Most magazines are there for the advertizing revenue. (But what about my subscription price? That pays for the paper it's printed on and the postage to get it to you. The magazine's profit comes from its advertizing content.) Where does that revenue come from? From the companies whose products are being reviewed. This quickly leads to a situation where the reviews are, shall we say, tainted. The manufacturer says,"You gave my last product a bad review. I'm pulling my ads from your magazine."
Blackmail?
No.
Business.
It's a cold, cruel world out there, and magazine reviews sell product for manufacturers. It's basically another form of advertizing. About all most magazines are good for are to let you know that the XYZ company has a new widget out, it looks like this, and sells for a fistful of dollars.
Read the last half dozen issues of whatever magazines you're getting. If the majority of the reviews end in a catch phrase like,"If you're in the market for a new subwoofer, you're cheating yourself if you don't check out the new ABC subwoofer," or, "Another strong effort from the talented engineers at XYZ company. You can't go wrong with this one," cancel your subscription.
Grey
Blackmail?
No.
Business.
It's a cold, cruel world out there, and magazine reviews sell product for manufacturers. It's basically another form of advertizing. About all most magazines are good for are to let you know that the XYZ company has a new widget out, it looks like this, and sells for a fistful of dollars.
Read the last half dozen issues of whatever magazines you're getting. If the majority of the reviews end in a catch phrase like,"If you're in the market for a new subwoofer, you're cheating yourself if you don't check out the new ABC subwoofer," or, "Another strong effort from the talented engineers at XYZ company. You can't go wrong with this one," cancel your subscription.
Grey
Gum:
Judging by advertising, I guess one could get the idea there are different standards for home theater and music. Why they do that, I don't know.
Here is REL, a well-known subwoofer manufacturer whose subwoofers run into the thousands of dollars. It's better line of subwoofers-they also have "compact" units-sports both sealed and ported models, with the ported being top-of-the-line model.
http://www.rel.net/products/stseries.shtml
Judging by advertising, I guess one could get the idea there are different standards for home theater and music. Why they do that, I don't know.
Here is REL, a well-known subwoofer manufacturer whose subwoofers run into the thousands of dollars. It's better line of subwoofers-they also have "compact" units-sports both sealed and ported models, with the ported being top-of-the-line model.
http://www.rel.net/products/stseries.shtml
Gum:
Now that the notion of ported=home-theater-only has been exploded, I recommend that you run those plots of the Blueprint 1503 in the 120 liter sealed box, and the Blueprint 1503 in the 120 liter ported box, tuned to 16 Hz-or higher, if you wish. Remember to take 15 liters off the ported to compensate for the 5" diameter vent. If you run Boxplot, make Alpha = 1, because Boxplot assumes a 10% reduction plus you are compensating for the port.
The response in the lower bass region jumps 6 dB. Just to give you an idea what that means, you must supply 4 times the power to raise the SPL 6 db.
If we have two Blueprint 1503's, one in a sealed 120 liter box, one in a ported 120 liter box tuned to 16 Hz:
At 16 Hz, 1,000 Watts through the ported box will yield the same SPL as 4,000 Watts thruough the sealed-assuming the excursion does not limit the output of the sealed by itself;
250 Watts through the ported box will yield the same SPL as 1,000 Watts through the sealed, at 16 Hz.
Other low basss frequencies have differentials almost as great.
My point is not that you absolutely must build the ported box. I only wish to make it clear that your decison to NOT port your box is a major one. The quality of the bass coming from the sealed enclosure had better be A LOT better to justify this loss of SPL. That is why I suggested you build the ported box with the plug, so that you may judge for yourself.
The decision is entirely yours. Good luck with your project, either way. 🙂
Now that the notion of ported=home-theater-only has been exploded, I recommend that you run those plots of the Blueprint 1503 in the 120 liter sealed box, and the Blueprint 1503 in the 120 liter ported box, tuned to 16 Hz-or higher, if you wish. Remember to take 15 liters off the ported to compensate for the 5" diameter vent. If you run Boxplot, make Alpha = 1, because Boxplot assumes a 10% reduction plus you are compensating for the port.
