Components

Synthasystem Home

General Thoughts

These modules were originally designed, built, sold in the mid to late 70s and early 80s. Not ancient times, but no internet, no Mouser online catalog, etc. A lot of the components were selected not for performance, but local availability and cost. 5% carbon resistors were the cheapest and metal film were only used when absolutely necessary. Granted, the eventual timbre of the sound depended on the performance of all these components, a little more noise in a carbon v. metal film resistor. stray inductance in those ugly disc capacitors, a littler drift here and there from temperature sensitive components, and on.

So, will your filter sound exactly like an "original"? First, you have to establish what an original sounded like. Did one even sound exactly like another? No. There are always differences, especially with analog circuits.

What I can promise is you will have a module from the original production schematics. I stayed absolutely true to Nyle's designs, except where Nyle made a modification himself or where he approved such. These are (should be) noted in each module's page. Like the VCO. This has a V/Oct trim and frequency span trim which were added. Nyle redesigned the sequencer to replace 3 Germanium diodes with 3 Silicon diodes and formally added some modifications he dreamed up for his last release.

I simply wanted to be able to build an authentic Steiner modular synthesizer. I want you to be able to, as well.

With that said, I did my best to lay these PCBs out so you could choose how true to the original you wanted to be. If you want to use hand matched transistor pairs, you can do it. It you would rather use a modern monolithic matched pair, you can do that, too.

You can choose to use 5% carbon resistors everywhere except for critical spots, like Nyle did, or use mil. spec. RN55E series resistors everywhere :)

Component Selection

General Parts Search

Please forgive me since I can't remember who set this site up, but a million thanks. This is a great place to hunt down parts in the US or UK.

http://burnit.co.uk/sdiy/part_search.php


So, you can only find the IC in a SOIC package?

Here is a web site which sells adapters to let you use SOIC, etc. in a DIP socket:

http://www.epboard.com/eproducts/protoadapter.htm


Hard to find or can't find a part?

When I captured the schematics, I laid them out exactly as the originals. I used the component values specified regardless whether or not they were standard or common. I wanted to preserve these modules as they were. So, what do you do when you can't find a 250 ohm trimmer or a 1.2u Electrolytic?

If you are building these things, I assume you have some skill and knowledge with electronics. Think about what the hard to find part is doing and how best to replace it. I've tried to give suggestions on the specific project pages. For example, the EGs call for a 2Meg audio taper pot for some of the controls. Good luck. But, this is a simple RC filter circuit. You can find a 1Meg audio taper pot though. Great, halve the resistor, double the capacitor and you'll get the same response.

You can't find a 250 ohm trimmer for the VCA or VCF? Me neither. Pick the next closest value, 200 ohm is available, and it should work fine. Or, maybe a 500 ohm trimmer, but reduce the two 2.2k resistors to 2k.

The 1.2u electrolytics are non-existent, so use a 1u or 1.5u or even a 1.2u Tantalum.

Use some common sense, maybe some basic electronics, and off you go!

All else fails, ask a question on Electro-Music, the SDIY list, MuffWiggler, or other resources. Send me an e-mail and if I can't help either, I'll pass it on to Nyle to see what he thinks.

I want your module to work.

Resistors

As I just wrote, these were originally built with carbon core, 5% resistors with one or two 1% metal film resistors where it was merited. So, you have a wide range of options here. I recommend using 1% tolerance, metal film resistors everywhere except as noted in the individual module pages. Some circuits, notably the VCO, will benefit from temperature stable, high precision resistors. But, you can do it anyway you want.

I use the 271 series, 1% metal film at Mouser. You order like this:

271-value-RC, pretty easy.

EX:
You want a 22k:                271-22k-RC
You want a 360 ohm:       271-360-RC
You want a 2 Meg:            271-2M-RC

Some of the input summing and feedback resistors and some resistors in the keyboard circuits need to be matched to 0.1% or closer. You can buy them that way, or you can just buy a bunch of 1% and hand match them. Make sure they are at room temperature and you aren't holding them with your hand when testing. The temp coefficients can mess it up for you, especially with doing the 0.01% matching.

For temperature compensation, Nyle used a 1k 3300 ppm Tel Labs thermistor. These are hard to find, expensive, and do nothing special that can't be done with a modern part. Nyle told me he has a bunch of Tel Labs tempcos in a bin. I told him he could make some money on Ebay :)

I'm no expert, but I think you can use anything in the 3000 to 3500 ppm range. Ideally, you want 3300 ppm I think.

There are several options for these resistors. I'm unfamiliar with out of the US sellers, but in the US, Precision Resistor sells them for about $4 or $5 each in single quantities. The Bridechamber, www.bridechamber.com, sells 1k tempcos, too.

