# Help With Home Audio Setup



## devdev (9/8/14)

Hi guys,

I have an amp that I am trying to run a 2.1 setup with. Basically Stereo and then a third channel to an active subwoofer.

Problem is the amp only has the L+R outputs and no third out for the sub.

Can I simply split the signal coming out of the RCA outputs and send one set to the Amp for stereo, and merge the other set into one lead which goes in to the active subwoofer?

I am not sure what signal usually gets sent to the subwoofer, if it is L/R or both.

I figured someone here would have the answer.


----------



## TylerD (9/8/14)

If you send, L to 2 speakers and R to the woofer, you will get stereo via 2 speakers an woofer. Wont have stereo on your two speakers. Don't think it's going to sound very cool.


----------



## Gazzacpt (9/8/14)

devdev said:


> Hi guys,
> 
> I have an amp that I am trying to run a 2.1 setup with. Basically Stereo and then a third channel to an active subwoofer.
> 
> ...


That should work. Does the active sub have built in low pass filters?

Reactions: Agree 1


----------



## RATZ (9/8/14)

Theoretically....

Would monitor for heat though.A second Sub would be better. just make sure the amp can drive the speakers.
You may destroy the stereo effect though as the Sub 'centre' would be receiving both left and right signals.


----------



## drew (9/8/14)

Hey @devdev

EDIT: Argh... post disappeared. When running a single sub it is a mono sum of L+R. Just grab 3 of these from a car audio or electronics shop. 2x to split the main output and 1x to combine the signal into the sub. Being an active sub it should have a built in crossover.

Reactions: Like 2 | Agree 2


----------



## devdev (9/8/14)

Lol Tylerd. Im gonna try that!

Gazza no idea. A good question though I will check

Reactions: Funny 1


----------



## Gazzacpt (9/8/14)

RATZ said:


> Theoretically....
> 
> Would monitor for heat though.A second Sub would be better. just make sure the amp can drive the speakers.
> You may destroy the stereo effect though as the Sub 'centre' would be receiving both left and right signals.


Low frequency is not directional. Its higher frequencies that give you the stereo effect. They are the ones you perceive to be coming from a certain direction. If its a decent sub you won't perceive any stereo seperation. We often use to hide subs behind cupboards and under things. The sound just fills the room.

Reactions: Agree 3


----------



## RATZ (9/8/14)

Gazzacpt said:


> Low frequency is not directional. Its higher frequencies that give you the stereo effect. They are the ones you perceive to be coming from a certain direction. If its a decent sub you won't perceive any stereo seperation. We often use to hide subs behind cupboards and under things. The sound just fills the room.


Accurate, I just don't know what sub it is.


----------



## devdev (9/8/14)

Ok Sub is an Onkyo (or however it is spelt) thing, about the size of a bedside table. Actually was just looking for an amp initially, but I got offered this as an end of line special from a contact at a retailer, bundled with 2 speakers.

I checked the manual, does not have an LPF.

It should be possible to use a resistor or some other bitty to filter out high frequency sound IIRC.

@johan would probably be able to advise on this. Going to get to work chopping up the RCAs and doing a solder job in the mean time.

Since the woofer itself is limited by its physical size regarding the range of frequencies it can play, I think it should be ok to run without an inline LPF. 

Or am I missing something here?


----------



## johan (9/8/14)

devdev said:


> Ok Sub is an Onkyo (or however it is spelt) thing, about the size of a bedside table. Actually was just looking for an amp initially, but I got offered this as an end of line special from a contact at a retailer, bundled with 2 speakers.
> 
> I checked the manual, does not have an LPF.
> 
> ...


 
The correct way (note: not the only way) is to use a 2.1 active or passive low pass filter cum splitter between the sound source and amp/s - should be available at Hi-Fi Installations. (1) What is the sound source? (2) Does the Sub have its own build in amp?

Reactions: Like 1


----------



## TylerD (9/8/14)

Do you have a cum splitter @devdev

Reactions: Funny 4


----------



## johan (9/8/14)

TylerD said:


> Do you have a cum splitter @devdev


 
Oi-vey! you need some Latin education!

Reactions: Agree 1 | Funny 1


----------



## devdev (9/8/14)

johan said:


> The correct way (note: not the only way) is to use a 2.1 active or passive low pass filter cum splitter between the sound source and amp/s - should be available at Hi-Fi Installations. (1) What is the sound source? (2) Does the Sub have its own build in amp?


 
The sound source will be anything playing from my TV (WD media player/Apple TV/DSTV). Audio out of TV will be a regular stereo RCA into the Amp. It would be at this point with the audio out that I would want to split (Solder) a macgyver jobbie and go one set of L+R to the amp and a second set, with the L+R merged into one channel running to the Sub.

I am much preferring the idea of finding a LPF from a proper shop though


----------



## TylerD (9/8/14)

johan said:


> Oi-vey! you need some Latin education!


Sorry @johan I'm a bit iliteratated. I'm a bit of a nut job. Sorry.

Reactions: Funny 2


----------



## johan (9/8/14)

devdev said:


> The sound source will be anything playing from my TV (WD media player/Apple TV/DSTV). Audio out of TV will be a regular stereo RCA into the Amp. It would be at this point with the audio out that I would want to split (Solder) a macgyver jobbie and go one set of L+R to the amp and a second set, with the L+R merged into one channel running to the Sub.
> 
> I am much preferring the idea of finding a LPF from a proper shop though


 
You can try it, but you might ran into impedance matching problems. I agree take your amp to a proper shop and get a LPF.


----------



## devdev (9/8/14)

johan said:


> You can try it, but you might ran into impedance matching problems. I agree take your amp to a proper shop and get a LPF.


