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DIY Audio switch for home automation

zuli

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I'm my current setup I'm using a manual switch to select what to route to the subwoofers, either the AVR's subwoofer outs or the RCA out from the DAC (see attached schema).
When I want to switch between the AVR configuration and the stereo-roon configuration a need to select the correct source in the DAC and to select the correct source in the switch.
In an effort to simplify and automate the process to be family friendly, I was thinking to implement an audio switch that I can control via home automation. I was considering to use something like this https://www.amazon.it/gp/product/B06XRJ6XBJ , to be used either via an ESP8266 or via the GPIO of the Raspberry PI that I'm using for Roon.
Do you think that this can work? Are these relays good enough for audio applications? Do you have other suggestions?

This is the schema of my setup:
Impianto audio schema.001.jpeg
 

dualazmak

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Hello zuli,

It looks that the subwoofers are active ones with a built-in power amplifier, and it appears you will "switch" only the line-level signal for the subwoofer, not the speaker's power level signal; that would be OK, in generally speaking.

As long as the "relay switch" has no (or minimal) magnetic negative effect on the line-level signal, I think this plan would be no problem. However, I do not know the level of negative magnetic effects due to the specific "relay switch" you would like to use. I also don't know how sensitive your audio system would be to such subtle magnetic effects due to relay switches. As you only deal with low Fq subwoofer line level signals, I assume it would be OK.

Anyway, good luck for your building the system with the relay switch!

Just for your reference, I very carefully avoid magnetic materials in speaker power level handling/wiring as I shared here and here;
I wrote there; Later, I found/learnt that most of the "Multi-Terminal Electromagnetic Relays" and "Multi-terminal Snap-Toggle Switches" for AC or DC power levels contain small but strong magnets in the contact terminal block for the purpose of "escaping" the possible electric arcs when operating at rather high voltage and current. I blieve these tiny magnets would significantly deteriorate the speaker level sound signals which should be fully avoided/eliminated in our HiFi audio speaker cable handling.

We also well know that many (all) of the HiFi amplifier manufacturers carefully avoiding as much as possible magnetic materials (including magnetic relays, magnetic screws, magnetic terminals) in the signal handling in line level as well as SP power level.
 
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somebodyelse

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I'd be looking for something with some signal relays rather than power relays. You'll probably be able to find something being sold as a relay input selector module for preamps. Depending on what you find you may be able to drive it directly from the Pi/ESP or you might need something like a ULN2003 in between. It shouldn't be too hard to make one on stripboard either.
 

dualazmak

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Looks nice, good luck!

I do hope these will give no (or negligible) negative effect on your audio signals.

According to the product description, you may switch line level signal and also SP power level signal, since the output terminal capabilities are up to;
Rating of output contact (relay switch) for each switch:
For AC, 120V AC / 0.5A.
For DC, 24 VDC / 1.0 Amp.

As these Electronics-Salon relay boards having the Takamisawa relays can be also found in Amazon Japan, I would like to test these, if needed, in my audio project in the future.

I would highly appreciate hearing about your progress and results, including the sound quality, in your project with these relays.
 

LTig

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As long as the "relay switch" has no (or minimal) magnetic negative effect on the line-level signal, I think this plan would be no problem. However, I do not know the level of negative magnetic effects due to the specific "relay switch" you would like to use. I also don't know how sensitive your audio system would be to such subtle magnetic effects due to relay switches.
Would you mind to explain how a static magnetic field created by the magnet in a relay influences AC signals running through the switches of said delay?
 

phoenixdogfan

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How about switching between zones in JRiver Media center? There are supposedly decision rules you can give J River to automatically switch between or among zones. Anyone have any information on how that's done?
 

dualazmak

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dualazmak

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How about switching between zones in JRiver Media center? There are supposedly decision rules you can give J River to automatically switch between or among zones. Anyone have any information on how that's done?

Hollo phoenixdogfan,

I am sorry but I do not understand your thoughts; the thread owner zuli just would like to physically switch the common subwoofers in his system-A and System-B...
 

LTig

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Let me just suggest you to visit the specific thread entitled "Electromagnetic Interference in Speaker Cables? (video)" where I also partly participated here and here, and thereafter.

And my stance on this issue was posted here...
I've already read quite a bunch of all these threads before I asked here because I could not find an explanation how a static magnetic field created by the magnet in a relay influences AC signals running through the switches of said delay.
 

TomekNet

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Do you have other suggestions?