The response in the lower bass region jumps 6 dB. Just to give you an idea what that means, you must supply 4 times the power to raise the SPL 6 db.
If we have two Blueprint 1503's, one in a sealed 120 liter box, one in a ported 120 liter box tuned to 16 Hz:
At 16 Hz, 1,000 Watts through the ported box will yield the same SPL as 4,000 Watts thruough the sealed-assuming the excursion does not limit the output of the sealed by itself;
250 Watts through the ported box will yield the same SPL as 1,000 Watts through the sealed, at 16 Hz.
Other low basss frequencies have differentials almost as great.
My point is not that you absolutely must build the ported box. I only wish to make it clear that your decison to NOT port your box is a major one. The quality of the bass coming from the sealed enclosure had better be A LOT better to justify this loss of SPL. That is why I suggested you build the ported box with the plug, so that you may judge for yourself.
The decision is entirely yours. Good luck with your project, either way. 🙂
kelticwizard
Nice post........
I'll offer one suggestion regarding port tuning for the BPD1503, use 18Hz not 16Hz. The 1503 is much happier doing that given it's relatively high Fs. It results in a smoother overall response curve. Less of a 'saddle' between the port output and the driver's natural oll-off.
And yep your right, the power requirement differences between ported and sealed boxes especially for the high excursion drivers is considerable. For the 1503 it works out to be around 10 dB more output at 20Hz in favor of the ported design.
I didn't save the sim for the 1503, but here's one for the 1203.
Nice post........
I'll offer one suggestion regarding port tuning for the BPD1503, use 18Hz not 16Hz. The 1503 is much happier doing that given it's relatively high Fs. It results in a smoother overall response curve. Less of a 'saddle' between the port output and the driver's natural oll-off.
And yep your right, the power requirement differences between ported and sealed boxes especially for the high excursion drivers is considerable. For the 1503 it works out to be around 10 dB more output at 20Hz in favor of the ported design.
I didn't save the sim for the 1503, but here's one for the 1203.
An externally hosted image should be here but it was not working when we last tested it.
Thomas W:
All the time I was writing the post, I had your Aerial Stryke Sub project in the back of my mind. You had written that 18 Hz was as low as you would recommend. You have also written that, as you have bought and used both TC Sounds HE-15 drivers and Blueprint 1503's, you consider them virtually identical.
As the Aerial Stryke Sub is about 6 cubic feet internal volume or so, and you recommended no lower than 18 Hz for that project, I kind of figured I was "pushing it" to speak of 16 Hz tuning for a 4.2 cubic foot subwoofer.
Since PKGum has given numbers down to 15 Hz for the sealed sub, I figured I would use the 16 Hz tuning as a comparison. But I also figured that if he shows any interest in using the ported method, it should be mentioned that a slighly higher tuning is an even better way to go.
I am taking the liberty of giving the link to your Aerial Stryke project, even though you already gave it in another thread by PKGum. He might decide to go a little larger than the 4.2 cubic feet he has been mentioning.
http://home.att.net/~tom1/page7.html
All the time I was writing the post, I had your Aerial Stryke Sub project in the back of my mind. You had written that 18 Hz was as low as you would recommend. You have also written that, as you have bought and used both TC Sounds HE-15 drivers and Blueprint 1503's, you consider them virtually identical.
As the Aerial Stryke Sub is about 6 cubic feet internal volume or so, and you recommended no lower than 18 Hz for that project, I kind of figured I was "pushing it" to speak of 16 Hz tuning for a 4.2 cubic foot subwoofer.
Since PKGum has given numbers down to 15 Hz for the sealed sub, I figured I would use the 16 Hz tuning as a comparison. But I also figured that if he shows any interest in using the ported method, it should be mentioned that a slighly higher tuning is an even better way to go.
I am taking the liberty of giving the link to your Aerial Stryke project, even though you already gave it in another thread by PKGum. He might decide to go a little larger than the 4.2 cubic feet he has been mentioning.
http://home.att.net/~tom1/page7.html
I do have an flexible option....Make a ported box with a 'plug'. One moment its a sealed box and another moment its a ported box
But..I don't want to make a 120L Ported box...port length is too long and I want a slimmer tall enclosure...I want to make a 200L one. Therefore if you put the plug in it will become a 200L sealed box with a QTC of 0.385. Is there any problems with such a low QTC?
