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New Home Theater Speaker Build - Page 2

post #31 of 105
Terrific WIP!!
Great pics with clear and concise explanation.
Well done indeed
post #32 of 105
Front page spotlight, congrats!

456
post #33 of 105
very cool!
I want to build my own "BoomBox" using old b&w parts from my job. How cool would it be to be on a jobsite and have a B&W radio?


So hey, can we get a close up of the speakers?
post #34 of 105
Thread Starter 
Quote:
Originally Posted by miahallen View Post

Front page spotlight, congrats!
456

Wow, I didn't even know that was possible. That's cool. I'll have to make sure I finish everything to be worthy of this.

Thanks.
post #35 of 105
Great attention to detail, both the thread and the build.

Have you run your receiver's auto calibration routine? (Audyssey, etc.)

As far as measurements, check out Room EQ Wizard (REW) - free and works great. You'll need a mic, preamp and a line in input on your PC.
post #36 of 105
Thread Starter 
Quote:
Originally Posted by Brad Horstkotte View Post

Great attention to detail, both the thread and the build.
Have you run your receiver's auto calibration routine? (Audyssey, etc.)
As far as measurements, check out Room EQ Wizard (REW) - free and works great. You'll need a mic, preamp and a line in input on your PC.

Hey, thanks Brad. That's the first reply I've gotten about measuring my speaker performance. I really want to do it but haven't figured it out yet. I will definitely try what you have suggested. I did use the Audyssey calibration that came with my Denon. Truthfully, after using it, I was not at all impressed. However, I do have them in my living room right now and not in their final place (theater). With that said, when I performed the setup with Audyssey, there were several different sounds throughout the house so it probably was not an ideal situation. For the REW, would the mic that came with the Denon work? Are there some pretty good instructions when you download the program? I'll get it tomorrow and see how it works for me. By the way, your home theater thread provided alot of ideas for me. Especially the false wall you built for your projector screen.

Thanks alot.
post #37 of 105
I don't think using a receiver's mic is recommended, because you need to load a calibration file for the mic into REW, and there usually isn't one available for those mics. It might work, but if for example you see your FR has a bump or rolloff, you can't be sure if it's the speakers or the mic. You could try it though?

There are some pretty good instructions for it at HomeTheaterShack, which is home base for REW. The program's help file is good too. Takes a little learning and fiddling to get it set up, but not too bad after that initial learning curve. Let me know if you need any help getting going with it if you decide to use it.
post #38 of 105
Looking good, man!
post #39 of 105
Thread Starter 
Quote:
Originally Posted by Brad Horstkotte View Post

I don't think using a receiver's mic is recommended, because you need to load a calibration file for the mic into REW, and there usually isn't one available for those mics. It might work, but if for example you see your FR has a bump or rolloff, you can't be sure if it's the speakers or the mic. You could try it though?
There are some pretty good instructions for it at HomeTheaterShack, which is home base for REW. The program's help file is good too. Takes a little learning and fiddling to get it set up, but not too bad after that initial learning curve. Let me know if you need any help getting going with it if you decide to use it.

Cool. Thanks Brad. I have been reading up on HomeTheaterShack. I downloaded REW and I am trying to figure out now exactly what equipment I need. I obviously want to get only what is needed to get good measurements. Maybe someone can give me some ideas for setups that they use effectively.

Matt
post #40 of 105
Thread Starter 
Quote:
Originally Posted by PassingInterest View Post

Looking good, man!

Thanks buddy. Been waiting on your reply. Nice to hear from you.
post #41 of 105
Quote:
Originally Posted by dwightp View Post

Nice looking speakers! I'm sure they sound great.
With paint, surface preparation is probably more important than what kind of paint you use. The pickier you are and the more time you spend preparing the surface, the better result you will get.
For painting by hand (that is, not spraying), I like this stuff:
237
Link: http://www.sherwin-williams.com/homeowners/products/catalog/proclassic-interior-waterbased-acrylicalkyd/?referringCategory=interior-paint-coatings/paint/
Dries to a pretty hard surface, not too much sheen, doesn't show brush strokes too badly, easy clean up. It should be available at any Sherwin Williams store. It's pretty easy to apply but you do have to move pretty quickly. For big flat surfaces, like the sides of your cabinets, I would probably roll it on with a roller and then go over it immediately with a brush using light, long strokes. Once you have brushed the whole surface, put your tools down and let the paint set up. If you play with it too long, you'll leave brush marks that won't level out.
I would probably prime the bare MDF before I put on the paint, but I don't know that it's really necessary. If you use a gray primer, you might be able to get by with a single coat of paint.

