No sound from subwoofer after installing new amp

Aug 7, 2018
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I have an RCA 5.1 surround sound system, but the receiver was on its way out so I replaced it with a Pioneer VSX-531 5.1 Receiver (https://www.amazon.com/gp/product/B01G5XKNKW/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1), and decided to use the old speakers because they sounded great when the receiver worked properly.

I hooked all of the speakers right up to the receiver with speaker wire and they work fine and sound great. The sub out on the receiver is a low level line out RCA port, but the subwoofer has speaker wire coming out of it. So I bought an Oneu stereo amp (https://www.amazon.com/gp/product/B01N5D5ONB/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1) to put the low level into, and I'd hookup the sub speaker wires to the rear of the amp.

Well I hooked everything up as the instructions seemed to imply, but the sub makes no sound while the speakers are playing fine. I hooked the power up, the amp power light turns on, and the blue crossover light flashes as well. I tried moving the wires around, and I get either nothing or a hum. I turn all of the knobs up and down and still nothing happens or the low hum intensifies. I'm using a Red/White RCA cable and just running the low level through the white wire on the cable into the white input on the back of the Oneu amp.

On amazon for the Oneu amp, it says 4-8ohm only, and the back of the sub says 3ohm. Would this make it so absolutely no sound comes out of the sub? I thought it would only mean more wattage would be pumped into the sub. Maybe I have this completely wrong - I'm no audio expert and apologize if this is a really stupid question..

I feel like it's a wiring issue but all of the available diagrams contradict themselves. This one on AliExpress says there's two sub outs on the bottom row as depicted here: https://www.aliexpress.com/item/2-1-channel-of-household-small-12V-car-power-amplifier-with-heavy-bass-adjustment-power-40W/32564836196.html
While the official instruction manual shows to plug sub - into the third port on bottom row and sub + into the first port on bottom row. Then the little cheat diagram on the back of the physical device seems to be very confusing.

I've tried (what I think to be) everything and nothing seems to work. Any ideas?

Thanks in advance.
 
Solution
I did the exact same thing with my old BSR 15" sub (remember the DAK catalog back in the 80's?), except I used a car sub amp (Riot 1100m) with an old PC power supply to power it up.

Looking at that diagram, it appears that OneU amp is a 4 channel output and your are bridging the output of the sub outputs to get the higher sub wattage... So you have to connect both terminals to the (-) and (+) terminals of your speaker. It's also possible that it does not work without a all 2.1 connections, would be good to use for a mini shelf system or maybe even a PC audio amp, not really made for a dedicated sub.

If possible return it and get something like this which is made for a dedicated sub. Unsure if it will auto-power on/off, you...
I did the exact same thing with my old BSR 15" sub (remember the DAK catalog back in the 80's?), except I used a car sub amp (Riot 1100m) with an old PC power supply to power it up.

Looking at that diagram, it appears that OneU amp is a 4 channel output and your are bridging the output of the sub outputs to get the higher sub wattage... So you have to connect both terminals to the (-) and (+) terminals of your speaker. It's also possible that it does not work without a all 2.1 connections, would be good to use for a mini shelf system or maybe even a PC audio amp, not really made for a dedicated sub.

If possible return it and get something like this which is made for a dedicated sub. Unsure if it will auto-power on/off, you may want to get an energy saving power strip like this so it will power on/off with your AVR (I have to use the PC power supply on/off to power mine up/down, I need one of these too lol!)

 
Solution
Aug 7, 2018
3
0
10


Ordering that amp as I type this. Will report back.
 
If the amp is rated to 4 ohms it would shut down (or blow a fuse) if you connect a 3 ohm load to it. Plus it's a 3 channel amp when all you need is a 1 channel amp. Get a mono car amp that is stable into 3 ohms or less and a power supply. Or just get a self powered sub which is likely to be better anyway.