Sub Hook-Up Question - Blu-ray Forum

Hawk · 08-17-2007, 12:23 PM

I am going to hook up a second Sub to my system, but my pre-amp has only one RCA Sub output. Someone told me just to use a Y-connector to hook both of them up. Does this in any way lessen or degrade the signal by splitting it?? Thanks.

HDJK · 08-17-2007, 01:08 PM

If you use a quality connector there shouldn't be any audible degredation. I do the same thing with my 2 K&Hs. If you received a microphone with your receiver you might want to measure your setup again (to detect possible gain loss and standing waves at listening position).

MatrixS2000 · 08-17-2007, 01:22 PM

The input signal will be dropped by 3dB, however, since you are adding a second driver, you will be moving more air. You can also increase the output of each sub amp. if you need more output.

Iceman_II · 08-17-2007, 01:45 PM

Are the Subs powered, if so, and you are splitting a pure "signal" output, and not a power output, not a problem.

Is your Amplifier driving the subs, then this is another situation all together. The concern I would have is that with the two subs in parallel, the impedance would be halved... not normally a problem, until you crank up the volume, at REALLY high volumes, you may find you are overdriving your amp, trying to push more Amps than the amp can safely push.

100W into 8 Ohms = 3.54A
100W into 4 Ohms = 5.0A
100W into 2 Ohms = 7.0A

Additionally, remember that sub-audible and very low base draw a LOT of power, much more than mids or highs, so while you may only nominally drive your mains speakers with a nominal 1W in a normal listening environment, the wattage driving the subs will be higher, depending on how much your like your subharmonics, sometimes, it may be MUCH higher. Crank up the volume, and I believe the the wattage increases geometricly with relation to sound pressure levels (SPL)

If your Amp has a protection circuit, it will only cause it to cut out when it overdrives, if not, you could damage your amplifier, with such nasty consequences as frying your amps power circuit.

Edit:
I would recommend using a separately amped sub circuit if you want to stack subwoofers

Hawk · 08-17-2007, 02:00 PM

Thanks for the advice. I am using powered subs. Two new SVS PB-13's with 750 watts per amp.

Iceman_II · 08-17-2007, 02:09 PM

Best way to go... enjoy

devils3023 · 08-17-2007, 02:57 PM

Do your subs have speaker wire inputs on them? If so, the DO NOT connect them using the rca output of your receiver!! That output is just the lfe channel on whatever disc your watching, or the .1 in 5.1. You should connect the front speaker outputs on your receiver to your subs and then in the receiver settings menu select large front speakers (no matter what size you have) and for subwoofer select none- trust me! That will basically force the receiver to output ALL bass frequencies through the front speaker outputs, not just the lfe channel. Then your subs will pick off the frequencies it can handle, you can adjust the crossover on the subs to set it, and then connect the speaker line outputs from your sub back to the front speakers. This connect will give you maximum bass from your subs and best performance from your front speakers. Sorry for the long post but if you got any questions or need clarification on how to hook it up just lemme know and ill try to clear things up for ya!!! good luck!!!

Iceman_II · 08-17-2007, 03:35 PM

By routing more than the ".1" as you called it through the subs, it seems to me that the above method kind of defeats the purpose of having lossless audio true to the intent of the director...

If your subs are compensating for crappy front speakers, that is one thing, but if you are using the sub-woofer as a true sub-woofer, it seems like a bad plan... sort of like the children driving hondas with more watts of bass, than they have horsepower.

I for one will stick with running only the ".1" through my sub, as the director and sound coordinator intended.

IamNhobdy · 08-17-2007, 03:36 PM

Iceman said it!

Just listen to him and you'll be fine. He obviously knows what he's talking about.

Heheh, Iceman, you wouldn't happen to be an audio engineer, would you? If so we should find some others on here & start like a help group or something. Ya know, like just a list of who to ask about what topics. Just a thought though.

The invite is open to any & all A/V PROS. who want to help and have some spare time with which to work.