You might use two Shellies 1 that have dry contact relays. You may easily control them with home automation with http API or MQTT, but also with Harmony Hub - with an addition of habridge instance.
 

Weeb Labs

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I'm my current setup I'm using a manual switch to select what to route to the subwoofers, either the AVR's subwoofer outs or the RCA out from the DAC (see attached schema).
When I want to switch between the AVR configuration and the stereo-roon configuration a need to select the correct source in the DAC and to select the correct source in the switch.
In an effort to simplify and automate the process to be family friendly, I was thinking to implement an audio switch that I can control via home automation. I was considering to use something like this https://www.amazon.it/gp/product/B06XRJ6XBJ , to be used either via an ESP8266 or via the GPIO of the Raspberry PI that I'm using for Roon.
Do you think that this can work? Are these relays good enough for audio applications? Do you have other suggestions?

This is the schema of my setup:
View attachment 125947
Those relays will work perfectly for your application in conjunction with an ESP. You could either make use of the Wemos protocol emulation library, Tasmota or ESPHome in the event that you also have an instance of HASS running.
 

dualazmak

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I've already read quite a bunch of all these threads before I asked here because I could not find an explanation how a static magnetic field created by the magnet in a relay influences AC signals running through the switches of said delay.

Hello LTig,

I read your inquiry as "I've already read quite a bunch of all these threads before I asked here because I could not find an explanation how a static magnetic field created by the magnet in a relay influences AC signals running through the switches of said relay."

Please understand that the followings are just my speculations as I am not an expert in these physics and theories ...

The static magnetic field given by rather strong permanent magnet or strong electromagnet (with coils) existing very near to the audio signal wires would be not fully static against the audio signal because of AC "electromagnetic induction" interaction, and may give audible negative effect, i.e. blurriness and/or uncleanliness, to the audio signals.

It would be also possible that in these relays with strong permanent magnet or strong electromagnet consist of magnetizable metals (contact plates, screws, housing, etc.), and such magnetic metals, together with the environmental strong static magnetic field may give audible negative effects to the audio signals.

About two years ago, I tentatively tested this type of (X-Y X-Z 4-terminal) snap (toggle) switch in my speaker level signal handling;
WS001528.JPG

I could purchase two different brand ones (switch-A and switch-B) of exactly same functionality, i.e. X-Y X-Z 4-terminal, for AC/DC toggle switching, up to "15A 250V AC/0.5A 250V DC/0.9A 125V DC/15A 30V DC", consists of magnetizable metal plates and magnetizable screws (which I can catch with magnetized screwdriver). Both of the switch-A and switch-B gave considerable negative effect to the audio signal which not only myself but also my wife could hear the sound deteriorations, blurriness and uncleanliness, and we found such negative effect was apparently more obvious with switch-A compared to switch-B.

In any way, I abandoned to use this type of toggle switches with magnetizable metals in my audio project in handling of speaker level signals, and I went back to use all non-magnet metal terminal strips (barrier strips) and non-magnet screws as shared in my specific post.

Then I contacted with the both manufacturers for the details of the specification and design of the switches, especially the use of tiny strong permanent magnet in it or not, and I fould very interestingly that switch-A (expensive one) contains small strong Neodymium magnet in it (for the purpose of maximum escape of the possible electric arc discharge in case of high voltage operations), on the other hand, switch-B (cheaper one) has no such magnet in it.

Furthermore, even for the simple screw terminal strips (screw barrier strips), the cheap magnetizable ones always give audible negative effect to the audio signal, while non-magnet audio grade strips (comparably rather expensive though) with non-magnet plate and non-magnet screws give no negative effect at all.

Please understand that the above findings are my empirical experiences, and I have no capabilities in giving physical and/or theoretical explanations or evidences for that.
 
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Weeb Labs

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This is an interesting idea but I'm afraid it is incorrect and there is no mechanism by which the phenomena described could occur. Below, you will find two null tests. The first is a control test, wherein a piece of music is recorded twice via loopback through my Motu M4 interface. The second is a test wherein one loopback recording is made with a powered relay in series and another without.

Control:
completelywithoutrellllay.PNG



Primary test:
test1.PNG


Note that the null depth remains essentially identical in both the control and primary tests, regardless of the presence of a powered, permanent magnet relay. Here is a photo of the relay used.

relay.jpg


In conclusion, any perceived deterioration of audio quality is purely psychological.
 
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dualazmak

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Hello Otaku+,

I understand your point and your results.

