PP Slot Loaded Sub with Alpine SWR 12D2

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#161
lawbiding said:
It is similar to the 1260w with 50 more watt then the 1260w.
Xrk971
Can you tell me know which driver works better in a tapped horn at f3 38hz

Thanks.
Click to expand...

Off hand, I would say Qts of 0.4 and high mms is not ideal for tapped horn. The 55-2421 with low Qts is better and you can run a pair of them. There is a plan out there for that already. You want Qts below 0.33 is my guess. It may work but you will have a big peak at the knee and a saddle between to the first null.
 
#163
xrk971 said:
Off hand, I would say Qts of 0.4 and high mms is not ideal for tapped horn. The 55-2421 with low Qts is better and you can run a pair of them. There is a plan out there for that already. You want Qts below 0.33 is my guess. It may work but you will have a big peak at the knee and a saddle between to the first null.
Click to expand...

What design would you suggest for the gto1214d what give the best performance and output.
 
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#165
Hi Y'all,

First, for the JBL GTO-1214D see the Kraken thread by Petter Persson:

http://www.diyaudio.com/forums/subwoofers/160879-build-your-own-2x12-th-kraken-212-th.html

Also, there are a lot of different designs for this driver (or the very similar Infinity 1260W), e.g.:

http://www.diyaudio.com/forums/subw...ded-transmission-line-od-ml-tl-design-bj.html

These drivers (and the Lab12 too) work very well in TH/TQWT/MLTL/TL/Br you name it.

Second, I have found the time to go back and work on the MCM 55-2421 PPSL_SlotVented design by xrk971. I finally unpacked one of my drivers, and tried to get the dimensions close enough for a drawing. Also, this one is build around the horn shaped slot, using an angle of 30°. This design is very forgiving, you should try to get close, but you don't need to get this to the last .001"s. Again, make sure you can get to the screws by building some mockup of the front slot before you invest a lot of time into building the whole thing.

Regards,
 

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#167
Hi Brian,

Sorry, I haven't gotten to measure anything (aside from work) in a while. I hope to find the corner the brand-new WT3 is resting in, but I'm not making any promises. 🙂 Until then I'll go w/ Zaph's data. There also have been confirming measurements by littlemike and Patrick Bateman (if I remember correctly); Patrick's data confirms Zaph's.

Regards,
 
#168
Tb46
Can you give me the measurements for the green and red line in the attach picture so i cam do my layout more accurately.


Thanks

mcm layout.jpg
 
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#169
tb46 said:
Hi Brian,

Sorry, I haven't gotten to measure anything (aside from work) in a while. I hope to find the corner the brand-new WT3 is resting in, but I'm not making any promises. 🙂 Until then I'll go w/ Zaph's data. There also have been confirming measurements by littlemike and Patrick Bateman (if I remember correctly); Patrick's data confirms Zaph's.

Regards,
Click to expand...

Zaph measured these drivers? Do you have a link to his data? I checked the zaphaudio.com site, but couldn't find it.
 
#170
Brian Steele said:
Has anyone measured the t/s params of those MCM drivers to see if they're actually on spec?
Click to expand...
Yes, Zaph measured them and they are close. I ran sims with factory TS and Zaph and got about same result. The data I got was posted by Sreten, who said they were measured by Zaph but I don't have that link. Look in Tb46's earlier post to see the Sreten reference.
 
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#171
tb46 said:
Hi Y'all,

First, for the JBL GTO-1214D see the Kraken thread by Petter Persson:

http://www.diyaudio.com/forums/subwoofers/160879-build-your-own-2x12-th-kraken-212-th.html

Also, there are a lot of different designs for this driver (or the very similar Infinity 1260W), e.g.:

http://www.diyaudio.com/forums/subw...ded-transmission-line-od-ml-tl-design-bj.html

These drivers (and the Lab12 too) work very well in TH/TQWT/MLTL/TL/Br you name it.

Second, I have found the time to go back and work on the MCM 55-2421 PPSL_SlotVented design by xrk971. I finally unpacked one of my drivers, and tried to get the dimensions close enough for a drawing. Also, this one is build around the horn shaped slot, using an angle of 30°. This design is very forgiving, you should try to get close, but you don't need to get this to the last .001"s. Again, make sure you can get to the screws by building some mockup of the front slot before you invest a lot of time into building the whole thing.

Regards,
Click to expand...

Tb46,
Thanks for the neat design drawing that makes the shape less tall. I am a bit concerned that there is asymmetry in the chambers and that may negate any advantage you may have of a push-pull arrangement to reduce 2nd harmonic distortion. The taller chamber has a total length of about 38in, which will have a half-wave resonance frequency of 177Hz - still above the passband of a sub. However, it may be big enough to make the P-P cancellation not effective. When I get some time, I can model the tall chamber as a series of waveguides rather than a simple volume to see if there are any effects. Awesome drawing though.
Thanks,
X
 
#172
Hi X,

The volumes of the front and back chambers should be very close once the driver contributions are taken into consideration (at least I tried); same for the ducts. I also have some concerns about the relatively long back chamber, and it would be great if you could run this through AkAbak using waveguides. I think that the LP filter will kill the upper resonances, that and some judicious application of filling and felt.


Hi lawbiding,

I hope to find the time today to get you additional dimensions. Wait for X's simulation, he might find a slightly different length or cross-section for the ducts advantageous. It all looks good when I run it through my simulation, but I'm still learning. 🙂

Regards,
 
#176
Hi BP1Fanatic,

Basically, this is the wood build thread. Lawbiding used two Alpine SWR 12D2, but a similar basic design. For the MCM I folded the enclosure to arrive at a different form factor, and reshaped the plenum to make the mounting bolts more accessible. Still the same basic design though.

Regards,
 
#177
Ref.: Drawing Post #165

Hi lawbiding,

Here are the additional measurements you asked for. Please note, the top and bottom boards are not placed on the side boards like the inner boards - they overlap the side boards. Also note that the bottom outside board below the plenum is 1/2" (not 3/4"), it should be plenty strong, and basically fall off one of the other pieces w/ the 15/75 degree angle cut.

Regards,
 

Attachments

#178
tb46 said:
Hi lawbiding,

Here are the additional measurements you asked for. Please note, the top and bottom boards are not placed on the side boards like the inner boards - they overlap the side boards. Also note that the bottom outside board below the plenum is 1/2" (not 3/4"), it should be plenty strong, and basically fall off one of the other pieces w/ the 15/75 degree angle cut.

Regards,
Click to expand...

Tb46
Thanks for the drawing this will help me out alot. Also I think I am going to add a plate amp to this box.Would adding a plate amp change anything on the drawing.

@Xrk
How much watts can this design take at 8 ohms.

Thanks
 
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#180
xrk971 said:
This design uses two 8ohm drivers so you can't get 8ohms. Either 4ohms (parallel) or 16ohms (series). The design can handle 47volts at 4ohms - that is about 550watts. This is peak and matches peak rating of 240watts ea. Continuous operation will be 240 watts which is about 40 volts rms.
Click to expand...

Xrk971
I will be using the Mcm two 55-2421 driver which is rated 4 ohm and series them to 8 ohms
 
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