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Discussion Starter · #1 ·
I'm looking at building a ported Tempest-X2 to go with the two Kepler's I'm going to build.

I'm thinking about doing something like Neo Dan's easy button end table or something of the sort. I'm a college student so no WAF to worry about but it needs to be transportable so I'm thinking anything up to 8ft^3 is ok. Is it best to just go for the 8ft^3 slot ported box or would it be better to go with a smaller box and add some fill. I'm open to suggestions.

I'm also open to suggestions regarding a pro amp.

At this point I'm looking at buying a Yamaha P2500S to power the sub, it looks like a good match.
(http://www.yamaha.com/yamahavgn/CDA/ContentDetail/ModelSeriesDetail.html?CNTID=15252&CTID=227600&ATRID=20&DETYP=ATTRIBUTE#)
I imagine the Tempest can handle the 1300w at 4 ohms but I'd like to make sure before I blow it up.

I should mention that I've also purchased a Reckhorn B-1 to use as a high pass/low pass as the Yamaha RX-797 this sub will be connected to does not have a variable crossover for the sub out, so the HPF is taken care of.
 

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Discussion Starter · #2 ·
Well I placed an order yesterday for one Tempest-X2.

Right now I'm looking at 7ft^3 tuned to about 21hz. There are 3 ports 2.5"x6"x39". BassBox says the port should be 39" to tune the box to 21hz but WinIsd says 36" so I'm not sure what it should really be. The port should add strength but I might need some more bracing. The external dimensions of the box are 24"x27"x30" (WxHxL).



This is the model using a 24db high pass at 17hz on the Reckhorn B-1.





What'ya guys think?
 

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why 3 ports instead of 1? why 21Hz..what you using it for? Other than that...loooks awesome! Build pics for sure! I got rid of my BBP6, don't even miss it. Stick with ISD IMHO :T
 

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Discussion Starter · #4 · (Edited)
Personally I'm just going for 3 ports for aesthetics. The plan was to do an Easy Button End Table and if I'm going to have 2 braces running up the port might as well bring them all the way to the end. Plus since I'm not using a Maelstrom I don't need all that port volume. I saw Neo Dan's pic on AVS of one of his other builds and liked the way the ports looked. (I sent him a PM to make sure it's ok for me to copy his design but haven't received a response yet.) It's kind of unique and offers another building challenge so why not. :T



As far as the tuning goes, this sub will probably end up being used for music more than movies as it'll be hooked up to my computer so I figured I'd concentrate on the 20-30hz region, don't need to get into the teens.

Don't worry, build pics will come when I get the chance to build this thing.
 

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sounds and looks great to me! I was just wondering, because I've been working on a large slot port for in-car, the slot is looking to be 46" x 5" but if I run a support down the center, as it really is needed, it will effectively become 2 smaller ports...and I can't have that :(
 

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Well the port tuning and length is based upon the cross sectional area, so if the cross sectional area of those 3 ports is the same as the 1 big one then the length and tuning is the same too. So the fact that he ran the dividers all the way to the end doesn't really matter except it makes it a bit more solid, and looks pretty sweet to be honest.
 

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Well the port tuning and length is based upon the cross sectional area, so if the cross sectional area of those 3 ports is the same as the 1 big one then the length and tuning is the same too. So the fact that he ran the dividers all the way to the end doesn't really matter except it makes it a bit more solid, and looks pretty sweet to be honest.
I'd like to think you are correct, but I'm gonna say that you're not. 10 6" ports, 28.26sq per, 282.6 total, is not the same as 1 19" port
 

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Well I'm no expert but just playing around in WinISD if you take any number of ports with a certain cross sectional area vs 1 big port with the same cross sectional area it gives you the same length. Maybe the program it's self is wrong I'm just assuming it knows what its doing.:dontknow:
 

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Ryan is right but in this case, it isn't off by much. If your modeling software will allow, try cutting the area by a third and comparing the length of three ports vs. one port with the same area. I know it is counter intuitive but it takes longer multiple ports to equal one equal area single port.

