Re: No compromises front loaded double 18” cab
Sorry I was mistaken, UHMW is the better product for this, I stand corrected
Sorry I was mistaken, UHMW is the better product for this, I stand corrected
No compromises front loaded double 18” cab
- Thread starter Luke Robinson
- Start date
Re: No compromises front loaded double 18” cab
Wow, there are some great suggestions here. It would seem by consensus that I should be looking in the direction of B&C. Lets take a look at the 18SW100 or the 18SW115. I know I said no compromises, but in the real world we do have to worry about things like the cost of drivers and more costly still Amplifier power. If the 100 os more efficient then maybe it will work better for me. What am I loosing by going with the 100 over the 115?
Phil, thanks for the List there is a lot of good information. I think I am going to grab on the DATS test systems, I have an old PC in the basement that I'll have to dust off and get working...
What about Dampening material, I have used the recycled denim material in the past, It works, but I don't know that it is the best thing out there. What has everyone else used, and if there is something that you like can you recommend a good source for it? how much dampening do I need?
Wow, there are some great suggestions here. It would seem by consensus that I should be looking in the direction of B&C. Lets take a look at the 18SW100 or the 18SW115. I know I said no compromises, but in the real world we do have to worry about things like the cost of drivers and more costly still Amplifier power. If the 100 os more efficient then maybe it will work better for me. What am I loosing by going with the 100 over the 115?
Phil, thanks for the List there is a lot of good information. I think I am going to grab on the DATS test systems, I have an old PC in the basement that I'll have to dust off and get working...
What about Dampening material, I have used the recycled denim material in the past, It works, but I don't know that it is the best thing out there. What has everyone else used, and if there is something that you like can you recommend a good source for it? how much dampening do I need?
Re: No compromises front loaded double 18” cab
Luke,
The 18SW115 is a little more of everything. More power handling, more magnet, more Xvar, and a different sound due to the larger coil. It's also more money, of course, which is why the 18SW100 exists. Same technologies, as pro a sub woofer, but a meaningful price reduction if you want the sound and the performance but don't plan on beating the hell out of it.
Luke,
The 18SW115 is a little more of everything. More power handling, more magnet, more Xvar, and a different sound due to the larger coil. It's also more money, of course, which is why the 18SW100 exists. Same technologies, as pro a sub woofer, but a meaningful price reduction if you want the sound and the performance but don't plan on beating the hell out of it.
Re: No compromises front loaded double 18” cab
I wonder if it would be possible to extend the lower left, middle divider and upper right panels of the ports all the way to the back of the cabinet, thus splitting the cabinet into two enclosures each with a port and providing more bracing. With the cabinet split, if you lose a driver the tuning doesn't go all to hell. It would be difficult to make a curved port with this configuration, but may be worth a look.
Ciao
Simon
I wonder if it would be possible to extend the lower left, middle divider and upper right panels of the ports all the way to the back of the cabinet, thus splitting the cabinet into two enclosures each with a port and providing more bracing. With the cabinet split, if you lose a driver the tuning doesn't go all to hell. It would be difficult to make a curved port with this configuration, but may be worth a look.
Ciao
Simon
Re: No compromises front loaded double 18” cab
Hello
I made quick comparison with "ancient" JBL-Speakershop ( early Harris Bassbox.. ) using RCF L18P200KN ( have few laying around...) and it turns out, that single departments require about 10% longer wents/ports with same area - so it would be very good thing in case one speaker goes kaputt.
So for those of us who have only small system, it might be best to build single-18 cabinets - a little more plywood and total weight - a bit more flexibility for smaller setups.
For "big boys" who have kadzillions of megawatts or so, simple logistics suggests double-18 cabinets - but they would benefit of internal dividing in case of single elemenet problem, too.
Hello
I made quick comparison with "ancient" JBL-Speakershop ( early Harris Bassbox.. ) using RCF L18P200KN ( have few laying around...) and it turns out, that single departments require about 10% longer wents/ports with same area - so it would be very good thing in case one speaker goes kaputt.
So for those of us who have only small system, it might be best to build single-18 cabinets - a little more plywood and total weight - a bit more flexibility for smaller setups.
