Nice, after all. If dimensions are so similar (internal volume and port) you don't have to worry. Only if they vary, is better to make a simulation. 
How do you plan the crossover! Do you have receiver/active or is it passive?!
http://www.jblpro.com/catalog/general/product.aspx?PId=206&MId=1
http://www.jblpro.com/pub/cinema/4645c.pdf
How do you plan the crossover! Do you have receiver/active or is it passive?!
http://www.jblpro.com/catalog/general/product.aspx?PId=206&MId=1
http://www.jblpro.com/pub/cinema/4645c.pdf
I am going somewhat lame on the amp... I have some ideas of what I'd really like to do but the $$ of this overall got a little out of hand. I'm going with this Dayton 1000W sub-woofer rack amp. It does 500W into 8 ohm. It should rock the house pretty good.
here it is... Dayton is pretty solid from other Dayton stuff I've got. Not the best but great performance per $1
Dayton Audio SA1000 Subwoofer Amplifier Rack Mountable 300-811
I'm glad you got me the issue to think about with wavelength modes and harmonics. I got into some reading and found more on bracing and think I needed a bit more bracing to make the box stronger. The actual 4645C bracing I found on another forum..
I added a brace extending 4 in up from the lower brace. I think this will make the side walls more rigid. I think the 3 braces will add some irregularity to the inside to help kill potential issues with wavelength modes and harmonics. I think I'll end up breaking down at some point and looking at measurement gear to test this thing when done.
Here is a pic of the 4 braces.. The one taking up the whole area front to back and side to side with 4 5in holes in it... Then the 3 (one extending down from ceiling, one from the rear wall and one up from the lower brace.)
before the added lower brace:
here it is... Dayton is pretty solid from other Dayton stuff I've got. Not the best but great performance per $1
Dayton Audio SA1000 Subwoofer Amplifier Rack Mountable 300-811
I'm glad you got me the issue to think about with wavelength modes and harmonics. I got into some reading and found more on bracing and think I needed a bit more bracing to make the box stronger. The actual 4645C bracing I found on another forum..
I added a brace extending 4 in up from the lower brace. I think this will make the side walls more rigid. I think the 3 braces will add some irregularity to the inside to help kill potential issues with wavelength modes and harmonics. I think I'll end up breaking down at some point and looking at measurement gear to test this thing when done.
Here is a pic of the 4 braces.. The one taking up the whole area front to back and side to side with 4 5in holes in it... Then the 3 (one extending down from ceiling, one from the rear wall and one up from the lower brace.)
before the added lower brace:
I'll press on and hope for the best with the box as it is and hope the wavelength modes and harmonics issue does not come into play.. Too deep to re-do.. Need to get this playing and see what happens..
What for damping? I was thinking of using some R13 insulation that I have... Then I have two 12' X 12" X 2-1/2" pieces of egg crate Acoustic Sound Deadening Foam
What for damping? I was thinking of using some R13 insulation that I have... Then I have two 12' X 12" X 2-1/2" pieces of egg crate Acoustic Sound Deadening Foam
I finished the sub and it sounds great. Real happy with the outcome. I'll take a photo tonight.
I put some work in last night and then today had a snow day in MN. I got to wrap up the build and it is a sub with some pretty serious authority. I got a Dayton amp that has a +3 dB boost at 25HZ. I think that will come in handy with this JBL 2242H.
The sub complements the 4PIs I built with JBL 15 in nice. I got to listen to some music and then ran some Blue Ray movie scenes where the BASS is intense.
I don't have any measurement tools the but the sound is fantastic. I can have the sub woofer amp gain set to 40% the thing is strong, full and clean. Big as hell and heavy as hell but oh well.
I put some work in last night and then today had a snow day in MN. I got to wrap up the build and it is a sub with some pretty serious authority. I got a Dayton amp that has a +3 dB boost at 25HZ. I think that will come in handy with this JBL 2242H.
The sub complements the 4PIs I built with JBL 15 in nice. I got to listen to some music and then ran some Blue Ray movie scenes where the BASS is intense.
I don't have any measurement tools the but the sound is fantastic. I can have the sub woofer amp gain set to 40% the thing is strong, full and clean. Big as hell and heavy as hell but oh well.
