Yusynth (Part 18)

Today I finished another Yusynth module. This time a Steiner VCF module. It is quite a versatile filter module that you can switch between High Pass, Low Pass, Band Pass and All Pass using a rotary switch. So actually you get three filters, because the all pass is kind of the same as your input signal :) Besides that it has two CV inputs with a potmeter to regulate the amount and also a potmeter for the input signal. I was wondering if this was the first module Yves designed by the way since it looks just that little bit different than the other modules that I build so far.

So here is the module all wired up. It is all quite straight forward. Yves provides a really neat wiring scheme on his website that makes wiring so easy. He even included the correct marking for the rotary switch so you don't even have to think :) Well after wiring it was time for testing. I applied power to the unit from my lab power supply and for the first time my current restriction kicked it. Lucky that I have it otherwise that would have meant magic smoke I guess ;) I did a quick visual check and found out quite quickly that I mounted the IC socket for the TL072 the wrong way around :( Luckily it was on a socket so I could turn it quite easily. But what a stupid mistake this time :(

Well nothing was damaged luckily. After applying power again everything looked OK and I started testing. I put a noise signal on the input from the PC Function Generator. I tested all three filter modes and that all worked like expected. There is only on 1 turn potmeter on the PCB for 1V/Oct tuning, but when I wanted to fiddle around with that I noticed something strange. When I up the resonance to get auto oscillation it didn't work at first. But only when I also fiddle with the cuttoff pot as well. I tried it several times and the same result. Maybe Yves can shed some light on this? His other modules start auto oscillating by only putting the resonance to 95% or so. And usually there is a trimpot to calibrate this. Ah well no big deal at all. Then I put a square wave at the input and actually got some very neat results. It is not a very clean filter, but that makes it exciting I think :) So I hope I didn't make any mistakes except for the wrongly mounted IC socket. It pretty much works like I expected besides the auto oscillation thing.

Bridechamber Multiples (Part 2)

This morning I finished the work on the first multiple panel. It is really kind of boring work. So I decided that I would keep it at one for today and start another project after that. I got a package from Mouser yesterday with a lot of missing pots for some unfinished projects. After finishing the multiple panel I did some simple tests to see if it worked like I anticipated. I used a couple of jack patch cables and a multimeter. First I inserted a patch cable in the first jack and the last. And they connected. Then I inserted another jack in one of the jacks that should break the circuit and that worked as well. So project finished. Later on I was just wondering if I wired it like Scott from Bridechamber did, but at least now it works like I would.

After testing I put it in place in my modular desk. Since yesterday I'm slowly putting some modules in place to think about the layout of the whole system. Here you can see the little black wood screws that I use to fasten the panels. I'm glad by the way that I didn't use larger screws. Some modules just barely overlap the wooden bar behind it and I already had some of the wood split with these small screws. But it is nice to finally see some modules in the desk. I will make a picture for you later on. Actually I already made one, but I wasn't satisfied with it. Not good enough for the blog. Well not much more exciting to tell about this panel. So I'm going to continue another project and then maybe later this week work on the other multiple panels.

Bridechamber Multiples (Part 1)

In a modular setup you often need to patch the output of a module to more inputs of other modules. So you need to split up the signal. To do that you can use 'multiples'. They are actually just a bunch of jack connectors wired together. So they are completely passive. The only problem is that sometimes you need a pair of 4 sometimes more. Bridechamber sells some multiple panels that are actually very flexible. In total you have 32 jacks in rows of 4. Each row is connected to each other, but is also normalized to the next row. If you insert a jack though in the first jack of the row, this connection is broken. So you can determine how the multiple works by inserting jacks in a certain place.

