That Time I Got a 246 Filled With 10 Turn Pots

People do crazy things.

After all of these years, I ended up with a 246. This one was part of the Audities Collection, I believe in the silver colored Zero Halliburton case they displayed before.  

I have never been into the idea of putting blue Rogan knobs on everything, even if Buchla never made it that way. I wanted it back to the right color switches too. But I never imagined that someone would have replaced all 64 pots with Bournes 10-turn pots! I guess one could get some real precision with that. Anyway, for me it's all back to original. I still love the build quality of these things. Those Dialight buttons....

 

City Mouse Meets Country Mouse

What happens when the Good meets Evil? East meets West? Then meets Now? Can't we all just get along!?

I had an original Buchla 288 in my shop. I got it working and was able to introduce it to my 288v. A good time was had by all. It's a cool module and a very powerful piece, even if it is noisy.

Made From the Best Stuff On Earth

 Don Buchla split up with CBS as a distributor of his products after the 100 Series and in 1970 released the 200 Series Electric Music Box. What is really mind blowing about these first, black knobbed modules is the serious quality of their build. The lighted push buttons on the 246 sequencer have an incandescent lamp in them and are about $75 if you find them now. The pots are military grade CTS panel mounted beauties. C&K toggle switches, Switchcraft audio jacks and Johnson banana jacks were used in all of the original Buchla stuff, so it's easy to overlook them. The LEDs on a 246 sequencer are from the first batch of LEDs to EVER HIT THE MARKET. They are a gold can with a glass dome. If you want to replace these LEDs, you're looking at about $20 EACH!!

Each module came in its own chassis box with a Cinch-Jones pigtail. They were meticulously hand wired. The cabinet holds them down from the front, covering the module and manufacturer's name. They have a significant weight to them. It's crazy stuff and a far cry from the plastic junk that gets churned out these days. Long live the original! (24 volt power rails and all!)

Video of the new Verbos 247v sequential voltage source

Here's a quick video of my 247v module in my Buchla 200 cabinet. It shows some of the sequencing features. The 247v is connected to a 259, 281 and 292. The 281 is in sustained mode to get the benefits of the variable pulse length on the 247v. To start, I run it from it's internal clock and switch around the stages' on-off-slide switches. Then, I run it from an external pulse from the 281. This shows how the TIME MULT control acts like a pulse length/slide length control. I then show some tricks with patching stages into the strobe input and send in voltage to the analog input from an off stage 254 to select which stages are playing. There are loads more features, using the yellow inputs to make envelopes and stuff. I hope this starts to show it off...

The 247v Sequential Voltage Source

I have been working on a new Sequential Voltage Source. It is only a single module space and packs a big punch. It does most of the things a MARF or ARF does, but without any menus. It can act as an 8 stage sequencer with two rows, voltage control of the clock/slide rate, switchable slides/pulses, pulse outs on each channel and the ability to loop from any stage to any stage.  It can act as a multi-stage envelope, up to all 8 stages with any stage as a sustain stage or any stage pausing unless a key is held. It can act as ADSR, AHDSR, HADSR, AD, AR, AHD, LFO saw, pulse, square, triangle, something more complex, LFO that only runs when a key is held, LFO that only runs when a key is lifted.

I wanted a small sequencer with every function on the panel. I wanted to do TB-303/MC-202 type sequences with slides selectable per stage, where the pulse output holds the whole stage on a slide stage but only pulses 25% of the stepped stages. I desperately scrambled to complete two for my performance during the NAMM show. I made panels from PCBs because they take less time to manufacture. I only got one finished and then it didn't work when I got there! Anyway, it's working now. It's pretty fun.

misc. banks on the 263v

The 263v has been a lot of fun. When I programmed the scales, I had a bunch of left over memory spaces. I filled those spaces with random voltage sequences that are similar to the ones in the middle sections of the 266. Of course they are addressed by control voltage instead of pulses, so they have different uses. I threw in a set of 16 smooth random patterns. If you send in an LFO, you get back something like the fluctuating randoms in a 266, well not "random" but fluctuating. Finally, I through in some pulse sequences and some melodic sequences. Using the random sequences and the melodic sequences is a bit like dropping a sample loop into music (you have to trim the start time and length using a voltage processor).  I hope that these functions add something useful to the toolkit.

