Subwoofer - passive to active conversion

Gojira

Standard Member
I have just completed the construction of my home cinema room. Unfortunately, I am now skint.

The overall sound produced is pretty good but the bass is somewhat feeble!

I have a ten year old JPW passive subwoofer & cannot afford a decent active replacement.

I am wondering if the the amplifying component used on active subwoofers can be put on a passive one with a little jiggery pokery?

If so, what would I need to get?

Or would it be cheaper to buy a Gale Sub from Richer Sounds to tide me over? (appx £50)
 

ReTrO

Well-known Member
All you need is an old integrated amp or somthing that you may have spare. Run a phono lead from the sub pre-out on your AV amp/receiver to an input on the spare amp and there u go. Just use the bass managment in the AV amp.
 

Member 14718

Active Member
If you passive sub has a pasive crossover then it will probably best to remove this, so there is a direct connection to the amp, then the proccesor will doing all the filtering.
 

ReTrO

Well-known Member
Good point Dan. Didn't think of that.
 

Gojira

Standard Member
Sorry, you've lost me!:blush:

The rear of the speaker has 2 amp in posts & 2 speaker out posts.

Is that what you meant?
 

ReTrO

Well-known Member
If you're not bothered about disecting your sub what you should do is open it up. Then you will need to remove any crossover from inside the sub and link the amp input directly to the terminals on the drive unit.

If there is only one set of terminals on the driver then it would be best to leave all the crossover bits in it still. The crossover will take up about 30% of the power output of the amp, which is why it is best removed.

I suspect that it probably cross's over at about 80hz whichg is probably the same as the bass managaemnet on your AV amp.
 

Gojira

Standard Member
Sorry, still not grasped it !!

Are you referring to some circuitry attached to the speaker terminals? Or is it something else?

I know I'm thick with regards to these things but having spent the last 6 weeks finding out everything I can about soundproofing, lcd pj's etc my brain has reached saturation point!

Your help is very much appreciated.
 
L

Lowrider

Guest
The two amp-in terminals get the full sound from the amplifier, then a crossover inside filters up to probably 80 hz to the sub driver, and the rest to the amp-out terminals, to the speakers...

You should remove the crossover, (electronics inside the sub), and connect the amp-in directly to the driver...
 

Gojira

Standard Member
Aaaaaah. Got it!!!

:D

Thanks all. Will set to work on it tommorrow.

Will let you know how it goes.........
 
J

jim.rae

Guest
I had the JPW sub woofer and although it's beautifully made, it need very insensitive speakers to go with it or it doesn't come across well.

A corner position in the room helps though.

I changed it for an Eltax from Richers which is active and can be a bit mental in 5:1 mode!

You sure know it's there though...

It's best on quiet material with deep soundtracks.
 

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