The book says that QTC outside the range of 0.5 - 1.5 is not recommended.
But..I don't want to make a 120L Ported box...port length is too long and I want a slimmer tall enclosure...I want to make a 200L one. Therefore if you put the plug in it will become a 200L sealed box with a QTC of 0.385. Is there any problems with such a low QTC?
The book says that QTC outside the range of 0.5 - 1.5 is not recommended.
Gum:
If you increase the size of the 1503's sealed enclosure to 200 liters-7 cubic feet-you get bass output virtually the same as the 120 liter sealed box.
Run the plot with 120 liter sealed box. Run the plot with the 200 liter sealed box. If you use Boxplot, reduce the size to 180 liters, making Alpha=.5. The curves of the sealed box of 120 liters and the sealed box of 200 liters are virtually identical. From a sealed box standpoint, you will be adding 66 percent more volume to produce no more output.
A woofer with a lower Q will fit into a smaller sealed box, and a much larger ported box. When the Qtc of the sealed box is around .5 or so, that is where they meet. Only in that range can you have a "convertible enclosure".
You can increase the enclosure size to 400 liters and not change the response much.
When a sealed box enclosure becomes much larger than the Vas of the speaker in it, it gets called an Infinite Baffle. The baffle is the board the speaker is mounted on. A true Infinite Baffle is a huge board which function is to prevent the back wave from curling around and cancelling the front wave. The frequency response charts of the unenclosed speakers that you see are from true Infinite Baffles. At least, some speaker manufacturers use them-others use a nearfield microphone.
If you put a speaker in a box with a volume that is much larger than the Vas, the box will affect the Q and the resonance frequency so little, it resembles the situation with an infinitely large board. Hence, the title Infinite Baffle.
Some people erroneously use the expression Infinite Baffle to mean any sealed box, but strictly speaking, that is not true. A sealed box with a volume much less than Vas is called an Acoustic Suspension enclosure.
Anyway, if you want to make a "convertible enclosure", I suggest you stick with the 120 liter size.
If you increase the size of the 1503's sealed enclosure to 200 liters-7 cubic feet-you get bass output virtually the same as the 120 liter sealed box.
Run the plot with 120 liter sealed box. Run the plot with the 200 liter sealed box. If you use Boxplot, reduce the size to 180 liters, making Alpha=.5. The curves of the sealed box of 120 liters and the sealed box of 200 liters are virtually identical. From a sealed box standpoint, you will be adding 66 percent more volume to produce no more output.
A woofer with a lower Q will fit into a smaller sealed box, and a much larger ported box. When the Qtc of the sealed box is around .5 or so, that is where they meet. Only in that range can you have a "convertible enclosure".
You can increase the enclosure size to 400 liters and not change the response much.
When a sealed box enclosure becomes much larger than the Vas of the speaker in it, it gets called an Infinite Baffle. The baffle is the board the speaker is mounted on. A true Infinite Baffle is a huge board which function is to prevent the back wave from curling around and cancelling the front wave. The frequency response charts of the unenclosed speakers that you see are from true Infinite Baffles. At least, some speaker manufacturers use them-others use a nearfield microphone.
If you put a speaker in a box with a volume that is much larger than the Vas, the box will affect the Q and the resonance frequency so little, it resembles the situation with an infinitely large board. Hence, the title Infinite Baffle.
Some people erroneously use the expression Infinite Baffle to mean any sealed box, but strictly speaking, that is not true. A sealed box with a volume much less than Vas is called an Acoustic Suspension enclosure.
Anyway, if you want to make a "convertible enclosure", I suggest you stick with the 120 liter size.
Gum:
I would just like to add that the internal volume of Thomas W's Aerial Stryke project-I gave you the link before-is 204 liters before you deduct for bracing, port, speaker size, etc. If you want to adjust the dimensions to make your box tall and skinny, go ahead. Otherwise I would follow what he has written there.
Since your box will be tall and slender, use an elbow to fit the port into the box. Speaker designers do it all the time.
