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# Building a Dinner Theater w/ DIY Speakers, Subs, etc... - Page 9

Just when I think I am getting savvy, I come up with another dumb question. When I wire speakers in series or in parallel (or both), I am changing the ohms resistance of what is on that channel. In the case of the XLS1000, I can fulfill the following scenarios:

1. 700W x 1 @ 8 Ohms
2. 350W x 2 @ 4 Ohms
3. 175W x 2 @ 8 Ohms

In the case of the two XLS1000 amps for the four subs, I am putting 350W x 2 @ 4 Ohms. In the case of the two XLS1000 amps for the eight surround speakers, I am putting 700W x 1 @ 8 Ohms. Finally, In the case of the two XLS1000 amps for the four rear-surround speakers, I am again putting 350W x 2 @ 4 Ohms.

My question is; does the amp automatically know the ohm resistance of what is connected to it and adjust the wattage accordingly, or is there an ohms setting on the amp that I have to adjust (I do not see one). So far, I have been working under the assumption that the wattage that makes it to the speaker is automatically dependent on the resistance of the driver.

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wiring in series will sum the resistance. wiring in parallel will divide it...

series = r1 + r2 + r3 ....
parallel = (r1 + r2 + r3) / n, where n is the number of loads.

If you have two 4 ohm speakers wired in parallel, its a 2 ohm load. If you have them wired in series, its an 8 ohm load.

The amp doesn't adjust anything. Amps produce voltage. Based on the resistance of the load, and the capabilities of the amplifier, the wattage output will be determined.

This is all ohms law.

i = v/r

amperage = voltage divided by resistance.

w = v * i
wattage = voltage * amperage

and a simpler formula here

w = v^2/r
wattage = (voltage * voltage) / resistance

so if your amp puts out 100v to a 2 ohm load, it is producing 5000w.
Yes I understand...and if I wire in series and parallel with my 8 ohm speakers (as I am doing with each of the set of four speakers that make up the left and right surround channels), then I have multiplied and divided and end up right back where I started at 8 ohms. The question was as to whether or not I have to do anything on the amp side to account for what kind of resistance is being hooked up to it. I said it was a dumb question.
Quote:
Originally Posted by dutchswan0311

Yes I understand...and if I wire in series and parallel with my 8 ohm speakers (as I am doing with each of the set of four speakers that make up the left and right surround channels), then I have multiplied and divided and end up right back where I started at 8 ohms. The question was as to whether or not I have to do anything on the amp side to account for what kind of resistance is being hooked up to it. I said it was a dumb question.

Nope, as I said...

The amp doesn't adjust anything. Amps produce voltage. Based on the resistance of the load, and the capabilities of the amplifier, the wattage output will be determined.

You don't have to do anything. Some receivers however will have a switch on them for 8 or 4 ohm load. This isn't normally something you see on a pro amp though.
Haha. Ok, just wanted to be sure.
I have been a little unsettled about the finish of the four 1pi speakers I made last winter (the only ones that I have installed the components in so far). The edges dinged too easily and the paint showed fingerprints and scuff marks, while the matte black paint was a dust magnet. I decided to round all of the edges of the remaining eight 1pis and use a textured spray paint instead of porch paint with a sponge roller. I really like the results! The original four will will need to be repainted, but will not need to be edged since the intent was always to embed the four balcony speakers into the wall, and this is more easily done with square corners. The image below was taken while the paint was still wet. The final dried product looks quiet excellent. It now looks like a professional cabinet that is robust and will not show wear nor dust.

Quote:
Originally Posted by dutchswan0311

I have been a little unsettled about the finish of the four 1pi speakers I made last winter (the only ones that I have installed the components in so far). The edges dinged too easily and the paint showed fingerprints and scuff marks, while the matte black paint was a dust magnet. I decided to round all of the edges of the remaining eight 1pis and use a textured spray paint instead of porch paint with a sponge roller. I really like the results! The original four will will need to be repainted, but will not need to be edged since the intent was always to embed the four balcony speakers into the wall, and this is more easily done with square corners. The image below was taken while the paint was still wet. The final dried product looks quiet excellent. It now looks like a professional cabinet that is robust and will not show wear nor dust.

Nice! I've used matte black on several occasions, and I've noticed the same problem with dust and hand prints. I'm beginning to think that painting my theater door flat black may have been a bad choice....
Like many others here, I have been following this build since its inception and am very interested in it.

It's been a couple of weeks, and I was wondering if you had any progress to report now that you have the avr, amps, and speakers most likely all ready to go.
Apologies in my delay. We have been very busy and I have been ill. As of right now, I have five 1pi speakers constructed, painted, and components installed. The other seven 1pi speakers are constructed, andI are still receiving their final sanding. I finished installing the JBL woofer and the B&C tweeter in the first 4pi last night. The second 4pi gets everything put in it this afternoon and I will be listening to the pair for the first time tonight. I am looking forward to this with great anticipation! The third 4pi is constructed, but is still being sanded with the unfinished 1pi cabinets. As you know, I have had two F20 subs done for some time, and have yet to construct the other two. I am waiting to finish with all of the pi cabinets before I build the last two F20s.

I am fairly pleased with the Onkyo so far. You can actually high pass each channel down to 40Hz using the receiver, which is convenient considering the 1pi gets high passed at 60Hz and the 4pi at 40Hz (at the recommendation of Wayne Parham).

