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post #241 of 1711 Old 05-13-2011, 06:30 PM - Thread Starter
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Quote:
Originally Posted by petew View Post

I was thought I was going to build a mess of Anarchys for my HT. But now you guys have come up with this one!

My dedicated HT is 17x26x9 with an attached hall for a total of about 4,400 ft^3. I'd guess two would absolutely kill my poor little B&W ASW1000. Is four overkill? I'd use a B&K AV5000 MKII that I have lying around - it's rated at 145x5 into 4 ohms. Also plan on using a MiniDSP.

Good stuff - you guys rock!

Thanks.

Options are good.....

I'm working on several more....

Two in there compared to that B&W? Probably see +10 dB over what you have now, maybe more. Figure the B&W is good for 110 dB max at 1M in a groundplane setting, and that's probably generous. One F-20 will crack 115 dB all by itself at 300 watts, or 112 dB at 145 watts. A pair? Add another 6 dB. Another pair? Another 6 dB....

That amp will leave a few dB on the table, but since you have it, use it - the price is right.
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post #242 of 1711 Old 05-13-2011, 07:49 PM
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ooooooooooo, after seeing how easy this one is I'm tempted... how does it compare against the THT for output?? and from what I'm seeing it looks like an easier build
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post #243 of 1711 Old 05-13-2011, 09:23 PM
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Originally Posted by wormraper View Post

ooooooooooo, after seeing how easy this one is I'm tempted... how does it compare against the THT for output?? and from what I'm seeing it looks like an easier build

Output should be very similar, however the F-20 goes slightly lower. And yes coming from someone who has built both. The F-20 is a much easier build and more user friendly being 3/4" plywood. :-)
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post #244 of 1711 Old 05-14-2011, 10:23 AM
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I am really wanting to build these as well. The cuts look possible for a NOOB. ERICH H is in the same city as me so I have easy access to purchase some 15's from him. It is the amp and Highpass that get me and how it all works. I don't want to do any thing half and want to get it right, or as "right" as it can be for my first build. I have to do much more research before I ever start cutting wood.
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post #245 of 1711 Old 05-14-2011, 10:52 AM - Thread Starter
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The cabinet is the hard part....honest.

Highpasses are not hard to implement.

Most plate amps have one already, some even have the "right" one to make it plug and play. The BASH 300 with the stock setup is a good fit for example, as is the non-boosted Dayton SA240 (according to wembley2000's measurements).

For a non-plate amp? There are several options there too. I personally like the MiniDSP, cause it does a TON of cool stuff in addition to highpass. The Behringer Mic2200 does highpass, as does the Reckhorn B2 and the eD EQ.

MiniDSP fundamentals:

If you're using consumer-type gear with RCA's, get the Kit or the DSP in a box with RCA's, Rev A should be fine in this case.

If you want to convert from unbalanced to balanced to drive a pro amp with an XLR input - that requires a level converter, or "bump box", that is something the MiniDSP does not do. You can run the bump-box behind the RCA-equipped Rev. A MiniDSP, or you could run the balanced MiniDSP after the bump box.

If you're running pro amps and have a balanced, pro-level signal already, get the balanced MiniDSP.

Really, this is not as hard as it seems. I don't want it to seem like it is out of reach because of the highpass. Perhaps I am worrying too much.
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post #246 of 1711 Old 05-14-2011, 01:26 PM
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Quote:
Originally Posted by dsully444 View Post

........It is the amp and Highpass that get me and how it all works........

Some basics:
For an amp, you need something with decent power but not crazy power. 150 watts or more when driving a 4 ohm load is probably okay.

Two general types of amps that differ in form factor.

A plate amp is single channel only, and designed to be bolted into a subwoofer enclosure. Here's a generic picture:


Normal chassis is just that - something that can be put into a conventional equipment rack or shelf that might look like this:


These aren't endorsements, just generic pictures! You can also use any regular mono, stereo or multichannel power amp that you might have lying around as long as it has enough power and is happy driving a 4 ohm load.

