Hello from the New Forest in the United Kingdom.
I've not built a sub before ( or any speaker for that matter ), so please be gentle. I can however build houses, so I do have some level of intelligence. I am converting a garage into a movie room and I'm looking at buying some second hand ( but working and in A1 condition ) JBL 2242HPL drivers.
These drivers are in :-
https://jblpro.com/products/4645c
I'm looking at getting two of these JBL 2242HPL drivers to make two Subs. These subs will sit behind a AT screen between my LCR speakers.
The LCR set of speakers are :-
https://jblpro.com/products/3677
L Sub C Sub R
As the LCR speakers are only 292mm deep I will not really want the sub to be more than this. Is it the case I need to ensure the enclosure is the same volume as the 4645c, with a hole of the same size ( port ) in it.
The 4645C shows an internal volume of 225ltrs ( 8 cubic feet )
1010mm high x 674mm wide x 450mm deep ( not taking into account thickness of materials used )
966mm x 630mm x 386mm ( taking into account materials used ) = 234Ltrs
So, if I built something that was ( internal ) :-
1600mm x 566mm x 256mm deep
This would then sit between studs that were 600mm wide and the sub would be 300mm deep ( based upon 22mm thick material for making it. I would put a port hole the same size as used in the 4645c.
I would put bracing inside too.
I am sure it is more complicated that what I have just mentioned, but any comments would be appreciated. Please don't be toooooo technical with me 🙂
NOTE: I have a new JBL 4645C but it won't fit ( nicely ) behind my AT screen. Thinking about it. It might not be a bad idea to just buy another and stick them both at the back of the room symmetrically. That would save an awful lot of hassle ! It's not too much more than buying 2 x drivers + time + materials !
I've not built a sub before ( or any speaker for that matter ), so please be gentle. I can however build houses, so I do have some level of intelligence. I am converting a garage into a movie room and I'm looking at buying some second hand ( but working and in A1 condition ) JBL 2242HPL drivers.
These drivers are in :-
https://jblpro.com/products/4645c
I'm looking at getting two of these JBL 2242HPL drivers to make two Subs. These subs will sit behind a AT screen between my LCR speakers.
The LCR set of speakers are :-
https://jblpro.com/products/3677
L Sub C Sub R
As the LCR speakers are only 292mm deep I will not really want the sub to be more than this. Is it the case I need to ensure the enclosure is the same volume as the 4645c, with a hole of the same size ( port ) in it.
The 4645C shows an internal volume of 225ltrs ( 8 cubic feet )
1010mm high x 674mm wide x 450mm deep ( not taking into account thickness of materials used )
966mm x 630mm x 386mm ( taking into account materials used ) = 234Ltrs
So, if I built something that was ( internal ) :-
1600mm x 566mm x 256mm deep
This would then sit between studs that were 600mm wide and the sub would be 300mm deep ( based upon 22mm thick material for making it. I would put a port hole the same size as used in the 4645c.
I would put bracing inside too.
I am sure it is more complicated that what I have just mentioned, but any comments would be appreciated. Please don't be toooooo technical with me 🙂
NOTE: I have a new JBL 4645C but it won't fit ( nicely ) behind my AT screen. Thinking about it. It might not be a bad idea to just buy another and stick them both at the back of the room symmetrically. That would save an awful lot of hassle ! It's not too much more than buying 2 x drivers + time + materials !
What are the dimensions of the room you are building?
Here is the thing... that room dominates low frequency response, by that I mean the room will create a complex pattern of nodes(peaks and troughs) in the response that are determined by the dimensions of the room and the subs position in it. So.. symetrical positioning of two subs rarely produces the smoothest response. in fact one of the benefits of multiple subs is using them to smooth out in room response by positioning them in non symetrical positions. That usually means one sub along the front wall and one along a side wall somewhere, the exact location of those is something that has to be determined through experimentation.
Here is the thing... that room dominates low frequency response, by that I mean the room will create a complex pattern of nodes(peaks and troughs) in the response that are determined by the dimensions of the room and the subs position in it. So.. symetrical positioning of two subs rarely produces the smoothest response. in fact one of the benefits of multiple subs is using them to smooth out in room response by positioning them in non symetrical positions. That usually means one sub along the front wall and one along a side wall somewhere, the exact location of those is something that has to be determined through experimentation.
@conanski It's a refit of an existing room, so the depth will be 5m, the width between 3.8m&4.2m and height about 2.3m ( Atmos heights into ceiling ). Screen is 3.2m wide.
I can use the harmon room mode calculator to determine the position of the Sub in the room based upon standing waves.
However, that's another subject ( very important ) that isn't what I'm asking about here. What I want to know here is if my assumption of keeping the volume of this sub the same but changing the dimensions a bit, will it be ok ?
I can use the harmon room mode calculator to determine the position of the Sub in the room based upon standing waves.
However, that's another subject ( very important ) that isn't what I'm asking about here. What I want to know here is if my assumption of keeping the volume of this sub the same but changing the dimensions a bit, will it be ok ?
