hello,
i just found this site and it is very interesting so i joined. i had a question. i have one alpine 1222D, and a mrp-m650. my sub is in a sealed box which i think is too big. but anyways i wanted to know if there is any possible way to get this sub down to 2ohms so it hits harder, like wiring only one of the voice coils? my box is 1.25cubic feet sealed and i think this is too big, how much of an effect would this have on the bass loudness and also distortion because it distorts it seems very quickly. any suggestions about any of this will be appreciated.
~Matt
Replies (7)
swez on 03/19/2009 21:41:48
Welcome to CK Matt.
If you can swap this SWR-1222D with a SWR-1242D, this would be a great match for a sealed box. (Using only 1 coil will damage/ruin the sub) This amp works best at 2 ohm loads.
However, you can still get very good bass from this 2+2 DVC sub when both coils are wired in series for a net 4 ohm load. That's 400 watt RMS to the sub and very suitable
As for sealed box size, the ideal target is 1.0 cf internal airspace for the SWR 12" sub series. You can use the box as is, but add a 0.25 cf of filler board(s) to bring it down to specs.
As for high distortion issues, this could be as simple as adjusting the the amp gain controls per instructions in the amp manual. Limit the use of bass boost on the amp and HU tone controls. Here's a copy of the manual & specs for you to print out and review:
http://akamaipix.crutchfield.com/Manuals/500/500MRPM450.PDF
http://www.crutchfield.com/S-UJ5fIC3rUaP/p_500MRPM650/Alpine-MRP-M650.html (Specs)
The larger the box, the lower the power handling and chrispness the sub will sound. (Sloppy, muddy low bass... especially at high power output) That's not good for the sub either.
Comments/Questions?
Swez
dayofgreen21 on 03/19/2009 21:45:52
thanks good info, what do you mean by filler board though? and how would i put that in cause i think that will help alot.
swez on 03/19/2009 22:18:27
Filler board in this case, would be simple 2"x6" dimensional pine boards. They are cheap, light weight and easy to cut and fit inside the box with the sub removed. (Glue and screws)
Example: 12" L x 1.5" H x 5.5" D = 99 cu in/1728 = 0.06 cf x 4 = 0.23 cf of filler board. That's pretty close and good enough huh?
The other options:
1. Chop the box and replace the rear panel to get the proper internal dimensions.
2. Build a new box or sell/swap the one you have now.
Comments?
Swez
dayofgreen21 on 03/20/2009 16:16:38
ok sounds good, just one more question, where inside the box should i put the boards? or does it not matter?, im thinking on the left and right oposite of the sub?
swez on 03/20/2009 17:01:59
Board placement is not a big issue in this size box and sub power noted. If the box had long, deep panels, we brace there to limit panel resonance issues.
Also, are you using sound dampening materials like fiberglass batting to dampen the rear cone waves in this box? I do in all sealed designs so that rear cone energy is absorbed and not reflected back into the woofer cone. It does not take much material to do this step. Figure 1.5-2.0" thickness of dampening material, all sides, back, top and bottom panels are dampened.
Comments?
Swez
dayofgreen21 on 03/21/2009 22:35:18
i bought the box from amazon so its not like i made it myself, but if the white cottony stuff is fiberglass then yes it does have it, its certainly not 1.5 inches thick though. if you could let me know exactly how to do that i would greatly appreciate it. thank you
swez on 03/21/2009 23:24:12
OK, that's Polyfill in there now and just as good as fiberglass for sound dampening. It does the same thing and you won't need to add more if it's about 1", (25mm) thick.
Good to go,
Swez
i just found this site and it is very interesting so i joined. i had a question. i have one alpine 1222D, and a mrp-m650. my sub is in a sealed box which i think is too big. but anyways i wanted to know if there is any possible way to get this sub down to 2ohms so it hits harder, like wiring only one of the voice coils? my box is 1.25cubic feet sealed and i think this is too big, how much of an effect would this have on the bass loudness and also distortion because it distorts it seems very quickly. any suggestions about any of this will be appreciated.
~Matt
Replies (7)
swez on 03/19/2009 21:41:48
Welcome to CK Matt.
If you can swap this SWR-1222D with a SWR-1242D, this would be a great match for a sealed box. (Using only 1 coil will damage/ruin the sub) This amp works best at 2 ohm loads.
However, you can still get very good bass from this 2+2 DVC sub when both coils are wired in series for a net 4 ohm load. That's 400 watt RMS to the sub and very suitable
As for sealed box size, the ideal target is 1.0 cf internal airspace for the SWR 12" sub series. You can use the box as is, but add a 0.25 cf of filler board(s) to bring it down to specs.
As for high distortion issues, this could be as simple as adjusting the the amp gain controls per instructions in the amp manual. Limit the use of bass boost on the amp and HU tone controls. Here's a copy of the manual & specs for you to print out and review:
http://akamaipix.crutchfield.com/Manuals/500/500MRPM450.PDF
http://www.crutchfield.com/S-UJ5fIC3rUaP/p_500MRPM650/Alpine-MRP-M650.html (Specs)
The larger the box, the lower the power handling and chrispness the sub will sound. (Sloppy, muddy low bass... especially at high power output) That's not good for the sub either.
Comments/Questions?
Swez
dayofgreen21 on 03/19/2009 21:45:52
thanks good info, what do you mean by filler board though? and how would i put that in cause i think that will help alot.
swez on 03/19/2009 22:18:27
Filler board in this case, would be simple 2"x6" dimensional pine boards. They are cheap, light weight and easy to cut and fit inside the box with the sub removed. (Glue and screws)
Example: 12" L x 1.5" H x 5.5" D = 99 cu in/1728 = 0.06 cf x 4 = 0.23 cf of filler board. That's pretty close and good enough huh?
The other options:
1. Chop the box and replace the rear panel to get the proper internal dimensions.
2. Build a new box or sell/swap the one you have now.
Comments?
Swez
dayofgreen21 on 03/20/2009 16:16:38
ok sounds good, just one more question, where inside the box should i put the boards? or does it not matter?, im thinking on the left and right oposite of the sub?
swez on 03/20/2009 17:01:59
Board placement is not a big issue in this size box and sub power noted. If the box had long, deep panels, we brace there to limit panel resonance issues.
Also, are you using sound dampening materials like fiberglass batting to dampen the rear cone waves in this box? I do in all sealed designs so that rear cone energy is absorbed and not reflected back into the woofer cone. It does not take much material to do this step. Figure 1.5-2.0" thickness of dampening material, all sides, back, top and bottom panels are dampened.
Comments?
Swez
dayofgreen21 on 03/21/2009 22:35:18
i bought the box from amazon so its not like i made it myself, but if the white cottony stuff is fiberglass then yes it does have it, its certainly not 1.5 inches thick though. if you could let me know exactly how to do that i would greatly appreciate it. thank you
swez on 03/21/2009 23:24:12
OK, that's Polyfill in there now and just as good as fiberglass for sound dampening. It does the same thing and you won't need to add more if it's about 1", (25mm) thick.
Good to go,
Swez
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