The high pass filter does just what the name implies. It blocks frequencies below a certian threshold, and passes higher frequencies. With this particular sub, the guru (lilmike) has recommended a 20 Hz high pass filter since there is a lot of distortion below 20Hz. So it's better to just block out those lowest frequencies instead of generating a bunch of distortion which may be audible. The filter is not like a brick wall. There is a gradual rolloff of the blocked frequencies (slope).

MiniDSP is a magic box that is a perfect high pass filter for this application.

DSP=Digital Signal Processor: a fancy name for a microprocessor that is optimized to deal with math needed for signal processing. It goes between the sub output from your receiver and the input to which ever power amp you choose. You can set the filter parameters by plugging in a laptop via USB. Note that the laptop is not required for operation, only programming. Once everything is set up the miniDSP does it's thing.

Since plate amps are designed to run subwoofers, they often have the high pass filter built in. Problem is, it might not be right for this particular sub design. Usually the filter parameters can be modified by changing out some components on the circuit board (resistors and capacitors) but that requires both information and electronics technical skills. But these will work:
Quote:
Originally Posted by lilmike View Post

The BASH 300 with the stock setup is a good fit for example, as is the non-boosted Dayton SA240

Also available are passive filters that just plug into the cable between the receiver and amp.

These aren't generally recommended because they may not have the right filter characteristics and may not be too precise. They come from the car audio world.

Hope this helps.

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post #247 of 1711 Old 05-14-2011, 02:39 PM
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ok box complete guys, sitting in my garage with NO ONE to help me move it to the theater room. Got the amp setup, however Im having some issues. First they sent me a XLS2000 instead of the 1500 I purchased, second, with my AVR's signal at +10 for the sub channel, im still having to run the gain at about half to get decent bass out of the one sealed MFW I ghetto rigged for the time being...

Does this sound right? or sound off? I guess I was expecting a lot more output with that much power running to a sealed 15, but the beast has yet to be unleashed, i will check back whenever someone shows up to help drag it down

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post #248 of 1711 Old 05-15-2011, 01:34 PM - Thread Starter
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Quote:
Originally Posted by beastaudio View Post

ok box complete guys, sitting in my garage with NO ONE to help me move it to the theater room. Got the amp setup, however Im having some issues. First they sent me a XLS2000 instead of the 1500 I purchased, second, with my AVR's signal at +10 for the sub channel, im still having to run the gain at about half to get decent bass out of the one sealed MFW I ghetto rigged for the time being...

Does this sound right? or sound off? I guess I was expecting a lot more output with that much power running to a sealed 15, but the beast has yet to be unleashed, i will check back whenever someone shows up to help drag it down

Congrats on getting your cabinet completed!

Wow on the amp. I wanna shop there.... That's awesome.

Nice. I just get the "Sorry, this item is backordered until forever." email, then a month later, they eventually refund my money.

You've got a lot of amp, but you can always turn it down.

Without knowing the voltage delivered to the driver, the amp gain settings are pretty much meaningless.

Remember, there are two limits here - thermal and excursion.

If we assume a 20 Hz highpass in place, the driver will probably still complain due to overexcursion if you feed it the XLS-2000's full 4-ohm rated power below 24 Hz.

Thermally? You'll cook the voicecoil in seconds with full power sine waves. Your amp delivers about 3X the driver's "rated" 225W power limit, though it seems that people have run 500 watts into this driver without issues. Exceeding the driver's thermal limit with a sine wave makes a stinky slinky - it will look like this, except a bit larger. This was the result of applying about ~3X the driver's rated power as a sine wave.



With music? You could probably get away with full rated power into the driver for quite a while, unless you're spinning dubstep or old-school booty-bass or other stuff designed to destroy subwoofers. I know Wisounds pumped a kilowatt of dubstep through a DVC in a THT all night long, and though it survived the show - it never worked again. Funny, they wouldn't warranty it.....

Having that other driver in a sealed cabinet can help you set your levels. Turn things up until it complains or you see ~40 mm peak to peak. This will essentially be the limit for the driver in the horn too.
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post #249 of 1711 Old 05-15-2011, 02:39 PM
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That is a nasty situation right there.