As you can see in the picture above mr. Braska was supervising my work on the mutiples. I started with the wiring of the ground signals. Those are all just interconnected. You can't see them so well in this picture, because I used black wire for it. I'm using yellow wire for the signal path. I think mr. Braska was a bit bored by this work. It looks like he fell asleep :) Well was tired as well and stopped for today. Tomorrow I will continue work on this little project and after that I need to make 2 more. So I don't have to be bored. Ah well I never am actually :)

Modular Desk Adjustment 2

Today my furniture builder Gerrit came back with the adjusted piece of my modular desk. We mounted the bar back in the cabinet, and tried to fit the synthesizers.com Q960 sequencers in, but they still didn't fit. Now just it is stuck in another place. It is just 1 mm, but Gerrit didn't bring any tools since he thought he was done. Well he was in the neighborhood again next week so he will do that final adjustment then. In the mean time also my black screws arrived so I can start fitting some modules now and try to think about a layout for the whole modular synthesizer. I'll make pictures of course ;)

Wilba MB-6582 (Part 1)

I bought a bunch of old 6581 sound chips a long time ago coming from the famous Commodore 64 home computer. And I was planning to build a synthesizer with them some day. And then I found the Wilba MB-6582 project on the Internet which is basically a Midibox design with 4 Pics and 8 SID chips on one big PCB. On the website is also a very nice design for a case and you can download the front panel files from there. I ordered the PCB's along with a components kit for the base PCB a long time ago and last week they finally arrived. And I couldn't wait to start on this project. Here you see some of the resistors already in place on the PCB.

The documentation for this project is neatly done online in a Wiki that is updated when necessary. It gives great information on the different build possibilities. It was originally designed for the 6582 SID chips as the name suggests. These run on 9 Volt, but it can also handle the other types of SID chips. I use the original 6581 and they need 12 Volts. The builder actually offers 4 options to build the PSU section. I chose option B because of the need for 12 Volts and I want to use an original Commodore 64 power supply to power the synthesizer later on. In the picture on the right you can see a picture where I just mounted all the IC sockets on the PCB. There are quite a lot as you can see.

Here is a picture where also the backpanel components are installed. On the left is the power switch that is actually the same switch as used in the original Commodore 64 and next to it the power connector. Then two midi connectors and next to that 4 stereo audio output jacks. Yes this baby has 4 stereo output channels :) You can also see that I installed the electronic parts behind that. This is all for the SID chips itself. It is quite dense in these parts and you actually have to install some resistors standing up because otherwise they wouldn't fit. You can also see the capacitors next to the SID IC sockets are on little parts of IC headers. This way you can swap them since for the 6581 you need different values than for the other SID types. And I don't know yet if mine actually work.

And here is a picture of the finished base PCB. Here also the PSU section is in place. I didn't put the IC's in yet. I need to run some power tests to see if I didn't make any mistakes in the PSU section. I don't want to blow up my precious SID chips :) But since they are all on IC sockets it is just a matter of putting them in. Next step is another PCB that is used for fitting the front panel components like all the leds, switches and rotary encoders. I just ordered these components from Mouser and I'm waiting for them. I also got a display from CrystalFontz in the US. If you are curious what this project is going to look like or want information to build one yourself do visit the MB-6582 Wiki at this URL: http://www.midibox.org/dokuwiki/wilba_mb_6582

AVRSynth 32 (Part 6)

Today I started testing the AVRSynth 32. And unfortunately it did nothing :) So I started debugging. I started with checking if I had a signal on the midi input. And I did actually had a signal on the input of the opto coupler but nothing came out there. So I started to look at the schematics. I couldn't find anything wrong actually. After that I measured at the DIN connector on the back and saw that I also had signals on the other pins. Now I was confused. To be honest I actually never looked at what pins do what on a Midi connector :) So I started looking for a schematic.

And that is why I love the Internet so much. It took me about 5 seconds to come up with this. And guess what. I had the wrong pins. I never knew that a DIN connector is numbered in this way. Well you are not to old to learn ever I guess. After rewiring the connector I had a signal on the output of the opto coupler right away. So I hooked up audio to the unit and it gave a signal right away while playing on the midi keyboard. So it actually works :) After that I started to check all the functionality.