I (we) repeatedly experienced, however, the audible negative effect of magnetizable metals (and permanent strong Neodymium magnet) very near beside the speaker level wiring; I also have done several quasi-blinded AxB tests with my audio friends...

If I can find some relaxing time in the near future, I would like to test the audio-grade switching board which the thread owner zuli would like to use in his system.

I believe any further discussion on physical and/or theoretical explanations/background would not be suitable on this thread of zuli. If needed, we may better to discuss this (endless?) issue on the specific thread entitled "Electromagnetic Interference in Speaker Cables? (video)".
 
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LTig

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LTig

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I (we) repeatedly experienced, however, the audible negative effect of magnetizable metals (and permanent strong Neodymium magnet) very near beside the speaker level wiring; I also have done several quasi-blinded AxB tests with my audio friends...
If you would claim to hear a negative effect in case of a relay which switches the signal of a low output MC phono cartridge and the coil of the relay is fed with AC you might have a point. But with speaker signal strength (high voltage, very low output impedance) any influence of the relay is utter inaudible. You should check whether the conditions used in the quasi-anechoic blind AxB test you mentioned were good enough to get valid results.
 

dualazmak

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Agreed, but please open a new thread because it is not about cables but about relays/switches. Like "Audible influence of magnets in switches and relays"?

If you would claim to hear a negative effect in case of a relay which switches the signal of a low output MC phono cartridge and the coil of the relay is fed with AC you might have a point. But with speaker signal strength (high voltage, very low output impedance) any influence of the relay is utter inaudible. You should check whether the conditions used in the quasi-anechoic blind AxB test you mentioned were good enough to get valid results.

Hello and thank you, Ltig,

After I have provisionally completed the long journey and intensive exploration of my multichannel multi-driver multi-amplifier project having my (personal?) solutions for this issue of negative magnetic effect (or negative magnetizable metal effect) on SP level signals, at least for the coming half year or so, I would like to go back to enjoy my beloved "music", not the physical "sound", while fully fine-tuning the completed system. This is why I started my new thread on lute music for which I am now rather concentrating myself.

Of course, I am still maintaining and responsible my multichannel thread since so many people daily visit there; the number of visits and views already exceeded 55,000 times as you may find in the statistics page.

I also become considerably busier in my main missions related to the vaccination for COVID-19 pandemic in Japan...

At present, therefore, I am rather reluctant in starting new technical/engineering thread which you kindly suggested. Your kind understandings will be highly appreciated.

In case if you or Otaku+ would kindly start such new thread by referring to my post #13 above, I would be happy to participate it with sharing my empirical experiences and further thoughts/speculations.
 
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LTig

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Hello and thank you, Ltig,

After I have provisionally completed the long journey and intensive exploration of my multichannel multi-driver multi-amplifier project having my (personal?) solutions for this issue of negative magnetic effect (or negative magnetizable metal effect) on SP level signals, at least for the coming half year or so, I would like to go back to enjoy my beloved "music", not the physical "sound", while fully fine-tuning the completed system. This is why I started my new thread on lute music for which I am now rather concentrating myself.

Of course, I am still maintaining and responsible my multichannel thread since so many people daily visit there; the number of visits and views already exceeded 55,000 times as you may find in the statistics page.

I also become considerably busier in my main missions related to the vaccination for COVID-19 pandemic in Japan...

At present, therefore, I am rather reluctant in starting new technical/engineering thread which you kindly suggested. Your kind understandings will be highly appreciated.
Fair enough. But I would prefer that as long as this point has not been laid to rest you should not claim the effects as being true and proven. Just mention that these are subjective opinions.:)
In case if you or Otaku+ would kindly start such new thread by referring to my post #13 above, I would be happy to participate it with sharing my empirical experiences and further thoughts/speculations.
I'm also a bit too busy, so sorry for now.
 
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zuli

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Those relays will work perfectly for your application in conjunction with an ESP. You could either make use of the Wemos protocol emulation library, Tasmota or ESPHome in the event that you also have an instance of HASS running.
Yes, HASS integration is what I'm looking for.
I've different options:
1. ESP-01S + relay board
2. use the GPIO of the raspberry Pi that I'm using as streamer to control a relay board, using the HA integration for remote raspberry PI
3. use the GPIO of the raspberry Pi that I'm using as streamer to control a relay board, using the moode GPIO automations (no integration with HA)
4. use a 12V trigger (no integration with HA)

I would like also to control the Benchmark DAC input selection. The only external method is to use an IR blaster (eg Broadlink RM).
 
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