I recommended staying within the limits of the driver and just building multiples.
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post #250 of 1711 Old 05-16-2011, 07:00 AM
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Finally was able to get a friend over saturday night to help me and WOW, the effort put into the box was more than worth the return. I am truly amazed at the output vs. the sealed mfw cab I was using. This thing is incredible!!! I didnt run it hard, or for very long as I dont want to run tests and all until I get the HPF on it.

In regards to my previous post, I did keep the gains about where I saw the sealed box starting to see stress so I am at about the 2:00 position on the knob in those regards now. While I do have more than enough power now, 600 wpc at 4 ohm, this will match up quite well once the tempest goes in there I could even bridge to get 1500 watts at 8 ohm should I need/want to...

Next up is working on location location locations. Room response is decent in the front of the theater but I am still seeing the best response from way in the back, by the dart board and the corner of the steps going upstairs. While i dont have too many options of where this thing can go, the front row (money) seats are within 5 feet of the mouth of the cab so yea, need to find a new location, perhaps either beside the second row standing up, or in the bar area out of the way...

Once again, this cab is awesome! So glad I jumped in, new build thread coming in for it either tonight or tomorrow night

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post #251 of 1711 Old 05-16-2011, 10:56 AM
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With the MFW drivers, does anyone know if real world I would get better bass (low end) going with 4 of the drivers in an infinite baffle setup (two sets of two drivers in manifolds facing each other) ? Would I really notice the 5-20hz band that much compared to the horn setup? Kind of on the fence as I could setup a room for IB if I was inclined to go that route and the cost isn't much different once you factor in horn box build costs for two.

Other option would be the F-20 up front and then a sealed 2.5 cu ft MFW in the back? Would the sealed sub be able to get really low end?
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post #252 of 1711 Old 05-16-2011, 11:11 AM
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mixing those subs could be tricky, the horns will have at least 2x the output per driver above tuning, prob more. Sealed do go lower.

Don't waste time reading signatures.....
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post #253 of 1711 Old 05-16-2011, 11:17 AM
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Quote:
Originally Posted by NicksHitachi View Post
mixing those subs could be tricky, the horns will have at least 2x the output per driver above tuning, prob more. Sealed do go lower.
I will confirm this. perhaps the sealed in the back will help even respose somewhat...I plan on playing with this a little tonight if I get the time. Sealed MFW 15 vs this particular build, there is no comparison

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post #254 of 1711 Old 05-16-2011, 11:41 AM
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Also, Mike, within the first 10 seconds of the first song I listened to, I became addicted to more. already ordered a tempest x-2 this morning, should hopefully arrive by next weekend. Depending on how this makes me feel, and if I can solve placement issues, I will be breaking ground on box #2, with the second tempest going in that, however, I may choose to do the MFW in there just long enough to measure differences in output, real world style.

I few side notes on the directions, I managed to still not do the access panel right, but ended up just making a flange to the exterior of the box instead of inside the access panel. I ended up with using about 1 1/4 tubes of PL so that was nice. I have pictures documenting the layout and panel installation steps should you want to link to them or use the pics in your directions. Might help other newbies like myself

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post #255 of 1711 Old 05-16-2011, 05:20 PM
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Quote:
Originally Posted by beastaudio View Post

Finally was able to get a friend over saturday night to help me and WOW, the effort put into the box was more than worth the return. I am truly amazed at the output vs. the sealed mfw cab I was using. This thing is incredible!!! I didnt run it hard, or for very long as I dont want to run tests and all until I get the HPF on it.

In regards to my previous post, I did keep the gains about where I saw the sealed box starting to see stress so I am at about the 2:00 position on the knob in those regards now. While I do have more than enough power now, 600 wpc at 4 ohm, this will match up quite well once the tempest goes in there I could even bridge to get 1500 watts at 8 ohm should I need/want to...

Next up is working on location location locations. Room response is decent in the front of the theater but I am still seeing the best response from way in the back, by the dart board and the corner of the steps going upstairs. While i dont have too many options of where this thing can go, the front row (money) seats are within 5 feet of the mouth of the cab so yea, need to find a new location, perhaps either beside the second row standing up, or in the bar area out of the way...