The first thing I noticed is that some switches worked the wrong way around. Here you see Oscillator A set to Square, well this looked like a Saw to me :) So I checked switch for switch. Strangly enough not all of them were wrong, but I'm pretty sure all the switches are mounted in the same orientation. Ah well. Who cares as long as it all works like it is supposed to. The only thing left to do now is hook up the power switch and attach the power to the power connector on the back panel. And I need to find a 12V adapter for it. I guess it will run on 9V as well btw.

And here is the end result. Looks neat doesn't it? I only need to clean the surface of the front panel. Some little speckles are on there. Well it sounds nice as well. It is a monophonic Virtual Analog synthesizer. As you can see with two Oscillators that can be switched between Square wave or Saw wave and only Oscillator B can be detuned. So oscillator A is always in tune. Makes it a neat tool to tune my modular I guess :) Tomorrow I'm going to show and demonstrate it to my daughter. And try to explain to her how it works. I hopes she likes it. I'm sure I'll do a last post about that.

The Frog Has Landed at the Apollo Studio

The coming period I'm having a visitor in my studio. The famous DIY Synthfrog mr. Braska travels around the whole world visiting studios that are run by musicians that also build their own synthesizers. The next days I will show mr. Braska around in my Apollo Studio and show him how it is done the Dutch way :) So you can expect some pictures on this blog reporting about this visit. Unfortunately mr. Braska had to spend Christmas at the local Post Office here. The mailman forgot to put a note in my postbox that he arrived. So I had to dig into the postal service (what a horror) to track him down and get a hold of him. Today I finally picked him up. You can find more information about mr. Braska and his travels ons this website: http://www.synthfrog.com

AVRSynth 32 (Part 5)

Today I worked a bit on the AVRSynth 32 again. Unfortunately my daughter really lost interest in this project now. I explained to her what had to be done to wire the front panel components on the PCB and she couldn't really understand. Now is the documentation not very easy on this. So I can imagine she didn't get it. So I started this job on my own. Here you see a picture with all the wiring in place to interconnect the front panel components. Basically a 5 Volt and ground line on all the pots and 4 groups of switches that share a common bus line later on. So far so good.

Here you see a picture of the flat cable that runs to the PCB. This was a lot more complicated. 40 wires that you need to connect to the right place and only wire 1 is red and the red is gray :) I counted and recounted a lot of times to make sure that I had the right wire. Even even then I made a mistake. I cut a wire short that I had to extend later on. I also did some cross checks with the schematic so that I could check the right connection to the PCB. After these checks I was quite convinced it should be OK. Time to apply the power to do the famous Magic Smoke test.

And luckily no smoke :) Nothing got warm so I started to measure the power on the components. All looked well on there as well. I used a lab power supply with a very restricted current setting to be sure I couldn't short circuit anything. After this I removed the PCB again from the case. I remembered that I still had to solder an extra resistor on the bottom of the PCB. And I also still had the extra capacitor. I decided not to mount that one. I think it is only necessary with the other crystal option. But I'm not sure. I can always solder it in there. It won't break anything I'm sure. Well at least I have a working power led now :) Further more I only looked at some digital signals and it seems that the clock is running. I see activity on the data lines. Next thing is to attach some Midi and audio and do some testing.

OceanoGraphy Reviews Added

First of all the best wishes for all of you for 2010! I hope all your dreams may come true. But now back to business :) Slowly the first reviews are coming of my OceanoGraphy album. If you would like to know more about my albums and what other people (and professional reviewers) think about it I think it is nice to read through them. You can find the reviews here on my website: http://www.synth.nl/reviews

Digital PC Scope (Part 3)

The Digital PC Oscilloscope returned from Velleman. And it turned out I was right. They have replaced the AD converter chip. So I didn't make a mistake it turns out and I even detected the right defective component. Well I hooked it up right away and did some tests and everything looks great now. In the picture you can see that I have put it next to the PC Function Generator under the keyboard. Fits quite nicely actually. Now I'm going to play a bit more with this combination and try out the Bode Plot functionality. I'll try to put some results up on my blog when I have them.

