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I'm switching audio signals (line level) with a solid state relay board (Keyes - 8x Q3MB-202P), but when I switch off one channel, it takes some milliseconds (maybe around 500ms to 2 seconds) to really stop the signal flow. I believe this happens due to either a capacitor or an inductor (I think it's an inductor) that's in the board, so I was wondering if I could remove (unsolder) one of these components from the board and make the switching off more precise.

I don't have an individual piece of a Q3MB-202P, but I believe this wouldn't happen with the individual piece. This is probably caused by the board circuitry, which does that for integrating LEDs or for some safety reasons which I don't mind sacrificing. I couldn't find a schematics of this board, but probably someone will know by the picture.

Attached are pictures of the board. What I have referred as inductor is the green piece (F), but I'm not sure if I'm right. In this piece it's also written 2A (or 2AE, it's not very legible).

enter image description here enter image description here

Note 1: the reason I'm switching signals with Solid State Relays is because I need low resistance. I'm avoiding using a IC (like 4066) as it has too much resistance for my audio signals and then the sound is too quiet.

Note 2: I don't want to use a mechanical relay to avoid the click noise.

Note 3: I don't have individual pieces of Solid State Relays (Q3MB-202P) and I don't have the time to buy them now. I need to sort out this problem quickly for a project as the deadline is in 3 days.

I really appreciate any help!!! Thanks!

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    \$\begingroup\$ I'm sorry, but solid state relays are simply the wrong tool to switch audio. Don't ask us to fix a circuit that is broken by principle. Your's broken by principle, because these SSRs come with a zero-crossing detection, which is probably what causes your delay. What you say about "too high resistance" makes no sense for line-level signals – the receiving end's impedance would typically be sooo much larger, that a small series resistance doesn't make any difference. But: SSRs definitely weren't designed for audio bandwidths.So, your approach is based on false claims and the wrong components. \$\endgroup\$ – Marcus Müller Jun 25 '17 at 19:16
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    \$\begingroup\$ Then your "line-level" signal is not what audio techs would call line-level. There's dedicated audio switch ICs (many!). Use these. There's not a single inductor nor a single capacitor in your photos. \$\endgroup\$ – Marcus Müller Jun 25 '17 at 19:24
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    \$\begingroup\$ "you bet" <--- says someone without any experience, contradicting the people he asked for their experience, that say otherwise. You can't be helped if you don't want to listen. \$\endgroup\$ – Marcus Müller Jun 25 '17 at 19:28
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    \$\begingroup\$ If it connects directly to a 1W speaker it is not "line level". \$\endgroup\$ – Spehro Pefhany Jun 25 '17 at 19:28
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    \$\begingroup\$ I explained why I downvoted in my first comment: you're doing something that makes no sense, and had you researched the word "line level", tried out the SSR in isolation (which you "bet" works"), and had described your overall system in the question, it'd be a well-researched, fact-backed question instead of you asking the internet to fix your faulty approach. Quality assurance happens through downvotes here, so don't take it personally! Your next question will surely be better received :) \$\endgroup\$ – Marcus Müller Jun 25 '17 at 19:42
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The green item is a fuse, not an inductor. There is nothing apparent on the board to delay other than what is inside the SSR itself.

You will not get good results with this type of (triac) SSR. You could try to find a compatible MOSFET-output SSR and replace the triac SSRs in your PCB or just start from scratch.

It is better to switch audio before an amplifier than to try to switch at the speakers, if that is what you are doing.

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  • \$\begingroup\$ OP says "line-level" signal, so I guess that's not switching speakers, but switching an amplifier input. \$\endgroup\$ – Marcus Müller Jun 25 '17 at 19:25
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    \$\begingroup\$ @MarcusMüller OPs say a lot of things. OP also says signal is attenuated by a few hundred ohms 4066, assuming they hooked it up right (not necessarily a safe assumption) . \$\endgroup\$ – Spehro Pefhany Jun 25 '17 at 19:26
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    \$\begingroup\$ I'm not using an amplifier. This goes straight to 1W speakers. The level is perfect for what I need. Thanks for letting me know about the fuse. It seems I will have to start from scratch then and I will try MOSFETs. \$\endgroup\$ – Chu Jun 25 '17 at 19:32
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    \$\begingroup\$ @ArtLyra I said "MOSFET-output SSR". You likely will have problems using MOSFETs by themselves at your current level of knowledge. \$\endgroup\$ – Spehro Pefhany Jun 25 '17 at 19:33
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    \$\begingroup\$ @SpehroPefhany Oh OK! MOSFET-output SSR...I understand it now. Thanks a lot for your help! \$\endgroup\$ – Chu Jun 25 '17 at 19:34

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