New input/output Selector

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From looking at the wiring diagram I assume I am suppose to connect the the grounds of the Left & right channel together and the run a single wire from them tto the board. Is that right?

Something like this??
 

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Hi :D

I'm upgrading the speakers for my DIY system nº2 (activelly biamped) and they are so efficient that I needed a preamp (formerly using active crossover's attenuator as pre) plus a source selector. I added a Kookaburra and a Darwin inside the CX' box. After a few inconvenients due to my lack of study of the diagrams...:guilty: I managed to make it work, but, I got an annoying buzz that made me separate preamp+source selector from active CX: now I got a silent, fully functional unit :cool: and I can listen at lower level and avoid spouse's recrimination :cannotbe:

As all tweastedpearaudio's units, they came brilliantly packaged and labeled. Building of Kooka (my second) was a breeze. I had a few troubles with Darwin connections due to lack of expertize and care, as I confessed before...anyway, it took me a day or two to build the preamp-selector into a complete, one box unit.

Want to see my "little" new speakers?:

my.php


Russ and Brian, you are spoiling us :mad:
Cheers
M
 
Can output section be used separately

Russ, I was thinking to use the output section of Darwin for switched outputs after Xbosoz and Joshua Tree (with the input section before Xbosoz).

But it seems that it would make a ground loop in Darwin board (inputs and outputs have common ground according to shematic), so maybe it should not be used that way ?

Even otherwise the ground would be quite same, but can be arranged as star ground. Maybe there is no problem, I am quite a beginnger in DIY.
 
Re: Can output section be used separately

khaho said:
Russ, I was thinking to use the output section of Darwin for switched outputs after Xbosoz and Joshua Tree (with the input section before Xbosoz).

But it seems that it would make a ground loop in Darwin board (inputs and outputs have common ground according to shematic), so maybe it should not be used that way ?

Even otherwise the ground would be quite same, but can be arranged as star ground. Maybe there is no problem, I am quite a beginnger in DIY.


Hi,

It is a good question.

The Darwin is designed to be used with common GND (a very common technique for source selectors) if you use one PCB for both channels.

It is also designed to you can use one PCB per channel and switch GND as well as hot. This would be the same as when using the Darwin for balanced operation, but GND would be connected where the inverted signal would be, and you would not connect GND to the normal GND location.

Cheers!
Russ
 
This input selector uses a 6-way rotary switch to select the input but I really want to use momentary switch(es).

Does anyone know a circuit/IC that could enable me to use a single momentary switch to cycle through the inputs in a loop fasion?

I'm not even sure how to google for such a thing...
 
Re: Re: Can output section be used separately

Russ White said:

It is also designed to you can use one PCB per channel and switch GND as well as hot. This would be the same as when using the Darwin for balanced operation, but GND would be connected where the inverted signal would be, and you would not connect GND to the normal GND location.

Yes I understand that but in the schematic all input/ouput header pins number 2 are connected even without the loop jumpers ? I think that the problem is this direct connection between input and output sections and a loop comes by going from loop jumpers to xbosoz and jt and back again.

I will use balanced operation, one board per channel. Well, I really dont need the switched outputs, I will just leave the output section unused.

One more question: in Control Wiring Diagram there is "Ground from Power Source" in the switches, but "+5V from Power Source" in the IDC connector, is one of those wrong ?
 
maxw said:
This input selector uses a 6-way rotary switch to select the input but I really want to use momentary switch(es).

Does anyone know a circuit/IC that could enable me to use a single momentary switch to cycle through the inputs in a loop fasion?

I'm not even sure how to google for such a thing...


The switch is only one way to control the Dawrin. Darwin is meant to be a building block PCB which will be used later with a more in depth controller.

We thought many people would like to try to build their own controllers. You could use an 18 - 20 pin PIC to control the Darwin pretty easily. Even without driver transistors. I would look at the PIC 16F690 or something similar. The PCB would be pretty simple, but you could really do such a circuit on protoboard without much problem.

If I ever get to were I can build something again here soon (after my move) I will be developing an "uber controller" that will control the Darwin and the JT with rotory encoder and remote control, as well as have some other options.

Have fun!

Cheers!
Russ
 
Re: Re: Re: Can output section be used separately

khaho said:


Yes I understand that but in the schematic all input/ouput header pins number 2 are connected even without the loop jumpers ? I think that the problem is this direct connection between input and output sections and a loop comes by going from loop jumpers to xbosoz and jt and back again.



The "loop" is there to inject something like a preamp. The outputs are there to go so some other amp (like power amps) that would share exactly one source and the loop.

The loop can simply be a jumper in which case the two outputs will be direct connected to a single selected source. The two outputs can either be on or off, but they must in order to share input be tied to a single signal(s) since they are sharring a common source.

The best place to put your preamp is in the "loop". Connect the side of the loop coming from the input to your preamp(with JT), then the output of the premp to the side of the loop connected to the two outputs. You can then switch between power amps or run two at the same time (say for biamping or multi room).

I hope that makes it more clear. :)

Cheers!
Russ
 
More directly, there is no way I can see to avoid connecting with a common GND for balanced circuits unless you use three pole relays :xeye: or three single pole relays, which would be a lot of relays....
As an example I am using the Darwin to select between balanced sources with a balanced preamp (twisted sibling) and two balanced power amps (LM3886 SuSy, and a super secret SuSy chipamp ;)) with no problems at all. Certainly no humm or anything that would indicate a problem with the shared GND.

Cheers!
Russ
 
Russ White said:
More directly, there is no way I can see to avoid connecting with a common GND for balanced circuits unless you use three pole relays :xeye: or three single pole relays, which would be a lot of relays....
As an example I am using the Darwin to select between balanced sources with a balanced preamp (twisted sibling) and two balanced power amps (LM3886 SuSy, and a super secret SuSy chipamp ;)) with no problems at all. Certainly no humm or anything that would indicate a problem with the shared GND.
Ok, thanks! Maybe newcomers just become afraid ot grounding issues in forums like this, nearly always problems seem to be humming and nearly always grounding is suspected to be the problem.
About my other question: can the IDC connector +5V used in the switches (even said to be ground in the diagram) or do I have to do separate ground wires and leave the +5V unconnected ?
 
khaho said:
About my other question: can the IDC connector +5V used in the switches (even said to be ground in the diagram) or do I have to do separate ground wires and leave the +5V unconnected ?


The +V should come from some power supply. It is common to all the relay coils. Each relay's negative pin goes to a control pin on the IDC connector, which in turn is switched to power GND (not signal GND) via the rotary switches. You don't connect +5V to anything else but the +5V pins on the IDC connector. :) The key here is that the +5V is common and the switches switch to GND.

Cheers!
Russ
 
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