that seem normal or should I adjust that out with the WS Trim or Sine Shape?
dannysound
oldsoulsound
Yeah adjust that out with the WS trim pot!
NTRMN
Hey everyone, first time poster here but I'm having some issues compiling the BOM for this build. Since I don't have a whole lot of money for the full kit, and since I live in the US, I think it'd wind up being a lot cheaper if I ordered everything (or the majority of the components) through Mouser. I've done a few kits in the past, but I've never actually bought a panel/pcb combo and sourced any of the components before, so I feel like I'm kind of in over my head. There are so many options out there, how do you know which ones to get?

The resistors seemed to be pretty easy, but I'm having a lot of trouble with the capacitors and pretty much everything in the "IC bag" portion of the BOM. For example, the BOM says I need 1 220pf standard ceramic capacitor and 1 100pf standard ceramic capacitor (C4 and C5 respectively). Obviously it's through-hole, so I can completely rule out all of the SMD components that come up, but it doesn't say if it's 50v or 100v, C0G or X7R, or the tolerance percentage. It doesn't seem like all caps are created equal, but how do you determine which ones to use?

Here's a link to the BOM that I've been working on with some mouser reference #'s for each component. It would be awesome if someone could double check to make sure I'm on the right track.

https://drive.google.com/file/d/10qA9RdvZihd2-WER4fEoCXh2cfFJ3rfC/view  ?usp=sharing
Waz
Is there a more in depth calibration procedure. I am unable to get this thing to calibrate 1v/o only using one trim pot. Where does the master tune trim pot come into play? Whats a rule of thumb for panel settings and master tune settings before adjusting the 1v/o trim?
dannysound
Waz
V/oct works from 0V to 10V. Middle C on most keyboards with 88 notes is 5V. You can use the master tune trimpot to set the Oscillator to middle C when the coarse and fine tune controls point to 12 o’clock or whatever position you prefer. Ensure the LFO switch is out!

The master tune trimpot also functions to tune multiple Cali Oscillators to each other if you’re playing polyphonicly.

With nothing plugged into the v/oct input it is normalled to around 4V via a switch in the socket. If you’re running v/oct in a lower range say 0V to 5V you can plug the v/oct out from you’re Controller to the log input of the Cali and turn the control up full. That should give you better range from the frequency controls.

The quickest way to tune v/oct trimpot is to play an arpeggio over 3 octaves then tune it by ear. If you can’t get it tune then send us an email.
Waz
If I set both tuning pots to 12 oclock, tune the module to middle c via the trim, I am unable to follow the 1vo tuning procedure. My module can't go down to C2? Am I setting pitch with a dummy cable in 1v/o?

Also there is some erratic behavior with module, Only when I am handling it, sometimes it knocks out of tune and "wobbles" pitch until I physically tap the module then it goes back into tune. I checked all of the solder joints under a microscope and nothing was fishy there. Is this the nature of the tempco and those 2 transistors? It only happens when I am holding the module.

Thank you for your help.
Waz
I think i got it...I think?

However, it seems like something is off. I set the pitch controls to noon, then I took 5v from Ornaments and Crime, plugged it into the 1vo and tuned the oscillator to middle c from the trim. Then I followed the calibration procedure. Everything kinda locked into tune and it sounds great. I have one small issue tho. The coarse frequency ranges from LFO territory to around D5 as a max frequency.

If this doesn't sound right, I might have to take you up on the email.

*edit
I didn't get it. I need some guidance on how to do this.
devinw1
When you have the LFO switch on or off?
Waz
devinw1 wrote:
When you have the LFO switch on or off?


Off. When it's on the module is a super slow LFO.
devinw1
Hmm that does seem off. And no CV source is plugged in?
four_corners
Just finished my build, and seems like it partially works but I can tell some off things are happening...

First, should the SINE_SHAPE trimpot change the pitch at all while turning? When I turn it, it does seems to go between a triangle and a sine wave, but also the pitch is changing some, is that normal?

Secondly, the O/P_LVL trimmer doesn't seem to do much of anything on mine. I'm assuming this should be changing the output level globally? I'm getting about 3V peak to peak with the switch both up and down on the main output, and exactly 10V from the PWM output. These values don't change while turning the O/P_LVL trimmer.

Lastly, I must have some sort of grounding issue, because when the switch is at the middle setting, everything seems to go a bit bonkers. The signal usually drops out, and touching the front panel I can hear obvious grounding on/off sounds. Any specific area I should check if this only seems to be happening with the switch at the middle position?

Thanks for the help!


EDIT:
I actually think it may not be as messed up as I originally thought after watching DivKids video and after super super carefully calibrating via listening and an oscilloscope.

I'm able to find the "pure" sine wave tone, as well as the point where the WS_trim starts to distort. At this point, the oscillator seems to almost work well, but if I use the waveshaper knob on the front, it only will shape/fold about half way from a sine wave to either the square or saw shape. At fully clockwise, the shape looks about half way to what DivKid gets, so about 50% on his video. I thought maybe I had too small of a value pot there, maybe 10k instead of the 100k needed, but that isn't the case. I'll go through and check all my resistors. Are there specific ones I should look around first before just checking every single one? Thanks!

EDIT #2:

Fixed! Turns out it was the 220p cap next to the O/P_LVL trimmer. Turns out, there was a 2.2nf cap inside the same bag as all my 220p caps, and I magically picked that one out of the bag. So the lesson is, check the actual marking even if you have a bag labelled a specific value.
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