If the port is too small, there will be chuffing sounds as the speaker hits the low bass notes. Making the port larger eliminates this, as does flaring the port. Thomas W has clearly gone to great lengths to make sure these chuffing sounds do not happen. If box construction is a problem, you can probably eliminate the flares and not get burned too bad. You can even probably use a 5 inch port, (most 15 inchers use a 4 inch), but why mess further with a successful design?
I would just like to add that the internal volume of Thomas W's Aerial Stryke project-I gave you the link before-is 204 liters before you deduct for bracing, port, speaker size, etc. If you want to adjust the dimensions to make your box tall and skinny, go ahead. Otherwise I would follow what he has written there.
Since your box will be tall and slender, use an elbow to fit the port into the box. Speaker designers do it all the time.
If the port is too small, there will be chuffing sounds as the speaker hits the low bass notes. Making the port larger eliminates this, as does flaring the port. Thomas W has clearly gone to great lengths to make sure these chuffing sounds do not happen. If box construction is a problem, you can probably eliminate the flares and not get burned too bad. You can even probably use a 5 inch port, (most 15 inchers use a 4 inch), but why mess further with a successful design?
Kelticwizard
I cannot make a 120L convertible (ported and sealed) box because the port length will be too long to be practical.
The Height should be nearly two times the width and the depth can be longer than the width if possible. The woofer should be forward firing. A 200L ported box is practical. (Practically a nearly identical clone of Thomas W's Aerial Stryke Sub)
Therefore I need to make a convertible box with a volume of around 180 - 200L to keep the port's length practical. But according to your last posts this should not be done.
QUOTE:
"A woofer with a lower Q will fit into a smaller sealed box, and a much larger ported box. When the Qtc of the sealed box is around .5 or so, that is where they meet. Only in that range can you have a "convertible enclosure"
Does this mean that I cannot make a convertible box?
The only other option is to stick to a ported box...but I seem to wander towards the Linkwitz Transform Equalised sealed box with better sound quality but with great loss of SPL.
NOTE:
After emailing Pat of BluePrintDrivers he informed that some of the specs on the DUMAX report was wrong because the RE wasn't measured properly. The specs on his website are correct.
The SPL 1W 1Meter is indeed 91Db. To make matters worse, the 120L sealed box does not have a Q of 0.5...according to the different parameters in the BP website a 0.5 Q box for the driver should be at around 74L.
I cannot make a 120L convertible (ported and sealed) box because the port length will be too long to be practical.
The Height should be nearly two times the width and the depth can be longer than the width if possible. The woofer should be forward firing. A 200L ported box is practical. (Practically a nearly identical clone of Thomas W's Aerial Stryke Sub)
Therefore I need to make a convertible box with a volume of around 180 - 200L to keep the port's length practical. But according to your last posts this should not be done.
QUOTE:
"A woofer with a lower Q will fit into a smaller sealed box, and a much larger ported box. When the Qtc of the sealed box is around .5 or so, that is where they meet. Only in that range can you have a "convertible enclosure"
Does this mean that I cannot make a convertible box?
The only other option is to stick to a ported box...but I seem to wander towards the Linkwitz Transform Equalised sealed box with better sound quality but with great loss of SPL.
NOTE:
After emailing Pat of BluePrintDrivers he informed that some of the specs on the DUMAX report was wrong because the RE wasn't measured properly. The specs on his website are correct.
The SPL 1W 1Meter is indeed 91Db. To make matters worse, the 120L sealed box does not have a Q of 0.5...according to the different parameters in the BP website a 0.5 Q box for the driver should be at around 74L.
Gum:
I will deal with the question of what Blueprint told you when I get a better chance to absorb it. It's halftime in the Jets game.
As for the question of the port not being suitable in the 120 liter box, I do not quite understand the question. Take 2 lengths of 5 inch diameter plastic pipe, (interior measurement), and join them with a 5" elbow. This will allow it to fit into the box. The elbow is a piece that allows two pipes to join together at a 90 degree angle. Plumbers use them all the time.
The total length of the port should be 45 inches to tune a 120 liter box to 16 Hz. It should be 35 inches to tune the box to 18 Hz.