Iceman_II · 08-17-2007, 03:44 PM

Thank you for the complement sir, but alas, I am not an audio engineer, actually I like to say I am a Petroleum Engineer by degree, and a Civil Engineer by OJT

Between taking a couple of EE "circuits" classes, and many years of experience, I have picked up a working knowledge of audio (hell, I still have records for Gods sake!)

IamNhobdy · 08-17-2007, 03:49 PM

Hey you can't beat records, man! I personally am an AE(graduate of SAE Miami campus last year), and I like so say I'm a half classic analog guy who realizes the benefits of the digital age. You're knowledge really impressed me. Well even though you're not an A/V Pro per say...you know what you know, and you know it very well. If this help ring does get started, people like you are also welcome. It's nice to see inteligent people that are helpful and not insulting.

Gives me hope for the human race in general.

buckshot · 08-17-2007, 03:59 PM

Quote:

Originally Posted by devils3023

Do your subs have speaker wire inputs on them? If so, the DO NOT connect them using the rca output of your receiver!! That output is just the lfe channel on whatever disc your watching, or the .1 in 5.1. You should connect the front speaker outputs on your receiver to your subs and then in the receiver settings menu select large front speakers (no matter what size you have) and for subwoofer select none- trust me! That will basically force the receiver to output ALL bass frequencies through the front speaker outputs, not just the lfe channel. Then your subs will pick off the frequencies it can handle, you can adjust the crossover on the subs to set it, and then connect the speaker line outputs from your sub back to the front speakers. This connect will give you maximum bass from your subs and best performance from your front speakers. Sorry for the long post but if you got any questions or need clarification on how to hook it up just lemme know and ill try to clear things up for ya!!! good luck!!!

I tried the dual sub thing with 2 different subs and it didn't work out well. I want to try again. are you saying that its a better setup to not use the sub output but instead use the speaker wire connections in the back of the sub. should it be 1 sub for each front channel? or 1 sub for both then 1 sub on the rca sub out? or 1 sub for the center channel then 1 for the front channels. not sure what will be better. I had been told that using 1 to beef up the surround speakers (either the sides or the rears in my 7.1 system) would be good too. i'm very interested in this subject.

Iceman_II · 08-17-2007, 04:02 PM

Quote:

Originally Posted by IamNhobdy

Gives me hope for the human race in general.

Just don't go over and read anything on AVS... you will loose all hope.

Hell, on the main title page they might as well put up a banner that reads..

Abandon all hope, ye who enter here!

Iceman_II · 08-17-2007, 04:04 PM

Buckshot, are you sure they were hooked up in phase? If they are 180 out, they will sound like crap

buckshot · 08-17-2007, 04:17 PM

Quote:

Originally Posted by Iceman_II

Buckshot, are you sure they were hooked up in phase? If they are 180 out, they will sound like crap

first that abandon hope thing hilarious. I have a 20' flagpole outside my house with a pirate flag and a sign that reads abandon hope. looking to get that tattooed as well.

the problem before was a crappy sub paired with a semi good sub. I have a velodyne 10'' 150w sub. I may get another one when frys has then for $150 again or if I scrounge up some scratch I might splurge on the dls-4000r. i'm just trying to figure out what will work best.

when I tried it before I had a different receiver as well. I now have the tx-sr605.

Iceman_II · 08-17-2007, 05:32 PM

The real question is, do you know from where the "abandon all hope" quote comes?

Hawk · 08-17-2007, 05:48 PM

Dante's Divine Comedy, originally.
Also, used in the move "The Sentinel."

Iceman_II · 08-17-2007, 05:57 PM

its the "Inferno" section of the divine comedy

"Abandon all Hope, Ye who enter here" is the inscription over the gates of hell, an appropriate greeting at AVS IMHO

buckshot · 08-17-2007, 06:54 PM

Quote:

Originally Posted by Iceman_II

The real question is, do you know from where the "abandon all hope" quote comes?

potc the ride suckah.

who is this dante guy?

kidding of course. but potc the ride does have it.