For "big boys" who have kadzillions of megawatts or so, simple logistics suggests double-18 cabinets - but they would benefit of internal dividing in case of single elemenet problem, too.
Re: No compromises front loaded double 18” cab
If you divide the box in half it will slightly lower its tuning frequency – in simple terms the port length, because it now includes the box wall on one side will appear a bit longer.
I would however joint the middle section of the port to the back of the box and add bracing on the top, bottom, back and sides. Bracing from side to side, or back to front will greatly reduce the cabinet’s deflection.
In simple terms the deflection of a beam is proportional to its length cubed, so halving the length has a dramatic effect. In this case it’s a rigidly supported plate … it’s a bit more complicated but in principle its similar.
Note: If you choose this box design it will need to be slightly retuned if you use a different driver eg. B&C 18WS115
If you divide the box in half it will slightly lower its tuning frequency – in simple terms the port length, because it now includes the box wall on one side will appear a bit longer.
I would however joint the middle section of the port to the back of the box and add bracing on the top, bottom, back and sides. Bracing from side to side, or back to front will greatly reduce the cabinet’s deflection.
In simple terms the deflection of a beam is proportional to its length cubed, so halving the length has a dramatic effect. In this case it’s a rigidly supported plate … it’s a bit more complicated but in principle its similar.
Note: If you choose this box design it will need to be slightly retuned if you use a different driver eg. B&C 18WS115
Re: No compromises front loaded double 18” cab
Yep, just adding to the "clever"...... We know that ports near surfaces, like the internal walls of a cabinet or the even the floor, acoustically appear longer and tune a little lower in freq than expected from just the physical tunnel length. It would appear with the BT218, that the symmetrically adjacent port arrangement in the middle is like having half the cabinet - one driver and one port - against a wall with the port closest to the wall. In this arrangement the effective port length is increased a little. And so for a given tuning, the physical port inside the cabinet can be slightly shorter. This all helps to maximize the port area, whilst minimizing the amount of cabinet volume the port consumes. Someone please correct me if I'm wrong here...
Yep, just adding to the "clever"...... We know that ports near surfaces, like the internal walls of a cabinet or the even the floor, acoustically appear longer and tune a little lower in freq than expected from just the physical tunnel length. It would appear with the BT218, that the symmetrically adjacent port arrangement in the middle is like having half the cabinet - one driver and one port - against a wall with the port closest to the wall. In this arrangement the effective port length is increased a little. And so for a given tuning, the physical port inside the cabinet can be slightly shorter. This all helps to maximize the port area, whilst minimizing the amount of cabinet volume the port consumes. Someone please correct me if I'm wrong here...
Re: No compromises front loaded double 18” cab
"the symmetrically adjacent port arrangement in the middle is like having half the cabinet - one driver and one port - against a wall with the port closest to the wall."
Although I have not stuck my hand into a BT-218 to confirm, it appears to me the central port wall literally makes the cabinet two enclosures, (saving some weight and hardware cost of two single enclosures) making the cabinet much stiffer, reducing distortion over a shared chamber, and also reducing potential loss of a second driver due to Fb changing if one driver were to fail (turning into a non optimal passive radiator), or be left un-powered.
Anyway, Big Port Volume=Good, Tapped Horns=+6dB More Good (per driver) ;^).
Art
Corner or shelf ports do tune lower than round ducts of the same length and volume, but the central port location does not change the boundary condition, which you seem to be implying:
"the symmetrically adjacent port arrangement in the middle is like having half the cabinet - one driver and one port - against a wall with the port closest to the wall."
Although I have not stuck my hand into a BT-218 to confirm, it appears to me the central port wall literally makes the cabinet two enclosures, (saving some weight and hardware cost of two single enclosures) making the cabinet much stiffer, reducing distortion over a shared chamber, and also reducing potential loss of a second driver due to Fb changing if one driver were to fail (turning into a non optimal passive radiator), or be left un-powered.
Anyway, Big Port Volume=Good, Tapped Horns=+6dB More Good (per driver) ;^).