Am I understanding you correctly? Is fitting the port into the box the problem here?
Also, I have been REDUCING the internal volume of the 120 liter ported box by 15 liters to make up for the space occupied by the port. The numbers I have been using have taken the volume of the port into consideration, if that is what your objection is.
I will deal with the question of what Blueprint told you when I get a better chance to absorb it. It's halftime in the Jets game.
As for the question of the port not being suitable in the 120 liter box, I do not quite understand the question. Take 2 lengths of 5 inch diameter plastic pipe, (interior measurement), and join them with a 5" elbow. This will allow it to fit into the box. The elbow is a piece that allows two pipes to join together at a 90 degree angle. Plumbers use them all the time.
The total length of the port should be 45 inches to tune a 120 liter box to 16 Hz. It should be 35 inches to tune the box to 18 Hz.
Am I understanding you correctly? Is fitting the port into the box the problem here?
Also, I have been REDUCING the internal volume of the 120 liter ported box by 15 liters to make up for the space occupied by the port. The numbers I have been using have taken the volume of the port into consideration, if that is what your objection is.
You are understanding me correctly, except that I didn't understand you correctly..I had misinterpreted what you meant by the elbow, now that I understand...
However it is a 74L box we're dealing with and its impossible to make a convertible box out of that, guess its time to stick to the ported box
However it is a 74L box we're dealing with and its impossible to make a convertible box out of that, guess its time to stick to the ported box
Gum:
Well, I hate to contradict myself, but I ran the plots for 120 liters with both blueprints's numbers and Dumax's numbers, and the 120 liter sealed with both sets of numbers is largely unchanged.
The numbers drop off 4 dB re at 16 Hz and 20 Hz from the midpoint-but the midpoint is 4 dB higher with the new numbers.
I don't want to confuse you, but if you study speakers, you will find that double the volume=6 dB of output=one half octave.
Blueprint's numbers give a Vas that is 43 percent higher than Dumax's numbers. That shoud result in a sensitivity @1Meter/1Watt that is 3 dB higher. Plus the higher free air resonance should boost the sensitivity another .1 dB higher.
Essentially, Blueprint numbers are prety much equivalent to the Dumax numbers, give or take half a decibel, when you take the 91 dB (Blueprint number) versus the 87.6 dB (Dumax number) differential. That is why the SPL's at 1,000 Hz of the two sets of numbers work out equivalently.
If this above confuses you, ignore it. The important things to remember are is that the new numbers don't change anything, they are equivalent. If you want to build a 120 liter "convertible subwoofer", you can. If you want to build a 200 liter "convertible subwoofer", you can, but the performance in the sealed
mode won't be much better than the 120 liter sealed box. The performance of the ported mode will improve over the 120 liter ported box.
And oh yes, the new numbers do NOT change anything if you want to build a tall skinny version of the Aerial Stryke project. If you don't have the woodworking tools to make Thomas W's fancy port supports but want to use flares on the port anyway-which flares prevent you from attaching the port to an inner wall-rig up something using muffler clamps. Just a suggestion.
Well, I hate to contradict myself, but I ran the plots for 120 liters with both blueprints's numbers and Dumax's numbers, and the 120 liter sealed with both sets of numbers is largely unchanged.
The numbers drop off 4 dB re at 16 Hz and 20 Hz from the midpoint-but the midpoint is 4 dB higher with the new numbers.
I don't want to confuse you, but if you study speakers, you will find that double the volume=6 dB of output=one half octave.
Blueprint's numbers give a Vas that is 43 percent higher than Dumax's numbers. That shoud result in a sensitivity @1Meter/1Watt that is 3 dB higher. Plus the higher free air resonance should boost the sensitivity another .1 dB higher.
Essentially, Blueprint numbers are prety much equivalent to the Dumax numbers, give or take half a decibel, when you take the 91 dB (Blueprint number) versus the 87.6 dB (Dumax number) differential. That is why the SPL's at 1,000 Hz of the two sets of numbers work out equivalently.