On Dave Brown's ModularSynthesis website on this page, about half way down, he shows how he makes a 2k tempco from 2 SMD resistors, Digikey P68CDCT-ND 3300 PPM resistors. You could do something similar with one 1k resistor.

 I'm sure there are other sources.

Capacitors

There are probably a billion different ceramic capacitors at a place like Mouser. Pick a capacitor that can fit the hole easily, typically 0.1 inch on centers.

Some people swear by Polystyrene capacitors over ceramic. There is a lot of buzz about how some capacitors are warmer sounding. Really, I don't know what to say. Unless noted in the modules's page, just use a good quality ceramic, electrolytic, tantalum, etc. In the VCO, the Polystyrene is probably warranted. You are certainly free to choose. For circuits "holding" a voltage, you should also use a polystyrene. The Selective inverter, however, uses a 0.15u capacitor to "hold" a voltage, but I can't find a polystyrene that big. A good second choice is polypropylene or polycarbonate. Here's a link to a good paper on capacitors by Harry Bissell.


All electrolytics should be rated for at least 25 or 35 volts.

You may have trouble finding some of the exact values, like 1.2u. My suggestion is to just use the next closet value, it should work fine. You can also substitute a tantalum for an electrolytic, but they are typically more money, but the come in more values. You can find a 1.2u Tantalum pretty easily, but they are a bit pricey.

Inductors

I think the only inductors are the ferrite beads in the power regulation/conditioning section. You can use a PTC fuse, ferrite bead or what ever you usually use. You can use this ferrite bead from Mouser:

You can use Mouser # 81-BL01RN1A2A2B

ICs

The majority of the ICs are LM741 OpAmps. There are many OpAmps with much better specs, but these ones will affect the sound to some degree. If you want a true re-release of a Steiner VCO, use the LM741 or equivalent. If you aren't too worried about it, use a newer OpAmp. Just make sure it is a single OpAmp with the proper pinout. The offset null is not used. If you can't find a derivation of this OpAmp, close your web browser and forget you ever heard of this project... :)

The keyboard and Selective Inverter specs a CA3140 which had a nice discussion going on the SDIY list. These are still available. I got some at Digikey in a DIP package. Be careful handling the CA3140. Apparently it's pretty sensitive to static discharge.

The Ring Modulator calls for a MC1495 multiplier chip. Nyle broke his rule and designed around a very specific chip, and sure enough, it went out of production. Fortunately, it isn't impossible to find and doesn't cost an arm and a leg. There is one website, I won't list, that wants $50.00 a chip!

As I write this, Arcadechips.com:

http://www.arcadechips.com/product_info.php?products_id=101

has them for about $5.00 a chip. He's told me he has 30,000 in stock of the ON Semi make. I can vouch for these On Semi parts. I bought 30 from Mark. I recommend you buy from him.

Regulators

If you are going to run more than 100 mA or so from a Power Regulation PCB, you might want a small heatsink on the regulators. I've used an Aavid Thermalloy "snap-on" heatsink. Not huge, but it helps.

Mouser p/n:     532-576802B00
Mfgr. p/n:         576802B00000G

Transistors

See here for some photos of new and vintage transistors and pinouts.

The original used 2N5172 NPN and 2N5138 PNP transistors. These are still available, but I could only find a "PN5138" which I think is the same transistor. In any event, you can use any standard NPN or PNP transistors and they should work.

*******************UPDATE*******************************
The PN5138s are still available, but the 2N5172s are being discontinued. Newark still has stock on some Fairchild parts, but it looks like these will be harder to find. Good thing is you can really use about any small signal NPN  as a substitute.
***********************************************************

The exponential pair in the VCO core should be matched. Either you need to hand match some NPNs, or you need to use a monolithic NPN pair. The SSM2210, LS318 are good choices, but any small signal monolithic matched pair should work. Analog Devices has a new part, the MAT12 which should work, too. Q3 is a PNP which is placed physically close to the match NPN pair and it should be in thermal/mechanical contact with the NPN pair and thermistor.

The Music From Outer Space website, on this page, has a long discussion on matching transistors with some circuits.

Bill and Will at Dragonfly Alley, http://dragonflyalley.com/constructionTransistorMatching.htm
also have a great page on matching transistor. Thanks!

See the VCO page for a schematic of a transistor matching circuit you can build yourself!

In the VCO, as an option, you can use a THAT340 (available at Mouser p/n 887-340P14-U) which has an NPN and PNP monolithic pair. This saves the problem of hand matching, or trying to squish 3 transistors and a resistor together and keep them there.