BTW. I also got it to track 2 volts/octave for the old Buchla guys who need that.

Quantizer/Analog Shift Register take II

In 1972 as a resident at CalArts, Fukushi Kawakami made four modules as additions to the school's rather extensive Buchla 200 system. The modules are a Control Voltage Switching Matrix, two Control Voltage Integrators and what I believe is the world's first Analog Shift Register. 

http://barryschrader.com/the_fortune_modules/

Since then, the world has fallen into disarray, computers have taken over, analog modulars have gone in and out of favor several times and those four Fortune Modules have ended up in Grant Richter's hands. Somewhere in the middle of all that, Serge made an analog shift register and wrote about it (under the nom de plume Arpad Benares) in Synapse. Even before the Fortune Modules, Buchla had made a rather amazing Control Voltage Integrator called the 155, but that's another post.

Anyway....

Analog Shift Registers are a bank of Sample and Holds. In fact, using only the first output, it is a Sample and Hold. When a pulse is applied, the CV on the input is stored on output one. Whatever was on output one is moved to output two, and so on. 

In 1997 I made 2 copies of a module that was a dual four stage analog shift register as well as an 8 channel voltage quantizer. One of these is still in daily use over at OSI music and the other is rotting on a shelf in my shop. When this photo went around the forums and blogs some people suggested that rearranging the panel to allow the analog shift register outputs to be quantized via shorting bars would be a good idea. Point taken.

 

I had a couple of ideas of my own that could make it a better module. Sadly, it got back-burnered and never saw the light of day until now. The new version has rotary switches to select the scale to quantize to. The ASR outputs can be plugged into the quantizer with  shorting bar. There is no longer a "slave" switch to chain the two ASR's together, but a cable and shorting bar can now do that too. Some new ideas have come up as well, like using the quantizer to look-up the voltages from the "random" voltage sequences from the 266. It's obviously not as glamorous as an oscillator or filter, but it will come in useful to some people.

Spring Chickens

In the golden age of analog synthesizers, everybody had a spring reverb in their system. In fact, sounding like the Radiophonic workshop is often as easy as adding spring reverb to simple sine and square wave sounds. Buchla was no exception including the 190, 275 and part of the 212, 208 and 227. The 275 in particular is a rare and interesting beast, offering voltage control of the wet/dry mix as well as simple EQ on the dry signal. 

 

The module itself sends out and receives a line level signal to an external reverb unit. Most likely, the signal is sent to a 17" x 7" x 3" box that has the reverb drivers and recovery amplifiers built inside, along with 2 15" dual spring tanks.  Any line level in/out unit could be used with the module though. The brochure reads, "The reverberation electronics and delay elements are remotely mounted. Interconnections are at line level, permitting the use of the control module with reverb units of alternate origin (E.M.T.'s, for example)." In the case of the module in my hand above, the "remotely mounted" electronics were not included. Rather than connect an "E.M.T.", the owner and I decided to whip up some electronics to use a couple of reverb tanks pulled from a 190 unit.

The electronics inside the remote unit for a 275 have a discrete amplifier, envelope follower and a variable gain recovery amplifier. In other words,  a compander is built in.  The slowed down attack makes a bit of a pre-delay on the reverb and the gain reducing as it decays takes out some of the noise from the spring reverb. Sadly, the amplifier uses +/-24 volts, which I wanted to stay away from. I created a similar circuit, using the same amplifier IC that is used in the 208 and 227, LM380, with a 275-like compander. I attached it to the back of the module and ran pigtails to the tanks, mounted on the back of the cabinet. The trims control how much action the compander has. I just trim them to have unity gain out when the signal is full strength. I wish I had made a sound clip once it was installed.