And for exactly 7 cubic feet (198L) with no fill, I show that three 2.5" x 6" port need to be about 34" to get a 21" Hz tune. You are probably using slightly different numbers in the modeling program hence the reason for the differences. Using 36" in my simulation gives only a half Hz difference in the tune so you are close enough for government work. You might want to use about 20% fill anyway which will drop it by about the same amount.

Kevin Haskins
Exodus Audio
 

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Discussion Starter · #11 · (Edited)
Are you using LspCad or WinIsd Kevin? In WinIsd I just did 7ft^3 with a 21hz tune and 3 2.5"x6" ports and it calculated 35.92 inches as the appropriate length. As I said before BassBox gave me a different length than WinIsd. With a 7ft^3 box, no fill, an Fb of 21hz, and 3 2.5"x6" ports (with "One Flared End") gives me 38.36 inches for the length. I'm not sure what the correct length is but like you said, I might be half a hz off and I can live with that. In this case I'd rather be under the tune than over it if any error is going to occur so the ports being a little too long is ok.

As far as fill goes I had been planning on putting some foam on the walls to cut down on resonance and what not, wasn't really considering fill. I saw the other thread discussing poly fill, egg crate, etc so I'm not sure now. You recommend 20% fill, so that would be about 22oz in my application assuming I calculated right. What about open cell foam? Would you recommend some of that? It seems to be a "cleaner" job to me and easier to control placement.

Something like Acoustic Foam maybe?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-516
 

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Are you using LspCad or WinIsd Kevin? In WinIsd I just did 7ft^3 with a 21hz tune and 3 2.5"x6" ports and it calculated 35.92 inches as the appropriate length. As I said before BassBox gave me a different length than WinIsd. With a 7ft^3 box, no fill, an Fb of 21hz, and 3 2.5"x6" ports (with "One Flared End") gives me 38.36 inches for the length. I'm not sure what the correct length is but like you said, I might be half a hz off and I can live with that. In this case I'd rather be under the tune than over it if any error is going to occur so the ports being a little too long is ok.

As far as fill goes I had been planning on putting some foam on the walls to cut down on resonance and what not, wasn't really considering fill. I saw the other thread discussing poly fill, egg crate, etc so I'm not sure now. You recommend 20% fill, so that would be about 22oz in my application assuming I calculated right. What about open cell foam? Would you recommend some of that? It seems to be a "cleaner" job to me and easier to control placement.

Something like Acoustic Foam maybe?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-516
I use LSPCad Pro for all my modeling. It has a goofy user interface but all the mathmatical/acoustical algorithms seem to be well done.

I use polyfill because for reasons I don't have time to go into, it is more effective than egg-crate foam. You WANT the fill in the off the walls of the enclosure. Polyfill just works better for the intended application and locating it inside the cabinet has never been a problem for me. I just stuff it in there and mount the driver. If it keeps you up at night, thinking of all that polyfill floating around inside the enclosure, just buy the pillows and stuff them in the enclosure. That way you won't have polyfill shooting out of the ports.

If it makes you feel better to use egg-crate foam, I've never found it to hurt anything but it does very little or nothing in terms of what we want from polyfill.

Kevin Haskins
Exodus Audio
 

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Discussion Starter · #13 ·
With any luck I should be starting this build late next week after my finals are over. That being the case I have some final questions before I get under way.

It may sound like a stupid question but as this is only my second sub build, and at the same time my first slot port build, I'm not sure I've got the port length dimensions correct. If I'm aiming for a port length of 36" long do I calculate the length as shown?



So it would be 25.25"+9.25"+1.5"(for the front baffle thickness) = 36"
I'm not sure how the corner of the port is measured with regards to length. Am I going to have any flow problems with the port the way it is? Should I put a little 45 degree wedge of MDF in the corner of the port or just not worry about it?

I also have some questions about hooking up the connections between my receiver and the sub itself.

I have ordered a Yamaha P2500S to power the Tempest. So, my plan is to run an rca cable from the sub out on my Yamaha RX-797 to the Reckhorn B-1. From there I will run another rca cable to the Yamaha P2500S and connect it using a 1/4" rca-phono adapter. Then to power the sub I was gonna try using the Speakon connectors. However, I'm not sure what gauge of wire I will need to use if I'm running 1000+ watts, for both the Speakon cable itself and the wire inside the sub running from a Speakon cup on the enclosure to the Tempest. Is awg 14 enough, etc. ? Am I going to have a conflict with the poles on the Speakon connectors?