Other modules have paired transistors, too. I don't think matched pairs are necessary, however, I laid them out using an 8 pin DIP package and list them as an SSM2210. You can probably just install 2 NPN transistors and call it good. You can certainly use highly matched pairs if you want to.

Originally, the Steiner modules used a 2N5163 JFET. In later modules, this was replaced with a 2N5246 JFET due to some quality problems with the 2N5163. The 2N5246s are still available and manufactured. Other JFETs will work here, too. I've tried some NTE equivalents for the 2N5163 which seemed to work fine. They are more expensive than the 2N5246s though and the 2N5246 is "vintage" :)

*************UPDATE****************************
It looks like the 2N5246 is being discontinued. Mouser still has stock as of this update, August 26, 2011 but they may get hard to find. I have some extras, so if you need some let me know and maybe we can work out a deal.
**************************************************

For a Unijunction Transistor (UJT), I found a 2N4871 or an NTE6409 work best. I've tried several different ones and they don't work with the values Nyle specified. The original was a 2N4891, but they are out of production. You can get both parts at Newark/Farnell.

There is a caveat. In the Sequencer, the NTE6409 saturates at high rates, so the 4871 is best. In the Trigger Generator, the 4871 stops oscillating at about 9 o'clock on the rate knob, about a 4 second rate. The 6409 works to full CCW on the Rate knob and about 10 to 20 second rate.

Bottom line, you may have to try them both to get the performance you want. I haven't tinkered with the other modules which use a UJT, like the Sample & Hold. When I do, I'll put the results here and on the module page.

You can buy the 2n4891s at Nikko:

http://www.dalbani.co.uk

They are EXPENSIVE! But they seem to be the real deal. I bought and they seem to work fine.

Diodes

Nothing special, 1N4148s and 1N4001s in the power supply are fine.

Pots

Your choice for your panel. If you use the panel I laid out, the holes and spacing will work for the Alpha 12 and 16mm pots. The 16mm are the Alpha/Mouser 313 series. They are a good carbon pot. You can probably use nicer BTI, Bourns, etc. 9mm pots with "pot chiclets". It's your choice. For the Alco knobs, I'm using a solid, "screwdriver" shaft with solder lugs. Clearly, use pots which work with the knobs you want to use. This is only a guide.

For Mouser, you can order them like this:
313-1000F-25k       for a 25k linear pot
313-1500F-25k       for a 25k log pot

313-1000F-1M        for a 1Meg linear pot
313-1500F-1M        for a 1Meg log pot

The only deviation is on the Sequencer. After much thought and deliberation, I decided to PCB mount most of the pots. I originally had it all on one PCB, no panel mount pots. The board was too big for most it not all Euro cabinets. I re-did it as two main PCBs, the power PCB, and trigger converter PCB. I then also decided to PCB mount the pots to further conserve space.

I chose a Panasonic vertical mount pot. There may be others which fit the form factor. It seems to be a reasonable layout, though I haven't checked. Here are the Digikey and Panasonic part numbers.

Digi-Key P/N - P3G7503-ND
Panasonic P/N - EVU-F2MFL3B54

Trimmers

Use good trimmers, please, really on this PCB use good trimmers. A good Bourns multi-turn trimmer like Bourns 3296Y series will fit the pad layout and works well. The pads are in a "Y" shape, so be sure you check the PCB to make sure what you buy will work.

Here again, the original modules used single turn, carbon trimmers. You can get a Bourns model that will fit the pad pattern if you want to. They cost about as much as the nicer multiturn pots, though. It's a Bourns 3352H series has the appropriate pin spacing/configuration. The 3329H and 3329W series are sealed versions which will work, too.

For the panel mount trimmers, I made a little PCB chiclets like the ones above to make this easier. I suggest using a Bourns adapter, p/n H-83P. It has plastic 5/16 inch threads, so the hole is 0.3125 inches in diameter. It seems to work with any standard 3.4 inch multiturn trimmer. Insert the trimmer and push it til it snaps into place.

Another option is a Vishay part p/n 006-1-0 or 006-1-1, or 006-1-2, or 006-1-3. It depends on what type of shaft you want to have. These have a smaller, metal bushing. A 0.22 inch hole works fine. They are a bit smaller than the Bourns and about 3 times as expensive. $5.00 compared to about $1.50. If you use this one, I'd also recommend getting the Vishay trimmer adjustment tool. It's made to fit down the hole if you don't buy the adapter with a shaft. No Vishay part number. Mouser p/n 594-8T000.

The Bourns trimmers which work are the 3006 series. Easy to find.

