How can I connect a (passive) sub to my AV Receiver?

Question

My friend gave me his old Marantz AV Surround Receiver SR7000. He told me that I need to replace the missing remote for it in order to set it up and ALSO (and what lead to my question) that sub output is dead. He told me that if I used a passive subwoofer I could still make that work but I don't know how.

The only device I currently use is my PS3, *mostly* for Netflix and DVD's/Blurays. I plan on running the picture directly to the TV via HDMI and using an optical audio cable from the PS3 to the receiver. I believe I read that this works and there are some PS3 settings to accomodate it.

I cannot for the life of my figure out how to hook up a passive subwoofer. First of all, I'm a little uncertain about what defines a passive sub - is there anything at all more than just the speaker driver and 2 wires? If not, I should be able to use the driver from my previous setup which was a Cambridge Soundworks sub/speakers without a receiver.

I searched around and found convoluted posts about "daisy chaining" and "impedance" but couldn't find anyone else with my specific situation.

My end goal is to have 5.1 surround. I don't mind buying some wires or adapters but if I can't do this without spending a bunch of money then I will just go back to a cheap 2.1 setup with no receiver. I am a starving college student so I have to draw the line.

Pictured: The back of the Marantz receiver.

Thanks in advance.

Answer 1

You don't want to use passive subwoofers. Assuming the sub-preamp output is dead on the receiver your only option would be to use an active subwoofer with speaker level input. This however presents a problem... You now have to run the main speakers in full range mode, you cannot use the receivers built in crossover to filter the bass out of your mains otherwise you also filter the bass out of your subwoofer.



There is really no good way to do it, the active sub with speaker level input is about the only option. You may want to verify that the sub preout is really dead, maybe it's just turned off in a menu setting someplace.



Btw, a passive sub is not just another front speaker. A passive sub is just a subwoofer that does not include its own power amplifier. An active subwoofer does include its own amplifier and typically will have an RCA preamp level input. Some however also have speaker level input and that's what you want. You will connect the left/right main speaker terminals to the left/right speaker level inputs of the subwoofer in parallel with your main speakers. This does not create an impedance problem because the input impedance of the active subwoofer will be very high relative to the typical 4 or 8 ohms in the main speakers.



mk

Answer 2

A passive subwoofer is just another front speaker. I use one on each side, 10 inchers crossed over at 115Hz. I also use a couple of active subs for movies or anything with LFEs. I like to tell people how I converted my whole speaker system to 4 ohm after I was putting some new speakers in my car I noticed the 6 1/2 inchers sounded just right for my ear, punchier, likely due to the materials they were made of. I removed the tweeters because I think the 6 1/2 inch mid woofer plus the tweeter doubles up and makes it seem blarey. I then added two supertweeters per front speaker because high freqs don't travel very well. Didn't use any crossover for the midwoofing because they have a natural rolloff at about 120 Hz (a trick I learned from the speaker manufacturer Acoustic Research back in the 1970's). There are (or there used to be) stand-alone passive subs having two voice coils in the same speaker, in fact that is where I found my crossover electronics and used that, replacing the double coil speaker (which was 8 ohm) with a single 10 inch 4 ohm and reused that cabinet also. I built a cabinet for the other side and even left the crossover in the cabinet I described and just routed the wires to the other side. 4 ohms are easier to drive and give full frequency response at moderate listening levels. I added a cooling fan to my Onkyo reciever because these older amps tend to run a little warm anyway, especially with 4 ohm speakers, but the new amps don't seem to care i.e. run cool with 4 ohms.

Answer 3

This is all besides the point. Get your receiver fixed, and download its operating manual.Read it. Acquire a remote for it, from the MFG. All speakers require an amplifier. "Active" just means they built one into the speaker's box. "Passive" means your on your own to supply one. An amp is that part of the electronics in anything that puts out the powered signal loud enough (strong enough) to drive (work) the speaker's motors. (that's right, speakers are electrically driven motors.) Speakers alone don't move, or make sound anymore than your electric toothbrush would work without a battery in it, or your car move without an engine attached to it. There are other subtleties, but this is the basic understanding you should start with..

Answer 4

Marantz Sr7000 Manual