Dizzy advice

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Blake Smith
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Dizzy advice

Post by Blake Smith » Mon Sep 04, 2017 5:41 am

I'm wondering if anyone has some insight into the best way to get multiple dizzy boards running off of a single power supply.

Currently I have a Power One Universal power supply running to the 4 connection terminal block of a single Dizzy, but I'm at the point where I've used all 12 connections and will need another distribution board to plug anything else in. There is lots of headroom on the PSU, the current draw is about a third of its rating.

Thanks.

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Synthbuilder
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Post by Synthbuilder » Mon Sep 04, 2017 6:57 am

Try to take the power for each Dizzy direct from the power supply. Do not daisy chain Dizzy boards. This may mean having multiple wires coming from the power supply's terminals - two is possible but three gets awkward.

Use the shortest and thickest wires you can to connect the power supply to the Dizzy. Any Dizzy should really be no more than a few inches away from your power supply to keep the connection wires' lengths as short as possible.

If you need more than two Dizzies or you can't get your wires onto the PSU output terminals then take a single set of short thick wires to a faston block like this:

Image

The power supply connects to this with very short thick wires terminated in 1/4" faston crimped connectors. Then each Dizzy connects to the faston block also with 1/4" faston connectors. It is imperative that the wires which go to the block and the Dizzies are kept as short and thick as possible.

If the wires going to the distribution hubs are too long then significant voltage drops will occur across them. This can, and usually does, cause crosstalk between modules. That is, a VCO may sound like its being modulated by a LFO even though its not patched up to do that.

Tony

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Leverkusen
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Post by Leverkusen » Mon Sep 04, 2017 7:07 am

Synthbuilder wrote:
The power supply connects to this with very short thick wires terminated in 1/4" faston crimped connectors. Then each Dizzy connects to the faston block also with 1/4" faston connectors. It is imperative that the wires which go to the block and the Dizzies are kept as short and thick as possible.

If the wires going to the distribution hubs are too long then significant voltage drops will occur across them. This can, and usually does, cause crosstalk between modules. That is, a VCO may sound like its being modulated by a LFO even though its not patched up to do that.

Tony
Good to know and right in time - does this mean it is okay to have longer wires from the dizzy board to the individual modules then, in a bigger case?

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Synthbuilder
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Post by Synthbuilder » Mon Sep 04, 2017 7:25 am

Leverkusen wrote:does this mean it is okay to have longer wires from the dizzy board to the individual modules then, in a bigger case?
The Dizzy to module wires should be the longer. They only have to take the current for that module and NOT every module connected to that Dizzy. So voltage drops along the module cables will be smaller for a given length of cable. That said, they shouldn't be any longer than they need to be.

As an example, the voltage output of the midiDAC will drop relative to the PSU's 0V when either of the gate or slide LEDs light up. The longer the power leads the bigger the drop. If the drop across the 0V lead exceeds a mV then you'll probably notice the pitch of a connected VCO slightly change as the LEDs turn on and off.

Power leads should be as thick as can be, and as short as can be.

Tony

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Leverkusen
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Post by Leverkusen » Mon Sep 04, 2017 9:21 am

Thanks for the support - sounds logical and I'll keep it in mind. :tu:

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Paradigm X
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Post by Paradigm X » Mon Sep 04, 2017 9:50 am

Yeah thanks i was going to post a similar query. I assume the same applies when connecting grounds to different cases with a banana plug? i.e. thicker the better?

i got a load of 4 core electrical power cable from a building site which i assumed would be good enough?

thanks

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Synthbuilder
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Post by Synthbuilder » Mon Sep 04, 2017 12:36 pm

Paradigm X wrote: I assume the same applies when connecting grounds to different cases with a banana plug?
Yes. I find a single banana lead is enough but I've not ever had to connect some of these vast systems that people are building up these days.

But yes the rule of thumb is connect your 0V together with the lowest resistance you can get. That means either thick cable or multiple thinner cables.

And get good banana plugs too. The ones they use on speaker cables will be better than the ones with just one sprung contact.

Tony

Blake Smith
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Post by Blake Smith » Tue Sep 05, 2017 8:30 pm

Thanks for the detailed info. I'll see if I can get a second set of wires on the terminal. Once the second dizzy is maxed out it think its time for another power supply. I understand its a good idea not to load up the PSU 100% and 24 modules is probably enough for a single cabinet ergonomically speaking.

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