I will post many more pictures sometime this week. Thanks for following along. I don't know where I would be if it were not for the help many of the members of this forum have offered.

Cheers!
Below are finally the images of my first two completed 4pi speakers (Left & Right). I am satisfied with the overall finish considering they will never be seen behind he AT screen. At this point, I have completely finished:

F20 x 2 (Using the Dayton RSS390HF-4)
1pi x 5
4pi x 2 (Using the JBL 2226H and the B&CDE250)

Here is what I have left to do:

1pi x 7 (Cabinets built & sanded, just need to paint and install components)
4pi x 1 (Cabinet built & sanded, just need to paint and install components)
F20 x 2 (Have not yet started on these. Trying to finish up the Pi speakers first)

Looking great!
Concurred! They look quite professional. Hope you're doing well and that the whole dinner theater is on track. Thanks for the update!

As soon as you're open for business, I'm going to strongly recommend some of my southeast SD winery and vineyard friends to schedule a visit, since you're not too far away. When are you planning to open?
Quote:
Originally Posted by nube

Concurred! They look quite professional. Hope you're doing well and that the whole dinner theater is on track. Thanks for the update!

As soon as you're open for business, I'm going to strongly recommend some of my southeast SD winery and vineyard friends to schedule a visit, since you're not too far away. When are you planning to open?

We hope to fully open the new location this fall with a soft opening around Labor Day (if there are no additional delays).
I am looking for feedback on what material I should use when I build the baffle wall. The wall will be about 14' wide, 13' Tall, and 30" deep (the depth of the F20s). I thought to build the wall out of 2x6s and 3/4" plywood with the three 4pi LCRs and the four F20 subs flush mounted. I would also angle the 4pis according to the JBL Pro-Cinema specifications. It seems like most recommend using a sound absorbing material on the plywood face so that sound reflected off the back of the AT screen is not reflected again off the baffle wall. Someone else suggested that a sound absorbing material on the baffle wall would reduce the benefits of flush mounting a 4pi main. If both are true, I am thinking that the reduction in reflection would be the higher priority.

Thoughts?
Quote:
Originally Posted by dutchswan0311

I am looking for feedback on what material I should use when I build the baffle wall. The wall will be about 14' wide, 13' Tall, and 30" deep (the depth of the F20s). I thought to build the wall out of 2x6s and 3/4" plywood with the three 4pi LCRs and the four F20 subs flush mounted. I would also angle the 4pis according to the JBL Pro-Cinema specifications. It seems like most recommend using a sound absorbing material on the plywood face so that sound reflected off the back of the AT screen is not reflected again off the baffle wall. Someone else suggested that a sound absorbing material on the baffle wall would reduce the benefits of flush mounting a 4pi main. If both are true, I am thinking that the reduction in reflection would be the higher priority.

Thoughts?

I wonder if this would work, I think it would.

I think that MLV is rather reflective. I thought that stuff was mainly to hinder sound vibration transmission through a wall.
7 Down, 5 to go. Well, actually; I finished another one since this picture was taken. They are going quickly now that they are all built and sanded. painting and installing doesn't take long by comparison.

Quote:
Originally Posted by dutchswan0311

7 Down, 5 to go. Well, actually; I finished another one since this picture was taken. They are going quickly now that they are all built and sanded. painting and installing doesn't take long by comparison.

Well done -- looks really nice.
I'm going to be really exited to see this in action when it's all done. ANd lucky for me, this is actually pretty close to home!
Well, I have had the opportunity to put some serious power through a pair of 4pis coupled with a pair of F20s. Wow. The clarity of the 4pis is fantastic. With my AVR at 100% volume and the XLS2000's set in bridged mode (\$1,300W x 50%) they were LOUD and CLEAR. The subs make my house shake like its being hit by an earthquake...but in a good way. I can just imagine what the output will feel like with an additional 4pi center channel and double the F20s.

But...that is with it all packed into my 10' x 10' music alcove adjacent my dining room. I am curious and anxious to see how a 45' x 30' room with 18' ceilings will react when I move everything to the winery.
I did not do this to the two that I have completed. How important is that?

According to Wayne it is not very important. I covered mine with Dynamat only because I had some laying around from a car audio installation project. I did not detect in any changes to the sound.
Thanks NWC.... I was really not looking forward to taking the horns off. There is only one thing worse than snapping off a terminal from a crossover....and that is stripping a t-nut on a finished cabinet that has everything already installed. That happened to me twice so far. I am much more careful about t-nut installation now.
I hear you, I also broke a tab on the crossover. Not easy to solder inside a cabinet.
We're not really wine drinkers but I think I'm going to have to drag my wife and boy up to Sully when you open.
Quote:
Originally Posted by dutchswan0311

It seems like most recommend using a sound absorbing material on the plywood face so that sound reflected off the back of the AT screen is not reflected again off the baffle wall.
Thoughts?

Haven't kept up with this thread enough to know what you're using for screen material but, if it is a fine weave material like Seymour XD, you probably don't need to put anything on the baffle. I use XD with two layers of black PE grill cloth (rather than black scrim) and only lose about 1db at 10k. Very little absorbed and/or reflected.
Wow dutch,

Can't wait to this this thing completed...

JSS
Quote:
Originally Posted by dutchswan0311

I did not do this to the two that I have completed. How important is that?

What is the grey stuff?
Quote:
Originally Posted by omegaslast

What is the grey stuff?

Plumbers putty applied to the horn to deaden it.
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