XPA-5 question - Driving 4 versus 5 speakers

[jjkessler]

I had a question about my XPA-5 out of curiosity. If I am driving 4 (4 ohm Axiom QS-8's), what happens to the rated power per channel versus having 5 speaker loads?

[novisnick]

Nov 19, 2014 10:37:12 GMT -5 jjkessler said:

I had a question about my XPA-5 out of curiosity. If I am driving 4 (4 ohm Axiom QS-8's), what happens to the rated power per channel versus having 5 speaker loads?

It don't hurt!!!,,,,,,he,,,,,,,he,,,,,,he,,,,,,,,

wattage per per speaker will go up fractionally!!
I don't think you'll hear any difference.

[jjkessler]

The reason I ask is I am acquiring my new HT components. I currently have an XMC-1, OPPO-105D, XPA-2 for the mains (Axiom M80), XPA-5 for the surrounds (Axiom QS-8) and the Center channel (Axiom M180). However, I am wondering if I am a bit underpowered running the surrounds and Center with the XPA-5. If so, should I run the Center Channel on a Mono and only run 4 channels on the XPA-5 for more headroom?

All of the Axiom's are rated at 400 Watts @ 4 ohms

[garbulky]

I own the axiom m80's and run it wth an old generation UPA-2 (not UPA-200). It is okay to underpower these speakers. However, they are dependent on the amp, for instance crown amps didn't pair very well with them but Emotiva amps seem to do pretty good.
However, having sufficient power does help - but I don't notice any MASSIVE deficiencies.
Running four channels will allow some of the unused power to go to the fifth channel.
However, your surrounds take up very little power as it is proportionally. So all that unused power goes to the front axioms.

My friend has m80 v4's and used both XPR-2, XPA-5, and XPA-1 L's to power them direct from an oppo 105. We both noticed an increase in dyanmics and soundstage when using an XSP-1 pre-amp with the oppo. However since you have an XMC-1, it may be just fine. I don't know as I haven't heard the pre-amp capabilities on the XMC-1. But other owners feel it is on par.
If you were doing anything, I would go monoblocks for the front left and right. Then use the XPA-5 for the center and rear. Since the rear takes up very little power anyway, the XPA-5 would have plenty for the center channel. Plus for music the fronts get the most important amplification and separation advantage of monoblocks.

If you haven't heard your new setup yet, go ahead and wait for it before making any decision. You may find you have plenty of power.

What you are going to want to do with the m80's is play around a whoooooooole lot with positioning. Do not just plonk it down where it seemed good adjust it for a few minutes and be done with it. The sound WILL be good, but I promise you it can be much much better. I've had them for years and still haven't got the best positioning for them though I've gotten somewhat close.
What matters a lot - it's toe in. Number 1 thing with these speakers!!
Also:
How far apart they are (they like to be far apart), and how far away from the backwall it is. Too far and they sound not full/lifeless, too close and it gets a little muddy.
Also things that matter is if there is stuff like cofee tables, side sofas in the way of the sound from the speaker to you.

[jlafrenz]

I wouldn't sweat it as it isn't likely that you are hitting SPL's high enough to where you are needing 400 watts. The Axioms are fairly sensitive and the XPA-5 puts out 300 watts at 4 ohms (this is conservative). You would have to be listening quite loud to need much more power.

[geebo]

Here's an old thread on the subject. XPA-5 info is down the page a bit.:

emotivalounge.proboards.com/thread/26492/rated-power-xpa-5

[broncsrule21]

As long as your center is getting enough juice (which it is getting plenty with an XPA-5 only running 4 channels) there is no reason to change anything. You have plenty of headroom in that configuration.

[jjkessler]

My thought was
Use the existing XPA-2 to drive the M80's main channels,
Use the XPA-5 to drive the 2 sets of QS-8's (4 speakers versus 5 with the center channel),
But a XPA Monoblock to power the center channel.

I would only need one more Amp (Mono Block) to properly power everything.

[broncsrule21]

Sure, I get ya. I personally use monos up front and a 2 channel amp for the rears (see sig). I'm just saying the XPA-5 is a proven beast. Driving only four channels, your center is far from starving for power unless you are playing at ear damaging levels. But hey, it only matters if it "worth" it to you.

[jjkessler]

So, from the old post, it will bump from 350 to 375 WPC when using 4 versus 5 channels. Not much difference indeed.