 

This unit could be built inside a box with the springs like the original one was. Since it has line level in and line level, 100% wet output, it could be put on a send of an analog mixer or on an insert of a DAW, like the vintage Roland and RCL units I have right now on my ProTools rig. I use them in my sessions and since they don't have any controls on the front to change, everything comes up the way I left it. Kinda cool I think. 

Harmonic Oscillators

Buchla made the 148 Harmonic Generator in 1969. It is a sawtooth oscillator core, the same as the 158, with waveshapers creating 9 harmonics above the fundamental. The even harmonics are created with full wave rectifiers doubling lower frequency triangles. The odd harmonics are shaped using a series of diode clippers that mix the triangle with a clipped version to make a higher frequency triangle. The effect is a wavefolder, the precursor to the Timbre circuit in the 259.





I built a modified version of that design 10 years ago. The original has no -15volt rail, so it AC couples the signal in many places. I eliminated all these caps and powered the circuit from +/-15 volts. I never got the quality of the waveforms to where I wanted them. I have since worked on a Buchla 148 and found the waveshapes to be about the same as my clone. They sound a little wavetabley, especially the higher odd harmonics.

Legend tells that Buchla made a version of the Harmonic Generator for the 200 series. It was based on the design of the 148, but had a few extra parts added. It had reversing attenuators on the CV ins and an output mixer with sliders and even/odd outs. I have never seen this module and don't even know the model number.

In 2009 I started designing my take on this forgotten concept. I made up my own waveshapers using distorted CMOS opamps, like the 259 Timbre circuit, instead of diode clippers. This does not sound good. I have since thrown the design out.

Finally, I have my finalized design. The Harmonic Oscillator. The analog oscillator core puts out saw, square, triangle, and spike (208 style). The waveshaper puts out 10 decent quality sine waves. The voltage controlled mixer has sliders and CV ins for all channels as well as scanning circuitry (sort of freq. and bandwidth for the harmonics) and tilt (to favor the high harmonics or the low harmonics from voltage).

Prototype Music Easel!?

The Music Easel is the street name for the combination of the Buchla 208 and 218 touchplate keyboard. I was recently called upon to repair the prototype unit, built in 1973. This unit was resurrected in 1987 and had since been in a basement, used from time to time without ever being moved. He built a very cool blue wood enclosure for it with a built in linear power supply.

When it changed hands, several problems appeared. The 208 module is built from a large motherboard with 12 perpendicular daughter cards, attached with .156" Molex connectors. The biggest problem was that the connectors had oxidized and the cards had to be jiggled around to get several of them to work. The 20 years that this thing sat in the same spot it was fine, but I guess shipping did a number on them. I replaced the female side on all 12 cards and things started to get better.


The Oscillator and some other parts were still not working properly, so I set out to find the problems. Being the prototype, there are several things that are not the same as other units. The panel has a sine wave in the modulation oscillator, when it actually puts out a triangle, the memory card edgecard connector is smaller, the Envelope and Pulser sliders are labeled backwards and the modulation oscillator's banana output jack covers some text. The boards are filled with cut traces and flying resistors. It was a lot of fun.


Finally, I got to the 218. It was only triggering notes while you touched one of the grounded frets. The original owner thought this was normal, but I have used these before so I had to figure out what was wrong. I found that the resistors controlling the keyboard signal's gain were different on the schematic, the parts overlay AND the picture that I had taken of a working unit when I serviced it. I tweaked these values until the keys triggered normally.

Good Ol' Filters

The Lopass Gate is widely recognized as a sweet sounding filter with a Vactrol-induced slew to it. Set into the top switch position, it is a Sallen-Key filter very similar to the Korg MS-10/MS-20 filter. The LED/photocell elements, known as Vactrols, add something around 10ms of slew on the attack and 100ms of slew on the decay. This is more than an OTA filter for sure, but what if there was some REAL slew on the CV?