Synth.nl in Syndae Christmas Special

Like last year I made a track especially for the Christmas Special from the German electronic music podcast Syndae. My track is called 'SynthCarol' and is my interpretation of the Christmas track 'Carol of the Bells' only with synthesizers in stead of bells. Stefan made a very nice show again of a little over an hour and left me the honor to finish of the show. All music in this Christmas Special is especially made by the artists involved for this show. I think that is quite unique. You can download the show from http://www.syndae.de and as said before my track is the last one at about 1:02:00. Have fun and Merry Christmas!

Yusynth (Part 17)

And this morning I finished another YuSynth module. It is a YuSynth Saw Animator module. As you can see this is a factory produced PCB. I this as a complete kit from Bridechamber including the components. While inspecting the components I found there were 2 resistors missing and there were 1 uF elcos supplied in stead of the polyester capacitors that should be there, but I could easily get them from Farnell. I didn't really bother to contact Bridechamber about it. One nice thing about this PCB is that the component values are on the silkscreen of the PCB. So documentation is close at hand :)

Wiring PCB is becoming standard production work here in my studio the last days :) So I got this one wired very quickly again. Actually this module is a dual module. There are two Saw Animators on the PCB. So you have wiring for module 1 and module 2 being an exact copy. There are also two LFO's standard on the PCB. The LFO's output is normalized to the Mod Input and is disrupted when you insert an external jack. Saw Input 1 is also normalized to Saw Input 2. So if you input a saw on input 1 it is replicated to input 2 automatically.

And here is the completed module. Calibrating is easy. You apply a 10V Peak Peak saw signal and then adjust one trim potmeter to get the output saw aligned and using another trim potmeter you balance the DC offset to get it nicely around the zero. Then you do the same for the output of the other part of the module. If you input other signals than a saw you get some neat output results as well by the way. Also when you don't input a full 10V peak peak signal the output is different. Quite funny what you can do with this fairly simple module.

And here is the finished module from the front. The leds you can see indicate the speed of the internal LFO. As said before you can override those with an external signal. But what does it do then? Well you can 'animate' or 'modulate' a boring saw into an alive one. It thickens up the sound. I heard my PC oscilloscope is back by the way. Maybe I'll grab some signal pictures with it later on so you can see what it does. I hope Gerrit comes back soon with the modified piece for my cabinet so I can finally screw some modules into place and start working with them. For now I'm going to look what is next on my backlog pile :) I'm sure I don't have to be bored the coming days. As always I'll keep you updated on the progress.

Modular Desk Adjustment

Gerrit my Furniture builder was here today to look at the adjustment that needed to be done to my modular desk to fit in the Synthesizers.com modules. So in the morning I cleared everyhing out of the desk to make room for him to work. But he thought it would be better to do it in his workshop, because he has better tools there. So he actually sawed out the upper bar and took it with him. Hopefully I will get it back next week. So still no Q960 sequencers in there unfortunately. Ah well patience will pay out I'm sure Gerrit will make it even nicer than I though. We also discussed a little extension on the desk today. I'm thinking to put some stuff left and right of the desk since there is still space there, but for now it are just ideas. I'll let you know when he has been back here.

Yusynth (Part 16)

Today I finished two YuSynth LFO modules. Again I made everything myself on these modules including etching the PCB's and the front panel designs. I also had these front panels made by Schaeffer. And I used a bridechamber 2 pot bracket as you can see in the picture on the left. I had some more holes to drill on these brackets since the PCB has 6 fastening points in stead of the usual 4. I guess because it is a long PCB and you don't want it to short circuit on the pot bracket when it should bend. I keep having trouble to drill these holes exactly on the right spot. Just clumsiness I guess ;)

And here is a picture of the wiring I did. As you can see there are quite some wires on this PCB. 6 of them already go to the rate selection switch. Which is kind of a cool features because it increases the frequency span a lot. Of course I had the wires correctly the first time on the switch, but doubted that later on and after switching them I found that they had to go back again ;) Ah well this way you learn to test better. The reason I started to fiddled with the wires was actually because it didn't function when I was calibrating the first one.