This is a great acrylic option and easily brushable, rollable, sprayble, however, it cannot be made black (use Solo instead). Dwight is correct in that this product has a short tack time. It needs to be put on and not over worked in order to level well. If you allow the product to do it's self leveling it will, but most people over brush it.

If you tell me more about how you plan on applying your finish, what type of finish you are going for, experience, equipment, etc I can point you in a few directions that will work.
post #42 of 105
Thread Starter 
Quote:
Originally Posted by tgse3 View Post

This is a great acrylic option and easily brushable, rollable, sprayble, however, it cannot be made black (use Solo instead). Dwight is correct in that this product has a short tack time. It needs to be put on and not over worked in order to level well. If you allow the product to do it's self leveling it will, but most people over brush it.
If you tell me more about how you plan on applying your finish, what type of finish you are going for, experience, equipment, etc I can point you in a few directions that will work.

tgse3, thanks for your reply. I have a Graco airless sprayer that I will use to apply the finish. I am not that experienced with it. I did paint some furniture a couple years ago with it. I applied a couple coats of primer and then a couple paint (latex). It was a bedroom set for my daughter. Came out nicely. I don't care what type of finish I apply. I do want it black and I would like for it to be pretty tough. I don't want it to be a dull or matte finish but not a piano finish either so somewhere in the middle. Hope this gives you an idea of where I'm looking. Any advice will be greatly appreciated.

Matt
post #43 of 105
Quote:
Originally Posted by mathu126 View Post

Cool. Thanks Brad. I have been reading up on HomeTheaterShack. I downloaded REW and I am trying to figure out now exactly what equipment I need. I obviously want to get only what is needed to get good measurements. Maybe someone can give me some ideas for setups that they use effectively.
Matt

By no means the only setup, but here's what I use:

mic: Behringer ECM8000
preamp: MAudio AudioBuddy
USB audio card: Behringer UCA202
post #44 of 105
Thread Starter 
Quote:
Originally Posted by Brad Horstkotte View Post

By no means the only setup, but here's what I use:
mic: Behringer ECM8000
preamp: MAudio AudioBuddy
USB audio card: Behringer UCA202

Sounds like a good list of equipment. Looking it all up, appears that I can get this setup for around $120-$130. Is there any single piece of equipment that would work for the preamp and audio card or do those always have to be separate? That might save a little money if it exists.

Matt
post #45 of 105
There could well be, and I'd like that too to simplify things. I know MAudio has something like that (USB audio device that also has mic preamp/phantom power), but it was like $250 when I checked, but maybe I didn't look hard enough. I ended up with my set because I started with a Radio Shack meter as the mic (doesn't need phantom power/preamp) connected to the UCA202; and then upgraded to the Behringer ECM8000 mic, so then I needed to add the mic preamp/phantom power device.
post #46 of 105
Quote:
Originally Posted by mathu126 View Post

Sounds like a good list of equipment. Looking it all up, appears that I can get this setup for around $120-$130. Is there any single piece of equipment that would work for the preamp and audio card or do those always have to be separate? That might save a little money if it exists.
Matt

A lot of people are opting for the Tascam 122 MKII USB soundcard with built-in phantom power as a companion to either the Behringer or Dayton EMM6 microphone. For the mic, you'll probably want to invest in a calibrated one (Dayton EMM-6, for example) purchased from Cross-Spectrum Labs for full-range measurements. The Tascam is only $80 at BHPhoto.

Like Brad, I'm also using Behringer UCA202 card because I already had a microphone and preamp.

REW is pretty powerful. I'm using it to dial in my subwoofer and my crossover with my mains. Eventually, when I am able to remodel my basement, I'll use it for testing room treatments and integrating a second subwoofer.

BTW, very nice job on the speakers!