IamNhobdy · 08-17-2007, 07:06 PM

Nice reference to AVS being Hell. I've seen that place & it's 98% BS, but it does entertain me.

08-17-2007, 12:23 PM	#1
Hawk Active Member Member since:Aug 2007 Location:Chicago 4K collection:142 Blu-ray collection:622 Blu-ray reviews:1	Sub Hook-Up Question I am going to hook up a second Sub to my system, but my pre-amp has only one RCA Sub output. Someone told me just to use a Y-connector to hook both of them up. Does this in any way lessen or degrade the signal by splitting it?? Thanks.

08-17-2007, 01:45 PM	#4
Iceman_II Expert Member Member since:Jan 2007 Location:Ft. Worth Home Theater Gallery:2 Blu-ray collection:308 Blu-ray reviews: 4	Are the Subs powered, if so, and you are splitting a pure "signal" output, and not a power output, not a problem. Is your Amplifier driving the subs, then this is another situation all together. The concern I would have is that with the two subs in parallel, the impedance would be halved... not normally a problem, until you crank up the volume, at REALLY high volumes, you may find you are overdriving your amp, trying to push more Amps than the amp can safely push. 100W into 8 Ohms = 3.54A 100W into 4 Ohms = 5.0A 100W into 2 Ohms = 7.0A Additionally, remember that sub-audible and very low base draw a LOT of power, much more than mids or highs, so while you may only nominally drive your mains speakers with a nominal 1W in a normal listening environment, the wattage driving the subs will be higher, depending on how much your like your subharmonics, sometimes, it may be MUCH higher. Crank up the volume, and I believe the the wattage increases geometricly with relation to sound pressure levels (SPL) If your Amp has a protection circuit, it will only cause it to cut out when it overdrives, if not, you could damage your amplifier, with such nasty consequences as frying your amps power circuit. Edit: I would recommend using a separately amped sub circuit if you want to stack subwoofers Last edited by Iceman_II; 08-17-2007 at 01:51 PM.

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08-17-2007, 01:08 PM	#2
HDJK Blu-ray Guru Member since:Oct 2006 Location:Switzerland Trading Score:2	If you use a quality connector there shouldn't be any audible degredation. I do the same thing with my 2 K&Hs. If you received a microphone with your receiver you might want to measure your setup again (to detect possible gain loss and standing waves at listening position).

08-17-2007, 01:22 PM	#3
MatrixS2000 Power Member Member since:Mar 2007 Location:Toronto, Canada 4K collection:48 Blu-ray collection:305 Trading Score:6	The input signal will be dropped by 3dB, however, since you are adding a second driver, you will be moving more air. You can also increase the output of each sub amp. if you need more output.

08-17-2007, 02:00 PM	#5
Hawk Active Member Member since:Aug 2007 Location:Chicago 4K collection:142 Blu-ray collection:622 Blu-ray reviews:1	Thanks for the advice. I am using powered subs. Two new SVS PB-13's with 750 watts per amp.

08-17-2007, 02:09 PM	#6
Iceman_II Expert Member Member since:Jan 2007 Location:Ft. Worth Home Theater Gallery:2 Blu-ray collection:308 Blu-ray reviews: 4	Best way to go... enjoy

08-17-2007, 02:57 PM	#7
devils3023 Active Member Member since:May 2007 Location:wayne, nj	Do your subs have speaker wire inputs on them? If so, the DO NOT connect them using the rca output of your receiver!! That output is just the lfe channel on whatever disc your watching, or the .1 in 5.1. You should connect the front speaker outputs on your receiver to your subs and then in the receiver settings menu select large front speakers (no matter what size you have) and for subwoofer select none- trust me! That will basically force the receiver to output ALL bass frequencies through the front speaker outputs, not just the lfe channel. Then your subs will pick off the frequencies it can handle, you can adjust the crossover on the subs to set it, and then connect the speaker line outputs from your sub back to the front speakers. This connect will give you maximum bass from your subs and best performance from your front speakers. Sorry for the long post but if you got any questions or need clarification on how to hook it up just lemme know and ill try to clear things up for ya!!! good luck!!!