The fundanental properties you would want to replicate would be the internal volume and the tuning of the port.
As you have a original JBL 4645C cabinet you can measure the port diameter and length to see if this will fit in your new cabinet size or even better measure the actual impedance VS frequency to find the cabinet / port tuning. Varying the dimensions of the cabinet can effect the port resonant frequency if it is ajacent to any of the cabinet walls.
Once you have this data then it will make it far easier to ensure the new cabinet is tuned to give a comparable performance.
As you have a original JBL 4645C cabinet you can measure the port diameter and length to see if this will fit in your new cabinet size or even better measure the actual impedance VS frequency to find the cabinet / port tuning. Varying the dimensions of the cabinet can effect the port resonant frequency if it is ajacent to any of the cabinet walls.
Once you have this data then it will make it far easier to ensure the new cabinet is tuned to give a comparable performance.
Oh.... That seems, err, complicated.... Does this link assist me ?
http://www.audioheritage.org/vbulletin/showthread.php?10652-2242H
I think it's the technical specs for the speaker. The port on this speaker is just a hole - nothing more, nothing less.
http://www.audioheritage.org/vbulletin/showthread.php?10652-2242H
I think it's the technical specs for the speaker. The port on this speaker is just a hole - nothing more, nothing less.
Since you're going to XO @ < ~120 Hz, no; and if you want to be technically 'picky' 😉, then locate the driver at ~0.42x the cab's internal height.
As you want to change the whole cabinet layout, i would start from start and model the driver in a cabinet like you wish and see if you get the response you want. It would be perfect if you could measure the drivers itself, but if not the specs are published also: http://warehousesound.com/r/jbl2242H.pdf. Free software to do that is virtuixcad or winISD. Hornrsp can do that also but is hard to learn (maybe not for starters).
@waxx Thanks for your comments. I looked at a video of Vituix and had no idea what was going on, I'm guessing winiSD will be the same. As such, I think I will try a different route. I won't buy the drivers. I will see if I can buy another 4645C and then position according to the Room Mode calculator but to the rear wall. If all else fails, I've seen someone ( in the UK ) selling box built 12" custom subs in back boxes at 1 Ohm that I can just plug into my wall at $140 a pop - driver, box, painted & connectors. Then I don't need to worry about this at all !!
I will prob. in the future look at building a Sub, but would prob. use a pre-built cut-out or design with a specified driver and ignore a custom build.
Thank you to all of your replies.
I will prob. in the future look at building a Sub, but would prob. use a pre-built cut-out or design with a specified driver and ignore a custom build.
Thank you to all of your replies.
Some info you may not have and should affect your decision. The 2242H is pretty much the best mid base slam sub you can buy.
If you have 2 subs, quite simply i would build a 5 ish cubic foot box, split it in half and port both sides. These subs will give you
the best tactile slam bass you can ever imagine in this configuration. Build the boxes heavy with Baltic birch to take a pounding.
Double up on the face plate and use t screws that suck into the wood as you tighten them. I would look for a second 24 for the low
end of bass that can shake your room as needed. Check this sub out. You shouldn't need anything else. Put this in a proper heavy built cab
and never look back. Power both with a fp14000 clone amp. In short, this will produce all the base you need. You will need a high pass filter to
control the bass so you don't bottom things out and ruin drivers. Monoprice has very good prices on Xlr to rca cables, Buckeye amps are very reasonable for class d amplification or an older sherbourn 2100/7 if your trying to save a few bucks. 1099s or 1299's front speakers bought in kits
are very reasonable and highly potent for the money if your going dyi.... AVSforum is a good place to get used gear too... Hifishark is a easy way
to find things and compare prices for what gear sells for. I wish some one had given me this advise when i started.....
Cheers... brent
https://stereointegrity.com/product/hs-24/
If you have 2 subs, quite simply i would build a 5 ish cubic foot box, split it in half and port both sides. These subs will give you
the best tactile slam bass you can ever imagine in this configuration. Build the boxes heavy with Baltic birch to take a pounding.
Double up on the face plate and use t screws that suck into the wood as you tighten them. I would look for a second 24 for the low
end of bass that can shake your room as needed. Check this sub out. You shouldn't need anything else. Put this in a proper heavy built cab
and never look back. Power both with a fp14000 clone amp. In short, this will produce all the base you need. You will need a high pass filter to
control the bass so you don't bottom things out and ruin drivers. Monoprice has very good prices on Xlr to rca cables, Buckeye amps are very reasonable for class d amplification or an older sherbourn 2100/7 if your trying to save a few bucks. 1099s or 1299's front speakers bought in kits
are very reasonable and highly potent for the money if your going dyi.... AVSforum is a good place to get used gear too... Hifishark is a easy way
to find things and compare prices for what gear sells for. I wish some one had given me this advise when i started.....
Cheers... brent
https://stereointegrity.com/product/hs-24/