If this above confuses you, ignore it. The important things to remember are is that the new numbers don't change anything, they are equivalent. If you want to build a 120 liter "convertible subwoofer", you can. If you want to build a 200 liter "convertible subwoofer", you can, but the performance in the sealed
mode won't be much better than the 120 liter sealed box. The performance of the ported mode will improve over the 120 liter ported box.
And oh yes, the new numbers do NOT change anything if you want to build a tall skinny version of the Aerial Stryke project. If you don't have the woodworking tools to make Thomas W's fancy port supports but want to use flares on the port anyway-which flares prevent you from attaching the port to an inner wall-rig up something using muffler clamps. Just a suggestion.
both 120L and 200L sealed enclosures for the driver are outside the range of 0.5 + and you said I should construct them if I want to.
However, both you and my Loudspeaker book state that sealed enclosures outside the range of 0.5 - 1.5 are not recommended.
Heres a quote:
"A woofer with a lower Q will fit into a smaller sealed box, and a much larger ported box. When the Qtc of the sealed box is around .5 or so, that is where they meet. Only in that range can you have a "convertible enclosure"
Can I build an enclosure with a Q below 0.5 without problems or will there be obstacles facing me?
"If you increase the size of the 1503's sealed enclosure to 200 liters-7 cubic feet-you get bass output virtually the same as the 120 liter sealed box. "
Don't need to explain this over again...I know!. I was forced to have a 200L box because I couldn't fit the port in until you suggested the elbow thingy. I MUCH prefer the 120L box over the 200L one because of less cabinet resonances
However, both you and my Loudspeaker book state that sealed enclosures outside the range of 0.5 - 1.5 are not recommended.
Heres a quote:
"A woofer with a lower Q will fit into a smaller sealed box, and a much larger ported box. When the Qtc of the sealed box is around .5 or so, that is where they meet. Only in that range can you have a "convertible enclosure"
Can I build an enclosure with a Q below 0.5 without problems or will there be obstacles facing me?
"If you increase the size of the 1503's sealed enclosure to 200 liters-7 cubic feet-you get bass output virtually the same as the 120 liter sealed box. "
Don't need to explain this over again...I know!. I was forced to have a 200L box because I couldn't fit the port in until you suggested the elbow thingy. I MUCH prefer the 120L box over the 200L one because of less cabinet resonances
keep it nice and simple
Dump the convertible box idea..I'm not messing around with it...I'm just going to build a decent 200L ported box with a 5" port tuned to 18Hz powered by cheap bridged 700 - 900W used QSC amp. Since the motor structure of the driver is superior, the so called 'transient response' in a ported enclosure should be OK. Simply a simpler clone of Thomas W's project with less elaborate bracing (Just one or two vertical shelf braces)...I don't have or have little woodworking skills. Maybe the port is flared...but I can't find 5" flares anyway.
Dump the convertible box idea..I'm not messing around with it...I'm just going to build a decent 200L ported box with a 5" port tuned to 18Hz powered by cheap bridged 700 - 900W used QSC amp. Since the motor structure of the driver is superior, the so called 'transient response' in a ported enclosure should be OK. Simply a simpler clone of Thomas W's project with less elaborate bracing (Just one or two vertical shelf braces)...I don't have or have little woodworking skills. Maybe the port is flared...but I can't find 5" flares anyway.
You must use adequate bracing otherwise the walls of the cabinet will be flexing and interferring with the sound made by the driver. Even the bracing in the AS-15 isn't quite enough. There is some wall flex from the 2 large sides. They should have been 3 layers of 3/4" material not just two.
5" flares don't exist. If you want to avoid 'chuffing' with a high excursion driver you need to use either use a 6" flared port or go to a 8" straight one.
If you aren't going to take the time and labor to make the box in a proper manner don't bother building it. There's no point in taking a world class driver and putting it in a under built flexible flyer enclosure.
If you want an easy way out make a tube sub. The BPD 1503 will work fine in one of those. That will save a lot of work and still sound fine.
5" flares don't exist. If you want to avoid 'chuffing' with a high excursion driver you need to use either use a 6" flared port or go to a 8" straight one.
If you aren't going to take the time and labor to make the box in a proper manner don't bother building it. There's no point in taking a world class driver and putting it in a under built flexible flyer enclosure.
