Befaco bf22

saemola · Post by **saemola** » Tue May 27, 2014 8:45 pm

cool!
I'm about to order one.
how tough is it to solder SMDs with a regular iron?

mha · Post by **mha** » Wed May 28, 2014 1:39 am

saemola wrote:cool!
I'm about to order one.
how tough is it to solder SMDs with a regular iron?

It's pretty tough, but try putting a glob of solder in both holes, then holding the SMD in place on top and melting the solder again.

Ginko · Post by **Ginko** » Wed May 28, 2014 2:13 am

mha wrote:
saemola wrote:cool!
I'm about to order one.
how tough is it to solder SMDs with a regular iron?
It's pretty tough, but try putting a glob of solder in both holes, then holding the SMD in place on top and melting the solder again.

I put a blob of solder on just one pad, get the smd in place with tweezers and melt the solder on the pad, then solder the other side, works every time piece of cake

I hope Befaco releases some more of their designs as kits, the bf22 is on the list though

I would like to build the sample and hold, the slope generator and probably the vco as well

saemola · Post by **saemola** » Wed May 28, 2014 5:34 am

cool, thanks for the tips guys!
hey mha, how mane SMDs are there in the BF-22 kit?

mha · Post by **mha** » Wed May 28, 2014 12:40 pm

saemola wrote:cool, thanks for the tips guys!
hey mha, how mane SMDs are there in the BF-22 kit?

Sorry, no idea. My SMD soldering experience comes from the Moogah SEM VCF

jimlinnell · Post by **jimlinnell** » Fri Oct 31, 2014 6:12 am

Old post, but I recently made one of these but wanted some advice.

Basically love it, works fine, but it seems to have a "ground" problem. When it's plugged in if I tap on any patch cables or the case I can hear the tapping through my amplifier. When not plugged in I don't get this problem. Anybody have any ideas or advice as to what this could be?

Thanks
James

jano · Post by **jano** » Fri Oct 31, 2014 11:00 am

hi!

seems like some resistor or any element on the path of the signal before it is amplified is touching the plate or the pillars who hold the back PCB (the screws who hold the back PCB are next to the ground plane), and seems that your case is not connected to ground
can you check if any input or part is touching the pillars or the ground plane?
can you check if the problem is present if you plug the module outside of the case?

cheers!

mwvm · Post by **mwvm** » Thu Feb 26, 2015 8:08 am

Just bought one. Sold my korgasmatron for this...

insula · Post by **insula** » Thu Feb 26, 2015 10:36 am

also have one here, they do a workshop at madrid too

badass filter, and really cheap!! good job befaco team!!!

insula · Post by **insula** » Thu Feb 26, 2015 10:38 am

saemola wrote:cool, thanks for the tips guys!
hey mha, how mane SMDs are there in the BF-22 kit?

i don't remmeber well ... but i think there is no smd componenets in this kit, i builded more than one year ago..

mwvm · Post by **mwvm** » Thu Feb 26, 2015 10:51 am

I'm in Madrid next week. Maybe i should pick it up

insula · Post by **insula** » Thu Feb 26, 2015 10:55 am

mwvm wrote:I'm in Madrid next week. Maybe i should pick it up

befaco base is at barcelona...

insula · Post by **insula** » Thu Feb 26, 2015 10:55 am

mwvm wrote:I'm in Madrid next week. Maybe i should pick it up

befaco base is at barcelona...

mwvm · Post by **mwvm** » Thu Feb 26, 2015 5:50 pm

insula wrote:
mwvm wrote:I'm in Madrid next week. Maybe i should pick it up
befaco base is at barcelona...

mwvm · Post by **mwvm** » Sat Mar 07, 2015 11:36 am

Built... Takes about 4 hours. Love it.

Dogma · Post by **Dogma** » Sat Mar 07, 2015 4:25 pm

mwvm wrote:Built... Takes about 4 hours. Love it.

Im very close to getting one of these. Im not a massive resonance freak though so if thats not over the top all the time then Im in. I love the attenuverter on cutoff. Befaco say its noisy but part of the charm.
I love twin filters and it would be entirely different to my Verbos 4pole and I would also love the Epoch Twin filter.

mwvm · Post by **mwvm** » Sun Mar 08, 2015 1:17 am

Dogma wrote:
mwvm wrote:Built... Takes about 4 hours. Love it.
Im very close to getting one of these. Im not a massive resonance freak though so if thats not over the top all the time then Im in. I love the attenuverter on cutoff. Befaco say its noisy but part of the charm.
I love twin filters and it would be entirely different to my Verbos 4pole and I would also love the Epoch Twin filter.