These are the components am currently looking at, please let me know if you see a problem with them or if you have a suggestion of where to get better/cheaper cables.

Dayton SW-12 Subwoofer Cable 12 ft.
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=181-642

Dayton SW-25 Subwoofer Cable 25 ft.
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=181-644

Dayton ADQM-RCAF RCA Jack To 1/4" Mono Plug
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=091-1010

Audio-Technica AT700-25 14 AWG Speakon Speaker Cable 25 ft.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=242-5024

Neutrik NL4MPR Speakon 4 Pole Round Chassis Mount
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=092-054

Kevin, I already have my pair of Kepler's built that are going with this Tempest and they sound great, I really like that Peerless HDS tweeter. They were a big hit with the relatives at Thanksgiving and both my father and brother now want a set so as soon as your Anarchy's come in you can expect a few more orders. Thanks again for your help on those, I'll post some pictures when I get a chance. :T
 

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With any luck I should be starting this build late next week after my finals are over. That being the case I have some final questions before I get under way.

It may sound like a stupid question but as this is only my second sub build, and at the same time my first slot port build, I'm not sure I've got the port length dimensions correct. If I'm aiming for a port length of 36" long do I calculate the length as shown?



So it would be 25.25"+9.25"+1.5"(for the front baffle thickness) = 36"
I'm not sure how the corner of the port is measured with regards to length. Am I going to have any flow problems with the port the way it is? Should I put a little 45 degree wedge of MDF in the corner of the port or just not worry about it?

I also have some questions about hooking up the connections between my receiver and the sub itself.

I have ordered a Yamaha P2500S to power the Tempest. So, my plan is to run an rca cable from the sub out on my Yamaha RX-797 to the Reckhorn B-1. From there I will run another rca cable to the Yamaha P2500S and connect it using a 1/4" rca-phono adapter. Then to power the sub I was gonna try using the Speakon connectors. However, I'm not sure what gauge of wire I will need to use if I'm running 1000+ watts, for both the Speakon cable itself and the wire inside the sub running from a Speakon cup on the enclosure to the Tempest. Is awg 14 enough, etc. ? Am I going to have a conflict with the poles on the Speakon connectors?

These are the components am currently looking at, please let me know if you see a problem with them or if you have a suggestion of where to get better/cheaper cables.

Dayton SW-12 Subwoofer Cable 12 ft.
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=181-642

Dayton SW-25 Subwoofer Cable 25 ft.
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=181-644

Dayton ADQM-RCAF RCA Jack To 1/4" Mono Plug
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=091-1010

Audio-Technica AT700-25 14 AWG Speakon Speaker Cable 25 ft.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=242-5024

Neutrik NL4MPR Speakon 4 Pole Round Chassis Mount
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=092-054

Kevin, I already have my pair of Kepler's built that are going with this Tempest and they sound great, I really like that Peerless HDS tweeter. They were a big hit with the relatives at Thanksgiving and both my father and brother now want a set so as soon as your Anarchy's come in you can expect a few more orders. Thanks again for your help on those, I'll post some pictures when I get a chance. :T
You basically pretend you are a little miniature guy and walk down the length of the port (center) with your pedometer on. I read 34.75" long. 25.5" (length of long run) + 1.25" (half the width of the port) + 8" (9.25" minus half the width of the port) = 34.75"

If you are off an inch or so it makes little difference. Check the model. The differences get swamped in all the other variables (driver specs, barometric pressure, temp etc.. etc...)

Kevin Haskins
Exodus Audio
 

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Discussion Starter · #16 ·


As of now, this is my finalized design with regards to the bracing. Does anyone see a problem with the airflow through the port as it is, am I going to have any problems? I was thinking of chamfering the upper edge in the bend of the port and putting a 45 degree sliver of MDF in the corner but I'm not sure if it's worth my time.

I will be cutting out the pieces for the ports tomorrow so this is my last chance to make any changes.
 
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