Ken
post #47 of 105
Oooh that Tascam looks pretty nice, has MIDI too, so another device I could toss / combine. Hmm...
post #48 of 105
Thread Starter 
Hello all. I have started the process of trying to figure out my subwoofer situation. Reading forums and trying to get advice from anyone that would give it to me, I have come to the conclusion that I will need to design the enclosures myself. Now, as I have stated throughout this build thread, I am no expert in speaker design so I will be very grateful for any help that can be provided.

To refresh memories, I will be using the Infinity Reference 1262W to build 2 subs for my HT. My plan is to build ported boxes. I don’t know at this point what type of ports I want to use (open to advice). I like the style of the dual ports below the subwoofer and I also like the style of the long slotted port at the bottom of the box.

I have been told my several people that I will need a 4.0 cu ft box. I’m not sure if it should be a cube shape, rectangle shape or just whatever dimensions that fit my application. I don’t have the theater finished yet so I don’t know exactly what dimensions I’ll need but it looks like I could potentially do a 20-21” cube and be ok to stay under my projector screen.

Now, what I am going to need help with first is understanding what the graphs that WinISD spits out mean. I understand to a certain degree but additional help would be appreciated. I’m sure this will also help when I start to measure my speakers performance later on. I plugged the driver parameters into the program and these are the charts I got. Didn’t do anything but plug in my driver numbers and 300W. What I need to understand about each chart is: 1) Are these numbers good for my application and box type? 2) How will the numbers affect the sound quality? 3) If the numbers are bad, how do I correct them (box volume, port dimensions, etc..)?

First, the parameters. Notice that I said a 4 cu ft box was recommended but WinISD shows a 5.3 cu ft box with the driver parameters:
winisdinfo7262012parame.jpg


Now, the charts. Starting with transfer function magnitude:
winisdinfo7262012transf.jpg

SPL:
winisdinfo7262012spl.jpg

Cone excursion:
winisdinfo7262012coneex.jpg

Impedance:
winisdinfo7262012impeda.jpg

And rear port air velocity:
winisdinfo7262012airvel.jpg

As mentioned, advice on anything above will be greatly appreciated. Also, I have been playing around in Google Sketchup so I can design the box once I have dimensions. I put together the Sten II's that I'm building for my surrounds in there and they look pretty good so I think it will come out well.

Thanks,

Matt
Edited by mathu126 - 7/27/12 at 3:33am
post #49 of 105
Thread Starter 
Quote:
Though I am no expert on ported designs, as no experts have chipped in I will give you my thoughts.

Thanks alot David. Yea, I thought I'd get a little more feedback from my post. Perhaps it was a bit too long and people got bored reading it. Maybe I'll get a few more responses.

Quote:
Judging by the graphs it looks like you have a good combination.
Virtually flat frequency response down to 20hz - Excellent
Your maximum excursion is 0.51 by the looks of it. For the most part the 300 watts keeps you under this point except around 30hz.
Looks like the tuning frequency is set just above 20hz correct? Might try raising it 5hz or so to tame the excursion around 30.
Means though that you will lose a few hz of extension on the low end. Probably not a big deal either way.
With some of the rediculous low frequencies hit in movie soundtracks you will want to be sure to use a steep hi-pass filter set at 20hz. With a ported design the driver essentialy flaps uncontrolled as if in freeair below the tuning frequency. (Look at excursion below 20hz.)

That makes sense. I simulated a highpass Butterworth filter at 20 hz and this is what I got. Maybe it looks better?
1262wconeexcursionwithh.jpg

Quote:
Port noise due to high velocity is always a concern in ported designs. As you probably know the same box tuning frequency can be had by using a narrow short tube or long wide tube(s). The difference is air velocity and port noise. Could be wrong here but I think the general principle is to go with the largest tubes you can cram into your enclosure while maintaining the required tuning frequency.

The port velocity confuses me a little bit. When I put in a larger sized port (slotted), WinISD shows me that it has to be longer. I would think that the bigger the port size, the shorter it would be but it seems to be just the opposite. I think I would like to go with the dual round port under the sub look but I'm not sure how to model that. Same here, when I added a second round port, it shows that I need them both longer than just one. Any explanation there would be helpful.

Quote:
Not sure if any of that helped. I like to stick with simple sealed designs to decrease the complication and to take full advantage of room gain to flatten the gently falling low end output.
Certainly advantages to both, and your drivers may not work in sealed anyway.
Good luck.