If you want an easy way out make a tube sub. The BPD 1503 will work fine in one of those. That will save a lot of work and still sound fine.
What??!!! I already though the bracing for your sub was overkill and it still flexes!!. The only other subs I've seen with more bracing than yours is the matrix braced subs (speakers) such as the B&W 501..etc...
Alright..I add more braces but they have to be simple since as I had stated before..I have little woodworking skills..maybe I get a hardware store to cut the MDF for me
Any other things I need to include besides an amp and paramteric EQ?
Alright..I add more braces but they have to be simple since as I had stated before..I have little woodworking skills..maybe I get a hardware store to cut the MDF for me
Any other things I need to include besides an amp and paramteric EQ?
Bracing suggestions
As Thomas has stated, bracing is absolutely crucial, especially when being subjected to high pressure levels from subwoofers.
One thing to remember when bracing is that circles are stronger than squares. Take a look at the internal bracing on the AS-15: circular supports. Then theres the matrix bracing: circular cutouts within the supports. Even when creating a simple window-pane brace, cutting 4 internal circles instead of 4 internal squares is going to offer a lot more rigidity and support.
Believe me, I'm no woodworker myself, but making circular and odd shapes can be a snap. The slightly more difficult way would be to use a router. But the common way to make these cutouts today is with a magical handheld tool called the <I>RotoZip</I>. You can cut just about any shape imaginable, as long as you can follow the pattern you traced out. Its also a life saver when you need to make cutouts for tweeters. For $80 US, its one of the best investments you can make...
As Thomas has stated, bracing is absolutely crucial, especially when being subjected to high pressure levels from subwoofers.
One thing to remember when bracing is that circles are stronger than squares. Take a look at the internal bracing on the AS-15: circular supports. Then theres the matrix bracing: circular cutouts within the supports. Even when creating a simple window-pane brace, cutting 4 internal circles instead of 4 internal squares is going to offer a lot more rigidity and support.
Believe me, I'm no woodworker myself, but making circular and odd shapes can be a snap. The slightly more difficult way would be to use a router. But the common way to make these cutouts today is with a magical handheld tool called the <I>RotoZip</I>. You can cut just about any shape imaginable, as long as you can follow the pattern you traced out. Its also a life saver when you need to make cutouts for tweeters. For $80 US, its one of the best investments you can make...
The AS-15 cabinet isn't overkill. It's designed for optimium performance. The only place where there are any palpable vibrations are the 2 larger side panels, and this is only when the driver output is quite high. As a result I wouldn't recommend making a cabinet with any less stiffening or decresase in wall thickness. All the flat exterior surfaces are 1-1/2" MDF except the front baffle, it's 3 layers of 3/4" MDF
I don't recommend using a RotoZip tool for MDF. They just don't have enough torque and will burn up. Using a router and the Jasper router jug is the easiest way to do the braces. But a saber saw and a steady hand will work well too.
I don't recommend using a RotoZip tool for MDF. They just don't have enough torque and will burn up. Using a router and the Jasper router jug is the easiest way to do the braces. But a saber saw and a steady hand will work well too.
Gum:
You wrote that the speaker would be "..powered by cheap bridged 700 - 900W used QSC amp."
We might have a problem.
In a thread I started about bridging amps, G. Rollins said: "The impedance of the driver is divided between the two channels, meaning each channel will see half of, say, a 4 ohm load, meaning 2 ohms--be sure the amp can take that sort of load.
The 1503 is a 4 ohm speaker. Can your amp handle a 2 ohm load? I am unfamiliar with it-I am not saying it cannot, just want to be sure that it can.
You wrote that the speaker would be "..powered by cheap bridged 700 - 900W used QSC amp."
We might have a problem.
In a thread I started about bridging amps, G. Rollins said: "The impedance of the driver is divided between the two channels, meaning each channel will see half of, say, a 4 ohm load, meaning 2 ohms--be sure the amp can take that sort of load.
The 1503 is a 4 ohm speaker. Can your amp handle a 2 ohm load? I am unfamiliar with it-I am not saying it cannot, just want to be sure that it can.
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