Art
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Re: No compromises front loaded double 18” cab
One of my Keystone Subs (plans are available online) can put out as much SPL as four Meyers 2x18" HP 650, but some people have to hear it before they believe it, and they won't hear it since they don't believe one BC18SW115-4 (also used in DSL's TH-118, though the spec sheets still depict the 18Sound drivers originally used..) in a single cabinet could possibly keep up with 8 (pathetic by today's standards) sub drivers. Glad I have retired from the business of "selling sound by the pound" ;^).
2) 15 mm of coil diameter, while gaining some sensitivity. As Bennett mentioned, if you are not "beating the hell out of it", ie running within specifications, not too much reason to go with the 18SW115 (other than weight reduction) in a BR. That said, the 18SW115 can hold up to the abuse of a high compression ratio horn load will require better than the 18SW100.
3) Neither do I, but I don't like any type of organic (hemp, denim, jute, etc.) moisture retaining, mold and mildew harboring stuffing in my cabinets, and I live in the high desert where humidity is low. If you expect to operate in humid environments, forget about organic damping unless you and your clients like the smell of rotting vegetables.
4) Fiberglass insulation, readily available at any building store, I choose which ever is closer or offers a better price. Polyfill (like used in pillows, available in fabric stores and at inflated prices from speaker supply companies) is the more "politically correct" filler, but doesn't work as well, requiring more to do less.
5) None, damping material wastes power and reduces SPL, and retains heat, causing power compression to rise. Damping is used in "Full range" BR cabinets to avoid reflected upper waves from coming out the phase inversion (BR) ports causing ragged (and hollow sounding) response due to not being in phase with the output of the cone's front radiation phase. Sub woofers are cut off below port resonance frequencies rear their nasty little head(s).
Art
1) If you are worried about cost, you should be looking at tapped horn designs, which can use half the drivers, power, and speaker cord for the same output, though at a slight increase in truck space over BR. When you consider only half the amps and cabling are needed, the space difference is not much (if any), but the cost goes down by 1/2 (sorry, Bennett and other driver, amplifier, and cord companies). Also, the cooling vent is exposed to the outside air in TH designs, so thermal compression, which is remarkably low for the B&C woofers, is reduced even more, further offsetting the slight space increase. Port compression is eliminated. The only downside is TH have to be explained to those who have simply specified "X number of 2x18".
One of my Keystone Subs (plans are available online) can put out as much SPL as four Meyers 2x18" HP 650, but some people have to hear it before they believe it, and they won't hear it since they don't believe one BC18SW115-4 (also used in DSL's TH-118, though the spec sheets still depict the 18Sound drivers originally used..) in a single cabinet could possibly keep up with 8 (pathetic by today's standards) sub drivers. Glad I have retired from the business of "selling sound by the pound" ;^).
2) 15 mm of coil diameter, while gaining some sensitivity. As Bennett mentioned, if you are not "beating the hell out of it", ie running within specifications, not too much reason to go with the 18SW115 (other than weight reduction) in a BR. That said, the 18SW115 can hold up to the abuse of a high compression ratio horn load will require better than the 18SW100.
3) Neither do I, but I don't like any type of organic (hemp, denim, jute, etc.) moisture retaining, mold and mildew harboring stuffing in my cabinets, and I live in the high desert where humidity is low. If you expect to operate in humid environments, forget about organic damping unless you and your clients like the smell of rotting vegetables.
4) Fiberglass insulation, readily available at any building store, I choose which ever is closer or offers a better price. Polyfill (like used in pillows, available in fabric stores and at inflated prices from speaker supply companies) is the more "politically correct" filler, but doesn't work as well, requiring more to do less.
5) None, damping material wastes power and reduces SPL, and retains heat, causing power compression to rise. Damping is used in "Full range" BR cabinets to avoid reflected upper waves from coming out the phase inversion (BR) ports causing ragged (and hollow sounding) response due to not being in phase with the output of the cone's front radiation phase. Sub woofers are cut off below port resonance frequencies rear their nasty little head(s).
