soundlab building experience (questions and mistakes too)

[pluto]

Hello,

I am so glad i randomly found out about the soundlab page. I had no idea there was such a community behind building your own analog synth, with people sharing design for analog synths. So i couldnt resist and decided to go at it

I am pretty newb at electronics, i used to solder leds for fun when i was a kid but i have no understandings of electronics (now a little bit more). So trying this project I had no idea what would be the outcome.

So I ordered the nice PCB from Ray and got some components from an online shop in germany ( http://www.banzaieffects.com/ ) which was good because I am in Europe and they have all the components (plus they have a nice selection of knobs). I then builded it...

Amazingly enough i have a soundlab working. Its mounted on a temporary shoe box for the moment until i get to make a nice panel and box. It sounds so nice, what a great piece of engineering, grats goes to Ray and the others that inspired him to do this. Pure electronic box, you can almost feel the volts going crazy thru these circuits. The resonance filter even goes past the usual whisteling to a scorched modem like sound. I love it

Here are a couple questions:

-My PWM switch seems to be working weirdly: the pwm is almost always on. If i switch it off it stays on. Sometimes it will be actually off when i start the soundlab, but then after i switch it on it's always on regarding of the position of the switch. I have tested the switch with a tester it ons and offs ok (would it possible that i damaged it while soldering?). Is this something that someone would know about or have clues for where to look?

-The BP filter is a bit quiet compared to the LP. But this is probably normal since LP has more bass frequencies.

-I put a 2.7M resitor instead of the 3M one, and a 1.8M instead of the 2M one. From what i read its no big deal, but if it is let me know.

Since i have learn a lot by reading in these forums I figured i'll post some mistakes i made during the building for other people to avoid:

-I bought some nice metal knobs (cheap but kinda cool...). When i tried to put one on a pot it didnt fit. The knobs are 6mm and the pots are 6.3 mm... so make sure you got the right diameter before ordering knobs and pots.

- dont get stranded wire that is too big (diameter) for the panel wiring. It took me ages to make the soldering and when there is more than one wire on a single place it gets really hard and messy.

- little switches are very sensitive to temperature. I melted the first one right away when soldering.

- when i first switched on the soundlab i could hear the sounds of the oscsillators but it was very low and there was a loud hum. I realised the next day that it was probably a ground problem. I then put a wire on the ground and then touched some parts to see if it helped. Sure enough when I touched the output jack the sound came loud nice and clear. I then grounded the jacks. (this is probably very obvious but remember i am a newby )

Here are a couple pictures of the temporary cardboard design and the mess in the back

Well, thats it, I'll post some pictures and samples when its complete.

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shoebox.jpg
Description:	Shoe box soundlab (temporary)
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back.jpg
Description:	Back wires and pcb
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[RF]

Congrats on the build! You did great.

The switch could have been damaged soldering it - I've done that
but it wouldn't seem likely that is your problem. Sounds more like an intermintant solder connection to me. I think the switch just wouldn't work at all...

The resistor subs are fine.

I look forward to your final panel and some sounds - great job!

[pluto]

Thanks RF for the reply. I went to your webpage and looked at your modular: that looks awesome. I dig the mp3 loop you put on there, very chilly

It was indeed the switch that I once again melted a bit while soldering. In some position it would work and some other not. I guess while i was testing it I was pushing the pin with the test probe and making a good contact. Anyways I changed the switch and now its working great. Btw the damaged switch was softer than the others when i activated it, so that should have been a clue.

New question:
Is it normal that square wave lfo clicks a bit when used on vca ? I am thinking it might be because it is so square it clicks but I just want to make sure this is a normal behavior and a not mistake in my wiring.

Also I wished the low end of the fast LFO was a bit slower than it is. I figure it is probably a resistance or capacitor value to be changed but i have no idea which. Any help would be apprecitated.

[RF]