The first thing I did after that was comparing the PCB's of both LFO modules. And after about 10 minutes of studying and measuring a bit, I found that I had two resistors wrong. On one PCB were two 2k7 resistors and on the other two 8K2 and there were supposed to be one 2K7 and one 8K2 on both of them. I had to remove the PCB's again from the pot brackets to desolder these resistors. Since this is a single layer PCB that is doable with just a desolder pump. I maned to do so even with saving the resistors and just switching from one PCB to the other.

And here are the two finished LFO modules. As you can see in the picture they have another neat feature called Sync. This makes it possible to synchronize two modules to each other of to for example to a sequencer clock or any other signal. Further it has an FM input making it possible to do frequency modulation on an external CV signal. I tested all the features and it works like expected. The only thing I see is a little dip just on the crossing point of the uppper and lower part of the Triangle and Sine wave. I'm not sure if this is normal, but I can't get it away using the trimmers anyway. Actually I don't think it is a big problem either. Well all in all a productive day and two new modules :) More to come soon. I'm on a roll now :) I'll let you know soon.

Modular Backlog Update

I promised to make a blog posting as well about the stuff that I still have to finish. In the picture on the left you see a stack of PCB's. Some are fully populated some not. On the left are some MOTM boards that will be used inside the modular for power distribution. Next to that are some CGS PCB's and on the right are a lot of Yusynth PCB that I made myself. Some of them are also spare. I made a lot of those twice while I will only completely build one. Maybe I will sell the other PCB or maybe keep them for spare for the future. Below the stack of Yusynth PCB's is also some MFOS stuff.

And here is another stack of PCB's. The stuff you see here is mostly populated as well. Most of them are Oakley PCB's but on the left is also a Mega Percussive Synthesizer from Electro-music.com also designed by Thomas Henry. Below is the Snare drum project on the breadboard. I'm saving this to make some video before I put it on a experiment PCB. In the picture on top you see also a front panel laying in the bottom of the picture. That is the Front Panel I designed for my Hip Bass Drum module. That one is quite complete so I can finish that very soon I guess.

There here some stuff I have laying on the floor right now. These are mostly front panels I'm populating. You will recognise the Klee Sequencer panel that I posted about before on the left and behind that is the MFOS Stereo Mixer I'm building. You can also see the VU meter panel on the bottom and some more Yusynth stuff that will come soon. On the far top left are the synthesizers.com Q960 sequencers. Hopefully my furniture builder Gerrit will fix the modular desk on Wednesday so that I can start installing and testing them. I can't wait for that :)

And here the last picture. On the top left is a Bridechamber multiple panel where I already put the jacks in. Then on the bottom next to the roll of black wire is an Oakley MidiDAC that will funtion as a Midi to CV converter in my modular desk. And on the right are three MOTM 300 VCO front panels. All in all quite some stuff I still have to finish, but I nearly got all the parts. Now I'm missing some potmeters that I will get from Mouser soon and I already used up all the jacks so I ordered some more of them too. I thought I had enough. But apparently I didn't ;) Well now you have seen everything, so I hope you can see why I'm a bit busy at the moment :)

Modular Progress Overview 2

I'm working very hard now on finishing some modules for my big modular. So I thought it was a nice moment to post another overview of the current status. I know some of you are following this blog for my DIY stuff and some of you have no idea what it is all about :) So from time to time I will show what it is becoming. In the picture on the left are the modules that I have finished or nearly finished. I'm working at the moment on the YuSynth LFO's and Saw Animator. So you can expect a post on those soon. If you click on the picture and zoom in you can see what it all is. Every module has a text label.

