Using 7 surround speakers on a 5.1 receiver.. possible?

[bjornb17]

Hi everyone, this is my first post.

Since the summer, i've been getting more and more into home theater stuff. I have put together a system that i really like which comprises of MTX Monitor series floorstandings as my mains and my surrounds, and a MTX Monitor center channel speaker. I also have a Velodyne CHT-12 sub and an HK AVR-130 receiver.

This is a 5.1 setup, and that is limited by my receiver. Since i haev no intentions to upgrade my receiver any time soon because of cost issues, i was wonder what would happen if i would wire 2 more speakers (1 for left and one for right) onto the existing surround channels?

Is this even possible? The receiver is an 8 ohm receiver, and the speakers are 4 and 8 ohm compatible.

What can i do?

Thanks a bunch!

Bjorn

[markw]

Odds are that when you connect another pair of speakers to the same terminal as another, the total impedance will be lowered, probably to lower than most amps can handle.

Of course, if you have a "B" speaker terminal, this might be a half-arsed solution since it would reproduce either the two stereo channels or the two front channels. RTFM for more info on this and see where this leads.

[bjornb17]

i already read the FM but it doesnt provide any info for this. Also, i dont have A/B switching.

[cam]

Running to speakers off one terminal can be done. Not recommended though because you will most likely want to listen to your system loud and your receiver will not beable to produce the power needed because of the ohm load. Your amp will see two 8ohm speakers now as a 4ohm load. You can however run them in series very easily. Just run one + to the + of one speaker and the - to the - of the other speaker and then join the remaining + and - together. Your amp will now see two 8ohm speakers as a 16ohm load. You will have to raise your speaker levels after because they will be lower.

[swgiust]

The best way to do this is to add an amp. You can wire your surrounds and use
the pre-outs at the same time. HK makes an amp thats only about $300. Of course
you will be getting the exact same sound out of each set of speakers. It won't truly
be 7.1 but I bet it sounds better than plain 5.1.

[bjornb17]

thanks for the info. but if i was going to spend $300 on a an extra amp, i could just buy a 7.1 receiver instead.

[mgripy]

Like previous wire in series. Only way to make it happen w/o another amp. And it won't truly be 6.1 or 7.1 but it will work.

[bjornb17]

Like previous wire in series. Only way to make it happen w/o another amp. And it won't truly be 6.1 or 7.1 but it will work.

thanks everyone, i think ill give that a try.

a couple questions though: its it bad for the receiver in any way to have the speakers at 16 ohms? what would the volume difference be?

Also, the current speakers on my surrounds are rated at 92 db at 1w/1m, and the ones i would add on are 90 db at 1w/1m (smaller versions of the same speaker). will this affect performance at all?

Thanks!

[markw]

As to your other question, since what you're doing is fairly unusual, and won't really add anything and nobody else has bothered with it, the audiable results will be unpredictable. ...maybe better, maybe worse, most certainly different.

I won't do the math for ya (I can't) but here's some things to think about.

Since the power at 16 ohms is LESS than that delivered to an 8 ohm speaker, and this available power will be SHARED between TWO speakers. I think you can do the math to come out with an approximate answer.

Also, having two speakers in series does funky things to the impedance curve and this will affect the sound somewhat.


Try it and see how it sounds. At least you can feel safe in that your receiver is not gonna blow up.

[Woochifer]

I wouldn't bother with that. A whole lotta trouble and expense for not a whole lotta gain, and high potential for things sounding a lot worse than before. The thing you need to first ask yourself is not whether such a setup is possible, but what kind of performance you want your system to deliver. Once you answer that question, THEN you figure out steps to achieve that performance goal. Otherwise, you're simply hooking up the extra surround speakers just because you can, not because they do anything to improve your audio quality.

In general, I would first make sure that your 5.1 setup is optimized before even bothering with 6.1 or "7.1" (a misnomer because the soundtracks are not discrete 7.1). Are the levels matched properly, and did you match them with a SPL meter? Do you have the surround speakers properly aligned? Have you compensated for differences in distance by changing the delay timing?

The back surrounds using a 5.1 receiver would be outputing the same signal as the L/R surrounds. Since you have two speakers for each channel reproducing the same thing, it will potentially create time domain distortions and screw up the imaging cues. The only way avoid this is to not only hook up another amp (which can only be done if your receiver has preouts), but to actually hook it up to one with a Pro Logic decoder so that it can decode the monophonic EX/ES back surround channel. Even there, you got fewer than 0.1% of all DVDs on the market with any kind of EX/ES encoding.

Hooking up two sets of speakers to each surround output is just asking for trouble, since h/k receivers of your vintage have had reliability issues in the power supply.

5.1 is the standard, and that's how the majority of DVDs get mixed nowadays. Get that right first, and you'll get a lot more enjoyment out of your system than trying force feed something it was not intended to do.

[SAPSEC]

You may toast your receiver if you double your connections in same terminals. Sell your receiver and either get the one with A & B switch or get a 7.1

[swgiust]

I have to agree with Woochifer, make sure youv'e done everything you can to your current
set up. Check levels, speakers placement, ect. A well set-up 5.1 system will outperform
a bad set up 7.1 system any day.I believe we all suffer from the more is better syndrom,
but that is not always good in the audio world.