my setup
X, I will take your advice and get the alpine swr 12's. I don't think the lab12 is going to be loud enough.
My setup
200amp alternator
two extra battery
1/0 Gauge wire
500 Amp Relay Isolator
nvx 1200.1 or audiopipe 1500d for bass
Audiopipe APK-250.2 for voice
Behringer ULTRA-DRIVE PRO DCX2496 Crossover.
X, I will take your advice and get the alpine swr 12's. I don't think the lab12 is going to be loud enough.
My setup
200amp alternator
two extra battery
1/0 Gauge wire
500 Amp Relay Isolator
nvx 1200.1 or audiopipe 1500d for bass
Audiopipe APK-250.2 for voice
Behringer ULTRA-DRIVE PRO DCX2496 Crossover.
123dB in 4pi is not loud enough? The PPSL V channel sub with the dual Alpine's is proven and tested so not a bad choice.
LOl. i love my bass loud. The 2 lab12 wired parallel =4 ohms. The amp i am going to use put out 500 watts at 4 ohms. The alpines can wired down to 1 ohm and put out more.My amp put out 1384 watts at 1ohms
Since you indicated that you have some Lab 12's you can use, I think this design may work. It is based on my XKi dual driver sub design shown here:
http://www.diyaudio.com/forums/full-range/268524-xki-xs-ab-initio-karlson-6th-order-bandpass-26.html#post4226956
But modified to be much bigger and to use plywood instead of foam core. The basic design is to make the back chamber about 90 liters, the front chamber about 45 liters, connect the front and back chambers with two wrap around channel vents 12.5in tall x 1.25in wide x 23in long. The drivers are mounted in the V panel which divides the box into front and rear chambers. Wire the 8ohm drivers in parallel for a 4ohm load. The front aperture a diamond shape with curved edges as shown for a Karlson aperture. Xmax of 13mm is reached at 45 volts of drive, and corresponding max SPL is 123dB in 4pi space or 126dB in 2pi (half space) with f3 of 35Hz. Sims below use a 4th order Butterworth high pass filter at 24Hz and a 8th order Butterworth low pass filter at 110Hz.
Here is predicted max SPL:
Here is predicted cone displacement at max SPL:
Here is electrical impedance:
Here is electrical power input at xmax:
The one prototype that I built with 5.5in Tang Band sub drivers is very smooth with deep clean bass. The front chamber provides great cone control for the high power to extract SPL. You will need about 800 watts rms amp to hit the max SPL. Peak power should be substantially more.
The sketch of the design, which I believe just fits exactly into your space, is attached as pdf. I would use 3/4in plywood on exterior panels and driver mount baffle and 1/2in ply for internal channels dividers and braces.
Xrk, I did some reading on your X's ab initio Karlson 6th Order Bandpass and I like it a lot. Since I will be using the alpine swr drivers, how well do they sim in your X's ab initio Karlson 6th Order Bandpass sub and compare to the PP Slot Loaded that you recommend. Which have more cone control, SQ,SPL and bass extension. Your X's ab initio Karlson 6th Order Bandpass aslo look easier to construct and i like the diamond shape font.
Let me run the XKi sims with the Alpines and get back to you. They should work quite well. The diamond or Karlson aperture does more than look cool, it makes the response smoother and is Kool.
XKi with dual Alpine SWR12D2's
The Alpine is a sweet driver for the XKi, it achieves extreme cone control and your max SPL will be thermally limited and port compression limited, not xmax limited. Here is a sim for two drivers (each wired in series and the pair in parallel for 2 ohm nominal load overall). The design is slightly modified with a smaller volume of 120 liters for the total volume or 90 liters for rear chamber and 30 liters for front. The vent is now 12.5in high x 1.5in wide x 29in long. The K-aperture on the exit remains the same. You may need to add a hairpin fold to fit a 29in long vent on either side.
Here is max SPL, assuming you have enough juice to drive 83 volts into the speaker 🙂. The speaker achieves 127dB SPL in 4pi space and the -3dB point is at 31.4Hz - digs very deep. That is 130dB in 2pi space!
Here is the predicted maximum cone displacement at 83 volts with a -24dB/oct Butterworth high pass filter @26.5Hz and a -48dB/oct LPF @110Hz:
Here is the predicted impedance curve showing the nominal 2ohm load and max impedance of about 25ohms:
Here is the predicted electrical power required at 83 volts drive (almost 3kW!). The SWR12D2 can handle 3kW peak loads so this is OK from a peak standpoint not sustained RMS. For sustained RMS, the rating is 1kW ea or 2kW total:
If you want to operate this at a thermally sustainable RMS of 2kW, then the max drive voltage will be 70 volts RMS (with 17mm cone excursion), and the resulting max SPL in 4pi will be 125dB, and 128dB in 2pi space - not bad at all:
The design has a negative going leading pulse if you look the impulse function, this means you should flip the polarity on the drive (or phase 180 deg flip) in order to get the proper kick on the leading edge:
Also note that the design has an inherent time delay, similar to a horn etc of about 14ms so you will need to use the DEQX to add delay to your tops for time alignment with this sub. Here is the Group Delay as a function of frequency:
I think that this design really surprised me with how loud and deep it can go for a 4+ cubic foot box (there will be another 0.75 cu ft for the vent volume). I hope you make it because it is nuts and must be experienced to be believed. 😀
Please build it! 🙂 I will leave it up to you to figure out the details of the box dimension and drawing for construction, but I am pretty sure it fits in your space. If you ask Tb46 nicely, he may even draw it for you 🙂
The Alpine is a sweet driver for the XKi, it achieves extreme cone control and your max SPL will be thermally limited and port compression limited, not xmax limited. Here is a sim for two drivers (each wired in series and the pair in parallel for 2 ohm nominal load overall). The design is slightly modified with a smaller volume of 120 liters for the total volume or 90 liters for rear chamber and 30 liters for front. The vent is now 12.5in high x 1.5in wide x 29in long. The K-aperture on the exit remains the same. You may need to add a hairpin fold to fit a 29in long vent on either side.