Never really understood impedance (pure lazyness) and I am not sure how this would impede me under the circumstances, but I will be checking online tonight for an LPF and placing an order if I find the right thingy.

Hope the neighbours enjoy the Sub as much as I plan too

Reactions: Like 1 | Funny 1


----------



## johan (9/8/14)

TylerD said:


> Sorry @johan I'm a bit iliteratated. I'm a bit of a nut job. Sorry.


 
No worries, some have a good eye for a pun (or in this case "cum") and other for language

Reactions: Winner 1


----------



## devdev (9/8/14)

johan said:


> No worries, some have a good eye for a pun (or in this case "cum") and other for language


 
Beleive me had to hold back at that point, otherwise:

Reactions: Funny 3


----------



## johan (9/8/14)

devdev said:


> Beleive me had to hold back at that point, otherwise:
> View attachment 9492


 
Since when did you turn FEMALE, or is the wording just wrong when I click on your custom banner?  I'm shocked!

Reactions: Funny 1


----------



## devdev (9/8/14)

If you are going to start a group with Girl vapers, I sure as hell have to be there, to ensure that only girls are there. part of a quality assurance initiative...


http://www.ecigssa.co.za/xfa-groups-thread/yeah-girls-i-love-vaping.2/?page=1#post-2


----------



## johan (9/8/14)

devdev said:


> If you are going to start a group with Girl vapers, I sure as hell have to be there, to ensure that only girls are there. part of a quality assurance initiative...
> 
> 
> http://www.ecigssa.co.za/xfa-groups-thread/yeah-girls-i-love-vaping.2/?page=1#post-2


 
LOL, I want to join with almost no hair! Oh! I only now realize it, you also a skinhead  or as the Irish will call you: "skanger"


----------



## Gazzacpt (9/8/14)

devdev said:


> Never really understood impedance (pure lazyness) and I am not sure how this would impede me under the circumstances, but I will be checking online tonight for an LPF and placing an order if I find the right thingy.
> 
> Hope the neighbours enjoy the Sub as much as I plan too


impedance shouldn't be a problem with the setup you planning but yeah sub woofers are designed for low frequency and putting anything over the recommended frequency cut out will sound, well, k@k and could cause damage. Onkyo is quite decent kit strange that it doesn't have built in filters if its an active sub. They normally have a volume and cut off frequency setting on them.
You sure the amp doesn't have a sub pre amp out?

Reactions: Agree 1


----------



## johan (9/8/14)

BTW its not derailing of the thread; "Onkyo," "amplify," "LPF" and the custom banner all make absolute sense, let alone the Latin.

Reactions: Funny 1


----------



## devdev (9/8/14)

SKW770B is the Sub, and based on the instructions it did not appear that it had a cutoff included.

The Amp is a Sony STR-DH130. Just checked again, definitely no Sub output


----------



## Gazzacpt (9/8/14)

devdev said:


> SKW770B is the Sub, and based on the instructions it did not appear that it had a cutoff included.
> 
> The Amp is a Sony STR-DH130. Just checked again, definitely no Sub output


My recommendation then is to get a Velodyne DD+15 .


----------



## johan (9/8/14)

devdev said:


> SKW770B is the Sub, and based on the instructions it did not appear that it had a cutoff included.
> 
> The Amp is a Sony STR-DH130. Just checked again, definitely no Sub output


 
Just looked at the specs: http://www.intl.onkyo.com/downloads/manuals/pdf/skw-770_manual_e.pdf, should not be a problem (impedance is quite low - input) to do it as some posters suggested previously: + from R-channel and + from L-channel and obviously screen / ground. If you experience bad sound ad small 10K Ω resistance in series with each channel.

Reactions: Winner 1


----------



## Silver (9/8/14)

@devdev 

I think you may need to solve the impedance problem by using the correct wire.

Try 26g

If that doesn't work, I think you may just need to connect it up with some 30g twisted. 
But twist it really really tight 
It won't sound good unless its tight.

Reactions: Winner 2 | Funny 1


----------



## drew (9/8/14)

johan said:


> Just looked at the specs: http://www.intl.onkyo.com/downloads/manuals/pdf/skw-770_manual_e.pdf, should not be a problem (impedance is quite low - input) to do it as some posters suggested previously: + from R-channel and + from L-channel and obviously screen / ground. If you experience bad sound ad small 10K Ω resistance in series with each channel.


 
Nice find. The manual also lists a frequency response of 25-150hz which suggests an internal LPF, the frequency response of the actual woofer would be much higher than that. No need to worry about an external crossover, just plug in and make some noise.


----------



## devdev (9/8/14)

drew said:


> Nice find. The manual also lists a frequency response of 25-150hz which suggests an internal LPF, the frequency response of the actual woofer would be much higher than that. No need to worry about an external crossover, just plug in and make some noise.


 
Thanks so much @drew, @johan and @Gazzacpt 

Got it all wired up, ready to make a racket, and then couldn't get anything to play. Check the back of the TV, and it doesnt have any RCA outs!!! I had it connected to the RCA inputs. TV Only has optical out, and Amp doesn't do optical. 

Another plan will be needed!


----------



## drew (9/8/14)

devdev said:


> Thanks so much @drew, @johan and @Gazzacpt
> 
> Got it all wired up, ready to make a racket, and then couldn't get anything to play. Check the back of the TV, and it doesnt have any RCA outs!!! I had it connected to the RCA inputs. TV Only has optical out, and Amp doesn't do optical.
> 
> Another plan will be needed!


 
Lol, no headphone jack?

Reactions: Funny 1


----------

