Splitting a single Ctr channel into two

[lgcubana]

I want to have dual center channels

AVR (RCA single channel out) --> RCA Y cable --> (two inputs) XPA-5, ver 2 

I don't see a closed loop, so I'm assuming this is a safe practice.




Originally I wired my two ELAC Unifi- UB5s (4 ohm) in series  (to get an 8 ohm load), but the amp got noticeably warm.

AVR (RCA single channel out) -->  XPA-5, ver 2

[copperpipe]

That's generally considered a bad idea; you shouldn't have two or more physical speakers playing sound from an identical source. I would sooner suggest getting a better center channel if you find your current one lacking in some way.

[novisnick]

Apr 24, 2017 11:44:21 GMT -5 copperpipe said:

That's generally considered a bad idea; you shouldn't have two or more physical speakers playing sound from an identical source. I would sooner suggest getting a better center channel if you find your current one lacking in some way.

So TRUE!!!

Sometimes, Bigger IS better!!



if it timber matched for music.

[Casey Leedom]

And get the Center Channel from the same company that makes your Left/Right in order to be properly matched.

Casey

[vneal]

Apr 24, 2017 11:44:21 GMT -5 copperpipe said:

That's generally considered a bad idea; you shouldn't have two or more physical speakers playing sound from an identical source. I would sooner suggest getting a better center channel if you find your current one lacking in some way.

agreed

[goozoo]

The reason to choose to do dual center channels varies based on the situation. Bear in mind a few limitations. First it assumes that you are placing the speakers horizontally (traditional center speaker) and NOT VERTICALLY. Second you also are assuming that there is adequate spacing between the two center channel speakers. The reason for this is because of comb filtering from one speaker onto the sound field of the other. This typically means using smaller center channel speakers placed above and below the screen, which in turn should produce a voice coming directly from the center of the screen (ideally). Size is critical as is distance apart in this scenario since any deviation will not produce the results you want. As to splitting the signal, it is how most people do it and generally a poor result. Signal splitting often translates into diffuse sound and dialogue that is not very intelligible. A better alternative is to wire the two center speakers in parallel thus cutting the resistance by half. So you end up with a 4 ohm load if using 8 ohm speakers. If you are using 4 ohm speakers, DON'T DO THIS!. It will result in a 2 ohm load and will become too unstable for your amp.

While the above explanation answers your original post, an easier approach would be to upgrade the center channel to a larger speaker placed underneath the screen. If this is not possible, then a final option would be to do a "ghosted center" if your main speakers are large enough to compensate for the lack of a center channel. In my own personal theater, I opted to go the dual center route wired in parallel due to space and lack of an acoustically transparent screen. Sounds great and am hard pressed to make a change.

Good luck.

[lgcubana]

Here's my current system, which is in transition:

Front:       Carver AL III+, XPA-2 
Center:    ELAC Unifi-UB5 (in a horizontal orientation), XPA-5
Rears:       JBL 530, same XPA-5
Couple of 15" subs

Timber matching the center to the mains isn't an issue for me, as I only playback music to the mains &  I only use the 5.2 setup for movies, where the center channel has to shine.

Is the recommendation to not split the center channel signal coming from the perspective of the audio play back or can this configuration in anyway harm the XPA-5 ?
 

[goozoo]

Apr 24, 2017 17:40:49 GMT -5 lgcubana said:

Here's my current system, which is in transition:

Front:       Carver AL III+, XPA-2 
Center:    ELAC Unifi-UB5 (in a horizontal orientation), XPA-5
Rears:       JBL 530, same XPA-5
Couple of 15" subs

Timber matching the center to the mains isn't an issue for me, as I only playback music to the mains &  I only use the 5.2 setup for movies, where the center channel has to shine.

Is the recommendation to not split the center channel signal coming from the perspective of the audio play back or can this configuration in anyway harm the XPA-5 ?
 

Just from an audio playback perspective.  Try it out and see if you like the sound or not.  

[jackpine]

Apr 24, 2017 11:13:39 GMT -5 lgcubana said:

Originally I wired my two ELAC Unifi- UB5s (4 ohm) in series  (to get an 8 ohm load), but the amp got noticeably warm.

AVR (RCA single channel out) -->  XPA-5, ver 2

Are you sure you wired the speakers in series? The amp shouldn't get hot if the speakers were wired correctly.

[lgcubana]

Definitely wired in series. Triple checked to make sure that I didn't do parallel, which would've brought my load down to 2 ohms.

