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I have an audio signal from a class-d 100V and 500W. amplifier.

I want to distribute this to 16 different sets of speakers and control the volume of each set individually. I am unable to find any solution for 100V.

If volume control isn't possible I would like to be able to switch ON/OFF.Relays are one of a solution but that will be taking a lot of board space ,which is limited for my application. I was interested in this Chip, but the availability is an issue and I cant find it.

Can someone please help me to find any solution for volume control, or finding me an alternate IC or any other solution.

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    \$\begingroup\$ I'm looking for a similar IC. Did you find anything? \$\endgroup\$ – user3490458 Dec 24 '14 at 12:07
  • \$\begingroup\$ Can you post a link to the amplifiers' manufacturer, data sheets or specifications, please? \$\endgroup\$ – EM Fields Dec 24 '14 at 14:03
  • \$\begingroup\$ @EMFields Its a 100A 500W class-D Amplifier. csinewave.com/up500 \$\endgroup\$ – dmSherazi Dec 24 '14 at 14:30
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This is traditionally done with a transformer for each speaker. Volume adjustment is by selecting a tap on the secondary to deliver the required power to the speaker; as such, you get a choice of maybe 6 volume levels, (and off!) which you could select with a rotary switch at the speaker.

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  • \$\begingroup\$ I would like to control the volume or switch ON/OFF using a micro-controller or raspberry pi via an app . \$\endgroup\$ – dmSherazi Dec 24 '14 at 12:38
  • \$\begingroup\$ @dmsherazi: Since it significantly changes the scope of your question, you should edit your question to include that requirement. \$\endgroup\$ – EM Fields Dec 24 '14 at 16:08
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    \$\begingroup\$ Unfortunately I'm not sure solid state relays would work to switch transformer taps because Ron is going to be high relative to the speaker resistance and Ron flatness (which is not something you usually see in an SSR datasheet because it's an AC characteristic) will introduce significant distortion. So I think you would have to use regular relays. \$\endgroup\$ – squarewav Dec 25 '14 at 4:33
  • \$\begingroup\$ @ioplex Should i be looking for the DC 100V rating or AC 100V rating for a relay for this purpose! I am noob as far as audio and amplifiers are considered. will this one be OK? omron.com/ecb/products/pdf/en-g5sb.pdf . Would Opening one of the two wires going to speaker, be enough , or do I need to Open both the wires? \$\endgroup\$ – dmSherazi Dec 25 '14 at 6:22
  • \$\begingroup\$ That relay should be fine. If you are switching after the transformer, switching a single pole is adequate. You can either preselect a tap for the best volume, or use several relays to choose volume levels. \$\endgroup\$ – Brian Drummond Dec 25 '14 at 10:42
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Volume control is usually performed before the power amplification stage. To drive multiple speakers with their own volume settings you would usually use a separate power amplifier for each set of speakers, each with its own volume control.

Implementing volume control after the power amplification stage is a tricky business since you have to work within the tight constraints of the impedance of the speaker system, and as you have found, often at higher voltages and currents.

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  • \$\begingroup\$ if I skip volume control, what would you suggest for switching on/off of different sets of speakers? any alternatives to this irf.com/product-info/datasheets/data/rdha701fp10a8ck.pdf \$\endgroup\$ – dmSherazi Dec 24 '14 at 13:39
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    \$\begingroup\$ Switching speakers on and off is itself not an easy task. The amplifier expects a certain load impedance. You have to try and match that load impedance with your speakers. By adding and removing extra speakers you are changing that impedance, and the amplifier may well have a fit. Some won't even start working if you have the wrong impedance. \$\endgroup\$ – Majenko Dec 24 '14 at 13:42
  • \$\begingroup\$ It won't be done quite often or even done only when the amplifier is OFF.I want to be able to control the sections of the building where the audio should be played. \$\endgroup\$ – dmSherazi Dec 24 '14 at 13:46
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    \$\begingroup\$ It's not a question of frequency, or if the amplifier is on or off - it's a question of getting the impedance right. You could arrange it so that certain combinations of speakers can be on at once, where those combinations equal the right impedance. \$\endgroup\$ – Majenko Dec 24 '14 at 13:49
  • \$\begingroup\$ OK. I got the point. But I am still in need of a solution to switch 100V signal to about 16 outputs \$\endgroup\$ – dmSherazi Dec 24 '14 at 13:59

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