Is this sub compatible with this amp (and how do I use it)?

[umami]

Hey guys,

 

Got handed down a sick sound system from a relative that's downsizing, and he said he's not sure whether or not the subwoofer actually works. He's not a massive hifi/electrical guy so it's up to me to diagnose it. For now I just need help knowing what the correct way to connect it is, so I can know whether it actually works under normal conditions, and if not then I'll open it up and get the multimeter out. 

 

Receiving this system is what spurred me on the join this site because I really want to optimise it and learn how to use it well, because I don't have any hardcore hifi experience, just tinkering with cheap junk over the years.

 

So far I've just tried connecting the amp's subwoofer port directly to the "low level input" with a 1 to 2 RCA cable, and didn't get anything. Fuse is intact.

 

So:

Looking at the photos of the inputs, are this sub and amplifier actually compatible, and if so, what's the best way to connect them?

 

Should I care about the speaker out part on the sub or just throw the speakers directly onto the amplifier?

 

Also, can someone give me a rundown on the gain/Freq knobs as well as the on/auto/off and phase switches? Like, I know what gain is from playing my guitar, and I understand that the frequency knob will be probably focusing the sub on a particular frequency to thump out or isolate, but I don't know what kind of range I want to keep it on for it to be good. Absolutely no clue what the phase bit is for.

 

Cheers, and happy listening

[GaryT]

It should word with just a single RCA - RCA mono cable.

Either you need to go into the settings on the receiver and enable the subwoofer, or the subwoofer is deceased.

 

If you turn the sub on (as it seems to be set in the photo, but try different switch settings) and plug a cable in then just touch the other end with a finger you should hear a pop or buzz, if not, there might be something wrong with the sub unfortunately.

[Quark]

Just confirming you connected your amp's subwoofer pre-out to one of the low level inputs on your sub.

 

You'll also need to set your AVR to have your main speakers as Small to divert low bass to the sub. Alternatively there may be an option to send low bass to both your mains and the sub.

 

I'd suggest starting with the sub's gain at 50% and phase set to Normal.

[umami]

Thanks for the reply mate

 

Are you saying it should be wired in mono for normal use, or just to do that for test purposes?

 

Also, if the sub doesn't give me anything, do you reckon I've got a chance at fixing it by replacing any components I find on the board that are blown/inoperative, or is it typically a nonserviceable part? I appreciate you may not be able to give a clear answer without actually working on it, I just don't know how serviceable hifi stuff is in general

[umami]

26 minutes ago, GaryT said:

It should word with just a single RCA - RCA mono cable.

Either you need to go into the settings on the receiver and enable the subwoofer, or the subwoofer is deceased.

 

If you turn the sub on (as it seems to be set in the photo, but try different switch settings) and plug a cable in then just touch the other end with a finger you should hear a pop or buzz, if not, there might be something wrong with the sub unfortunately.

 

Thanks for the reply mate

 

Are you saying it should be wired in mono for normal use, or just to do that for test purposes?

 

Also, if the sub doesn't give me anything, do you reckon I've got a chance at fixing it by replacing any components I find on the board that are blown/inoperative, or is it typically a nonserviceable part? I appreciate you may not be able to give a clear answer without actually working on it, I just don't know how serviceable hifi stuff is in general

[GaryT]

Everything is repairable! it's probably nothing major. 

 

The sub is a mono device, so both inputs are internally summed together anyway, so a single cable is no different from a Y splitter, in terms of the electrical connection.

[spammoj]

Easiest way to test a sub in my opinion is get a 3.5mm to RCA cable, plug the 3.5mm into your phone (or anything else), plug the RCAs into the sub R&L inputs.

 

Turn down the volume on your phone, start playing a song with bass in it then gradually work the volume up.

[spammoj]

Some reading I found on the google to get you started on phase, gain, freq range:

 

https://blog.fluance.com/set-phase-crossover-frequency-on-subwoofer/

 

https://rel.net/blog/2020-07-15/principles-of-sound/how-to-set-the-crossover-and-gain-on-a-subwoofer/

 

https://www.svsound.com/blogs/subwoofer-setup-and-tuning/tips-for-setting-the-proper-crossover-frequency-for-a-subwoofer

[umami]

Little update

 

Opened up the sub and had a poke around, thought I found a blown resistor but it tested fine, closed it up and shelved it for another day.

 

Tragedy struck though, did some rearrangement and when I wired the speakers back in I think I accidentally shorted out one of the amp circuits. I thought these types of spring loaded connections had little tunnels to hold the cables, turns out it's just a hole with a metal strip at the back, and if you're a dumbass who strips his cable too long you can bridge them out. Won't turn on at all, even with nothing plugged in, even after clearing the error, and even after trying a factory reset. Gonna organise repairs tomorrow. Might send the sub off too and save myself the hassle. Cry for me.

[Richard Tremain]

If you want to find out if it works simply put your spk wire to the Hi level sub input terminals and set  Gain to max

and set freq to highest setting. Play anything with a Bass content and bingo it works or it doesnt.

( PS. For Stereo Hi fi, not TV which dosent  matter much,Best results are wiring direct to Amp spk terminals

not via a RCA cable)

[Richard Tremain]

Do you not have fuse protection on a AV type amp?