Once again, this cab is awesome! So glad I jumped in, new build thread coming in for it either tonight or tomorrow night

It's hard not to like this sub. Really hits nice and stiff and does a good job with music and a great job with Movies. It definitely is a rock and roll sub as far as music goes. I think I am going to build something ported as soon as I finish the speaker build I just started.
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post #256 of 1711 Old 05-16-2011, 07:20 PM - Thread Starter
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Quote:
Originally Posted by NicksHitachi View Post

...... Sealed do go lower.

Not exactly.

Comparing apples to apples here is not really possible, but a single sealed MFW vs the MFW in an F-20? The 1 W SPL lines do not cross until ~12 Hz, and there is a LOT of area between those curves where it matters most.



Certainly - if we took a number of drivers and piled them in a number of sealed cabinets that were equal in volume to the F-20, we'd see different results, but that is not exactly apples to apples either.

But what about excursion???

Well - remember that the back chamber in the F-20 is a sealed box, a rather small one at that, and the driver is still working against the acoustic load of the horn...the horn driver's excursion is actually lower than the sealed box too, except for 18 to 20 Hz, 40 Hz, and a few points up higher in frequency where excursion is not the limit we're concerned with.



Since nothing is ever free....we still have to consider the downsides of the horn. The box is complex, and huge. Those are two big strikes. Also - when out of band (playing below the horn's tune) there will be distortion generated, and the distortion products that fall within the horn's passband will likely be louder than those from the sealed cabinet, even though the driver is moving less in the horn.
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post #257 of 1711 Old 05-16-2011, 07:46 PM
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now that my other mfw driver is on the mend I plan on building one of these baddies..

Plan on getting some birch or maple ply this weekend.

Matt

"The main reason Santa is so jolly is because he knows where all the bad girls live." - George Carlin
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post #258 of 1711 Old 05-16-2011, 09:49 PM
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Quote:
Originally Posted by lilmike View Post

Not exactly.

Comparing apples to apples here is not really possible, but a single sealed MFW vs the MFW in an F-20? The 1 W SPL lines do not cross until ~12 Hz, and there is a LOT of area between those curves where it matters most.



Certainly - if we took a number of drivers and piled them in a number of sealed cabinets that were equal in volume to the F-20, we'd see different results, but that is not exactly apples to apples either.

But what about excursion???

Well - remember that the back chamber in the F-20 is a sealed box, a rather small one at that, and the driver is still working against the acoustic load of the horn...the horn driver's excursion is actually lower than the sealed box too, except for 18 to 20 Hz, 40 Hz, and a few points up higher in frequency where excursion is not the limit we're concerned with.



Since nothing is ever free....we still have to consider the downsides of the horn. The box is complex, and huge. Those are two big strikes. Also - when out of band (playing below the horn's tune) there will be distortion generated, and the distortion products that fall within the horn's passband will likely be louder than those from the sealed cabinet, even though the driver is moving less in the horn.

While I wont go into Mike's technical aspects of the box, I will speak for a well sealed MFW 15 in about 2.5 cuft, vs the f-20, across the entire band, the sub/cab displays less distortion, higher output, and all in all, better tonal quality than I can even explain... but only in an apples to apples comparison, one sealed vs one f-20 application comparison that is.

My advice, save the dough on 4,6,8 MFW sealed drivers, build one of these f-20's, find a nice place to put it, and GOPHER IT!!!!!

On another note, the tempest isnt showing getting here until either this weekend or early next week. I was hoping to get it Friday and get another build going for the second. Now that I have the design aspect down, it shouldnt take more than a good Friday night to cut and assemble (a 12 pack of beer, good music, and Im ready)

A good rock n roll type enclosure? I listen to a mix of Metal and underground rap with a few good well recorded recent rap songs mixed in. I will say, I was slightly hesitant about how this design would do with the double kicks I love in my metal tracks and I will say it certainly does NOT dissapoint

how do you think the tempest will improve on that? I think quite well

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post #259 of 1711 Old 05-16-2011, 09:54 PM
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Mike, how do you feel about standing this thing up with the mouth on the top as opposed to on the floor?

