diy center and surrounds (pics) - now a ZA5.2 build thread

[owdi]

Just looking for some general advice on where to go with my HT. We bought our first home 8 months ago, and it's about time I upgrade a few things :B

My immediate need is a center and surrounds to round out my HT. The fronts will remain as a pair of Zaph L18/27TBFC/G bookshelfs and a sealed Dayton RS 12" will handle the bottom end. My thought was to keep with the shiny metal theme and use the ZA5.2iw (in-wall) for the surrounds, and ZA5.3c for a center.

My new living room is larger than what I had in my old apartment, but my couch will remain about the same distance from the tv and speakers. Will the ZA5's be enough to provide an immersive HT experience? They will be crossed at 80hz, 2nd order, which I suspect is pushing it. I'm open to other options, budget is $300ish.

Now for pics...

The TV will be mounted in the center of the wall, a new TV stand and wall mount are already on their way. I'd like to place the center below the TV (red box)

The surrounds need to be in-wall and stealth, for maximum WAF. The smaller holes I need to make, the better.

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[ruseriousclark]

Lets start with getting a HD box for that TV and losing the grey bars to bring it into ratio. And I think the misses has a thing for Paul Walker or really likes Fast and the Furious.

On to more serious observations. Your initial thoughts given you already invested in the L18's is staying metal will eliminate timbre matching between your CC and the LR Main's. So I'd say yes to consideration on driver compisition. Stick with Aluminum on your CC.

Only concern I have with the Z5.3 is its only two 5" drivers and you have a pretty open listening area. You may need to go bigger. High freq. stuff you'll hear, mid and lower stuff needs boundries and about 85-90% of everything you hear in a HT setting comes from your CC. Just a little concern you may find you lack something when you hear them crossed over where you intended. 80hz is too low for the Z5.3 IMO. 100-120hz would be better and I don't think you'll miss anything. It'll play in the 80's yes but at high HT SPL's (i.e. explosions, gun shots, etc.) your just as well off having your sub and mains pick up that duty given the listening area.

Matching the front three is much more crucial than the rear channels but if your already leaning that way go with the Z5.2's. Your not going to make a mistake there.

With the most crucial choice of LR Main's already having been made you are just in a position to match them as best you can.

[omarmipi]

Only concern I have with the Z5.3 is its only two 5" drivers and you have a pretty open listening area. You may need to go bigger.

That's a shame because I have a similar sized living room and I planned on using the PE Dayton RS621CK (RS150S & RS28AS) speaker kit as surrounds.

[owdi]

85-90% from the center? :E I was wondering why I see people build these huge WTMW centers.

I chose 80hz as the crossover frequency because (apparently) the THX spec is 2nd order 80hz for the 5 speakers, and 4th order 80hz for the .1 sub. The assumption is the speakers have a natural 2nd order rolloff at 80hz, so the slopes are symmetrical. The receiver I had in mind cannot set different xover frequencies for fronts/surrounds/center, so I figured 80hz was a good compromise.

I ran a few sims with the ZA5.3c in WinISD to see where the driver reaches xmax, these are all @ 2M

Vented 20l, tuned to 52hz.

Filter       Power       Output @ 2m
None         23 watts    100db
2nd @ 80hz   48 watts    103db
2nd @ 120hz  110 watts   107db
4th @ 80hz   73 watts    105db

Since the ZA5.3c does not have a natural rolloff at 80hz, a 4th order @ 80hz xover would do it, but that is not an option in the receiver. Lets see what happens if I go sealed instead.

ZA5.3c sealed in 14l (-3db @ 100hz)

Filter       Power       Output @ 2m
None         12 watts    97db
2nd @ 80hz   48 watts    103db
2nd @ 100hz  74 watts    105db

Looks like it will get the job done when I'm on the couch, but there's not a lot of headroom.

[cjd]

The surrounds I did for my HT might serve you quite well. Could tuck them in the corners up a bit higher, or even in the ceiling if you're brave. A slightly different option.

C

[owdi]

The surrounds I did for my HT might serve you quite well. Could tuck them in the corners up a bit higher, or even in the ceiling if you're brave. A slightly different option.

C

Link?

Ceiling is not an option, I'm not willing to tear up that much drywall. I thought about tucking the surrounds right against the ceiling to get a horn like effect, but everything I've read says you want to keep your surrounds 90* - 110* behind and above your listening position.

