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sonosub planning phase

6K views 46 replies 4 participants last post by  Mike P. 
#1 ·
Since the new theater will be quite a bit bigger than the last and the rsw10 was inadequite for even that, its time for a build. Budget being tight as usual, im close to settled on the Titanic 15" in a sonotube with an ep4000 for enough power for future abition. However, i could be convinced to look at other drivers if the price/performance quotiant is right.

The room is 17x19 and im looking to tune pretty low, say 13hz or so. Size isnt a rpoblem but construction cost and effort is. Is a single titanic 15 going to be my best bet or should i consider beefier 18s? I figure worst case i could build another 15 down the line but where id put it is a mystery. I would like to put most of the ep4000s power to good use...

Just to make it a challenge, im not looking to spend over a grand including EQ. Sock it to me guys!:hsd:
 
#31 ·
Ive been modeling the Titanic 15 in a few differet arrangements and im getting some nice looking graphs with about 400 liters and 1, 2 or three ports 6" ID and about 20" long. Tuning would be 14.72hz with one port open, 20.82hz with two ports open, and 25.5hz with all three open. All three potrs blocked gives a sealed qtc of .584 and respectable looking response into the teens.

One question now is whether the ports that are blocked should still be deducted from the overall volume of the enclosure. I wouldnt think so, but air acts all crazy like sometimes.

Im also trying to estimate how much power I can feed them in the different alignments, so Im tinkering with highpass filters, which I have somehow avoided learning much about, but if I apply filters to the appropriate frequencies for each alignment and power them accordingly to stay at or slightly under xmax at all times, the middle and high tunings seem to jump out as the best performersfor daily use, while the lowest tune has major extension for those times i may want to trigger tsunami.
 
#32 ·
I was trying to model the Shiva a while back with just such a design. The limitation I found wasn't xmax so much that it was air speed when using only the higher tunings/fewer ports. I suppose your choice of 6" ports may have alleviated that, just check that they're not above ~26 m/s while driving them near xmax with those higher tunings (fewer ports). :T
 
#36 ·
Why do i keep reading!!??!!??

Im looking at the Fi SSD18 now. Havent had a chance to model it yet but i would think an 18 with higher power handling and mor x max at almost the same price would be a move in the right direction.
 
#37 ·
Looks like the last post I made didnt come up.

Im trying to figure out why I have such a humpy response curve with the SSD18.Is this telling me its not suited for what Im doing or what?

Maybe this will help...



All three plots use the same size enclosure. The ports are all 6" diameter and 27.82" long.
 
#38 ·
Heres the port velocity. Its in FPS, but still is insanely high. I presume ill be able to keep it under control once I figure out how to set up highpass filters to keep excursion in check.

 
#39 ·
Oh! What i had asked in my missing post was how the unused potrs will affect the enclosure volume.im guessing the unused ports will act like theyre not there and add to the net volume, corrrect? So if i build to 16cu ft with three ports, plugging two of the ports will add their volume to the net system volume. This might be helpful but id like some opinions.

Also, what port size am i going to need to keep velocity reasonable? Length and volume compensation start to get pretty extreme if i go with an 8". How much do very large flares help? If need be i could make some pretty hardcore flare ends in a cnc.
 
#40 ·
Anyone want to comment on this design or did i drive you all away with my indecision? Hehe If everything looks good i think im going to order drivers next week.
 
#42 ·
I thinkbthe longer port length was to accomodate an 8" port diameter. I dont have access to win isd but i think that was how it broke down. I *should* be able to fit three 8" ports I think.

What are your thoughts on the volume changes involved in the inactive ports? Should I add that volume to the models of the lower two tunes to be more accurate?

Thanks for checking my work, I tend to miss some important details...
 
#44 ·
Thanks a bunch, Mike. They seem to roll off a little more steeply than id hoped, but thats the HPF, in your opinion is there anything to gain by lengthening the ports a bit more to get the low tune right at 14hz? Also, would you say 8" is adequite with some big flares? Or do i need to figure something else out? I was thinking of either square or even rounde triangular mdf ports. So long as the area is the same the shape doesnt matter much, right?
 
#46 ·
Is there any rule on how far apart the ports sould be? Im thinking of trying to fit them all behind an 18" speaker grille. Either that or im sure ill have enough scrap to make an mdf ring and slap some fabric over it.
 
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