Speaker switch

[lasse]

Hi all,

Really no big deal compared to the design of new systems but still….

Best regards//lasse
Stockholm, Sweden

[Billet]

I could use one of those, maybe I will build one someday also. I like the look of the metallic toggle switches...

[Wolf]

Make sure you switch only when the signal is stopped with this type of switch, and that it is a break before make type of switch. There are no safeguards present in this box.
When I built the relay-driven box for 3 pairs, I made sure I had safeguards in place. I also had a lot of help with it.

There should be a Boucherot cell across the input side on both channels, about 0.1uF and 10 ohms. I used a 0.047 and 12 ohms in case another Boucherot would be present in the chain. This loads the amplifier when no speaker load is present during switching.
I added an avalanche device across the outputs, similar to MDC Z131-20UL. This is to prevent inductor arcing during a stored voltage spike if switching while signal is running.
Contacts should be as low resistance as possible, so use the highest amperage switches you can.

Do not run this with a tube-amp.

Later,
Wolf

[lasse]

Make sure you switch only when the signal is stopped with this type of switch, and that it is a break before make type of switch. There are no safeguards present in this box.
When I built the relay-driven box for 3 pairs, I made sure I had safeguards in place. I also had a lot of help with it.

There should be a Boucherot cell across the input side on both channels, about 0.1uF and 10 ohms. I used a 0.047 and 12 ohms in case another Boucherot would be present in the chain. This loads the amplifier when no speaker load is present during switching.
I added an avalanche device across the outputs, similar to MDC Z131-20UL. This is to prevent inductor arcing during a stored voltage spike if switching while signal is running.
Contacts should be as low resistance as possible, so use the highest amperage switches you can.

Do not run this with a tube-amp.

Later,
Wolf

Hi Wolf,

Lots of info in your post that is new to me.

Perhaps lots of people are interested in this so please, can you post schematics on your switch?

But, bu the way. In a ordinary amp with two speaker pairs outputs, is there more components than a switch comparable to my build?

Regards//lasse

[Wolf]

Typically, there are relays that kick on and off in an amplifier with A and B switched channels, at least nowadays.

https://techtalk.parts-express.com/forum/tech-talk-forum/68689-wolfy-s-3-pair-speaker-switch

Later,
Wolf

[Wolf]

If you want to see the images cleanly, look here:

https://www.diyaudio.com/community/threads/switch-for-a-b-speaker-test.313177/#post-5206523

Wolf

[neildavis]

Wow, this topic never dies .

One of the volume-compensated speaker switchers that I made about 20 years ago died, and it was no longer repairable. The flex cable going to the LCD display put too much pressure on the 30-pin connector and ripped traces off the board. That was a custom CPU board with a 6801-series microprocessor with code written in assembly language. Obsolete board with obsolete code...sigh.

I made a replacement CPU board that uses an ESP32 and re-wrote all the code using the Arduino IDE. Also, I replaced the LCD with one of those Nextion displays. The Nextion display looks nicer:



However, with the ESP32 you can control the relay boxes using a cell phone app and Bluetooth BLE. I got a TCLA30 cell phone at Walmart for $20, and that is the remote control. It still has an IR remote control, but the cell phone is far nicer. This is a screenshot of the Android app design:




This is still a custom design using an DIY PGA4311 board layout. And the relays are in separate boxes, connected to a serial cable attached to the controller. But it might be nice to come up with a variant that uses one of those PGA2311 preamps that you can buy for around $70, and to use a wireless connection to the relay boxes. That would require some major changes to the code, but a lot of the code in this updated controller could be reused. I'm not going to make one, but if someone wants to give it a try, I'll gladly provide this Arduino and Android Studio code.

[neildavis]

Controller with relay boxes before update