Then, there's the Buchla 192. A simple, nonresonant, 2 pole lopass filter, featuring an all discrete transistor signal path with the control elements made from photocells and incandescent lamps in a little bit of heat shrink tubing! The original run (it's quite rare, but I don't know how many are out there) of this module didn't even have a CV input. It has a slew of several seconds when the cutoff is changed.


The one that landed on my workbench was living behind a Dual Reverb front panel with the labels scratched off. It was not functioning. Since I discovered at least one dead "optical element" and this device was such a hack anyway, the owner and I decided to mod it for actual VTL5C3/2 Vactrols. After all was said and done, it is a very interesting sounding lopass. Sort of like a 292 in lopass mode, but with an all discrete signal path.

Just because

I didn't know Vactrols could do that!

I recently repaired a 227. It has several problems: A dead channel, reverb wasn't working, I forget. It seemed like a quick turn around repair, until I sent it home and got the dreaded, "this thing's broken again!" phone call. Only now, it was completely shutting off the main output whenever it got hot. So, as long as I kept it on my bench, with air flowing around it, no problem showed up. After 5 minutes inside the boat, the main output went dead. This problem drove me nuts for a while, and in the end it was a Vactrol! Since the main output buss is quad, the panel volume control is actually a 4 channel Vactrol VCA. I guess diodes sometimes go open with heat if they're old enough. In this case the diode was a vintage Vactrol.

Good Times In Anaheim.

It was great to meet everyone at NAMM. I'm glad I decided to go.

"I can't fit all these amazing modules in my system!"

I'm going to NAMM

BTW. If anyone is going to be at NAMM and would like to meet. Please email me in private.

MARF making

I repaired a MArF a few years back, but nothing was like the undertaking of getting the 248-3206 from the Buchla garage sale working. I only know of a couple of these in existence and I don't know that any of them work. Someone bought the panels with only the motherboards attached. I have had them in my possession for more than 2 years. I had to design, assemble and troubleshoot the input board and 3 output boards for this beast. Each board is 14" x 6" or so, no small task. Today it worked for the first time.

Pictured is the working MArF as a reference. and the 2 panels from the double size expanded unit. A 3206 is a normal 1602 unit with an additional 4 space panel added to it. The expander adds another 16 stages of sliders and memory as well as 4 more output channels. The 6 total output channels can address the 32 steps in any way. This thing could be a 200 system's only source of modulation generators. LFOs, Envelopes, Sequencers, Quantizers, Voltage Processors are all possible. More infos to come.

Much more info to follow.

Finally

I got the panels finished.

Some audio demos

I have thrown together some quick examples of what the different functions of the Time Domain Processor sound like. There's no art here, it's just an ARP sequencer, 259, 281, 292 together with the delay unit. I think this thing takes simple stuff to the next level.

DELAYS


this is the simple sequence run through the module in delay mode. Since it has 8 delays happening at once, the sound can be very complex. I add a little feedback, just to make things interesting. Later in the clip I position the sliders so that the delays get louder as they go to the right, creating the reverse reverb type sound I mentioned in the last post.

PITCH


In this clip, the module is in pitch mode. The sense is set to turn on with each note. When the envelope follower opens, it hard syncs a sawtooth oscillator that is sweeping the delay time. This sounds like a pitch shift. With feedback it sounds like rising or falling echos.

SAMPLE FX


Here I send some sound in and then grab it in the loop mode. I retune the sample and sequence it. Basic loop stuff.

SAMPLE AS OSCILLATOR

Sometimes Experiments Work

I have been talking about digging into the 288 schematics and redesigning the digital section to eliminate the obsolete shift registers. It's an 8 stage voltage controlled digital delay, BTW.

Well, upon building up the prototype, I came to find that several of my original ideas didn't work as I hoped they would. After some rethinking and experimenting, I solved those digital problems. I now have a working version of the design. It makes some very interesting sounds, that I haven't heard before. It's cool sounding to have the short delays very quiet and them get louder as they get longer, it sounds like reverse reverb. Also, the looping stuff is out of this world. Woah. Now I just need to get my silk screening done.