can u guys help...

[meccalli]

hey guys..im a new member....im regular on ssa but as i posted there ..i had an epiphany from car audio to home....but anyways.lol..my current setup is a kenwood vr-60 rs reciever ,a pair of logitech front speakers(i removed the sub),and 2 LA STRIKE subs in a 5 cubic ft box.......im trashing the subs and logitech....im going for 2 polk monitor 70's front stage ,a behringer ep 2500 and 2 18 Q's.........my prob is..the sub box..i calculated one using RE's calculator but what ive heard there not accurate and i really cant test it myself with winisd cause im not familiar with tech specs too much(im 15 btw)..so i was wonderin if u guys could help me with the box....planned on the calculator...here it is width=60" height=30" depth=20".port width=4" and total port length =37"(which im confused by since the 2 port pieces add up to 29.5 in length but i take itfor granted that RE knows their stuff) the tuning worked out to be 20 hz..............so any input would be helpful...thanks brandon.

[Mike P.]

Hello fellow SSA-er and welcome to the Shack! If the box measurements that you posted are external, then you'll have a net volume of 16.5 cu.ft. after deductions for the sub, ports and bracing. I'll assume each Q18 gets its own box and this will be used for HT. Am I right?

[meccalli]

yes external dimensions and will be for HT ,however i was thinking common chamber...is that bad??

[Mike P.]

I wouldn't say it's bad just maybe not ideal. The Q18 likes a big box and you won't get the full potenial out of 2 of them in 16.5 cu.ft. Green is two Q18's in 16.5 cu.ft. and pink is 1 in the same size box. Notice the extended low end response of the single Q18. The modeling is of the Q18 dual 2 ohm.

brandon2.JPG

[meccalli]

yikes!!.........thats a nice and bad in a good way since i nearly built this box ..and what a diference.......this is winisd right?.....so can you recommend something for me and also is slot port good in HT applications(sorry it seems irrelevant ..just most people seem to prefer round ports)...space is basically at a premium so not really worries.........just not ib large(it will be my first build so...something simple perhaps??)thanks

[Mike P.]

For the slot port requirements, you will be using two Q18's in 16.5 cu.ft.?

[meccalli]

im asking..lol

[Mike P.]

I understood you almost finished the box for 2 Q18's. Are you going that way or will you do each sub has its own box? That will determine your port requirements.

[Robert_J]

Technically, round ports are the best since they maximize port area while minimizing surface area. Less friction between the air and the sides of the port. Is this audible? Hard to say. Also, round ports are easier to flare. Flared ports do make a huge difference.

And 15 is not too young to start understanding the physics and math behind speakers. At your age I already had my copy of Designing and Building Loudspeakers by David Weems from Radio Shack.

Welcome to the Shack from another SSA member. There is a home audio section there as well.

-Robert

[meccalli]

mike p...i think ill follow your suggestion and go with 2 boxes ..(i meant i was about to build it but i decided to join HTS for professional opinions)....robert_j ...well i guess ill go with the circle ports and thanks.......when i said im 15 i was implying my young age for this stuff....and yeah i have the loudspeaker cookbook and i basically kill my physics paper on any subject to do with electricity/magnets..specially magnets and coils(hehe),..the math gonna take some more work (addmath that is) ...i do alot of reading off of ssa (alot from neil:devildriver like magnetic treatments)yeah im trying to get the most that i can and thanks again................about my setup.......i have the kenwood receiver and was wondering..........can a male rca jack to 2 1/4" tr jacks connect the receiver's sub out to input 1 and 2 on the ep 2500 for operation??

[Mike P.]

15 cu.ft. net works well. Build the box 16 cu.ft. internal so you wind up with 15 cu.ft. after deductions of the sub, port and bracing. The sub will handle 1000 watts in this setup with a subsonic filter at 15hz. Porting will need to be a 8 inch round port or a 2" x 25" slot port to keep the airspeed down. Both need to be 29 inches long.

Adaptors can be used to connect the receiver to the amp. And you have to take lots of pics of the build.

[meccalli]

ok...you will see the box build but the full works wont happen until christmas ..and yeah..lots of pics!!....so this will be a single 8" circle port 29"long........will this cause any turbulence ..and should i dampen the enclosure?

[Mike P.]

The port is big enough that turbulence won't be an issue. Lining the walls with egg crate foam will damp the sub.

[meccalli]

thank you!!!