XPA-5 – high impedance load

[arthurz]

I need to hook up 2 x 8Ω speakers per single XPA-5 channel.

I'm a little worried about attempting parallel wiring, since the impedance would be 4Ω nominally, but could drop lower.

The serial approach gives me a 16Ω load, which sounds high.

So, what's the best solution? The speakers will be GoldenEar Invisa 650.

[creimes]

I couldn't see parallel wiring being an issue as 4ohm speakers also dip down lower, best bet would be to call Emotiva and ask them.

[DYohn]

It is always preferable to connect loudspeakers in parallel rather than series if you need to power more than one from a single amp channel. I wouldn't hesitate to connect two nominal 8-ohm speakers to one channel of the XPA-5 if I had to.

[Deleted]

Ummm, I think it would be far safer to run the speakers in series. 16 ohms is no big deal for the XPA-5. A dip to 1 or 2 ohms would probably be a recipe for severe overheating. Especially the way some guys around here seem to listen continuously at 100+ db volumes...

-RW-

[roadrunner]

This question has come up several times in the past. On one of those threads, Lonnie posted that the XPA amps should have no problem driving two 8 Ohm speakers in parallel. He did qualify his statement by pointing out that there are a few 8 Ohm nominal speakers that drop below 2 Ohms, but they are rare and you would want to connect them in series if they become a problem. You can always check to find out the speaker's impedance curve if you have any doubts about the safety of running them in parallel.

[repeetavx]

arthurz,

From page 8 of the GoldenEar Invisa 650 manual:

If you plan to use multiple speakers per amplifier channel. The minimum impedance of ONE Invisa in-wall/in-ceiling speaker is 4 ohms per channel

Somehow I find the meaning of this statement less than clear. I think that what they're saying is that the minimum impedance on each speakers impedance curve is 4 ohms.

Speaker impedance ratings are stated at the "average" and not the minimum. Amplifier output tolerances are stated similarly. So since the GoldenEar web page states the speakers impedance as "compatible with 8 ohms". I would use that for your impedance calculations.

Therefore since your Emotiva amp is rated for 4 ohm (rated average) speakers. I believe that two 8 ohm rated speakers in parallel would perform the same as one 4 ohm rated speaker. Which is within the stated acceptable perimeters.

[arthurz]

Repeetavx, yes, it does seem like they're being pretty aggressive guaranteeing they never dip below 4Ω, but it does make sense that regular 4Ω speakers would dip as well, so the amp should handle it. I guess my question is do I dare to wire the speakers in parallel behind the drywall or do I splurge for more BJC cable and do the wiring behind the amp?

[AudioHTIT]

Feb 9, 2013 17:29:22 GMT -5 arthurz said:

Repeetavx, yes, it does seem like they're being pretty aggressive guaranteeing they never dip below 4Ω, but it does make sense that regular 4Ω speakers would dip as well, so the amp should handle it. I guess my question is do I dare to wire the speakers in parallel behind the drywall or do I splurge for more BJC cable and do the wiring behind the amp?

I wouldn't 'build' a wiring scheme into your construction. Run separate pairs to each speaker, you then have the flexibility to experiment and change, you might even want some multi-channel option in the future. These aren't the last speakers you'll ever buy are they? Also as DYohn pointed out, parallel speaker wiring is always preferred for its electrical characteristics that go beyond just impedance.

[ocezam]

I agree with most of the posts here that you could probably do it parallel, and series would also be OK should you encounter problems with parallel.

But I'd also ask why do you "need" or want to?

Multiple speakers in the same channel introduce some unwanted SQ characteristics. Comb filtering and erratic frequency response at different seats are the main problems. These can be severe, and create really weird sound fluctuations. This results from the identical drivers producing identical sound waves from different locations. SOME of the sound waves are enhanced, and SOME of the sound waves are actually cancelled. These enhancements and cancelations vary from one listening position to another, depending on sound wave timing/location. This is one drawback to "Line Array" speakers (maybe the only drawback other than size). Engineers work hard to overcome it when designing line array.

This erratic frequency response might be somewhat masked in a multichannel HT, but might render the audio "unlistenable" in stereo.

The only advantage I can see is more volume. Why not get a bigger amp and/or more sensitive speakers?

[arthurz]

Good point ocezam. My thinking was to create a more even sound field. The rooms in question are the living room, kitchen, and the dining room. The acoustics won't be ideal, so I'm thinking more speakers at a lower level would be best. Does that make sense?

[AudioHTIT]

So for a given channel, like say the left, would the two parallel speakers 'serve' the same space (like the living room), or would they serve different spaces (like living room and dining room)? If the former then ozecam's point is well taken, a single well placed and higher quality speaker is better than two lesser speakers in compromised locations. If they are to cover two rooms then your plan may work, but if they're close together you may hear reflections or reverb from the other room.

[arthurz]

The parallel speakers would serve the same space. So you guys aren't buying the sound field argument? It seems like an issue to me, no matter how good the speakers get, but maybe I'm over thinking. Coincidentally, I'd love to hear suggestions for better ceiling speakers. Most high end models (including the GoldenEar 7000) are directional, which probably won't work for my application.

Of course I wanted a set of full range floor speakers as a decoration for the living room, but my wife killed the idea very quickly. The compromise is that I can still put in a sub.