Art
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Re: No compromises front loaded double 18” cab
I just happen to be playing with some of your mentioned 18's. I use the xl 1500 in my box's but B+C would be a equal choice. Depending on how much power you are going to give them. I have a crest 8200 bridged on each of my double 18 subs loaded with xl 1500
I just happen to be playing with some of your mentioned 18's. I use the xl 1500 in my box's but B+C would be a equal choice. Depending on how much power you are going to give them. I have a crest 8200 bridged on each of my double 18 subs loaded with xl 1500
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Re: No compromises front loaded double 18” cab
Actually, I am suggesting/guessing that there's a boundary condition across the center since each half is the mirror image of the other. (This assumes that both drivers are driven with exactly the same signal and that the upper and lower ports are identical in area and depth.) It follows that if the ports were at the ends - top and one at the bottom - (and ignoring the floor in the photo) the ports might have to be a little deeper/longer for the same tuning? Maybe I'm completely off base.
Actually, I am suggesting/guessing that there's a boundary condition across the center since each half is the mirror image of the other. (This assumes that both drivers are driven with exactly the same signal and that the upper and lower ports are identical in area and depth.) It follows that if the ports were at the ends - top and one at the bottom - (and ignoring the floor in the photo) the ports might have to be a little deeper/longer for the same tuning? Maybe I'm completely off base.
Re: No compromises front loaded double 18” cab
I finally Plugged in some numbers, After fooling around with dimensions, it seemed like a 48x22.5x30 box would work well, with a port design similar to the one on the Eighteen sound box design. for the purposes of the software I used a rectangular port, but i will adjust the geometry of the port to be two trapezoids with the same surface area of the 21x4 rectangle.
I started with the 18SW100, then the 18SW115, and Decided to try out a couple of Faital Pro models.
So keeping the box this size it looks like the B&C 18SW100 and the Faital 18HP1013 are the front runners. I am guessing that I would need a bigger box for the other two drivers, and I really don't want to have to move something bigger than that.
The B&C looks like it will get a little louder, and have better performance from 60-100hz, but the Faital will go a bit lower, but have a little peak around 45-50hz, and might not get quite as loud. it May however not require as much amp power as the B&C to get to an acceptable level.
I think that I am going to order up 2 of each driver and build a pair of boxes as soon as time allows. The model is only going to tell me so much. Hearing is believing. As soon as I have a winner I will be building 12-20 boxes over the winter.
I finally Plugged in some numbers, After fooling around with dimensions, it seemed like a 48x22.5x30 box would work well, with a port design similar to the one on the Eighteen sound box design. for the purposes of the software I used a rectangular port, but i will adjust the geometry of the port to be two trapezoids with the same surface area of the 21x4 rectangle.
I started with the 18SW100, then the 18SW115, and Decided to try out a couple of Faital Pro models.
So keeping the box this size it looks like the B&C 18SW100 and the Faital 18HP1013 are the front runners. I am guessing that I would need a bigger box for the other two drivers, and I really don't want to have to move something bigger than that.
The B&C looks like it will get a little louder, and have better performance from 60-100hz, but the Faital will go a bit lower, but have a little peak around 45-50hz, and might not get quite as loud. it May however not require as much amp power as the B&C to get to an acceptable level.
I think that I am going to order up 2 of each driver and build a pair of boxes as soon as time allows. The model is only going to tell me so much. Hearing is believing. As soon as I have a winner I will be building 12-20 boxes over the winter.
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The SW100 and the HP1030 are not in the same class, not even remotely IMO.
Though I need to admit, that I never had the HP1030 on my work bench.
Just look at VC winding depth versus gap height and Xdamage.
In the beginning you talked about no compromise subs, for that the contenders are: Faital 18XL1600, the SWs from B&C and Eighteensound NLW9000, the 9601 might be an overkill.
The colourfull pictures Ive seen here are just that, nothing more.
Without LEAP 5 and some high power impedance measurements of the drivers in question you cannot simulate what happens, if you drive them hard
Uwe
Though I need to admit, that I never had the HP1030 on my work bench.
Just look at VC winding depth versus gap height and Xdamage.
In the beginning you talked about no compromise subs, for that the contenders are: Faital 18XL1600, the SWs from B&C and Eighteensound NLW9000, the 9601 might be an overkill.
