Many of us know the MiniDSP boards. Many of us have built DACs and have realised that we need an input selector, something which most DIY DACs don't seem to have.
Having built a system around the MiniDSP 4x10HD, I now realise that the only practical system "architecture" if you will, is to have a single box which has input selector, feeding to MiniDSP, and then do volume control at the output of the MiniDSP.
MiniDSP boards don't come with multiple inputs of each type. They come with at most one input of each type. I have a need for three digital audio inputs. Looking at other threads of 2004, 2007, 2011, it's clear that others have faced similar challenges with their DACs.
I'd like to build a single input selector using a mechanical rotary switch, so that I can select from a set of digital and analog inputs with a single knob. Ideally, I'd like to build something which lets me select from among:
How do I build something like this? Looking through old threads, I'm seeing suggestions to use
Any suggestions? Can you point me to anything more ready-to-use?
And any suggestions for which Toslink or SPDIF input modules to use? I was thinking of using this Toslink input module and this SPDIF input selector module as possible starting points.
Ebay is full of analog input selection boards, but nothing exists for digital inputs.
Having built a system around the MiniDSP 4x10HD, I now realise that the only practical system "architecture" if you will, is to have a single box which has input selector, feeding to MiniDSP, and then do volume control at the output of the MiniDSP.
MiniDSP boards don't come with multiple inputs of each type. They come with at most one input of each type. I have a need for three digital audio inputs. Looking at other threads of 2004, 2007, 2011, it's clear that others have faced similar challenges with their DACs.
I'd like to build a single input selector using a mechanical rotary switch, so that I can select from a set of digital and analog inputs with a single knob. Ideally, I'd like to build something which lets me select from among:
- Analog 1
- Analog 2
- Analog 3
- Toslink 1, Toslink 2, Toslink 3
- SPDIF 1, 2, 3
How do I build something like this? Looking through old threads, I'm seeing suggestions to use
- small signal relays
- 74HC125 quad buffers for selection
- 74HCU04 hex buffers for level translation
- 74LS153 for input selection
Any suggestions? Can you point me to anything more ready-to-use?
And any suggestions for which Toslink or SPDIF input modules to use? I was thinking of using this Toslink input module and this SPDIF input selector module as possible starting points.
Ebay is full of analog input selection boards, but nothing exists for digital inputs.
If I use the Twisted Pear 4-to-1 input selector and optical-to-electrical interfaces, there are a few doubts:
Is there any other kit available which I can look at?
- When I add the optical interfaces, will I need relays in between the SPDIF interface and the optical-to-SPDIF module to let the user select between optical and electrical?
- Can the 74HC125 chip be used as an alternative to relays?
- Do those modules do speeds higher than 48KHz? I couldn't find any mention of any speed spec in the pages about those modules.
Is there any other kit available which I can look at?
For nine inputs you would need a 9-way switch. Two poles for analogue, and one pole for digital (assuming separate toslink adaptors for each optical input). With careful wiring it should work.
Might be better to separate analogue and digital switching; this should make it easier to provide each type of switching with what it needs: well screened for analogue, short connections for digital. Then you need a 4-way 2-pole switch for analogue (3 inputs plus digital), and a 6-way 1-pole for digital.
Might be better to separate analogue and digital switching; this should make it easier to provide each type of switching with what it needs: well screened for analogue, short connections for digital. Then you need a 4-way 2-pole switch for analogue (3 inputs plus digital), and a 6-way 1-pole for digital.
Actually, I am willing to reduce the number of inputs. Each of us will have different levels of need about the number of inputs they need. Let's say, for the purpose of discussion, that we will work with a 6-way rotary switch, and do the best we can within it. Let's also assume that we'll use relays for analog switching, so we don't need two-pole switches... we will be able to switch 2 channels with a single-pole rotary switch.
Given this, what approach should we take? Do we need relays to select optical and coax? Do we use the 4-way selector board from Twisted Pear, is that suitable? Should we use the 74HC IC for switching instead of relays?
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Given this, what approach should we take? Do we need relays to select optical and coax? Do we use the 4-way selector board from Twisted Pear, is that suitable? Should we use the 74HC IC for switching instead of relays?
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You can switch SPDIF with a switch or relays or logic. You just need to avoid disrupting the 75ohm impedance too much, so connections need to be short and the signal and ground need to be kept close together. I would use a switch - but then I am used to doing RF stuff.
You can't switch optical with electronics. Convert it to electrical, then switch.
You can't switch optical with electronics. Convert it to electrical, then switch.
Great. Thanks for the details about SPDIF. As you can imagine, I have zero experience with all this.
I want to use relays and a rotary switch so that I can keep the analog signals far away from the digital. Maybe I can use relays just for the analog signals, and route the digital through the rotary switch?
About optical, I was thinking of using the optical-to-electrical modules offered by Twisted Pear Audio. I had given a link to that module in my first post in this thread. What do you think of them?
Sent from my Moto G (4) using Tapatalk
I want to use relays and a rotary switch so that I can keep the analog signals far away from the digital. Maybe I can use relays just for the analog signals, and route the digital through the rotary switch?
About optical, I was thinking of using the optical-to-electrical modules offered by Twisted Pear Audio. I had given a link to that module in my first post in this thread. What do you think of them?
Sent from my Moto G (4) using Tapatalk
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