08-17-2007, 03:35 PM	#8
Iceman_II Expert Member Member since:Jan 2007 Location:Ft. Worth Home Theater Gallery:2 Blu-ray collection:308 Blu-ray reviews: 4	By routing more than the ".1" as you called it through the subs, it seems to me that the above method kind of defeats the purpose of having lossless audio true to the intent of the director... If your subs are compensating for crappy front speakers, that is one thing, but if you are using the sub-woofer as a true sub-woofer, it seems like a bad plan... sort of like the children driving hondas with more watts of bass, than they have horsepower. I for one will stick with running only the ".1" through my sub, as the director and sound coordinator intended.

08-17-2007, 03:36 PM	#9
IamNhobdy Senior Member Member since:May 2007 Location:Earth..I think...no, wait yeah...I think Blu-ray collection:342	Iceman said it! Just listen to him and you'll be fine. He obviously knows what he's talking about. Heheh, Iceman, you wouldn't happen to be an audio engineer, would you? If so we should find some others on here & start like a help group or something. Ya know, like just a list of who to ask about what topics. Just a thought though. The invite is open to any & all A/V PROS. who want to help and have some spare time with which to work.

08-17-2007, 03:44 PM	#10
Iceman_II Expert Member Member since:Jan 2007 Location:Ft. Worth Home Theater Gallery:2 Blu-ray collection:308 Blu-ray reviews: 4	Thank you for the complement sir, but alas, I am not an audio engineer, actually I like to say I am a Petroleum Engineer by degree, and a Civil Engineer by OJT Between taking a couple of EE "circuits" classes, and many years of experience, I have picked up a working knowledge of audio (hell, I still have records for Gods sake!)

08-17-2007, 03:49 PM	#11
IamNhobdy Senior Member Member since:May 2007 Location:Earth..I think...no, wait yeah...I think Blu-ray collection:342	Hey you can't beat records, man! I personally am an AE(graduate of SAE Miami campus last year), and I like so say I'm a half classic analog guy who realizes the benefits of the digital age. You're knowledge really impressed me. Well even though you're not an A/V Pro per say...you know what you know, and you know it very well. If this help ring does get started, people like you are also welcome. It's nice to see inteligent people that are helpful and not insulting. Gives me hope for the human race in general.

08-17-2007, 04:04 PM	#14
Iceman_II Expert Member Member since:Jan 2007 Location:Ft. Worth Home Theater Gallery:2 Blu-ray collection:308 Blu-ray reviews: 4	Buckshot, are you sure they were hooked up in phase? If they are 180 out, they will sound like crap

08-17-2007, 05:32 PM	#16
Iceman_II Expert Member Member since:Jan 2007 Location:Ft. Worth Home Theater Gallery:2 Blu-ray collection:308 Blu-ray reviews: 4	The real question is, do you know from where the "abandon all hope" quote comes?

08-17-2007, 05:48 PM	#17
Hawk Active Member Member since:Aug 2007 Location:Chicago 4K collection:142 Blu-ray collection:622 Blu-ray reviews:1	Dante's Divine Comedy, originally. Also, used in the move "The Sentinel."

08-17-2007, 05:57 PM	#18
Iceman_II Expert Member Member since:Jan 2007 Location:Ft. Worth Home Theater Gallery:2 Blu-ray collection:308 Blu-ray reviews: 4	its the "Inferno" section of the divine comedy "Abandon all Hope, Ye who enter here" is the inscription over the gates of hell, an appropriate greeting at AVS IMHO

08-17-2007, 07:06 PM	#20
IamNhobdy Senior Member Member since:May 2007 Location:Earth..I think...no, wait yeah...I think Blu-ray collection:342	Nice reference to AVS being Hell. I've seen that place & it's 98% BS, but it does entertain me.

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