It isn't noisy at all. All I can say is if you like the korg ms20 growl/snarl and the series HPF >LPF then it's for you.

I spent a night in that mode with a stackable in the cut att cv, modulating both filters with one env. Very excited about this filter. To me it effectively means I have a ms20 for a £130 and 4ish hours out of my life.

Not a difficult built, just >100 components and some calibration which is time consuming.

The built information is actually a BOM so you do need to have experience ref using a bit of nous as it not clear... Though y know. Smallest/flattest parts first isn't ground breaking.

Landsphere · Post by **Landsphere** » Tue May 16, 2017 3:42 am

OK, to help any other fellow DIYers out there.. Have recently built this myself. One pass worked, and the other didn't. (though I hadn't calibrated it yet).. the working filter does indeed scream.. there is a lot of noise to it, but thats one of the characteristics of it. After having a good look at my soldering (got some illuminated magnifying glasses which is a big help), tidied one or two possibilities up, but still no pass two. Anyways, borrowed a scope from work, and it was here that I identified the problem, the trimmer for pass two was way out... so it had indeed worked, it just needed a great amount of calibration to show me it was.. Hope that helps someone..

Ginko · Post by **Ginko** » Tue May 16, 2017 4:16 am

@landsphere it's been a couple of years since I built mine, but I seem to remember that I had exactly the same problem - it confused me for some time!!

Enjoy your BF22! (P.S. it FMs like a badman!!)

GryphonP3 · Post by **GryphonP3** » Tue May 16, 2017 8:39 pm

Landsphere wrote:OK, to help any other fellow DIYers out there.. Have recently built this myself. One pass worked, and the other didn't. (though I hadn't calibrated it yet).. the working filter does indeed scream.. there is a lot of noise to it, but thats one of the characteristics of it. After having a good look at my soldering (got some illuminated magnifying glasses which is a big help), tidied one or two possibilities up, but still no pass two. Anyways, borrowed a scope from work, and it was here that I identified the problem, the trimmer for pass two was way out... so it had indeed worked, it just needed a great amount of calibration to show me it was.. Hope that helps someone..

Also had this issue wheb I built mine! Funny

jakobprogsch · Post by **jakobprogsch** » Sun Dec 09, 2018 7:06 am

A bit old but this seemed the best suited thread. When people talk about "noise" do they mean as in "uncorrelated" noise or it picking up other parts of the system? Mine picks up all the oscillators on the same power supply quite significantly.

I tried it in a befaco jumpskiff where it picked up the Even VCOs and a different one that uses a Koma Strom where it picked up a Wogglebug. I also disconnected a bunch of modules in the befaco skiff to make sure the psu isn't overloaded. So I feel this isn't just a psu issue (or at least dozens of other modules have no issue with the same two psus I tried).

Both channels behave identically despite being almost entirely separate circuits. So I checked a few things that are shared. Namely the caps in the supply filter and the bypass caps of the LM13700.

So I should probably ask. Is that just the expected "noise" or should I continue looking for an issue?

jakobprogsch · Post by **jakobprogsch** » Sun Dec 09, 2018 5:18 pm

I did some measuring and spice simulating and think this is probably caused by the circuitry around IC1A/IC2B which is extremely sensitive to fluctuations in ground. It essentially acts as an inverting amplifier with an amplification of over 50x. One could replace R19/R20 with smaller values to reduce this factor but this will also reduce the distortion. Not sure if there is a way to change this in the module itself. I guess a very high quality PSU/power distribution might indeed help.

erocfx · Post by **erocfx** » Wed Feb 27, 2019 12:51 am

I built a BF-22 from a pcb + panel. I get no audio though it on either channels.
All solder looks good, all parts in then correct place. I really want to hear it in action!!!

mbroers · Post by **mbroers** » Mon Jan 11, 2021 11:00 pm

jakobprogsch wrote: ↑
Sun Dec 09, 2018 5:18 pm
I did some measuring and spice simulating and think this is probably caused by the circuitry around IC1A/IC2B which is extremely sensitive to fluctuations in ground. It essentially acts as an inverting amplifier with an amplification of over 50x. One could replace R19/R20 with smaller values to reduce this factor but this will also reduce the distortion. Not sure if there is a way to change this in the module itself. I guess a very high quality PSU/power distribution might indeed help.

I've had a diy bf22 that was my only vcf and used constantly, all of a sudden I'm getting this noticeable white noise on each channel which then becomes twice as loud in link mode :\ .. Did you ever resolve this issue for yourself? I also have been thinking about the shared power supply circuit but havent swapped any components out yet.

MUFF WIGGLER

MUFF WIGGLER

Befaco bf22

The woes of building

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