You certainly did help me alot. I absolutely know nothing about this stuff so anything is a help. Thanks again.
post #50 of 105
Thread Starter 
Another thing I need to know while I still haven't finished hanging my drywall is, if I run my two subs with a Behringer or Crown amp from my A/V closet and don't put plate amps in, what gauge wire should I run. I have already ran the wire but It's 14 gauge. Is this enough for 300W? If not, I need to run new wire before hanging the drywall. From this type of amp, do you just run normal two stand wire or would you run a different type of wire? Haven't thought about this til now.

Matt
post #51 of 105
http://www.roger-russell.com/wire/wire.htm#wiretable

Just normal two strand wire is fine - Monoprice or what you can find at Home Depot or Lowes.
post #52 of 105
Thread Starter 
Quote:
Originally Posted by Brad Horstkotte View Post

http://www.roger-russell.com/wire/wire.htm#wiretable
Just normal two strand wire is fine - Monoprice or what you can find at Home Depot or Lowes.

Thanks Brad. That's a good link you posted there. Sounds like the 14-2 I already have ran will be fine for this. By the way, you can wire my subs at 2 or 8 ohms. Any advice as to which is best? Should I wire them in series or parallel? Guess I'll need to know this when building them.

Matt
post #53 of 105
I would wire for 8 ohms. 8 ohms is easy to drive with any amp, 2 ohms will kill some amps (although some pro amps are Ok with it). Basically, unless you really need maximum output from the amp, I wouldn't do 2 amps.
post #54 of 105
Thread Starter 
Quote:
Originally Posted by Brad Horstkotte View Post

I would wire for 8 ohms. 8 ohms is easy to drive with any amp, 2 ohms will kill some amps (although some pro amps are Ok with it). Basically, unless you really need maximum output from the amp, I wouldn't do 2 amps.

Ok. I'll keep that in mind. If they are dual voice coil, are there instructions somewhere on how to wire them for 8 ohm? Here's a picture of what I plan to do for my projector screen wall (modeled this from your HT build). I like the false wall idea. The outer area where I have it shaded black (transparent), I will use some type of black material. Need some ideas there. I've heard of black velvet or velveteen. Not sure what other materials might be good to use. On the left and right side, I plan to make those panels that I can move in and out to get access to the back where my speakers are. You'll notice that I modeled a sub with two round ports and one with a slotted port. As mentioned, I like both styles. Just need to figure out which is the best option.
picofprojectorscreenwal.jpg

Matt
post #55 of 105
Here's a doc on wiring dual voice coil drivers:

http://stereointegrity.com/docs/DVCwiring.pdf

As far as screen wall fabric, I originally used Commando Cloth - for no other reason really than I received way more of it than I ordered for my soffit. It worked OK, but not quite as black as I wanted - so replacing it with Syfabrics triple black velvet, and its looking much better, really sucks up the light. I'll probably take a work in progress picture tomorrow to my thread.
post #56 of 105
Thread Starter 
Okay, so I just got finished with the initial design (draft) of my subwoofers. I have attached a few images from Google Sketchup of them. I am looking for feedback if possible on the design. So WinISD told me I needed to tune it to 20hz and the box should be about 4 cu ft. So, here are the specs of the box:

21" cube- 19.5" internal dimensions
2 round ports at 3" and 21.54" long
Enclosure volume calculator told me that the final volume would be 3.832 cu ft. This would be without the final brace that is up front near the driver. I'm looking for ideas on the shape of this last brace if anyone input.
Here are the images:

1)
sketchupsub1.jpg

2)
sketchupsub2.jpg

3)
sketchupsub3.jpg


Feedback is welcomed. Thanks.
post #57 of 105
Nice DIY project, mate! Very cool...
post #58 of 105
Thread Starter 
Quote:
Originally Posted by treyrhodes View Post

Nice DIY project, mate! Very cool...

Thanks for the encouragement treyrhodes. I appreciate it.

Surprised I haven't had any advice on the box. Anybody got anything?

Thanks.
post #59 of 105
My advice is to not go ported.. i dont see the point in it. You can buy cheap 15" drivers or cheap 12" drivers and have much deeper bass. It just doesnt make much sense to me.
post #60 of 105
what it loses in deep, it makes up for in spl near the tuning frequency.
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