The colourfull pictures Ive seen here are just that, nothing more.
Without LEAP 5 and some high power impedance measurements of the drivers in question you cannot simulate what happens, if you drive them hard
Uwe
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Re: No compromises front loaded double 18” cab
Luke, Run the 18 xl 1600, tbw100 and see what ya come up with also. How much power do you plan on putting into each double 18?
Luke, Run the 18 xl 1600, tbw100 and see what ya come up with also. How much power do you plan on putting into each double 18?
Re: No compromises front loaded double 18” cab
Art, I think what Michael is suggesting is that the air in the region in red below acts as part of the port air mass, whereas without the central divider, the actual port walls would need extended back to the end of the red region to achieve the same tuning. (If you can excuse the rather basic diagram & description...)
That would be consistent with your first sentence above I think.
Regards,
David.
Art, I think what Michael is suggesting is that the air in the region in red below acts as part of the port air mass, whereas without the central divider, the actual port walls would need extended back to the end of the red region to achieve the same tuning. (If you can excuse the rather basic diagram & description...)
That would be consistent with your first sentence above I think.
Regards,
David.
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Re: No compromises front loaded double 18” cab
This is how it works / measured .... and more or less my design (very rough) that I mentioned at the start of the thread (Box 1220mm x 550mm x 750mm ... 21.5" x 48" x 30") with 18NLW9000s
This is how it works / measured .... and more or less my design (very rough) that I mentioned at the start of the thread (Box 1220mm x 550mm x 750mm ... 21.5" x 48" x 30") with 18NLW9000s
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Re: No compromises front loaded double 18” cab
On paper the 9000 and 9601 look similar. Same power, Fs, similar Qt, slightly different Vas but the Voice Coil construction is quite different and I suspect the 9601 will behave better when you drive them hard.
Have you compared them in any detail?
On paper the 9000 and 9601 look similar. Same power, Fs, similar Qt, slightly different Vas but the Voice Coil construction is quite different and I suspect the 9601 will behave better when you drive them hard.
Have you compared them in any detail?
Re: No compromises front loaded double 18” cab
Interesting, I am glad that I came here, I am learning of much. :razz:
I am pretty sure that I am going to split the cab like this, In my prediction software we were looking at a 12" deep port so going this route I guess we are looking at making them 10" to start.
Interesting, I am glad that I came here, I am learning of much. :razz:
I am pretty sure that I am going to split the cab like this, In my prediction software we were looking at a 12" deep port so going this route I guess we are looking at making them 10" to start.
Re: No compromises front loaded double 18” cab
I did run the 18xl1600 and it created kind of a big bump at the bottom, I am not sure that I like this. I could play with the size of the box but I am growing attached to the size of the box I am looking at for logistical reasons. I did not look at the TBW but I suppose I should.
Power is another discussion. I am looking at amps now. Up until now I have been using mostly QSC. Short of running everything bridged (not my favorite way of doing things), It looks like I am going to have to take a look at other manufacturers to get the power that these beasts are going to demand. So it seems like either the Powersoft k20, or Lab Gruppen FP14000 are the contenders.
Does anyone have any opinions as to why one may be better than the other? I may find myself running either at 2 ohms from time to time. On Paper the K20 is the front runner, the power rating is higher, and it takes up half the rack space. My price on both is close enough that price is not a big factor.
I did run the 18xl1600 and it created kind of a big bump at the bottom, I am not sure that I like this. I could play with the size of the box but I am growing attached to the size of the box I am looking at for logistical reasons. I did not look at the TBW but I suppose I should.
Power is another discussion. I am looking at amps now. Up until now I have been using mostly QSC. Short of running everything bridged (not my favorite way of doing things), It looks like I am going to have to take a look at other manufacturers to get the power that these beasts are going to demand. So it seems like either the Powersoft k20, or Lab Gruppen FP14000 are the contenders.
Does anyone have any opinions as to why one may be better than the other? I may find myself running either at 2 ohms from time to time. On Paper the K20 is the front runner, the power rating is higher, and it takes up half the rack space. My price on both is close enough that price is not a big factor.