low pass filter?

[satan165]

I have a question related to the use of subwoofers in a home audio application. This is not being used for multimedia or surround sound, only music.

I have a Kenwood Receiver KR-V7050. It has outputs for (2) 'Speaker A' and (2) outputs for 'Speaker B' via standard speaker cable. I can switch either 'A' or 'B' on/off.

I have this hooked up to two 6" Insignia (8 ohm) speakers on channel A. They sound great - no problems there.

However, many years ago I had a mobile audio setup in my car. I no longer have the car and I sold everything except the subs because they were two big to ship.

So I have a sealed box with (2) Rockford 12" subs in it. I actually took the box into a speaker shop as they were blown, from the abuse I put them through years ago. These subs are 8 ohm also - I just put a multimeter into them.

So I have the subs hooked up to Channel B. I generally leave this off, but I have used it, and they do push bass, no rattling or problems or anything. But since this is not a dedicated subwoofer output (nor do I have such a thing on my receiver) I feel like it is muddy as I cannot EQ the output to just that channel.

I was thinking about a low pass filter but I do not at all understand what I need, if its useful or just pointless. Also it seems I may be limited by the fact that I am using speaker cable to connect to the subs as opposed to an RCA or something like that. I have looked at many of these filters but I can't even get my head around how they are powered or what connections they use.

If this does not make sense I am glad to offer clarification, pics, etc... Just wondering what the general thought is. I use the receiver and the Insignia speakers daily and love it. I would like to use the subs some/all of the time since as I said, I use this almost primarily for music.

Thanks very much for the help!

 

[j_garcia]

IMO,the right way to do it is with something like this: Dayton Audio SA230 230W Subwoofer Amplifier 300-813 It has the ability to manage and power the subs and has a high pass for the mains. BUT, you need preamp outputs for that.

If you don't want to get fancy, something as simple as this might work: 80 Hz Low Pass 8 Ohm Crossover 266-442 Rather generic, but should server the purpose.

Did you have the drivers repaired? The B terminals are typically full range regardless of the receiver's capabilities and using them for a subwoofer isn't a great idea if the receiver isn't fairly hefty. I know, because I've done it before with an old receiver and an old car sub I built The "muddy" sound likely isn't due to not being properly filtered, but it may help. Measuring the raw driver doesn't tell you the true impedance since impedance varies with frequency.

The way I see it: having them connected to A and B combines the load of all of them as if they were a single speaker (and if I am not mistaken) also treat them as if they were wired in parallel. This will halve the impedance seen by the amp and cause greater current draw. Drivers for cars are also designed to work best with "car" gain, ie; small volumes, not large open rooms, though you will get sound out of them; it just might not be the best sound.

 

[satan165]

the crossover you posted makes sense to me, it has terminals i recognize and doesnt seem to require power

i was looking at something like this DIY Dual NE5532 Subwoofer Processing Circuit Low Pass Filter Circuit Board Kit - Blue - Free Shipping - DealExtreme

what would that be for?

the crossover you mentioned is in my future i believe, thank you so much for taking the time and not seeming too disgusted with my setup. thank you very much.

 

[j_garcia]

That module looks to be one portion of what would go into a plate amp, allowing you to basically build another "black box" that theoretically could be used to convert any amp into a sub amp. Essentially like the first link I posted; if you cracked that amp open, something like that module would be inside there.

The x-over I linked is a straight passive x-over and will definitely provide the filtering, so yes, it does not need to be powered

 

[satan165]

youve been very helpful. thanks for your patience and sharing your knowledge!

 

[satan165]

follow up - i got the crossovers mid week but did not have time to go over them until last night and this morning.

i soldered all the connections and then climbed back behind my rack this AM getting everything connected.

AMAZING - this is definately working as advertised.....i did my initial test using some bass heavy music and clicked on only speakers 'B'. until the bass hit i heard NOTHING.

sounds GREAT! thank you so much! this is exactly what i was looking for!

 

[j_garcia]

Glad it worked out and wasn't expensive