I also suspect having the surrounds lower on the wall will create a ceiling bounce that will make the room sound larger.

[cjd]

http://www.htguide.com/forum/showthread.php4?t=33761

They do amazingly well in oddball placements.

[omarmipi]

http://www.htguide.com/forum/showthread.php4?t=33761
They do amazingly well in oddball placements.

Found my PE Dayton RS621CK replacements. Thanks for sharing!

[owdi]

Finally pulled the trigger and ordered a pair of Zaph Audio ZA14's and crossover parts for the ZA5.2iw. I'm not going to build them in-wall just yet, round 1 will be an on-wall enclosure that is 4.5" x 8" x 12", tuned to 50hz, for -3db @ 80hz.

Anyone know of a program I can use to calculate peaks and nulls from wall bounce? I expect my first null will be at 750hz which has a quarter wavelength of 4.5"

[owdi]

I'm turning this into a build thread :-)

My surround speakers will be a pair of Zaph Audio ZA5.2IW built into a vented enclosure mounted directly on a wall.

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The small enclosure + low tuning + .8 ohm series resistance results in a -3db right around 80hz

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Response with the 2nd order highpass from the receiver

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Excursion at 50 watts with crossover

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Port air velocity at 50 watts with crossover (1.125" x 6.5" port)

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The parts have arrived

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The ZA5 magnet is rather large for a mid.

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I built the enclosure from .5" baltic birch plywood. It was cheap at $37 for a 4x8 sheet and is not void free. I hope nothing rattles...

I ran all the side pieces through this jig to ensure they were all the same height.

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Gluing the side pieces, leaving a little extra to trim later

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Gluing the front and back, again leaving extra to be trimmed later

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Using my 3-flute flush-trim bit to remove excess. This is a lot easier than making precise cuts with my old circular saw.

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Enclosures are ready for what I hope will be minimal sanding

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That's it for now.

[owdi]

The initial build is complete. Running wires through my walls was a pain, I need to make grills and I need to paint some of the mounting hardware, but they are installed and playing.

They are still sealed at this point. I'll decide if the vent is needed after taking on-wall measurements. So far it sounds like I have the headroom to EQ them flat.

Latest pics from my shared HT / living room. You can see where I ended up mounting these surrounds on the far left and right of the picture. I got OK marks for WAF which should get better once they are done.

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Close up

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[---k---]

Wow, those are shallow, but look great. How do they sound?

[tominizer]

Curious as well....... as I've been eye-balling the in-wall MTM versions for a L/C/R.

[owdi]

woot, the thread title has been renamed

It's hard to say how they sound because they just disappear. Whether watching movies or using DSP effects with a stereo source, they blend perfectly with the L18/27TBFCG mains. Surround effects seem to fill the room rather than coming from the speaker.

I have the crossover set at 80hz and notice nothing offensive at high volume. The first movie I watched was Black Hawk Down on blu ray at -10db on my 90wpc receiver. That is about as loud as I can stand and it was awesome. I've had friends over to watch Avatar and Up and received lots of compliments about how realistic the sound effects are, but I think they were more impressed with the low end my Dayton Ref 12 sub. :W

I want to take measurements before posting a full write-up. In the mean time, here are a few more pics. Building a crossover that would fit in this little box was a challenge, especially with all that 1" sonic barrier.

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[evilskillit]

Lookin quite dapper there. I'd be proud to have those speakers on my walls. I've got a friend who is looking at buying some in wall options from PE and while he's not a speaker builder he's not shy about working with wood and tools. So this may be another option for him.

[JonP]

Very nice... with that shallow box and similar color to the wall paint, it's the next best thing to actually embedding them in the wall.

Took a bit of shoehorning to get that crossover into the box, eh? Nicely laid out, looks like you did some research on how to space and orient the inductors, etc. I like tiewraps as well, for part mounting.

Only one tiny thing I'd suggest checking, do those resistors get very hot with hard use? They may or may not, but if they do, you might have an issue with the tiewraps holding them down, or even contacting the board. Running them hard for a while, then quickly opening up and feeling them (cautiously) will tell if it would be better to support them up off the board a bit, just by their leads , for better airflow.

Great build, and that ZA14 is a handsome driver! I can understand the high WAF marks...

[owdi]

Thanks for the compliments.

Only one tiny thing I'd suggest checking, do those resistors get very hot with hard use?

I could pull the tweeter and attach a probe from an instant read thermometer to them. What would you consider to be very hot?