How do I use a PreAmp?

vascobrissos14

Estimable
Jul 14, 2015
52
0
4,580
Hello, I'm building a boombox and I'm making it a 3 way (with tweeters, woofers and a subwoofer)

Woofers:http://www.ebay.com/itm/331196777540?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Tweeters:http://www.ebay.com/itm/151787714089?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Now my question is about the subwoofer. I found a 3W subwoofer that is a bit old but stills gives awesome bass and is "small" and I really like it so I wanted to add it to my boom box to give some more bass felling.

I only got the subwoofer, the amplifier was broken and I tried a 5W amplifier and put some lower frequencies on the subwoofer and it worked really well. But this way the subwoofer gets higher frequencies so I went to ebay, did my searching and found this Pre Amp that supposdely works as a subwoofer crossover.

Pre Amp: http://www.ebay.com/itm/332006640502?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Now, I know I have to plug the Audio input and the 12V but where does the output go? To my 5W amplifier input with one channel only? (So the stereo ampifier turns into a mono one) and plug the subwoofer on its output?

Heres a schematic for you to understand it better.: http://prntscr.com/ec6wgl

Do I wire it as shown on the image?

Thank you all for your help!

 
Solution
You need to send pre-amplified signal to your pre-amp.

So you have your audio source to ground loop issolator to Y cable (or solder) to then send signal to BOTH the speaker amp and the pre-amp for L, R and ground.
Then you can wire your speaker amp to crossover to woffers/tweaters, and your pre amp to sub amp to sub

vascobrissos14

Estimable
Jul 14, 2015
52
0
4,580
PS: I dont know if the woofers can do the sub's job but I don't have them yet and even if they do and I don't need the subwoofer I have no problem on buying this pre amp in case I need it for a separate project. Thank you!
 

vascobrissos14

Estimable
Jul 14, 2015
52
0
4,580


I didn't understand you... the input comes from the stereo jack that comes from my phone and then gets lowered on the frequencies and then gets amplfied by the 5W amplifier. Am I wrong? Thank you

 

vascobrissos14

Estimable
Jul 14, 2015
52
0
4,580


Ye you got me, I want to do the first thing you said. Will it work fine? I just need your confirmation to buy the PreAmp!
Thank you!
 

vascobrissos14

Estimable
Jul 14, 2015
52
0
4,580


Amplifier: http://www.ebay.com/itm/201724495451?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Crossovers (I bought 2 obviously): http://www.ebay.com/itm/142011058607?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

And a ground loop isolator for the noise: http://www.ebay.com/itm/191816781092?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
 

Yes.

You are doubting yourself for nothing.

and plug the subwoofer on its output?
Yes gain.

Heres a schematic for you to understand it better.: http://prntscr.com/ec6wgl
U have my blessing.


The only thing I have to say is, there is no such thing as a small subwoofer. A subwoofer achieves what it does by having a large-ish cone, 8" or bigger in my book, but what you are doing is hobby so hook it up and see how it sounds.
 

vascobrissos14

Estimable
Jul 14, 2015
52
0
4,580


I just want to be sure of what I'm doing. And the subwoofer is "small". I say small because it's height isnt very large. and it's a ~5inch subwoofer. I know it's not much but I don't want to pay 35$ (22 for shipping) for a subwoofer.

~You can see the subwoofer right there. It is beaten up but still works REALLY good for what it is, that why I want to add it to my boombox! :)

http://prntscr.com/ec7tdn

 
You need to send pre-amplified signal to your pre-amp.

So you have your audio source to ground loop issolator to Y cable (or solder) to then send signal to BOTH the speaker amp and the pre-amp for L, R and ground.
Then you can wire your speaker amp to crossover to woffers/tweaters, and your pre amp to sub amp to sub
 
Solution

vascobrissos14

Estimable
Jul 14, 2015
52
0
4,580


I think I got you. I'll buy the PreAmp and try it!. Thank you for your help, I really appreciate it!