My DIY Orb Audio Mod 4 Like System, DIY Home Theatre Satellite System

Hello Everyone.

Parts express recently had a smoking deal for Christmas, with Spherex
Satellite Speakers which have Omnipolar technology licensed from Mirage
at $19 a pair. I know it sounds crazy, but I purchased 12 pairs for $228
with free shipping.



Xbox Spherex Satellite Speaker Pair

Specs for the speakers are as follows:

*Power handling: 55 watts max
*Impedance: 8 ohms
*Frequency response: 135-20,000 Hz
*Dimensions: 5-1/2" H x 6-1/2" L x 3-1/4" W.

My plan is to create a 7.1 system using multiple satellites similar to
what OrbAudio.com has for it's Mod 4 setup. Here's what I am talking
about:

Orb Mod 4 System

I am hoping having multiple drivers will allow the system to function at
a very competent level. Each "channel" (i.e. Left/Center/Right
and Surrounds) will be comprised of 4 individual satellites wired together.

I'm looking for ideas on how to create the appropriate wall mounts
or stands and a way to replace the RCA connection with standard
speaker terminals. Paired with my PSB Subsonic III 12" Sub, it
should make a pretty reasonable system.

What do you think? Am I completely out of left field with this idea?
Do you have any ideas or suggestions on how I could do this?
I would certainly welcome hearing from you, even if you think I
was crazy (as my wife told me several times already today) for
buying so many of these speakers!

Thankfully I have plenty of friends and family who have PC's, so
if this idea turns out not be feasable, everyone next year is going to
get the same present from me, for Birthdays etc...

Merry Christmas to all!

Igo2Xs

i have no idea what you are in store for with this project, but it definitely looks interesting ....

no matter how it turns out, it should be a great test-bed for similar endeavors. i'm looking forward to how it progresses.

Hey...thanks for the vote of confidence! I think it should
be a good learning experience for me at the very least. I'll
certainly let you know how this progresses.

First off, 7 channels x 4 speakers each = 28 speakers. You said you only have 12 pairs, or 24 speakers. So it would seem you are 4 speakers short of what you need.

Assuming these are decent sounding speakers and using 4 per channel gives you good power handling, I don't see why this wouldn't work well. In particular you will have the ability to point the individual speakers in the surround arrays in various directions to achieve good dispersion of the surround channels. In other words you should be able to play with placement to address any shortcomings with your room.

My main concern with these speakers is their frequency response only goes down to 135Hz. On top of that they look like a ported design (isn't that a port at the top). So taking the rolloff below 135Hz into account you are probably going to need to crossover the subwoofers at 150Hz (maybe even a little higher). Such a high crossover frequency will make it very easy to hear the location of the subwoofer. About the only way you can crossover so high and still have acceptable imaging is if the subwoofer is directly under the center channel. If you had two subs, I would put one under each left and right front array.

So I don't think your idea is bad. In fact you gain great flexibilty to point individual speakers in each array to tweak the sound. However, your challenge will be integrating the sound from the subwoofer with the rest of the system.

Good luck, and let us know how it turns out.

Rob

Hi Rob,

Wow...do I feel stupid! Thanks for pointing out I'm two pairs short
of my target. Duh... Oh well. As it turns out Parts Express raised
the price of the speakers to $30, so I think I'll probably have to
do a 3 speaker setup for the rear channels. Perhaps this is for the
best, as front speakers tend to get the most sound/info when watching
movies.

To answer your question, the speakers are ported. Your point of
having to set the sub a high crossover frequency (~150hz) is a
great observation. Thank you for that! I didn't even consider that.
I'm not attached to my PSB sub, so if I were to get two reasonable
subs in it's place that might be an option. My plan is to get a flatsreen
display next year and mount if above the fireplace. The center channel
would be mounted just below the display. That being said, I don't think
I could put the sub below there as it would be in front of the fireplace.
That means getting two sub's is probably what I would end up having
to do. Of course this means an increase in the $ I wanted to spend in
the 1st place, but what HiFi plan even stays within budget???

Speakers are set to arrive early next week. In the mean time
I'm trying to come up with the best array pattern for the front and
reach channels. What do you think about a line array for the fronts:

O-O-O-O

The above example is for the center channel. Left and right would be
rotated 90 degress. I would frame the flatscreen with L/R/C channels.
Though I could opt to mount the L/R channels on the wall corners, but
I am not sure if this would help increase sweet spot? FYI, the wall which
the display will be mounted is about 18' W.

I am thinking about using 3 Leaf Clover pattern for the rears, like a
mathematical symbol for "therefore" I'll try my best to do this via text:

..O
O..O

Or, I could opt to do the following for the rear channels (of course rotated)
90 degress for the 6.0 (Left/Right) channels and horizontal for 7.0
(L/R):

O-O-O

Does this make sense? Do you have any advice as to which would be
the best pattern to array these speakers? Thanks again for your insight.
I'm really looking forward to starting this project!

All the best,

Igo2Xs

This post has been edited by igo2xs on December 26, 2007 08:28 pm

Um, not trying to pile on, but I have heard, but some of our other folks here with flat screen tv's might know, but, From what I have been told, you shouldnt put your tv above a fireplace because of the heat, I believe those tv's dont like heat and it will take the so-called life span down a lot. anyway just my 2 cents, somebody will chime in, I hope and veryfy if I'm wrong or not.

elroy

Hey no worries! I guess I should explain that we we have an electric
insert installed to give the appearance of a fire when switched on, but
with the option to turn on/off electric heat as needed. Do you think the
heat generated from the insert would be enough to affect the
display? Thanks for your comments though!

