Hooking up subwooder (with amp) with studio monitors

[le perp]

Ok so I have got a pair of KRK Rokit 8, have an external sound card Sound Blaster X-Fi Surround 5.1. Recently I have got my car subwoofer along with its amplifier, and I'm thinking to make some use of it, hooking it up with my studio monitor. My subwoofer is JB, don't remember the model exactly but it has only plus electric input and ground (minus) output; the amp is GAS pro80.2, has input/output L and R, along with some frequency nobs, on the other side there is speaker outputs, +12V, REM and Ground.

I'm basically clueless on how to get this started. Should I buy an amp that is designed for desktop use and not for car? I have seen videos where people hook up subwoofer with a PSU, I'm not going for that kind of config, as I don't have an extra PSU and even if I do I would try to avoid the mess. Any suggestions are welcome!!

 

[Lkaos]

Your best bet is connecting the amp to the Optical out of your soundcard...I dont know about a car's amp though...Without seeing it or knowing the brand/model cant help you further...

 

[jsmithepa]

Car amplifier is a mess because you need a spiffy 12v supply, your car's battery puts out 50 amps, so you figure that out. if you want real output, you need a dedicated home amp I say capable of at least delivering 80 watts RMS, and able and handle 4 ohms.

 

[le perp]

Your best bet is connecting the amp to the Optical out of your soundcard...I dont know about a car's amp though...Without seeing it or knowing the brand/model cant help you further...

The amp is GAS PRO80.2, there is a reference here, I don't think there is an optical output? http/www.brl.se/sv/varumarken/gas-pro-amp.html

 

[le perp]

Car amplifier is a mess because you need a spiffy 12v supply, your car's battery puts out 50 amps, so you figure that out. if you want real output, you need a dedicated home amp I say capable of at least delivering 80 watts RMS, and able and handle 4 ohms.

I am open to buying an amp that's suitable, but the woofer only takes L/R inputs.

 

[Natsukage]

Hello.

You will absolutely need a PSU or 12V supply of sorts to drive your PRO80.2. So if you do no want to buy a PSU or play around with that, then I'd suggest getting immediately an amp made for home audio.

If you are willing to get a 12V supply, it is possible to hook up this amp and speaker to your sound card without any issues. No optical converter or anything is needed. Just a 3.5MM to RCA adapter cable to your amp's RCA inputs, directly from the sound card.

 

[Natsukage]

Can you post your subwoofer model? Or a picture of the inputs?

If it has only two plugs in the back, red and black, then it is a unpowered subwoofer. An amp such as a Lepai (amazon) would do wonders for a small setup such as yours.

 

[Lkaos]

Your best bet is connecting the amp to the Optical out of your soundcard...I dont know about a car's amp though...Without seeing it or knowing the brand/model cant help you further...

The amp is GAS PRO80.2, there is a reference here, I don't think there is an optical output? http/www.brl.se/sv/varumarken/gas-pro-amp.html

Well, i know car audios can be set up at home with some work, i had one at home when i was a kid, but i dont think this kind of amp is made for "Sound System" use...You home equipment, if you have one, is the one you want...plug the amp to the soundcard and that's it...

See this pic? That's the one i'm using in my PC...
http/www.audiobaz.webd.pl/images/Denon%20AVR-1705%20b.jpg

 

[le perp]

Hello.

You will absolutely need a PSU or 12V supply of sorts to drive your PRO80.2. So if you do no want to buy a PSU or play around with that, then I'd suggest getting immediately an amp made for home audio.

If you are willing to get a 12V supply, it is possible to hook up this amp and speaker to your sound card without any issues. No optical converter or anything is needed. Just a 3.5MM to RCA adapter cable to your amp's RCA inputs, directly from the sound card.

Can you post your subwoofer model? Or a picture of the inputs?

If it has only two plugs in the back, red and black, then it is a unpowered subwoofer. An amp such as a Lepai (amazon) would do wonders for a small setup such as yours.

I unfortunately don't have an extra/old PSU for it, and would probably avoid it too for less space use and cables. It seems that I will have to get a new amp, and thanks so much for your suggestion, it seems to be a solid solution.

Yes, the woofer has only two inputs red and black. I upload a picture here.

I checked out your link to Amazon. Looking at the second picture

If I'm not mistaking, the middle ports L and R, I'm to connect them to my sub's red/black inputs. But I'm not sure where I can get the input R/L (the red and white port to the left) from? In my car I used to use a RCA converter that connects my rear left and right car speakers to the amp. But in this case, where or what should I connect to the R/L audio input on the Lepai amp?

 

[le perp]

Well, i know car audios can be set up at home with some work, i had one at home when i was a kid, but i dont think this kind of amp is made for "Sound System" use...You home equipment, if you have one, is the one you want...plug the amp to the soundcard and that's it...

See this pic? That's the one i'm using in my PC...
http/www.audiobaz.webd.pl/images/Denon%20AVR-1705%20b.jpg

That seems to be a little overkilled for my little setup. I have a simply USB external soundcard. I bought the subwoofer to my car but at the moment I'm not using my car, so I thought I might put the subwoofer in use. I think I'm going for the kind of amp that draw power from wall, instead of using an extra PSU.

 

[Natsukage]

I checked out your link to Amazon. Looking at the second picture

If I'm not mistaking, the middle ports L and R, I'm to connect them to my sub's red/black inputs. But I'm not sure where I can get the input R/L (the red and white port to the left) from? In my car I used to use a RCA converter that connects my rear left and right car speakers to the amp. But in this case, where or what should I connect to the R/L audio input on the Lepai amp?

If you get such an amp, the subwoofer will connect on the two middle-bottom black connectors, where it is written "Sub". Sound has no positive/negative in a single speaker setup, it is AC. Connect a speaker wire from one of the two black connectors, and connect them to either the red or black connector on the rear of your JBL woofer.