In looking back at my 1st wiring scheme, I used Monoprice RCA to XLR cables on the XPA-5;  which kept the amp cool to the touch. The amp only started warming up when I used conventional RCA cables.

Once I get a definitive answer on not harming the amp (by feeding it a split signal), I'll try the Monoprice cables again.

[leonski]

Apr 24, 2017 18:54:39 GMT -5 jackpine said:

Apr 24, 2017 11:13:39 GMT -5 lgcubana said:

Originally I wired my two ELAC Unifi- UB5s (4 ohm) in series  (to get an 8 ohm load), but the amp got noticeably warm.

AVR (RCA single channel out) -->  XPA-5, ver 2

Are you sure you wired the speakers in series? The amp shouldn't get hot if the speakers were wired correctly.

Kind of a puzzler, isn't it?    The only thing I can come up with is the user played VERY loudly.  

[goozoo]

The split signal is no the issue. We have done this multiple times for clients and all is stable. It has to be the wiring configuration or perhaps a short somewhere in the interconnect. We do always do this with full balanced XLR connections and no issues, but if anything the RCA connections draw less voltage than XLR. It could also be the speaker connection to the amp itself. Try a different speaker and RCA cable which you know to be good; not from Monoprice. If problems persists, then it may be the amp or speakers themselves.

Alternatively, you could just plug the center channel from your amp into an audio splitter then out to the speakers (which should not be attached to each other).

[leonski]

Balanced is 6db 'louder' than single ended.
Balanced has 2 'legs' and a ground. I think this ends up as 4 volts per leg while single ended is 2 volts. (voltage is example only)

This doesn't hold true for systems which are not 'native' balanced.

For example: I'd expect a system with 30k input impedance balanced and single ended to be 15k Per Leg of the balanced side. The balanced side would be far more
vulnerable to a high output impedance source.

For splitting done at line level, the real issue is NOT voltage but rather impedance. I don't know what the output impedane of the source component is. Or the XPR-5, either.

As the ratio of int to out drops to maybe 5:1, you have problems and potential interactions causing frequency shifts and maybe even inability to drive the load.

[mgbpuff]

Splitting at the RCA line level is rarely a problem, especially with high input impedance solid state amplifiers, but of course you must have an extra amplifier channel. If you only have one amplifier for the center channel, wiring in series is preferable because the speakers will see the exact same current with no phase differences due to wire length differences (apparent speaker impedance is doubled). You can also wire themf in parallel but as stated by others the apparent speaker impedance is half and if your speakers are 4 ohm or less you may tax the amplifier. A long time ago I derived a center channel from two speakers placed on either side of my 27" CRT and stand. I know the caveat of lobbing, but I never heard anything horrible out of them, in fact I liked it and had the same type of speakers wider for left and right mains. The Dolby Surround (old analog type) at the time was just fine.

[KeithL]

The RCA-to-XLR cables most definitely should NOT cause anything to get warm.
(Even a totally shorted or miswired line-level connection, which might distort or not work at all, and might make the amp go into protect, STILL won't make the amp get warm.)
Splitting a line level signal should not hurt anything.

Also, in general, I've never seen an amp that ran warmer into a higher impedance load.
In general, the opposite is true; into a low impedance load the amplifier will deliver more power, but may get very warm.
(Some older amps with unusual forms of protection may limit their output into a low impedance load - but mos modern amps will not.)

Apr 24, 2017 19:33:37 GMT -5 lgcubana said:

Definitely wired in series. Triple checked to make sure that I didn't do parallel, which would've brought my load down to 2 ohms.

In looking back at my 1st wiring scheme, I used Monoprice RCA to XLR cables on the XPA-5;  which kept the amp cool to the touch. The amp only started warming up when I used conventional RCA cables.

Once I get a definitive answer on not harming the amp (by feeding it a split signal), I'll try the Monoprice cables again.

[leonski]

Like my first reaction: A Puzzler.

Was more than ONE thing changed at the same time?

[lgcubana]

Now that I feel more comfortable going forward with the split RCA signal, I'm going to do proper step by step diagnostics/configurations.

I threw a lot of information into this thread, as my setup kept changing. So I have no one but myself to blame, for muddying the thread.

I'm going to go back to a base configuration and and go from there.


Thanks for all of the insight.

[Hair Nick]

I'm currently doing a split center with two Airmotiv 5Ss.

[pontiacmn11]

I actually was using 2 Klipsch RB-81's split for center for awhile before moving to a RC-64. To be honest, the 81's sounded as good as the 64 does? Just my 2 cents