And here is the big overview picture of the hole modular desk. As you can see there is still a lot of empty space, but that will become all filled some time to form one big modular synthesizer. Most stuff will be self build, but there will also be some pre-build modules in there soon like the Synthesizers.com modules I bought recently. On the top left you see the ASM-2 that I'm also still building and in the middle on top is the Elektor Formant that I still need to restore as well. I tried to repair the old power supply that came with it, but it is so damaged that I decided to go for a new power supply for it actually.

And there is lot to some soon. I have been working on a lot of modules the last year that all are missing parts. 95% of the components on the PCB's is very ordinary and cheap stuff that I can find in my local electronics shop, but some parts are very difficult to track down and sometimes quite expensive. So I have a huge backlog of stuff I need to finish right now. I will do a post about that as well later on so you have an idea. I'm still enjoying especially the DIY stuff a lot, but the whole modular is still not in any state to produce music with it. So I'm really eager to create some sounds with it soon, that is why I'm working very hard now to finish enough stuff to be able to hook it all up soon :)

Yusynth (Part 15)

I finished another module today. I had this PCB lying around for a long time. It is a Yusynth VCA module. There is one tricky thing you need to do while building this module and that is to match two BC547C transistors. It is only possible to do this when you have a multimeter that is capable of measuring the HFE (amplification) factor of a transistor. The reason this is necessary is that they will work in pairs.

Building this module even though it is not that complicated was special for me, because it is the first module that both has a PCB that I made myself and a front panel that I designed myself. Again I used a 2 potmeter bracket from Bridechamber. After this it was time to start wiring again. I started as usual with the wiring to connect the front panel components. After that the wires on the PCB. Because there is no silk screen on the PCB, I made sure to use different colored wires to be able to tell what is what later on.

Then it was time to test and calibrate. Yves has a nice calibration procedure on this website, but I misread it. I spend over an hour trying to calibrate it, but it didn't work like I expected. The first thing to do is put the front panel potmeters for the audio and CV input to maximum, but I also put the Gain potmeter to maximum while it should have been on the minimum position. After I found that out calibration was a piece of cake actually :) It is a nice VCA, quite quick actually. I even used the LFO to do audio rate stuff with it.

Here is the finished module in my modular desk. As you can see I still haven't fastened any of them. I have been looking for nice black screws for a long time. I think I found them now. Actually guitar screws for mounting pickups to a guitar body. They have a big head and are not too long. I found them on E-bay somewhere in the UK from a guitar shop. Another thing I'm still thinking about is how I should layout all the modules so that it is kind of logical. Because I'm screwing them directly into the wood of the cabinet I don't want to move them too much since I'm sure that the wood will get damaged and after a couple of times it won't hold anymore. Well next up are the two Yusynth LFO modules you also see in the picture. I'll update you soon.

Resonant Lopass Gate (Buchla 292c Clone)

Today I finished another module. It is called the Resonant Lopass Gate and it is a clone of the Buchla 292c. The PCB is designed by Thomas White with permission of Don Buchla. Construction of the PCB is quite straight forward but there are a few jumpers on the PCB you have to set when you want to use the resonance function. Thomas also added the deep switch mod. Another thing you can chose is to use 3 inputs for both CV and audio inputs through a on board mixer, of you can use direct audio and CV in. The two bbig lack components on the PCB are Vactrols. I got them from Bridechamber. They are not very easy to get anywhere else I think.

Here you see the finished module from the back. I didn't install two potmeters on the PCB but directly on the front panel, because I used a Bridechamber pot bracket. I gambled on the orientation of the switch, but got it right in one time. And this time no potmeters the wrong way around either ;) I'm getting quite handy now in wiring modules to the front panel. It is going faster every time. I only had to fidle a bit with the rotary switch. I never used one before with 4 layers and 3 positions. But with a multimeter I found out quite easily what should go where according to the documentation. I had this front panel made by Schaeffer by the way, but saw later that Bridechamber also has it now. Too bad because that would have been a bit cheaper.

