RM 6750 sub - low/no output

hicountryrider

New to forum and home theater setup. Just purchased a RM6750 Home Theater 5.1 system. I've hooked all speakers to the new Yamaha RX-V367 AV receiver. Speakers all working fine except for sub.

1. First of all, I have it connected to the RX-V367 sub out with a AudioQuest VDM-Xr 75 ohm digital audio/video cable. Is this an acceptable cable to use or should I be using something else?
2. I'm not using a Y cable to hook into the L & R inputs on the back of the sub but have it plugged into the L channel. Do I need to get a Y cable to plug it into both channels?
3. I have set the low pass control all the way to the right per instructions and the volume control to just below 50% on the back of the sub. I have configured the RX-V367 speaker setup to YES for Sub woofer, the crossover at 80 Hz and the sub phase to NORMAL.

With this setup I am not receiving anything out of the sub. If I turn up the volume control on the sub to about 75 % I will hear some muffled bass. I have increased the volume of the sub on the RX-V367 setup but that doesn't seem to have any effect. When I use the Test Tone feature on the 367 all speakers EXCEPT the sub produce a tone.

Being new at this I'm not sure what the problem is. The included instructions on both the RM 6750 and the RX-V367 don't seem to be of any help as least as far as I can see.

Appreciate any assistance.

thuffman03

Welcome to the forum!

Did you turn on that you have a sub in your AVR?

hicountryrider

thuffman03 wrote: »

Welcome to the forum!

Did you turn on that you have a sub in your AVR?

Thanks for the reply. Yes, I made sure that SWFR = Yes in the speaker setup in the AVR.

spock 2054

hicountryrider wrote: »

Thanks for the reply. Yes, I made sure that SWFR = Yes in the speaker setup in the AVR.

Make sure your speakers are set as below - Check page 16 in your rm 6750 manual:

OPTION #1—
Receivers that include a “Sub Out” feature—the most common hookup method with
Dolby® Digital receivers.
NOTE: Use either the L or R Line input (another hookup option is to use a Y-split cable
and connect both L and R Line inputs). After you make this Sub Out connection, turn
the "Low Pass" filter fully clockwise.
• Connect all speakers directly to the receiver. When using method #1, adjust
your receiver’s speaker configurations as follows: Set Front, Center and Surround
speakers to “small.”
• Receiver Settings:
• Front, Center, and Surrounds = “SMALL”
• Subwoofer = “ON,” or “YES,” or “PRESENT”
• Set the crossover frequency on the receiver to 120Hz.
Consult your receiver’s owner’s manual for speaker configuration.

Check your cable, and the owner's guide for your Yamaha.

hicountryrider

Thanks for the additional information. I did pickup a Y adapter and that didn't seem to make any difference so I went back to plugging it into the L channel only, re-configured the crossover setting in the AVR and yes, it is on. My sub appears to only have 2 settings - Off and Auto/On, no separate On position. I have it set to Auto/On.

I haven't had much experience with subs so not sure what I should be expecting. I'm now playing a DVD movie, 5.1 audio and there is definitely now a presence of the sub. I'll have to try an audio CD with a heavy bass line and see what the results are.

This entire setup is in a very small area, actually an RV, so the sub is definitely over sized. It is also sitting on a carpet and I notice it has no legs. Should I raise it off the carpet?

Thanks to all who responded and your patience with a newb! It appears now that I will just have to play with tweaking it to optimize it's performance. Guess I was expecting ground-shaking results out of the box when in reality, like all electronics and computers, you have to pay your dues and explore all the possible settings to get the most out of it.

mdaudioguy

Ideally, a sub should have just what you said - presence. It should never draw attention to itself. Sounds like you're getting there.

Oh yeah, welcome to Club Polk. Enjoy the ride!

hicountryrider

OK, playing around with the settings in the AVR I have set the SWFER level at about 7.5 of 10 in speaker settings and have set the volume control on the back of the sub at about 55-60 %. Seems to be working good for broadcast HDTV.

I can see that it will probably take some tweaking of the sub settings for various inputs, i.e., broadcast TV, DVD, CD, etc. but that's OK as long as I know that is the norm. Probably doesn't help that I'm forced to have the sub too close to my viewing/listening position because of the confines of my RV. I do notice that the farther away I am from the sub the more pronounced the effect is. Ah well, that's the reality of a mobile lifestyle!

