I decided to start this thread as I was thinking about sine143 and his favourite driver, the B&C 18SW115, with 15mm of Xmax. Now trouble is, over here these drivers are £605 on Blue Aran. While you may be able to find them cheaper than this they'll still leave a hole in your pocket.
Now what if I could find an 18" driver with 20mm of Xmax that was only £330?
As far as I know, no such driver exists (well maybe in car audio).
But you can have 3 P-Audio IMF HP-18B, or P-Audio E18-600S, each with 6.5mm of Xmax for this money.
So this focuses on two designs. I will start with the P-Audio E18-600S, the first untested concept design for good deep bass to 35 hz and multiples in a corner being useable to 30 hz.
Now I like horn loaded designs, but they do take a while to knock up. With this design, I'm looking to combine the efficiency of horns with the simplicity of bass reflex. In space, money, amp power and output I decided to sacrifice space I don't promise the most output for the box size, so this is a simple to build, cheap, high efficiency design that aspiring DJs can knock up in multiples and have lots of bass on limited amp power.
I have no idea what to call it, so it will be known as the 'British Budget Bass Bin'
Now what if I could find an 18" driver with 20mm of Xmax that was only £330?
As far as I know, no such driver exists (well maybe in car audio).
But you can have 3 P-Audio IMF HP-18B, or P-Audio E18-600S, each with 6.5mm of Xmax for this money.
So this focuses on two designs. I will start with the P-Audio E18-600S, the first untested concept design for good deep bass to 35 hz and multiples in a corner being useable to 30 hz.
Now I like horn loaded designs, but they do take a while to knock up. With this design, I'm looking to combine the efficiency of horns with the simplicity of bass reflex. In space, money, amp power and output I decided to sacrifice space I don't promise the most output for the box size, so this is a simple to build, cheap, high efficiency design that aspiring DJs can knock up in multiples and have lots of bass on limited amp power.
I have no idea what to call it, so it will be known as the 'British Budget Bass Bin'
The maximum SPL per cab is between 120 and 123dB at the voltage limit of about 35. It sounds quite low, but displacement limits usually are on drivers with 6.5mm of Xmax and 35Hz tuning. This is where horn cabs shine, not squandering displacement! The 600 Watt AES Power handling won't get used, but it ensures the voice coils run cool and power compression is kept down.
Did I mention in theory you could run 24+ of these (6 series double 18 format per channel) off a single Peavey IPR300? With a ~70 voltage swing and useable to 2 ohms with some spare leeway.
Did I mention in theory you could run 24+ of these (6 series double 18 format per channel) off a single Peavey IPR300? With a ~70 voltage swing and useable to 2 ohms with some spare leeway.
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Feel free to pick holes in the design (Be polite!!). Compared to some of the awesome tapped horn designs on here, it is simple and boring, but that's the point. It's the 'Simplexx' of the UK, no paying expensive shipping on Eminence drivers across the pond.
2 things you'll notice about the design, the box is quite big for a single 18, but hey, horns are big too, and just look at that SPL chart! It also has a heck of a lot of port area. This will be in the form of 4 triangular ports with short sides of 8". Reason? Bracing.. ports 14" long also brace further back. 2nd Reason? You'll have hardly any port noise at all! You'll inevitably have a touch of harmonic distortion compared to horns, but I'd expect a reasonably good sound from this cabinet.
Now as this just a hornresp output, it's useless for building, so instructions and part dimensions are pending. This is the first design I am to release to the public, free of charge!
2 things you'll notice about the design, the box is quite big for a single 18, but hey, horns are big too, and just look at that SPL chart! It also has a heck of a lot of port area. This will be in the form of 4 triangular ports with short sides of 8". Reason? Bracing.. ports 14" long also brace further back. 2nd Reason? You'll have hardly any port noise at all! You'll inevitably have a touch of harmonic distortion compared to horns, but I'd expect a reasonably good sound from this cabinet.
Now as this just a hornresp output, it's useless for building, so instructions and part dimensions are pending. This is the first design I am to release to the public, free of charge!
Good find! On the face of it - at a glance, similar specs I'd expect to the B&C 18SW115 - slightly less Xmax but half the price! Some money is saved I expect by using a ceramic magnet and no shipping charges. I may pass that one on to XoC1 for TH18 approval as I feel it's wasted as a bass reflex driver.
Hahaa you'll be lucky 😉, just bought a DBX Driverack PA+ today for £300.. Come down lower than the Behringer stuff and has built in EQ!
I remember the Driverack stuff being super expensive perhaps the 260.
Just need to sort out power amps, though I wish I'd found that driver earlier as it probably pees all over my 2 Kappalite 3012lf.. Well they can go in an Omni 212 or something when I've finished with them. Good upgrade to my Marshall MB30 bass amp!
Was planning on Bill Fitzmaurice Titans but needed temporary mini boxes to house the drivers as my car is tiny. Then Precision Devices come out with the 15BR40!! On the face of it, perfect potential Titan 48 Material.... arghh the grass is always greener.
Now power amps - heavy LD Systems Deep 4950 (4 channel) vs lightweight digital Peavey IPR300. I can start with 1 and upgrade to two for a posh stereo rig!
Anyway less of me thinking out loud and blabbering on about my DJ rig in progress and I'll keep updating the 'British Budget Bass Bin'
American members: The Eminence Sigma Pro 18 and P-Audio E18-600S are almost identical in response. How much is the Eminence Sigma Pro 18 across the pond? The Selenium 18sw1p also models well.