In thinking about this further, I might stick with my original design of using the XPA-2 for the Main channels and the XPA 5 for the surrounds AND center channel and see how it behaves for a while. If I really think I need the extra 25 WPC on the surrounds, then I will add a single Monoblock to power the Center channel however, even though I am not quite hitting the full power rating of the surround and center speakers, it will probably be enough for my comfort as I don't see running this at full volume very often at all and if I did, it would most likely happen while in pure 2 channel mode

[danny01]

When you are at 300 watts, 25 watts will do nothing for you. The XPA-5 will be fine in driving a center and 4 surrounds. The power supply will pretty much be dedicated to the center 99% of the time since surrounds usually only need power in very short bursts.

Sent from my SM-P600 using proboards

[garbulky]

You already have an XPA-2?! Oh that makes it easy.
Okay so you have 4 surround speakers and a center - USE THE XPA-5. It's really MORE than plenty power for a single (demanding) center and four low demand surrounds. They really will be low demand. Most surround sounds material aren't very demanding.
Then use the XPA-2 for the mains.
If you are going to be using a subwoofer, the power demands go down even more.

There's also another budget way of doing it. Get you a monoblock for the center. Use the XPA-2.
And buy a UPA-500 and use it for the surrounds. The gain levels are identical so there won't be any volume imbalance.

[jjkessler]

I do have dual subs as well and will use this model for now

4 surround speakers and a center - USE THE XPA-5. It's really MORE than plenty power for a single (demanding) center and four low demand surrounds. They really will be low demand. Most surround sounds material aren't very demanding.
Then use the XPA-2 for the mains.

[repeetavx]

Nov 19, 2014 11:18:57 GMT -5 jjkessler said:

My thought was
Use the existing XPA-2 to drive the M80's main channels,
Use the XPA-5 to drive the 2 sets of QS-8's (4 speakers versus 5 with the center channel),
But a XPA Monoblock to power the center channel.

I would only need one more Amp (Mono Block) to properly power everything.

It sounds to me like you've pretty much got it together. Your only one question is should you buy one more amp (a mono-block) for your center channel to give you more "omph" for the surrounds. If you have the money, sure why not. Would you hear a difference? Well maybe on multichannel music played very loud, or a particularly raucous movie. It would only make a difference when your system is being pushed really hard.

For your set-up, I think that you would be really impressed with an XPA-100 on your center channel.

[jlafrenz]

Nov 19, 2014 11:33:22 GMT -5 jjkessler said:

So, from the old post, it will bump from 350 to 375 WPC when using 4 versus 5 channels. Not much difference indeed.

In thinking about this further, I might stick with my original design of using the XPA-2 for the Main channels and the XPA 5 for the surrounds AND center channel and see how it behaves for a while. If I really think I need the extra 25 WPC on the surrounds, then I will add a single Monoblock to power the Center channel however, even though I am not quite hitting the full power rating of the surround and center speakers, it will probably be enough for my comfort as I don't see running this at full volume very often at all and if I did, it would most likely happen while in pure 2 channel mode

Keep in mind that just because a speaker is capable of handling a certain amount of power and an amp is capable of producing a certain amount of power does not mean that either is demanding or producing this specific amount at any one time. A speaker is dynamic so its demands for power will change with the music. The other factor here is output level or volume. listening louder takes more power (assuming the same seating distance). The reality is that at normal listening levels, a speaker is only requiring a fraction of the power it is rated at. The extra power reserves of the amplifier is what we call headroom. This allows power on hand for dynamic passages.

This is simply put that an amplifier rated at 300 watts is not always producing or feeding your speakers 300 watts.

Here area couple of links that go over this a bit more in detail.

www.chuckhawks.com/speaker_spl_amp_power.htm
www.axiomaudio.com/power

Here is a calculator that shows you how much power you use based upon distance, sensitivity and desired volume.

www.crownaudio.com/elect-pwr-req.htm

[dally]

Unless your system is in an auditorium, there's no way your gonna clip the XPA-5 with four surrounds and a center channel attached to it. Your subs are handling the bass, the XPA-2 is doing the heavy lifting by carrying the mains, and your XPA-5 will just be coasting along with those surrounds and center.A Mono would be nice for the center but DEFINATELY not needed. I used to run 5 polk LSi's ( much more current hungry than your axiom surrounds and center) full range on an XPA-5 and never drove it to clipping.