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post #260 of 1711 Old 05-16-2011, 10:14 PM
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lilmike or anyone else that might know.....I have a version 2 mfw-15 amp that I got for my original mfw-15 as a replacement spare. It is sitting in a box and I don't think I will ever be needing it as I have one of the original first ten mfw-15's that were ever made and is still working like a charm.

I need the upper control panel and combine them together could I jimmy-rig a full working amp in order to use it for an f-20 build?

Would there be any real difference between my original mfw-15 and the f-20 in regard to output/sound quality?

Also does anyone know if there are mfw-15 drivers still available still?

Thanks all,
Aaron
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post #261 of 1711 Old 05-16-2011, 10:30 PM
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Quote:
Originally Posted by A-Rone View Post


Also does anyone know if there are mfw-15 drivers still available still?

Thanks all,
Aaron



I double boxed about 25 more last weekend if you need any for this project.
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post #262 of 1711 Old 05-16-2011, 10:47 PM - Thread Starter
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Quote:
Originally Posted by A-Rone View Post

lilmike or anyone else that might know.....I have a version 2 mfw-15 amp that I got for my original mfw-15 as a replacement spare. It is sitting in a box and I don't think I will ever be needing it as I have one of the original first ten mfw-15's that were ever made and is still working like a charm.

I need the upper control panel and combine them together could I jimmy-rig a full working amp in order to use it for an f-20 build?

Would there be any real difference between my original mfw-15 and the f-20 in regard to output/sound quality?

Also does anyone know if there are mfw-15 drivers still available still?

Thanks all,
Aaron

The MFW does well in a ported box, but ported boxes suffer from distortion and port compression. Mark Seaton did a very good job designing the MFW-15. It is a great ported subwoofer.

That being said, above 20 Hz, the F-20 should get significantly louder, as it is about 6 dB louder than the MFW-15 is at a watt in, and since they use the same driver, they both take the same amount of power. Distortion will also be lower with the horn. Sound quality? I like the sound of horns. Some may not. For me - they're worth the extra effort.

No idea on the amp, but it's my understanding that they were tailored to the ported box, and have some EQ and filtering as appropriate for that enclosure.
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post #263 of 1711 Old 05-16-2011, 10:50 PM - Thread Starter
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Quote:
Originally Posted by beastaudio View Post

Mike, how do you feel about standing this thing up with the mouth on the top as opposed to on the floor?

How close to the ceiling will the mouth be?

Try it and see - probably not a good idea though, you'll probably get a response null and lose some of the effects of boundary loading.

How wide is your room? Can you lay two across the front, then set the mains and center on top of them?
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post #264 of 1711 Old 05-17-2011, 03:15 AM
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Quote:
Originally Posted by lilmike View Post


Not exactly.

Comparing apples to apples here is not really possible, but a single sealed MFW vs the MFW in an F-20? The 1 W SPL lines do not cross until ~12 Hz, and there is a LOT of area between those curves where it matters most.

Certainly - if we took a number of drivers and piled them in a number of sealed cabinets that were equal in volume to the F-20, we'd see different results, but that is not exactly apples to apples either.

But what about excursion???

Well - remember that the back chamber in the F-20 is a sealed box, a rather small one at that, and the driver is still working against the acoustic load of the horn...the horn driver's excursion is actually lower than the sealed box too, except for 18 to 20 Hz, 40 Hz, and a few points up higher in frequency where excursion is not the limit we're concerned with.

Since nothing is ever free....we still have to consider the downsides of the horn. The box is complex, and huge. Those are two big strikes. Also - when out of band (playing below the horn's tune) there will be distortion generated, and the distortion products that fall within the horn's passband will likely be louder than those from the sealed cabinet, even though the driver is moving less in the horn.

that's good to know, although is it relevant to compare 1w spl behavior when most instances at those frequencies the power will be at the thermal rating of the driver? what does the horn do at 12hz 250w and no high pass? where do the lines cross on that comparison? Wouldn't it be making all kinds of bad sounds by then?

