SIAM 295b

[MonoCutter]

Thank you very much for your help! As soon as i find the time, i'll go on with this project.

It might not help you, but in case you want to experiment, i can send you a set of pcbs.

 

[krabbencutter]

MonoCutter was kind enough to send me some PCBs for testing and it worked out really well I've managed to add all the recent changes either by slightly modifiying the PCB or through the addition of a small daughter board. During testing I also spotted a small mistake in my schematics, which has now been corrected in Rev 05d.

 

[MonoCutter]

The pcbs for krabbencutters REV 05d arrived and i couldn't wait to test them. The EQ worked as it should right from the first power up.
A next step will be to replace the pots with rotary switches. After that i would like to try different transformers.

Sometime in the future (after finishing all other projects ) there might be another revision of the pcb.

 

[phetus]

anything to watch out for if running this on 17V?

 

[krabbencutter]

anything to watch out for if running this on 17V?

Not that I can think of, the TL074 is rated for up to +/-20V.

 

[krabbencutter]

Update: I've renamed the repository https://github.com/greyboxaudio/SIAM-295b and the schematic has also been updated with some minor changes to the gyrators. I'm also happy to announce that I plan to design a PCB this year

 

[krabbencutter]

Update: I've renamed the repository https://github.com/greyboxaudio/SIAM-295b and the schematic has also been updated with some minor changes to the gyrators. I'm also happy to announce that I plan to design a PCB this year

I've been playing around with the circuit a bit more and I will try to replace the mid band with a matching state variable filter design. My current Q-mod implementation still feels too much like a hack for my taste and with an SVF design the Q will become fully variable. It would also reduce the total amount of opamps & film capacitors needed.

 

[stojadin653]

Thanks for making this module more widely available without inductors and all , i made a PCB layout for this and built 4 PCB's ,will test them these coming weeks

 

[krabbencutter]

Awesome, crossing my fingers that it will work right away!

 

[stojadin653]

me too ,i've built a lot more complicated circuits for synthesizers so this should work fine unless i messed up something ,i noticed one mistake i made is the 100pF capacitor .. but it's an easy fix , i hope it's alright to post the gerbers if the modules are working ,i have a little collection here : https://synthesizerunderconstruction.blogspot.com

 

[stojadin653]

here are the built PCB's ,not completely populated for few parts here and there .. i didn't had 150uF at the moment ,i used whatever type of caps i could find ,not attempting to sound like the original

 

[krabbencutter]

Nice! I love the visible DIY spirit. You can also use 100u + 47u in parallel for the high shelf, if you have those values at hand.

 

[stojadin653]

i bought 150uF ,these should be part of a mixer i am building 8 channels it's packed with features and i just hope it'll work

 

[samic]

here are the built PCB's ,not completely populated for few parts here and there .. i didn't had 150uF at the moment ,i used whatever type of caps i could find ,not attempting to sound like the original

View attachment 133656

do you have the gerber

Thanks for making this module more widely available without inductors and all , i made a PCB layout for this and built 4 PCB's ,will test them these coming weeks

Hi do you have the gerber files ?

 

[stojadin653]

yes ,but it's not tested yet my boards are populated i need to complete the wiring and plug it in ,if you can't wait for it here they are https://www.dropbox.com/scl/fi/w0x3...ey=c7h3648qmg6j0ra6pxh550g8k&st=2u28607y&dl=0

 

[samic]

great i think i'll try to make one this winter to pass the time
thanks

 

[stojadin653]

i can confirm that this is a working layout ,i don't know much about eq's ,it's a first eq i built ,i like it ,i just tested 2 of the 4 PCB's and they are working fine , now to wire the rest

 

[zzzzz]

Update: I've renamed the repository https://github.com/greyboxaudio/SIAM-295b and the schematic has also been updated with some minor changes to the gyrators. I'm also happy to announce that I plan to design a PCB this year

Nice project. Following.

 

[samic]

i can confirm that this is a working layout ,i don't know much about eq's ,it's a first eq i built ,i like it ,i just tested 2 of the 4 PCB's and they are working fine , now to wire the rest

thanks for the link, would you have some time to make a wiring diagram? there is little information on the pcb to understand the layout
best.

 

[stojadin653]

I have time ,just i have never made a wiring diagram so not sure where to start for that , i have Gimp i might try something not sure how it's gonna turn out ..those F1,F2 ...points are for the gyrators x 6 so that switch wires to the 4 position switch and that one to the midle pin of the Mid potentiometer , the other two pots are high and low ,the 3 points labeled switch are part of the cut/boost switch along with the point coming from the 150uF < that one connects to the pot i think it's high - control ,the other pot at the bottom left is for lows ,in the far right you have 4 pads for the 4 position switch as four positions and the one between 1K and the last 4M7 is the first postion of the 4 position switch the same one that connects to the 6 position switch centar ,and that's it