The Vishay trimmers which work are the model 43P 3/4" 20 turn series. Easy to find.

Jacks

For the panel I laid out, a good 3.5mm or 1/8 inch jack will work. I use the Switchcraft 42A Tini-Jax true 1/8 inch jack. These are switched jacks and they work with 1/8 inch plugs and 3.5 mm plugs.

Switchcraft also makes a plastic bodied switched jack, 142AX which would work, too, but it is about 2 or 3 times the cost.

Mouser p/n 502-42A and 502-142AX

Plugs

You need plugs, too. While a 3.5mm plug will go into the Tini-Jax, it is a bit loose and you might get what I call "wiggle noise". Not fatal but annoying. If you are using teh true 1/8 inch Tini-Jax above, you need these. They come in black or red. I got mine at Mouser but I think DigiKey has them, too.

Mouser p/n 502-750, Switchcraft p/n 750 for Black
Mouser p/n 502-755, Switchcraft p/n 755 for Red

Patch Cord Wire

I'm not using shielded cable on the Synthasystem. So, I found a really good, flexible, test lead cable which works great.

Mouser p/n 565-6733-0, Pomona p/n 6733-0

Switches

There are several SPST, SPDT, pushbutton, and rotary switches in these modules. Use a good quality switch which fits your panel. For my panels, I use Mountain switches for the toggle and NKK for the push buttons and Electrocraft switches for the rotary switches.

Mountain:
108-1MS1T1B1M1QE-EVX       SPDT  ON - ON
108-0010-EVX                            DPDT ON - ON

NKK:
MB2011SS1W01                          SPDT ON - (ON)

You also need a button. There are different sizes and colors
AT407C                                          0.394 dia. RED

Electroswitch:
C5P0112N-A                                 2-12 pos/1 pole/1 section
C5P0206N-A                                 2- 6 pos/2 pole/1 section

Knobs

What good is an analog modular synthesizer without knobs? Not much if you ask me.

Alco make a knob that closely resembles the original used on the Synthasystem and other modulars. I think it must of been the only knob available. Anyway, they are nice looking and come in two flavors which work well on a Euro panel. There is a 19mm one with a skirt and a 16mm one without a skirt. The 16mm is about twice the cost of the 19mm one. I have no clue why.

I am using the one with the skirt for general knobs and the unskirted one for "other" pots. For example, on the VCO, I'm using a pot for the VC3 Var control and will outfit it with an unskirted knob. I'll use one on the VC Var Adj pot on the VCF, too.

These knobs have a brass bushing insert and setscrew. They are intended for a round shaft, but will work with the Panasonic pots on the Sequencer, too.

Tyco Electronics / Alcoswitch:
PKES60B1/4                    With skirt, 19mm diameter, 1/4 inch shaft
PKE60B1/4                      Without skirt, 16mm diameter, 1/4 inch shaft

PCB Connectors

I'm using some standard MTA connectors.

2 pin female (make sure you get the right ones for the wire size you are using):

Mouser: 571-3-640440-2
Tyco/Amp: 3-640440-2

2 pin male:
Mouser: 571-6404562
Tyco/Amp: 640456-2

3 pin female:

Mouser: 571-3-640440-3
Tyco/Amp: 3-640440-3

3 pin male:
Mouser: 571-6404563
Tyco/Amp: 640456-3

This is the crimping tool I bought to make the connections. You need the grip and the head.

http://www.mouser.com/Search/ProductDetail.aspx?R=58074-1virtualkey57100000virtualkey571-580741

http://www.mouser.com/Search/ProductDetail.aspx?R=58246-1virtualkey57100000virtualkey571-58246-1

Mouser p/n: 571-580741
Tyco/Amp: 58074-1

The head:

Mouser p/n: 571-58246-1
Tyco/Amp: 58246-1

Power Connectors

For the Power Cables, I used these connectors and tools:

Connectors

These are the right angle connectors
Mouser p/n: 571-3-640426-4
Tyco/Amp p/n: 3-640426-4

These are the straight connectors.
Mouser p/n: 538-09-50-3041
Molex p/n: 09-50-3041

Pins for straight connectors:

These are for 18 gauge wire
Mouser p/n: 538-08-50-0106
Molex p/n: 08-50-0106

Crimping:

This tool will crimp the Molex pins for the 0.156 spaced straight connectors from 24 to 18 gauge wire. Worth every penny!

Mouser p/n: 538-63811-7500
Molex p/n: 63811-7500

This tool is for the right angle connectors. It uses the same grip as above and you only need one handle. It's a snap to exchange the heads.

Mouser part number: 571-580741
Tyco/Amp: 58074-1


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