Thanks again to all who contributed suggestions. A little late in life for getting the full effect of good surround sound and subwoofer effects but better late than never!

tonyb

I'm not up to speed on Audioquest cables, but is that a digital cable you have hooked up to the sub ? If so, thats not the right cable.

hicountryrider

tonyb wrote: »

I'm not up to speed on Audioquest cables, but is that a digital cable you have hooked up to the sub ? If so, thats not the right cable.

I think it is a digital cable. Here is a link to the cable I purchased. If this is not right do you have a recommendation for the right cable to use? Would this work and if so would I need a Y adapter to connect both channels on the back of the sub?

mdaudioguy

tonyb wrote: »

I'm not up to speed on Audioquest cables, but is that a digital cable you have hooked up to the sub ? If so, thats not the right cable.

I think that cable should be fine. What do you think is wrong with it? Digital coax can be used just fine for a subwoofer.

tonyb

mdaudioguy wrote: »

I think that cable should be fine. What do you think is wrong with it? Digital coax can be used just fine for a subwoofer.

I've never seen anyone using a digital coax cable for a sub, thats just me though, I could be wrong.

mdaudioguy

tonyb wrote: »

I've never seen anyone using a digital coax cable for a sub, thats just me though, I could be wrong.

Not the highest-end stuff, but notice the description: "for S/PDIF, Digital Coax, Subwoofer & Composite Video"

75 ohm cable seems to work for many applications.

http://www.monoprice.com/products/subdepartment.asp?c_id=102&cp_id=10236

tonyb

Still, a regular analog cable to me would be better. Have you ever tried using a coax digital cable as an analog IC ? You'll get a loud humm.......the way I understand it, the OP is using the line in's on the sub,analog, from the receivers preouts, also analog. Maybe I'm missing something, I dunno.

hicountryrider

Well guys, should I get an analog cable and a Y adapter? Also, @mdaudioguy, thanks for the link to Monoprice. They appear to have a great selection of cables and accessories.

mdaudioguy

Personally, I don't think you would notice any difference at all by using a different sub cable. I had a 6750 set. There's just not enough resolution in that system for a change such as that to be noticeable. Save your money. You're more likely to get the most out of this system by continuing to tweak your settings. Eventually, you'll reach a sweet spot where your system will sound as good as it possibly can.

hicountryrider

Thanks for the update. As long as the cable I'm currently using is correct I think I'll do as you say and just continue to tweak.

One other question. I'm currently using the L & R surround, sub and center channel speakers that came with the 6750 system. I'm using a pair of bookshelf speakers that I had before I did this whole upgrade. They are fairly decent but would I be better off using the 2 smaller Polk speakers that came with the system? I think the current front speakers have a 6 inch mid-range/tweeter combo and are ported. Not sure if that is causing any performance issues with the sub.

mdaudioguy

Well, some will jump on this and tell you your front three speakers should be matched. I say if it sounds good to you, then it's ok. Then again, since you have them, why not try them?

hicountryrider

OK, I've replaced the original front speakers I had with the Polk speakers and I must say I am quite pleased with the sound. I've also tweaked the settings for the sub and it's working well. I do see that I will always be tweaking the settings for the speaker setup depending on the content source and type. That is no problem as the Yamaha receiver makes it pretty easy.

Would like to thank all who responded for their time and information. I am quickly becoming a convert to Polk Audio!

mdaudioguy

Great to hear you're doing what you should be with your speakers - enjoying them!

rubin

Deleted

mdaudioguy

rubin wrote: »

One Gotham or two F113's. Both use the same driver and the combined amp power of the 113's exceedes the Gotham.

Yeah, in an RV (LOL!)... Did you really mean to post this here?

rubin

No I meant to create a new post....mistake

Jaeger

I have a simple powered 30W 4" sub with 2 satellite speakers hooked up to either a laptop or MP3 player. Either source sounds great and I get all the bass I need.

So when someone gave me the RM6750 which is twice as big and powerful, the last thing I expected was that I wasn't able to get enough bass out of it. I'm plugging directly into the RCA left channel. I crank my source up way higher than normal and still getting barely any output.

Does it need a LOT of signal input to drive it? Since both this one and my smaller one are powered I didn't think this would be an issue. Any ideas appreciated that don't involve fiddling with a receiver setting since I'm not using one.