After assembling it was time to test and calibrate again. Everything worked right away. I used the good old LFO again to create a gate signal. This thing is really fun. The resonance adds a great edge to the filter and the Vactrol make the edges smoother. You can create very interesting sounds with this modules just by applying a saw to the audio input and a square on the CV input. I'm sure I'm going to use this module a lot in my future audio productions. I used a similar software tool in the past, but this really beats the crap out of that one :)

Here you see the finished module. I think it looks very nice. As said before I had the front panel made by Schaeffer and you can actually download the Front Panel Design (.fpd) file from Thomas White's website. Here you can find the file and more information about the module. You can also order the PCB from here: http://www.naturalrhythmmusic.com/lopass.html. I can really recommend this one. Thomas White also has some other nice front panel designs on his website that you can download. I'll make some more for sure in the future with his panels. It is great that people share this kind of stuff in the DIY community. As said before if you want any of my panels just let me know. I'd be happy to share them to. Maybe I should put them on my website too in the future.

Magic Smoke Electronics TH-201 Mankato Filter

When I ordered something from E-bay recently I was offered a nearly populated PCB by Magic Smoke Electronics. It is a TH-201 Mankato Filter. This filter is designed by Thomas Henry by the way who also designed the drum modules I'm building currently. When I examined what was missing using the bill of components, I found that the guy I bought it from installed all 5% resistors in stead of the 1% resistors that were recommended. So I mailed Magic Smoke Electronics if that was a problem. They stated that it will probably not track on 1V/Oct but should work fine.

Well actually I don't really care about that. So I finished installing the missing components and started wiring it. I got a front panel and pot bracket from Bridechamber for it. Actually I should be on a 4 pot bracket, but I used that already on another module. With a bit of effort I could just fit it on a 3 pot bracket by drilling the holes on the bracket very close to the edge. I also got a tempco from Bridechamber for it, but I didn't bother installing it since it won't track any way. I'm sure I can use it somewhere else in the future where it will matter.

After wiring I started testing it. I first put an input signal on it from my PC Function Generator. It sounded alright, but I found quickly that I wired the input potmeter the wrong way around. And since I used the same system for all potmeters I figured they would be all wrong. And after checking they were indeed. Luckily I anticipated this and left the outer two wires on the potmeters long enough so that I could swamp them. Not really a problem even though some wires were not so easy to reach anymore. After swapping them I found that the filters didn't auto resonate.

Again not a difficult task to fix this. There are two trimpotmeters on the PCB. One for the resonance and one for the 1V/Oct tracking. I didn't bother the last one but set the resonance potmeter so that it starts auto oscillating on 95% of the resonance potmeter. As you can see this filter has lots of outputs. All with different phases. The frequency scope of this filter is also very wide. So you can use it as an LFO or an oscillator too. When used as an LFO the phase shifted outputs are handy. Well after testing everything I put the knobs on and think it is another successful project and nice addition to my modular setup. Here you can find more information on the TH-201 Mankato if you are interested:

http://magsmoke.com/TH-201-Mankato-Filter-VCF.asp

Synthesizers.com Sequencers Arrived

As you will know by now I'm building a big modular synthesizer myself. But there were some modules I couldn't build buy as a kit, so I bought they assembled. In the picture you see two Synthesizers.com Q960 sequencers and below some utility modules to accompany them. These sequencers are build after the original Moog sequencers that were used by bands like Tangerine Dream in the 70's and are still used by a lot of people these days to make 'Berliner Schule' music. I want to try and use these sequencers next to the sequencers I'm building myself to create some inspiring melodies that I can use in my own music. The only thing I noticed right away is that they don't fit in the modular desk that I had build in my studio. I already contacted Gerrit that build the desk and he will come by next week and see if he can solve it. I'm quite convinced that he can actually :)