Congrats, nice job. I have the big brother to your sub and love it!
Its the 5749 http://www.jblproservice.com/pdf/Theatre Series/5749.pdf. I use a combo of QSC DSP-30 for tweaking and a QSC 4050HD to power it. Nothing finer for music.
Its the 5749 http://www.jblproservice.com/pdf/Theatre Series/5749.pdf. I use a combo of QSC DSP-30 for tweaking and a QSC 4050HD to power it. Nothing finer for music.
Who would say that...
In this case you don't need a pair of subs...
(Subs, I hate them?!) But you have to have in mind that in this case, Pi kits (and JBL many times) you never have the low frequency extension because all goes to the sensitivity and SPL. Usually audiophiles use 10W or 30W tube amps not 300W or 3000W SS.
By the way wrager, did you measure the low frequencies (room/system gain) or just set it up at pleasure.
Wavelength modes won't be an issue if your crossover is at all competent. Consider the 22" side: the first mode will have nodes at the walls, so the full wave will be 44" long, which at 13500 inches / second means it'll fall at 300 Hz. A similar calculation for the height (about 33" internal) indicates a mode at 200 Hz.
If your subwoofer is producing useful output at those frequencies then you have more pressing problems than cabinet modes. That's why the usual rules about staggering cabinet XYZ dimensions are superfluous to subwoofers, so cubes are perfectly acceptable for that use. Let the signal get into the mids, though, and you may have problems.
A JBL 5749 must be a beast! I can't imagine the dual 2242. One of these is an unreal experience.
DSP_Geak - What you are saying makes a lot of sense. Thanks for dropping some knowledge my way and have a good weekend. I'm looking forward to some time with the addition to my system with a cold beer in hand.
DSP_Geak - What you are saying makes a lot of sense. Thanks for dropping some knowledge my way and have a good weekend. I'm looking forward to some time with the addition to my system with a cold beer in hand.
I ran the sub solo during some of the better bass scene DVDs/Blue Rays I have... Jurasic Park, Pulse, Kung Foo Panda.... I was not expecting the lower end I was hearing/feeling. The 25Hz 3dB booster of my Dayton amp does help. A plesant suprise on the lower end sound and feel. The range up from the 25Hz to around 100 Hz is something special. I think having just 1 of these running mono will be cool. maybe mix in another sub that would complement this one and get some deeper range. I have a pretty big room so a few subs would be good. Long term. For now the budget is spent for a bit.
PS - I wish I had a stock 4645C I could compare mine to... The Okoume wood and that big fat heavy port in mine seems to sound a bit more focused and clean. Could be my mind playing tricks on me. For some reason the cardboard tube on a stock 4645C I didn't like the idea of. The Schedule 80 8inch PVC I think has a nice touch on the sound. This is fat walled PVC at nearly 3/4" thick. You can round the inner edge on it a bit. The PVC is 10 lbs. So the inner tube is rounded a bit and then I ran a router with a rounder bit on the opening of the port on the baffle.
PS - I wish I had a stock 4645C I could compare mine to... The Okoume wood and that big fat heavy port in mine seems to sound a bit more focused and clean. Could be my mind playing tricks on me. For some reason the cardboard tube on a stock 4645C I didn't like the idea of. The Schedule 80 8inch PVC I think has a nice touch on the sound. This is fat walled PVC at nearly 3/4" thick. You can round the inner edge on it a bit. The PVC is 10 lbs. So the inner tube is rounded a bit and then I ran a router with a rounder bit on the opening of the port on the baffle.
Thanks all.
Just kidding on the wife leaving bit. If anything building this giant clunker of a subwoofer had her thinking it is time to go.
The thing is an old school tank of a thing... But it really does do some magic with music and even movies. Bass drums and the like are fast and furious.
I thought about this and some folded horn subs... I'm happy and I'd do it again.
Just kidding on the wife leaving bit. If anything building this giant clunker of a subwoofer had her thinking it is time to go.
The thing is an old school tank of a thing... But it really does do some magic with music and even movies. Bass drums and the like are fast and furious.
I thought about this and some folded horn subs... I'm happy and I'd do it again.
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