As for how to connect this, you need to connect to your usb sound card on the green output, which is a 3.5mm plug. You can use a wire such as this to do this:
Amazon
RCA and earphone connectors (3.5mm) are entirely the same type of signal. Just connect using such an adapter, power on the amp and it should work immediately.

If you have already a cable connected to your sound card, use a 3.5mm splitter:
Amazon

 

[le perp]

I checked out your link to Amazon. Looking at the second picture

If I'm not mistaking, the middle ports L and R, I'm to connect them to my sub's red/black inputs. But I'm not sure where I can get the input R/L (the red and white port to the left) from? In my car I used to use a RCA converter that connects my rear left and right car speakers to the amp. But in this case, where or what should I connect to the R/L audio input on the Lepai amp?

If you get such an amp, the subwoofer will connect on the two middle-bottom black connectors, where it is written "Sub". Sound has no positive/negative in a single speaker setup, it is AC. Connect a speaker wire from one of the two black connectors, and connect them to either the red or black connector on the rear of your JBL woofer.

As for how to connect this, you need to connect to your usb sound card on the green output, which is a 3.5mm plug. You can use a wire such as this to do this:
Amazon
RCA and earphone connectors (3.5mm) are entirely the same type of signal. Just connect using such an adapter, power on the amp and it should work immediately.

If you have already a cable connected to your sound card, use a 3.5mm splitter:
Amazon

Ok, so with the greem output om the sound card, are you referring to this?

Because I see also on the back of the usb sound card,there is an orange output label 'sub', like this

Shoulndn't I use that orange one instead?

 

[Natsukage]

Hello again.

I did not know which model of sound card you used, thus suggesting you use the green output, since subwoofer outputs on external cards are not common. Since you have a subwoofer (SUB) output, that is the best choice.

For sound cutoff, the orange output is the best choice for a subwoofer, and will give you quality subwoofer sound. Since your sound card has also White and Red RCA outputs, you can also connect a rca cable directly from this output to an amplifier, but there will be higher frequencies going to the subwoofer, which isn't the best choice.

So: Orange 3.5mm output -> 3.5mm to RCA (white/red) adapter -> amplifier (White and Red)
Using the adapter, this is a single wire setup from your SUB out, to the amplifier. Then you connect the SUB OUT of the amplifier to the speaker, using two speaker wires.

 

[le perp]

Hello again.

I did not know which model of sound card you used, thus suggesting you use the green output, since subwoofer outputs on external cards are not common. Since you have a subwoofer (SUB) output, that is the best choice.

For sound cutoff, the orange output is the best choice for a subwoofer, and will give you quality subwoofer sound. Since your sound card has also White and Red RCA outputs, you can also connect a rca cable directly from this output to an amplifier, but there will be higher frequencies going to the subwoofer, which isn't the best choice.

So: Orange 3.5mm output -> 3.5mm to RCA (white/red) adapter -> amplifier (White and Red)
Using the adapter, this is a single wire setup from your SUB out, to the amplifier. Then you connect the SUB OUT of the amplifier to the speaker, using two speaker wires.

Ok, thanks so much for all your help so far. I made this rough sketch just to be sure I'm on the right track before buying an amp. Please take a look at the image, items in black is what I have at the moment, in blue is what I'm about to add. If they look correct?

And here is also something I have been wondering after receiving your answer. I had two speaker wires connected from car amp to the sub when it was used in my car (so the red and black ports are wired), I was wondering how/why it is enough to wire just one of them when I use it at home?

Btw, I looked closer on the Lepai amp, it seems that it only outputs max 68W for subwoofer, and my sub's power handling is rated 275W RMS in the spec pdf. I could look around for an alternative, but also open to suggestions if you have any! Thanks again!

 

[Natsukage]

Sorry for the wait.

In my last I've post I've written "2 speaker wires". By single speaker wire, I meant a wire with two conductors, such as this:

Spoiler

There is one wire from each of the two holes for SUB on the amp.
Here's a revised diagram:

Spoiler

Wired this way, you cannot plug any other speaker to the Lepai. It is essentially bridged, and both amplifiers are connected together in push pull.

Unless you absolutely want to shake the windows, near 70W is a lot for a subwoofer. Most speaker systems from logitech, etc. have close to the same output. I suggest simply the Lepai since it's cheap and looks good. Any other amp will connect the same way, or similarly.

 

[le perp]

Sorry for the wait.

In my last I've post I've written "2 speaker wires". By single speaker wire, I meant a wire with two conductors, such as this:

Spoiler

There is one wire from each of the two holes for SUB on the amp.
Here's a revised diagram:

Spoiler

Wired this way, you cannot plug any other speaker to the Lepai. It is essentially bridged, and both amplifiers are connected together in push pull.

Unless you absolutely want to shake the windows, near 70W is a lot for a subwoofer. Most speaker systems from logitech, etc. have close to the same output. I suggest simply the Lepai since it's cheap and looks good. Any other amp will connect the same way, or similarly.

Ah I see! thanks for clearing up. I now have a clear idea of how to wire this up!

As for the amp alternative, I was just afraid that the Lepai amp might not be able to run the sub to its full, since I read some articles about matching the Watts RMS when choosing amp and sub. I will spend a little more time on that! Again, you have been a huge help! thank you and you the best!

 

[Natsukage]

You're welcome. ^^

You do not need to match the watts of the amp and the speakers. An 5W amp can work with a 1000W speaker. But a 1000W amp will destroy a 5W speaker....if you put the volume too high. Ideally, the amp has to be close to equal or less powerful than the speakers.
The impedance is important too, but you don't have to worry about this if you use a good sub amp as they support next to everything.