Igo2xs

This post has been edited by igo2xs on December 27, 2007 09:03 am

was hoping someone with a bunch of knowledge on the subject would chime in, but I read that somewhere I think, that heat is bad for some of those type of flat panel tv's. I believe it was talking about plasma types, not sure if it applies to lcd's or other types.

elroy

Oh Ok... I am looking in the direction of a plasma display. The one I have
my eye on was highly rated by Consumer Reports this year:

Panasonic TH-50PZ700U

It's 50" plasma and I actually had the chance to see it at a local retail
store. I was blown away... This purchase is t least 6-9 months away.
I am sure by mid next year there will be another display that will eclipse
the performance of this one, so I'll have to do my research all over
again.... I'm rather looking forward to it

Igo2Xs

This post has been edited by igo2xs on December 27, 2007 09:29 am

Um, not trying to pile on, but I have heard, but some of our other folks here with flat screen tv's might know, but, From what I have been told, you shouldnt put your tv above a fireplace because of the heat, I believe those tv's dont like heat and it will take the so-called life span down a lot. anyway just my 2 cents, somebody will chime in, I hope and veryfy if I'm wrong or not.

elroy

I was also going to comment about the flat panel TV over the fireplace. While the mention of possible heat issues is important, my concern with this is how high the TV is. I think most people do this for looks, but realize soon that the TV is simply too high to sit on the couch and watch. Try it. Hang a picture up there and sit and stare at it for 15-20 minutes. If you still think you can live with that elevation then go for it, but it isn't for me.

You have to remember impedance when wiring multiple speakers together. With four speakers you are safe. You first wire two speakers in series to get 16 ohms, then wire both series pairs together in parallel which give you 8 ohms overall impedance for the array.

If you have only three speakers and wire them all in series you will have 24 ohms, and limit amplifier output accordingly. If you wire two in series and then the third in parallel with those two, you will end up with 4.9 ohms, too low for many A/V receivers to deal with reliably. The best thing would be to bite the bullet and buy 2 more pairs of these speakers. If that is out of the question, I would simply use two speakers each for the surrounds, and wire them in series, for 16 ohms.

BTW, you need to make sure that your receiver allows you to set the crossover frequency this high.

See my other reply regarding my concerns with this being too high.

Yep, the closer the better, otherwise it will seem wierd with the voices coming too far from the pictures on the screen.

Yep.

Yep on the 90 degrees. Moving the L and R speakers out a bit will increase the sweet spot. However, if you move them out too far the sound will feel disconnected from the action on the screen. I think a good rule of thumb is that your L & R speakers should not be further to side of the screen than half of the screen's width. So if the screen is 4' wide, the speakers should not be further than 2' to the sides of the screen (which would have them about 8' apart).

See my notes about impedance above. If using two speakers in series for each surround channel, I would place them next to each other horizontally. I would also angle them to the side at a 45 degree angle (90 degree angle to each other) to better disperse the sound from the surround channels.

HTH,

Rob

Hi Rob,

Sorry for my slow reply! Things picked up at work recently and I didn't
have the chance to respond until now. I really appreciate your detailed
resoponse, especially about insuring impedence is taken into consideration.
I have rethought my initial idea of trying for a 7.1 setup. After reading
some articles on 6.1 vs 7.1 sound, I have come to the conlusion that a 6.1
setup will more than suffice for my needs. With a 6.1 setup I'll be able
to wire the two reach channels and a single center channel w/ 4 speakers
each.

In any case, I received all sets of speakers from parts-express a week
back. As a test, I setup 6 individual speakers and connected
them to my Outlaw 1050. As it turns out the amp has ability to set
cross over as high as 200hz. I have it set to 110hz at the moment.
I set my sub crossover to approx the same (100hz) and I have to say
the sound quality with just 6 individual speakers was quite decent. It gives
me a lot of hope that 4 put together for a single channel will sound a lot
better!

I think the biggest hurdle I have at the moment is figuring out
how to replace the RCA input of each speaker with binding posts.
I haven't had the chance to open up one of the speakers to see
how it's wired internally, though someone already went to the trouble:



I'm wondering if it would be easier to simply maintain RCA connections
and save myself the trouble of potentially damaging the speakers?
Do you think I would sacrifice any sonic quality going that route? I'm
also trying to figure out the best way to create a mount for the speakers.
I have to say they are a lot larger and heavier than I first anticipated!
Thankfully the speakers have threaded inserts installed so I think I
should be able to leverage this.

Well, back to the grindstone. Thanks again for all your input.
Your guidance has been invaluable and I have learned a lot from
you!

Take care,

iGo2xs

As far as mounting goes, all I can say is that you probably should just wander around a Home Depot or Lowes for a while staring at pieces and parts until somethings hits you. I don't know what else to tell you.

Regarding the RCA connectors, they will probably work fine. I would be concerned if you need to get full range sound because I would worry about having enough conductor for powerful bass. However, given that you will only be driving them above the subwoofer x-over frequency, the RCA connectors will probably be OK.

BTW, you should disable the subwoofer's internal crossover (or set it to its highest value). You only want to use the subwoofer's internal x-over if you are sending it a full range signal. However, setting the x-over frequency in the receiver should control both high-pass to the front and surround channels, and low-pass to the subwoofer. If you also have the subwoofer x-over working in that same range you will further steepen the high-end rolloff of the sub and create a hole in the system's overall response near the x-over frequency.