# Speaker setup issue



## kaufam7 (Nov 9, 2014)

I found a set of two Dell computer speakers at a garage sale recently but am not sure how to get them to work. They have a male DB9 connector and a stereo audio RCA connector. I could not find a model number anywhere, but after doing some research online, they appear similar to the small speakers that are part of the Dell A425 Speaker System. They are apparently made to work with a sub-woofer (that I lack) which provides power to the small speakers via the DB9 connector. I have a desktop computer that has an SPDIF connection via a male DB9 connector port. Is it possible for the speakers to work if I used a male to female adapter and plugged the DB9 connector from the speakers into the SPDIF port on the computer, and if so, would the computer's audio be fed directly to the speakers via the DB9 connector without having to use the RCA connector?


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## DBCooper (Jun 11, 2010)

Hi kaufam7,

May I ask, would it be possible to post a pic of the speakers and it's connectors?


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## kaufam7 (Nov 9, 2014)

Here is a picture I found online that appears similar to my setup, except I do not have the sub-woofer and would like to be able to use the small speakers with my computer's DB9 SPDIF connector. There is a volume control on one of the small speakers, and they require a power source normally supplied by the sub-woofer (which is powered separately from a wall plug) through the DB9 connector. The audio signal normally feeds from the source to the small speakers via the RCA connector, and then feeds the sub-woofer via the DB9 connector. I believe I should be able to feed both the power and audio from my computer's DB9 SPDIF connector. I want to have some idea that it will work, however, BEFORE I actually make the hook-up and accidentally fry my motherboard or the speakers. What do you think?


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## JimE (Apr 16, 2009)

The only time a speaker requires AC power, is when they have a built in power supply for an amplifier. All units with a sub and many without require AC power.

In this case, the sub has the amplifier. The DB9 cable contains a pair of wires for the power switch, a pair for the volume control, and the left/right stereo signals.

You can't use the S/PDIF as it's a digital signal. The signal would need to be converted to analog and amplified to power the speakers.


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## kaufam7 (Nov 9, 2014)

If what you say is true, that the speakers require no AC power, then I should be able to just plug in the RCA connector and get sound, but I don't. I suppose the speakers or the wiring could be bad, but given they look brand new, I doubt that is the case. I haven't tried using a separate amplifier for the RCA connection, but doing so would be impractical as it means adding another large piece of equipment to my computer set up. I will probably try it just to make sure the speakers work, then try to re-sell them on eBay or something, unless someone has any other suggestions on getting them to work.


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## kaufam7 (Nov 9, 2014)

Would it be a problem to plug the speakers into the S/PDIF connection on the computer just to try it? Or do I stand a chance of frying something if I do?


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## JimE (Apr 16, 2009)

First, a clarification in terms. RCA are the old standard audio connectors, and in regards to audio, consist of two (red and white).








Computer audio, uses 3.5mm phono plugs. A standard stereo output is typically color coded green.








The image you attached, shows a 3.5mm plug. Assuming the 3.5mm cable is connected to the speakers, it is likely passed through the speaker, to the sub, where it is filtered (low pass for the sub, all else for the speakers) and amplified, and then sent back to the speakers. So it's not surprising you are getting no audio.

Neither RCA nor 3.5mm will plug into a S/PDIF connector. And if you created some sort of converter to make it possible, it won't work. As noted previously, S/PDIF is digital, speakers are analog. The signal needs to be converted (by hardware) from digital to analog, and then amplified to drive the speakers. 

It will not work, and yes, it can cause damage.


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## kaufam7 (Nov 9, 2014)

Dell's description of the speaker system called the phono plug an RCA connector, apparently by mistake. I should have picked up on that, but didn't. My bad. Yes, in reality it is a 3.5mm phono plug, and it is green. I know the phono plug will not fit in the computer's S/PDIF connection, but the DB9 connector that normally plugs into the sub-woofer will connect to it. 

Apparently the sub-woofer contains an amplifier, and has no reason to change the signal from analog to digital, but amplifies the analog signal and sends it back to the small speakers through the DB9 connector. So it makes sense that the S/PDIF port on the computer cannot be used (even though it will connect to the DB9 connector) because it sends a digital signal instead of analog. 

So the bottom line is that I cannot use the speakers with my computer without adding some type of hardware that can either change the S/PDIF signal to analog, or amplify the analog signal through the phono connection. Is that correct?

If that is the case, then I might as well sell the speakers, unless I can find a cheap compatible sub-woofer somewhere.

