Need Your Help Wiring in 2nd Sub!

[SoCalAudioNewb]

Hi everyone. I recently have been getting some awesome help HERE on which budget speakers to buy, and I have a separate question about wiring setup that I thought I should put into it's own post. The Take Classic 5.1 system I recently bought includes a 8" sub, and I have been advised to use that 8" sub in conjunction with the Velodyne CT-100 10" sub I already have. I am posting here because I need help with how to wire in the 2nd sub.

Objective:
- Speakers in normal location for 5.1 surround setup (done - no issue here).
- Smaller Sub: 8" Take Classic subwoofer in front of room, per advice on the thread I referenced above. This sub delivers 33Hz-150Hz, and is self powered (done - no issue here).
- Larger Sub: 10" Velodyne CT-100 sub in back of room to provide the gut shaking LFE. This sub can deliver 28Hz-120Hz, and is self powered.

Summary of Issue: I need to wire in the Velodyne sub that's in the back of the room, but need to do so using speaker wire I already have run under the carpet.

Details of Issue:
- I knew I wanted a 5.1 surround sound setup, so when we had new carpet installed 6 months ago I had the forethought to quickly run speaker wire under the carpet for the two rear channels. I also ran an extra wire to the rear middle of the room in case I ever wanted to do 6.1.
- I would like to use that extra wire to feed the sub that will go in the back of the room, but my very modest Yamaha HTR-5830 receiver has only 1 sub output (coaxial). I am using the coaxial sub output to connect the Take Classic sub that sits in the front of the room.
- I need help with how to wire in the Velodyne sub that sits in the back of the room.

Possible Approaches:
- Ideally I would just run a speaker level output form the Take Classic Sub to the Velodyne sub. I already have the wire under the carpet, and this would be easy. Unfortunately the inexpensive Take Classic sub does not have speaker level output, only speaker level input (which doesn't help me wire back out to the Velodyne sub).
- Because there is no speaker level output for sub on the receiver, it occurred to me that I could just run one of the speaker level outputs from the receiver to the sub (i.e use either the left rear or right rear wiring post on the receiver). That's great, but doing so would leave one of my rear speakers without a wire. No biggie I figured, I will just take the single speaker cable I have for the rear right channel, and "splice" in two more cables using some electrical wiring nuts I had from installing an AC outlet recently, and then run one of the spliced wires to the Velodyne sub, and the other spliced wire to the rear right speaker. Doing so did provide some bass noise from the Velodyne sub, but it was greatly diminished from what I heard when I reconnected the Velodyne directly to the receiver via coax. I did some playing around in the receiver setup options, and there is in fact an option of where to send LFE to: A) front speakers, B) sub, C) both. This tells me that the receiver does not send full bass frequencies to the rear speakers output of the receiver; rather it only sends LFE frequencies to the sub coax output and/or to the front speaker output of the receiver.

QUESTION:
- Can I just use wire nuts to splice the Velodyne sub and the front right speaker into the front speaker output of the receiver? Will this approach still deliver full bass frequencies and volume levels to the sub? (I assume there should be no volume issues because the Velodyne sub is self powered, and therefor does not diminish available power delivered from the receiver to the rear right speaker.) Does this approach negatively impact the signal to the Velodyne sub or the front right speaker in any appreciable way? (in the audiophile world I realize this would be heresy; but bear in mind this is a $300 5.1 system and a $175 receiver, so I am not terribly concerned about nuance, only easily discernable sound issues or potential equipment damage).

 

[Davemcc]

I think you are overthinking the situation. Run the Velodyne sub from the LFE output. Forget about the other sub. Done.

 

[SoCalAudioNewb]

I think you are overthinking the situation. Run the Velodyne sub from the LFE output. Forget about the other sub. Done.

Dave-thanks for the input. Your suggestion doesn't quite address my issue. To wire the Velodyne sub at the opposite end of the room I would like to use the existing speaker wire that I ran under the carpet (either the unused wire, or somehow tap into one of the wires feeding one of the rear channels), does that make sense?

 

[SoCalAudioNewb]

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[Davemcc]

Dave-thanks for the input. Your suggestion doesn't quite address my issue. To wire the Velodyne sub at the opposite end of the room I would like to use the existing speaker wire that I ran under the carpet (either the unused wire, or somehow tap into one of the wires feeding one of the rear channels), does that make sense?

Well, if you have an unused speaker wire running under the carpet, use an RCA Y-splitter at the LFE output. Run one of the cables to the small sub. Cut the end off the other RCA and splice the wires into the wire that goes under the carpet. On the other end, splice the RCA connector onto the other end of the speaker wire and into the Velo sub.

My point about overthinking the issue is that the Velo sub is likely perform as good or better on it's own than trying to combine it with an under-achieving sub. I suggest moving the Velo up front or to whichever location sounds the best and just using that.

 

[SoCalAudioNewb]

Well, if you have an unused speaker wire running under the carpet, use an RCA Y-splitter at the LFE output. Run one of the cables to the small sub. Cut the end off the other RCA and splice the wires into the wire that goes under the carpet. On the other end, splice the RCA connector onto the other end of the speaker wire and into the Velo sub.

My point about overthinking the issue is that the Velo sub is likely perform as good or better on it's own than trying to combine it with an under-achieving sub. I suggest moving the Velo up front or to whichever location sounds the best and just using that.

Dave - thanks much for the help! I did not know if splicing the RCA to speaker wire was a valid option, or if doing so could damage equipment. To splice the wires, is a DIY splice using electrician's wiring nuts an ok approach?

With regards to the single vs dual sub question, it was suggested to me that the 150Hz upper range of the new Take Classic sub would be good for filling in the lower-mid frequency range that the Take Classic speakers don't deliver. I realize a sub is not ideal for this as localization effects may become evident, but given my contrained budget I'm told it's better than having a glaring hole in a given frequency range where I'd hear *nothing*. Does that make sense?

Please let me know if I am out in left field on this

 

[Davemcc]

The Take satellites have extension down to 115Hz and the Velodyne has extension up to 120Hz. With the rolloff slopes of the drivers, there will be enough overlap that you should be able to come up with a full range sound with no gaps. It may require a little tinkering with the receiver's crossover point and other settings. Put the receiver in double bass or LFE+Main mode so that the satellites receive a full range signal down to their lowest extension. Then choose a crossover point for the sub at 150Hz or so in order that the sub receives the fullest range signal that it can handle. Like I said, it may take some tinkering with the setup but it's fully viable combination.

If you still choose to run both subs, I would put them both at the front, one on top of the other. This way, you can use the Y-splitter from the receiver and simply use RCA cords to each sub without having to do any splicing. It may also eliminate any room modes or frequency cancellation caused by the room itself. Using two subs, especially two very mismatched subs, can cause a lot of issues due to interaction with the room's boundaries. The two sub solution can require a lot of setup tinkering, location experimenting and testing. Getting it right can be far more difficult than running the single sub and the payoff may or may not be there.

 

[SoCalAudioNewb]

Thanks Davemcc. I will play around with single vs dual subs tonight and I may take your advice and use just one instead of both. I appreciate the recommendations.