First post on this forum... Hi everyone!
I want to build a device I call the 'AB/XY Switch Box'. Being my first DIY & soldering project, I want to use this thread to receive advice and help where needed. Please keep in mind I don't know all kinds of available electronical parts and lack knowledge in this field. So if you think something is not feasible, unnecessarily complicated or just wrong, please point it out.
First off, let me explain why I want to build it and what it does.
The situation:
Balanced XLR In-/Outputs everywhere.
2 Sources: DAC (A) and Phono-Pre (B)
2 Outputs: ADC (X) and Monitor Controller (Y)
The goal:
Routing 1:
B -> Y (Phono-Pre -> Monitor Controller) AND
A -> X (DAC -> ADC)
This is for directly listening to Vinyl, as well as for some tests (DAC-ADC loops).
Routing 2:
B -> X (Phono-Pre -> ADC) AND
A -> Y (DAC -> Monitor Controller)
This is for doing and monitoring needle drops.
This is an extension to the commercially available A/B switch boxes. By not connecting B or Y, my box would function like such a switch box.
I want the box to be passive with a single switch on the front plate.
Wiring scheme will be uploaded later.
Here are the first questions:
1) Which switch(es)?
I need 8 switches for the outputs + and -, X and Y, left and right channel, each having the corresponding A and B signal as inputs.
Afaik I'd need a 8PDT switch, but only found 4PDT.
Anyhow, wanting to prevent cross bleed, I think I should aim at 4 2PDT or even 8 1PDT. Contact material: I assume gold contacts are the best, non-corrosive choice.
2) How to passively throw multiple switches at once?
Assuming I'll have at least two switches in my box, how can I throw them all by one switch on the front plate? What I could think of so far is using some kind of (metal/3D print) bar connected to the xPDT switches and the main switch/lever on the front plate.
Cheers,
WheatKing
I want to build a device I call the 'AB/XY Switch Box'. Being my first DIY & soldering project, I want to use this thread to receive advice and help where needed. Please keep in mind I don't know all kinds of available electronical parts and lack knowledge in this field. So if you think something is not feasible, unnecessarily complicated or just wrong, please point it out.
First off, let me explain why I want to build it and what it does.
The situation:
Balanced XLR In-/Outputs everywhere.
2 Sources: DAC (A) and Phono-Pre (B)
2 Outputs: ADC (X) and Monitor Controller (Y)
The goal:
Routing 1:
B -> Y (Phono-Pre -> Monitor Controller) AND
A -> X (DAC -> ADC)
This is for directly listening to Vinyl, as well as for some tests (DAC-ADC loops).
Routing 2:
B -> X (Phono-Pre -> ADC) AND
A -> Y (DAC -> Monitor Controller)
This is for doing and monitoring needle drops.
This is an extension to the commercially available A/B switch boxes. By not connecting B or Y, my box would function like such a switch box.
I want the box to be passive with a single switch on the front plate.
Wiring scheme will be uploaded later.
Here are the first questions:
1) Which switch(es)?
I need 8 switches for the outputs + and -, X and Y, left and right channel, each having the corresponding A and B signal as inputs.
Afaik I'd need a 8PDT switch, but only found 4PDT.
Anyhow, wanting to prevent cross bleed, I think I should aim at 4 2PDT or even 8 1PDT. Contact material: I assume gold contacts are the best, non-corrosive choice.
2) How to passively throw multiple switches at once?
Assuming I'll have at least two switches in my box, how can I throw them all by one switch on the front plate? What I could think of so far is using some kind of (metal/3D print) bar connected to the xPDT switches and the main switch/lever on the front plate.
Cheers,
WheatKing
Normally you would use signal level relays for this purpose. This does require a power supply
for the relay coils, in the range of 5-12VDC. A wall wart would work.
You should either have two switches (one for the input and one for the output) or seriously consider using relays (as I did here https://theslowdiyer.wordpress.com/2017/03/01/switched-on/)
/U.
/U.
Nice blog, Nisbeth!
It seems instead of just soldering some wires between the Ins/Outs and a switch I'll need to add:
- power socket
- basic power supply (a small Power IRM PSU with Voltage matched to the relays coil voltage?)
- 4 DPDT or 8 SPDT relays (latching, any preferred contact material? mounting style? Switching Voltage >= 5 V for Line level?)
- custom PCB (pick software, design PCB)
A more generic question:
- What are the pros and cons of routing the signal on PCB vs. using cables (as in Nisbeth's linked project)?
A potential feature creep:
In order to do ABX-tests for Inputs or Outputs, I'd need to level match A to B (or X to Y). To stay in line level specifications, attenuation (no amplification) has to be applied to the louder of A/B or X/Y, depending on whether Inputs or Outputs are compared.
So my consideration: One (two) attenuators for A/B/X/Y (A/B and X/Y). I'll upload a new layout soon (and propably first find a proper software for that).
It seems instead of just soldering some wires between the Ins/Outs and a switch I'll need to add:
- power socket
- basic power supply (a small Power IRM PSU with Voltage matched to the relays coil voltage?)
- 4 DPDT or 8 SPDT relays (latching, any preferred contact material? mounting style? Switching Voltage >= 5 V for Line level?)
- custom PCB (pick software, design PCB)
A more generic question:
- What are the pros and cons of routing the signal on PCB vs. using cables (as in Nisbeth's linked project)?
A potential feature creep:
In order to do ABX-tests for Inputs or Outputs, I'd need to level match A to B (or X to Y). To stay in line level specifications, attenuation (no amplification) has to be applied to the louder of A/B or X/Y, depending on whether Inputs or Outputs are compared.
So my consideration: One (two) attenuators for A/B/X/Y (A/B and X/Y). I'll upload a new layout soon (and propably first find a proper software for that).
Here's an updated nicer basic schematic.
I still don't know which specific parts I should take, so I just use those with the desired functionality. For example I've taken some random PSU with a hot and cold side and the relays can be switched with some tbd voltage/current, connected either parallel (as pictured) or in series.
Here's my agenda:
1) Schematic 2: Add attenuation as mentioned in last post.
2) Schematic 3: Add ABX-function, short mute for switching.
3) Schematic 4: Try to add IR remote control / leave spaces where required for future addition.
4) Design PCB from schematic, review & improve layout.
5) Design front & back panel.
6) Finalize BOM, order everything, make it happen!
So for now I'm looking for a good attenuation solution which must be high quality and allow for 0.1 dB steps. I assume a lower figure of maximum attenuation will suffice if it's needed for achieving small steps.
ABX will likely happen with Arduino or sth similar. So far I've only read about this very briefly...
I still don't know which specific parts I should take, so I just use those with the desired functionality. For example I've taken some random PSU with a hot and cold side and the relays can be switched with some tbd voltage/current, connected either parallel (as pictured) or in series.
Here's my agenda:
1) Schematic 2: Add attenuation as mentioned in last post.
2) Schematic 3: Add ABX-function, short mute for switching.
3) Schematic 4: Try to add IR remote control / leave spaces where required for future addition.
4) Design PCB from schematic, review & improve layout.
5) Design front & back panel.
6) Finalize BOM, order everything, make it happen!
So for now I'm looking for a good attenuation solution which must be high quality and allow for 0.1 dB steps. I assume a lower figure of maximum attenuation will suffice if it's needed for achieving small steps.
ABX will likely happen with Arduino or sth similar. So far I've only read about this very briefly...
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