Thank you to all who helped clarify this matter.

Anyone interested in buying a nice set of Dell speakers really cheap?! :wink:


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## JimE (Apr 16, 2009)

Why are you trying to use the S/PDIF and not the analog output? Motherboards for years have included an onboard audio chipset with at least a stereo analog output or you could simply install a sound card.

Having said that, you would still need an amplifier to drive the speakers. Audio chispets don't have sufficient power to drive speakers.


Also, further clarification. 

S/PDIF uses a single RCA connector or an optical connector:








DB9 is a 9 pin connector:








So you can't connect a DB9 cable to a S/PDIF port.

If there is a DB9 on the motherboard, it is not a S/PDIF port, it's a serial port. Typically used for modems and input devices such as gamepads/joysticks.


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## kaufam7 (Nov 9, 2014)

Not so. My computer's S/PDIF port is a DB9 connection. Also, I DO have a sound card, but the fact that the analog signal requires a separate amplifier is the reason I am not able (or willing, rather) to use the standard phono connection from the sound card. I have another set of regular computer speakers that also plug into the wall and have their own amplifier. They work great! I just wanted to be able to put these other speakers to good use too.


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## kaufam7 (Nov 9, 2014)

The 9 - pin connector port on my computer is actually labeled S PDIF right on the motherboard and on the back plate it protrudes through. It is an older ASUS motherboard. Maybe the connections were different 10 years ago. (?) There is another 9 - pin connection that I plug my monitor into.


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## Rich-M (May 2, 2007)

Nothing changes the fact that these speakers need amplification supplied by the sub woofer unit.


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## JimE (Apr 16, 2009)

Model number of the Asus motherboard? I've not seen that, and now I'm curious. It's likely a non-spec output for a specific use.

But again, even if you could use it, you would need a digital to analog converter AND an amp to drive the speakers.


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## kaufam7 (Nov 9, 2014)

The motherboard is an ASUS model M2N-E (green). I took a look at the specs, however, and a coax S/PDIF out port IS listed, so I took another closer look at the back of the computer. The 9-pin connection port is located right next to an RCA connector port which apparently is what the S/PDIF label corresponds to (and is incorrectly called a "coax" port in the specs - maybe they made the motherboard both ways and just never changed the description in the specs). The male 9-pin connector port is actually labeled IOIOI, and I also have one of these ports on my laptop with the same label. Perhaps it is a serial port as you have suggested, although there is no mention of any serial port in the specs, but it does mention a COM port, so I am assuming they are one and the same. I believe older mice and printers used to use a serial port to communicate, whereas today they are mostly USB or wireless. Are there any modern hardware devices that still use a serial port?

Anyway, it looks like the phono jack is the only possible connection for the speakers, and would require either the purchase of a separate amplifier or an amplified sub-woofer with a compatible DB9 connection.

As I said, I will probably just re-sell them on eBay. Thanks for all your help!


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## JimE (Apr 16, 2009)

So yes, you have S/PDIF and a serial port/COM port.

Serial ports aren't included on most newer models. The most common use in my years of computing were as a "game port" or for a modem. Aside from modems, I've not seen any other hardware that still uses a serial connection aside from specialized hardware.

Printers used a parallel port (printer port) and most now use USB.

Serial port/COM port (9 pin): Serial port - Wikipedia, the free encyclopedia








VGA port (video output)(15 pin): VGA connector - Wikipedia, the free encyclopedia








Parallel port (printer)(25 pin): Parallel port - Wikipedia, the free encyclopedia


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## oscer1 (Jan 27, 2010)

Here at work we need a serial port for one specific software. Been real pain to find a laptop with that port have special order it.


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## kaufam7 (Nov 9, 2014)

Reply to oscer1,

My laptop (which has a serial port) is a Dell Latitude D620. It is an older laptop, but was one of the best made laptops ever. They seem to be very durable and last a long time. You can find plenty of good used ones online between $50 and $200. They were very popular about 8 to 10 years ago with businesses who had employees who needed a reliable laptop to use in the field. My original one made many trips up wind towers around the country in both very hot and cold conditions. I continued to use it at home for several years until the screen finally decided to go bad, probably from the rough and tumble life it had. I immediately got online and bought another used one just like it on eBay for about $100. I upgraded it a bit with more memory and a larger hard drive, and it is the computer I am still using today. It works great! Just thought you might want to know. Good luck!


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