Re-wiring question when replacing blown subwoofer (1 Viewer)

[MarcusJT]

I have been using a Sony Active Super Woofer (SA-W641) from my old Pro Logic system as the sub for my newer system. In its Pro Logic life, it worked as the amplifier for all the speakers in the system. Now the only connection into it is the LFE connection. Well, the sub blew out this week.

Being cheap, I am only going to replace the 8in speaker that was blown. Someday I will upgrade to another sub. Wife already thinks the bass is too much.

My question is: Could I re-wire it a bit to actually use the outputs of either of the old front connections to power the speaker instead of the way it works now. I will only being using this sub as a sub only, so if I rewire up some things it won't matter.

The specs say:

Overall Output:

1. 140W + 140W (front, at center/rear/woofer off at 1 kHz, 8 ohms)
2. 25W + 25W (rear, at front/center/woofer off at 1kHz, 8 ohms)
3. 40W (center, at front/rear/woofer off at 1kHz, 6 ohms)
4. 50W (woofer, at front/center/rear off at 40 Hz 4 ohms)

Unless, I am missing something I could use the old front output to power the woofer and get more wattage.

Is this worth doing or should I just replace the speaker, and leave the rest alone?

Thanks in advance. I want to get this done tomorrow. I can't go all weekend without a sub.

 

[Dave Poehlman]

I think I understand what you're driving at. You're looking to run the sub via the 140w outputs rather than the 50W.
To answer your question in short, no, I don't think this would work. The amp should contain a crossover that feeds only mid/upper frequencies to that 140W output.
I would say if you're frugal.. replace the driver for now. If you're looking for cheap drivers, check Parts Express or MCM Electronics. I built Link Removed from scratch with MCM parts for around $100. And it actually sounds quite good!

 

[MarcusJT]

You're right. It does have a crossover knob on the front of it. I forgot all about it. I did look at PartsExpress. I saw it mentioned here in other posts.

I'll have to give yours a look.

Thanks for the response.

 

[MarcusJT]

I got to thinking over lunch.

From the manual:
"The super woofer is automatically turned off when an amplifier connected to this unit is in the PHONO mode and it cannot be controlled."

The sub has another input into it that came from the old receiver. I bet this other input is used to control this. It probably just has a voltage on the line indicating that the receiver is in PHONO mode.

Do you think in this mode the Cutoff would be ignored and everything would have been sent through to the 140W outputs? It wouldn't be hard to fake that signal coming in.

 

[Dave Poehlman]

1. 140W + 140W (front, at center/rear/woofer off at 1 kHz, 8 ohms)
2. 25W + 25W (rear, at front/center/woofer off at 1kHz, 8 ohms)
3. 40W (center, at front/rear/woofer off at 1kHz, 6 ohms)
4. 50W (woofer, at front/center/rear off at 40 Hz 4 ohms)

I am not real familiar with this model... but now that I think about it... the wattage ratings for everything are probably coming from the receiver/amp. Meaning, you only have a 50 Watt sub amp there. The original receiver was doleing out the 140W to the fronts.. it was just being passed through the sub amp; the sub amp was weeding out the lower freqs and running them through its own 50W amp. So, in short, theres no way to get from here to there.
I would say, your only option, if you want to keep this sub is to replace the driver. (or tell the wife it's blown and you need a new one. ) Just make sure you get another 4ohm driver.
It may sound a little different than the original driver.. (maybe better!). BTW, what is the size of the enclosure (internal)?

 

[MarcusJT]

Thanks, Just replacing the driver would get me up and running again faster. Hopefully later, I'll be allowed a new sub.

I'm not sure about the size of the enclosure. It doesn't say in the skimpy manual anywhere. To guess, I think the subwoofer is about a 19"X19". The first section from the front to the speaker is about 3". Then there is a hole connecting that section into the section containing the back of the speaker. I would guess that section may be another 3". I had the speaker out the other night but I didn't get any exact measurements. Brain already fried from working on Friday to try and convert these guesses to cubic feet.

 

[MarcusJT]

If anyone wants an update, I went to a local stereo shop yesterday and picked up a used Punch Z for $50. I think it sounds a little better than the original.