Here is max SPL, assuming you have enough juice to drive 83 volts into the speaker 🙂. The speaker achieves 127dB SPL in 4pi space and the -3dB point is at 31.4Hz - digs very deep. That is 130dB in 2pi space!
Here is the predicted maximum cone displacement at 83 volts with a -24dB/oct Butterworth high pass filter @26.5Hz and a -48dB/oct LPF @110Hz:
Here is the predicted impedance curve showing the nominal 2ohm load and max impedance of about 25ohms:
Here is the predicted electrical power required at 83 volts drive (almost 3kW!). The SWR12D2 can handle 3kW peak loads so this is OK from a peak standpoint not sustained RMS. For sustained RMS, the rating is 1kW ea or 2kW total:
If you want to operate this at a thermally sustainable RMS of 2kW, then the max drive voltage will be 70 volts RMS (with 17mm cone excursion), and the resulting max SPL in 4pi will be 125dB, and 128dB in 2pi space - not bad at all:
The design has a negative going leading pulse if you look the impulse function, this means you should flip the polarity on the drive (or phase 180 deg flip) in order to get the proper kick on the leading edge:
Also note that the design has an inherent time delay, similar to a horn etc of about 14ms so you will need to use the DEQX to add delay to your tops for time alignment with this sub. Here is the Group Delay as a function of frequency:
I think that this design really surprised me with how loud and deep it can go for a 4+ cubic foot box (there will be another 0.75 cu ft for the vent volume). I hope you make it because it is nuts and must be experienced to be believed. 😀
Please build it! 🙂 I will leave it up to you to figure out the details of the box dimension and drawing for construction, but I am pretty sure it fits in your space. If you ask Tb46 nicely, he may even draw it for you 🙂
Attachments
Last edited:
Design your vent ports to blow air across the magnet rear basket area - that will help cool it some. If you put both magnets facing out on front chamber, you will get better cooling because the vents as designed will blow air across the baskets. You will not get the benefit of reduction of 2nd order harmonic distortion as much but that is minor compared to the gains you will get with better cooling. Port compression can be reduced by making vents bigger. Either make box taller than 14in or make vents wider than 1.5in. This will make vents longer and increase box volume. In the size you have for the box, not much you can do be happy with what you can achieve with this current design and just take wheat you can get with port compression. It will probably mean a -3dB in max SPL but then if you are at 2pi space so you buy some back.
Last edited:
My calcs show 162 liters for that trunk size.
15x15.5x42.5=9881 cu inches.
16.38 cc per cubic inch
1000 cc per liter
15x15.5x42.5=9881 cu inches.
16.38 cc per cubic inch
1000 cc per liter
Last edited:
To answer that you will have to draw out a rough sketch that accounts for wood thickness to calculate the volume you have left over for a vent. You know your total external volume, and you know the internal volume required, not including the vent volume and material volume. Once you know your vent volume, figure out what the new cross sectional area is. Currently it is 12.5in tall x 1.5in wide x 29in long. Don't forget to add material thickness for the vent. It takes due dilligence, and is easier if you have a CAD drawing.
If you get your vent to be 2in wide x 13.5in tall that will help but length will grow to maybe 36in long - that is a lot of volume for the vent.
Hi xrk971 and Beat Street,
Beat Street pm'ed me w/ the following information looking for a sketch of the enclosure he is planning for his car:
"BeatStreet enclosure details:
2015, June 03
- dual Alpine SWR12D2
- like picture in Post #26
- details in Post #28, but: size 15x40x15 vent 1.75x13x33.5"long"
I sketched out a rough first TRY. There just is not enough volume here to do this, maybe X can figure out some other way to do this? But, it looks like Beat Street needs a larger box. Or, just go w/ dual sealed.
Regards,
P.S.: Please, check the math! 🙂
Beat Street pm'ed me w/ the following information looking for a sketch of the enclosure he is planning for his car:
"BeatStreet enclosure details:
2015, June 03
- dual Alpine SWR12D2
- like picture in Post #26
- details in Post #28, but: size 15x40x15 vent 1.75x13x33.5"long"
I sketched out a rough first TRY. There just is not enough volume here to do this, maybe X can figure out some other way to do this? But, it looks like Beat Street needs a larger box. Or, just go w/ dual sealed.
Regards,
P.S.: Please, check the math! 🙂
😱
Tb46 would 15x40x15 be enough volume for the original size vent size 12.5in high x 1.5in wide x 29in long.If not you can draw it 15x42-44x15.
Last edited:
Tb46,
Thanks for doing that. The XKi has wraparound vents on the ends of the box. The front chamber volume is half of rear chamber volume, total volume was 125 liters IIRC. It's a tight fit and given how big that rear magnet is, we may have to go with the chamber ratios as you have drawn. I can rerun sim but this will decrease cone control. We keep running into envelope problem of too small. Even with BR - the volume is the volume of you are optimizing for extension and power.
Maybe dual 10 in SWR's are in order for this small trunk space?
Thanks for doing that. The XKi has wraparound vents on the ends of the box. The front chamber volume is half of rear chamber volume, total volume was 125 liters IIRC. It's a tight fit and given how big that rear magnet is, we may have to go with the chamber ratios as you have drawn. I can rerun sim but this will decrease cone control. We keep running into envelope problem of too small. Even with BR - the volume is the volume of you are optimizing for extension and power.
Maybe dual 10 in SWR's are in order for this small trunk space?
- Status
- Not open for further replies.