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Question about Eurorack dimensions & power supply standa
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author Question about Eurorack dimensions & power supply standa
D33K
I'm interested in building some of my own Eurorack modules but have some questions about why things are why they are. Coming from a computer background, modular synths feel like the wild west and I really like that. I also discovered 500 series audio gear and really like the backplane implementation; you can just slide modules in and out without having to plug in a ribbon cable. Does anyone know why eurorack doesn't incorporate a static backplane or something similar? Not saying it's bad, just asking out of curiosity. I do like Eurorack's use of idc ribbon because the fingers on a 500 series module would be prone to wearing/oxidiation, vibration, etc...

Also does anyone know why the 500 series industry didn't just use eurorack dimensions? 500/frac rack is 133.35 vs euro's 128.5
ersatzplanet
Basically it is a cost thing. To use a backplane all the PCBs in the modules have to be the same depth to reach it. There are many modules in systems today whose circuitry is so small that the unused PCB space would be rather large. Also a backplane requires modules to be a certain width to connect into those sockets on the backplane and to use the slotted bits to align them into. Backplanes make for a great computer or test setup but are too restrictive for the flexibility of modular synthesizers.
Graham Hinton
D33K wrote:
Does anyone know why eurorack doesn't incorporate a static backplane or something similar?


Eurorack is a tiny subset of the Eurocard standard or IEC 60297 (formerly DIN41494) which is widely used in industrial electronics. I doubt if the early adopters were really familiar with this standard and all the options, they just took what they needed at the time (the front panels) and ignored the rest.

It isn't just a straight choice between loose wiring and backplanes. There are a wide variety of DIN 41612 connectors, from 16- to 96- ways, that mount on rear rails on a 1HP pitch and they come in pcb, wire wrap and individual crimp contact types. The H11 and H15 types take faston connectors directly and may be used for plug in PSUs. There is a lot of flexibility, it's like Lego.

The good thing is that you can mount Eurorack modules in a Eurocard frame. Just not the other way around.


Quote:

Not saying it's bad, just asking out of curiosity. I do like Eurorack's use of idc ribbon because the fingers on a 500 series module would be prone to wearing/oxidiation, vibration, etc...


Again, it's not a simple binary choice. Neither are particularly good. Using edge connectors puts the price of pcbs up because they need gold plating. DIN 41612 connectors are indirect.

All connectors are subject to wear, the gold plating is rated for a minimum number of mating cycles, 25, 50, 250, etc. You choose the one suitable for the application.

Quote:

Also does anyone know why the 500 series industry didn't just use eurorack dimensions?


500 series is a proprietary US standard where IEC 60297 is not widely used. They re-invented the wheel and made it square. 500 series is limited by the connector definition to a simple signal path and there is not enough I/O on it. That's why you get a Moog VCF module that you can't VC.

The trouble with proprietary standards is that you have to get all the metalwork custom made and that puts the prices up or the quality down. Eurorack adopted Eurocard panels precisely because all the metalwork existed as standard catalogue parts. In turn this caused the Eurorack explosion because anybody can make a module with just a pcb and a panel and not have to worry about the rest.

Quote:
500/frac rack is 133.35 vs euro's 128.5


133.35mm is 3U with no clearance. 128.5mm is 3U with clearance and a lip on the rail. Making panels with no clearance means that a fit is not guaranteed.
whinger
Sorry to hikack the thread, just wanted to thank you Graham Hinton for all the amazing advice throughout the years. I always learn something when I read your posts (I don't always retain it, but I do learn something each time). Thanks for taking your time to educate people on the forum, it's appreciated.
dubonaire
Graham Hinton wrote:
D33K wrote:
Does anyone know why eurorack doesn't incorporate a static backplane or something similar?


Eurorack is a tiny subset of the Eurocard standard or IEC 60297 (formerly DIN41494) which is widely used in industrial electronics. I doubt if the early adopters were really familiar with this standard and all the options, they just took what they needed at the time (the front panels) and ignored the rest.


Well according to Dieter Doepfer who was not so much an early adopter but the creator of Eurorack, he consciously chose to replace (in his words) "the ridiculously expensive bus boards and inflexible circuit board sizes used by the industry (Euro-Format 100x160mm) with a less expensive and more flexible bus/circuit board system. That allows the circuit board size to vary from module to module."

So, as ersatzplanet says, it was a cost thing. It wasn't done in ignorance. And when looking at where Eurorack is today it might never have got to this if it wasn't for Doepfer's lower cost but arguably technically inferior business decision. Hindsight is a wonderful thing, and in hindsight, there might never have been Eurorack without Doefper making that design decision.
Rex Coil 7
*Marrs = SPAMBOT!!! KILL THE SPAMMER!!!
FraMauro
Marrs wrote:
Eurorack adopted Eurocard panels precisely because all the metalwork existed as standard catalogue parts.


Interesting, I didn't realise that, thanks.
dubonaire
FraMauro wrote:
Marrs wrote:
Eurorack adopted Eurocard panels precisely because all the metalwork existed as standard catalogue parts.


Interesting, I didn't realise that, thanks.


But not true.
Graham Hinton
dubonaire wrote:
Well according to Dieter Doepfer who was not so much an early adopter but the creator of Eurorack,


Early adopter of IEC 60297, like Analogue Systems and Analogue Solutions.

Quote:
he consciously chose to replace (in his words) "the ridiculously expensive bus boards and inflexible circuit board sizes used by the industry (Euro-Format 100x160mm) with a less expensive and more flexible bus/circuit board system. That allows the circuit board size to vary from module to module."


That statement as it stands (albeit quoted out of context) shows unfamiliarity with the system and makes false assumptions. IEC 60297 does not define any bus boards, only the positions of the connectors. It is other standards like VME or PXI or STE that build upon the mechanical standard and define their own buses. Yes, a multilayer backplane for high power and high speed, impedance controlled buses with 96-way connectors is expensive, but a double sided pcb with 16 way connectors would cost about the same as a Eurorack buscard except you could lose the ribbons and two connectors and not blow up modules by connecting in reverse.
100x160mm is called a single Eurocard, but there is a family of standard pcb sizes up and down and you can have non-standard sizes too.

Quote:
But not true.


That is just a contradiction with nothing to support it.
Doepfer's original 19" frames and the ones they make now are made out of standard parts. Maybe customised by the manufacturer, but neither Doepfer nor the ASes had to tool up for an extrusion or rack mounting angles. They had been in production already for around 20 years, with similar versions available from many manufacturers.
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