All the above are posed as questions, and based on possible misconceptions

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post #265 of 1711 Old 05-17-2011, 04:11 AM
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Originally Posted by lilmike View Post

How close to the ceiling will the mouth be?

Try it and see - probably not a good idea though, you'll probably get a response null and lose some of the effects of boundary loading.

How wide is your room? Can you lay two across the front, then set the mains and center on top of them?

This is a strictly theoretical question as my wife would probably put rat poison in my meat loaf if I added a second box.

Having said that, how would you orient the mouth of two horns side by side in the front of the theater.

And on another somewhat off topic question, where would I get some good black velvet to cover these in. Even with them painted flat charcoal black I am getting a reflection off the top of it due to the fact it sits just below the bottom frame of the screen.

And to close... We had a birthday party last night for my daughter and had around 30-40 people over. At one point I had them racked and stacked like sardines last night watching Avatar. The sub left them all slack jawed from the impact it makes in my space. And I learned something. 25 people is about the right amount of acoustical treatment for my space. They are good bass traps.
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post #266 of 1711 Old 05-17-2011, 05:22 AM
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This is what I used to frame my DIY AT screen.

http://cgi.ebay.com/BLACK-PLUSH-TRIP...30359658222080

Moto
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post #267 of 1711 Old 05-17-2011, 05:25 AM
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Quote:
Originally Posted by Rob Flanery View Post

And on another somewhat off topic question, where would I get some good black velvet to cover these in. Even with them painted flat charcoal black I am getting a reflection off the top of it due to the fact it sits just below the bottom frame of the screen.

Do they have JoAnn Fabrics down there? They have a Royal--something or other black velvet that I used in my theater.
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post #268 of 1711 Old 05-17-2011, 07:23 AM
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This is what I used to frame my DIY AT screen.

http://cgi.ebay.com/BLACK-PLUSH-TRIP...30359658222080

Moto

I used this too, but you might want to go for something a little bit higher quality. for box this size that will probably see a little more wear and tear, check your local fabric shop and see what they got... it may cost a little more, but it should also hold together better than the triple velvet.

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post #269 of 1711 Old 05-17-2011, 07:31 AM
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Quote:
Originally Posted by lilmike View Post

How close to the ceiling will the mouth be?

Try it and see - probably not a good idea though, you'll probably get a response null and lose some of the effects of boundary loading.

How wide is your room? Can you lay two across the front, then set the mains and center on top of them?

well in the three locations I want to try out, the ceiling is at 8 ft. so I have three feet from the top of the mouth to the ceiling. it is also a drop ceiling so who knows what else that entails...

in two of the locations, the riser I have my second row seating on would basically cover the mouth, therefore standing it the other way up might benefit. This would also help to put the access panel with the speaker wire coming through it against the wall (will look much better that way for sure)

Im pretty sure I could fit two across the front with my towers on top, but then the towers would be significantly taller than they should be (Tweeter would be ear level standing instead of sitting)

I think the main problem I am having is the front row is just too close the cab as it is, pulling it away from the front row a bit, and either tucking it in the bar area (which would be a great corner load) or midway in the room beside the second row might help to even response. Obviously I want my seat to sound the best

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post #270 of 1711 Old 05-17-2011, 09:15 AM
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I have done some placement experimentation in my room and found with the mouth facing into the room rather then corner loading it's less localizable. However, corner loading gave me a 6-7db gain (Once, I build a second for the other corner it will fix the localize issues and balance the room).

I am using a Behringer a500 amp right now and it is sufficient power with just one channel. However, I can clip the amp at exactly -0 (reference level on my receiver) so maybe a little more power would be nice or when I build the second it will give the extra headroom needed. I can peg my RS SPL meter at 126 DB at 21hz test tones. I haven't used any EQ yet and by ear it is pretty darn flat. I am gonna try and get some REW measurements this weekend.

I'm trying to get another MFW from Erich ASAP to start building on a second.

Great design LiLMIKE!

Btw, I've heard both the THT and now the F-20. The tonal quality seems alittle more
solid with the F-20. I dunno if this is due to the design or the room differences or the sub itself. But I can definitely detect a different tone.
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