Help! My contractor did not run the right wires!!!

Meathead

I had my basement finished a couple months ago & I am just now getting to setting my stereo up. I currently have the Polk RM6800 surround sound setup (pictured here)

In anticipation of upgrading to a 7.1 receiver in the future, I had my contractor run wires from the wall behind the receiver to each of the speaker locations and a single RCA cable from the receiver to the sub location. Then, so I could use what I have in the meantime, I told him to wire me up for the RM6800. This basically meant running two additional lines from the receiver to the sub (located in the back of the room) & two more lines from the sub to the two front speakers. I explicitly told him this and even drew up wiring diagrams.

Last night as I was beginning to wire up the speakers, I realized that my contractor only ran one speaker wire from the receiver to the sub. The RCA cable (from the receiver to the sub) is there and the speaker wire from the sub to the fronts are there, but only one speaker wire from the receiver to the sub. Because all of the wiring was done when the basement was framed in & not sheetrocked, the wires have been stapled to the studs & tucked in areas that are no longer accessible. This means that there is no way for me to fish a new wire from the receiver to the sub.

Using the preferred and alternate wiring methods in the Polk instructions, I am screwed as I need two lines from the receiver to the sub. but I am reading around that I can just run all the speakers directly off my Onkyo TX-DS747 5.1 receiver and use only the single RCA cable going from the receiver's sub output to connect the sub. Is this a viable option for the RM6800?

PolkThug

You're fine, just use the direct method. Welcome to the forum!

northhillca

I have RM6900. Pretty much same as RM6800 I believe. I tried polk recommended method, and conventional method of connecting LFE out to LFE into sub. I like the second better. Set your fronts to small and crossover freq to 100-110 Hz.

If you dont have LFE input in RM 6800 sub then connect LFE out from receiver to one of the line level in (red or white). Set sub crossover knob to max. It will work fine.

Polk recommends using front out to feed sub because some basic receivers have fixed crossover control at 150Hz or some other wrong frequency for RM 6800.

Meathead

I know that my receiver has a sub out similar to the one pictured here:



The rear of the sub that comes with the RM6800 looks like this:



So if I understand you both correctly. I should only run the RCA cable from the receiver to the sub and wire all the other speakers directly to the receiver. What should I set the knobs & switches on the sub to? Should the volume be turned all the way up? What about the auto on & phase switches? I assume the Low Pass dial is only if I was running the speakers directly through the sub, right?

Looking through my receiver owners manual, I can see that I can set the receiver the size of the speakers (small, medium, large), but I do not have the ability to set the crossover frequency. This leads me to believe that the receiver has a fixed crossover frequency (I am trying to look that exact frequency up right now). How critical is this?

Meathead

And thank you for your quick reply & help with my very noob-esque questions

PolkThug

I usually have my sub volume knob around the 12 o'clock position. Just run the subwoofer out to the "L" input on the back of the sub.

Meathead

I'll try it when I get home tonight. Thanks again!

I almost punched a hole in the wall last night when I realized that my contractor screwed this up for me. I then kept kicking myself for not double & triple checking it before they put the sheetrock up. Glad to know that it is not a total loss!

northhillca

Since you have fixed crossover in your receiver, set the low pass filter knob to max. You can set volume and phase control based on whatever sounds good to your ears unless you want to get your hands dirty with technical details and precise calibration. If you are still not satisfied with sound, try moving sub to a different location in room. Correct positioning of sub can make it sound twice as loud compared to poor position.

Connect LFE out from receiver to one of the line level inputs (red or white). Set all other speakers to small. Power switch to auto. That will put sub into standby and save power if there is no signal, i.e. when receiver is off.

Meathead

I FINALLY got everything hooked up last night. After dealing with a nightmare of mislabeled wires, I got everything wired up correctly. The sub only has the single coax line going to it and after some tweaking, I got it set to where I wanted it. I tested it out with the title sequence from Top Gun. When the bass part hit, my wife shouted down to the basement that I was shaking the whole house. I had to do a little dance on that one!

Thanks again everyone. What started as a crisis turned out to have a fantastic resolution.

Ricardo

Good to hear you have it all fixed; now go get that contractor and get your money back.

engtaz

Congrats and enjoy and do what HTrookie said because he is master of his domain. (aka 2 channel room)