Now as an alternative, I propose this cab be made of 3/8" ply to save weight, and also reduce bulk somewhat. This requires me to think up some bracing designs. I want the front external to be 24" x 24" to allow close packing and have it fit through doors.
Now as an alternative, I propose this cab be made of 3/8" ply to save weight, and also reduce bulk somewhat. This requires me to think up some bracing designs. I want the front external to be 24" x 24" to allow close packing and have it fit through doors.
Hi,
Will work with extensive / intelligent bracing.
FWIW cheap low density ply (thicker) is better
than really good ply for PA boxes. Weight for
weight the thicker ply is better. You don't
need the strength of high quality ply.
rgds, sreten.
Stiffness is a cubic function of thickness.
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It's true, spreading out the material over a wider width reduces the flexibility. It does however increase the total bulk of the enclosure, which is already a big cab at 2' x 2' x 3' 3 3/8".
If I was to design for cheapo ply, it would be 1/2". Using Italian Poplar
Due to the internal depth of the cab at about 95cm (Lrc in hornresp), I have been having troubles in the simulation of a standing wave at about 170Hz. On the impulse spectogram charts, it shows up as a slight boom when upper bass is played through it. (It is also reducing the output of the low bass by 1dB and increasing the displacement very slightly).
Any suggestions for breaking up standing waves?
I have thought of bracing with 'swiss cheesed' sheets of 1/4" ply so the waves do not have a direct run to the back of the box.
The reinforcement at the back end of the ports (not in uploaded parts list, but similar to the baffle but with multiple smaller holes) might diffuse some waves.
Also another idea is an angled back, or angled diffuser plates.
Would acoustic foam have any effect at 170Hz?
Oops, the outer dimensions of the baffle backer are wrong, the diagonals should be taken in at least 3/8" for them to fit within the ports.
If I was to design for cheapo ply, it would be 1/2". Using Italian Poplar
Due to the internal depth of the cab at about 95cm (Lrc in hornresp), I have been having troubles in the simulation of a standing wave at about 170Hz. On the impulse spectogram charts, it shows up as a slight boom when upper bass is played through it. (It is also reducing the output of the low bass by 1dB and increasing the displacement very slightly).
Any suggestions for breaking up standing waves?
I have thought of bracing with 'swiss cheesed' sheets of 1/4" ply so the waves do not have a direct run to the back of the box.
The reinforcement at the back end of the ports (not in uploaded parts list, but similar to the baffle but with multiple smaller holes) might diffuse some waves.
Also another idea is an angled back, or angled diffuser plates.
Would acoustic foam have any effect at 170Hz?
Oops, the outer dimensions of the baffle backer are wrong, the diagonals should be taken in at least 3/8" for them to fit within the ports.
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175 dollars is 103 pounds so USA builders can use the sigma pro 18A or possibly the selenium 18sw1p with 9mm of xmax.
I saw a price of £211 on the first place I looked!!
Blue aran has them for about £150
I saw a price of £211 on the first place I looked!!
Blue aran has them for about £150
I went away and had a think about this design, and decided to shrink the box volume sans port area to 250 litres. This is because I believe that when corner loaded, the extension was unnecessary for most work. With 2 cabs corner loaded, it was getting to 28Hz, but after shrinking the box, it helps raise the standing wave, increase the sensitivity, make the box easier to transport and raise the Xmax voltage handling to about 40.
tim, nice design. About standing waves, at wavelengths longer than the longest internal dimension standing waves do not form in an enclosed space, the resonance you saw may have been a parasitic panel resonance.
as far as a thin walled box i can agree, if we can know where the resonances will form we can deal with them, as do instrument makers.
energy storage and release(group Delay) is often the high price we pay for mass loading energy to damp it.
I'd like to see a design implemented in both fashions and hear how they sound different. Can't make my own sawdust unfortunately.
as far as a thin walled box i can agree, if we can know where the resonances will form we can deal with them, as do instrument makers.
energy storage and release(group Delay) is often the high price we pay for mass loading energy to damp it.
I'd like to see a design implemented in both fashions and hear how they sound different. Can't make my own sawdust unfortunately.
As I have not built the box, only modeled it - the standing waves appeared in the hornresp at about 170-180Hz with Lrc (length of the rear chamber or 'depth' of the box) set to 95cm, which is about a half wavelength. I believe the sim is showing a flutter echo, bouncing off the back wall of the box. They seemed to somehow lower the box's 'tuning' and increase displacement slightly (it's hard to explain) and in real world might add some level of resonant boom to harmonics present.
I am also in somewhat of a space constraint with regard to building, though I'd probably have to build one before others took the plunge so to speak. They are for people who wanted the efficiency and lower driver cost of horns with the simplicity (and lighter weight cabs) of bass reflex. I also think these will deliver more low frequency efficiency than most horns, but may not handle as much power due to Xmax limitations, but £110 for an 18 with 6.5mm of Xmax is a good deal. Super 18s with 13+ mm of Xmax cannot be had for £220.
If you've ever seen the multicoloured impulse spectogram charts on hornresp, the standing waves show up as a series of marks instead of a smooth decay. These were starting to encroach on the ~100Hz part of the graph. Shortening the box would shift these further up and away from the subwoofer's passband where they would be less problematic. This is one of the things I've had to watch out for with the large and low tuned boxes I modeled - making them too deep can affect the response.
I am also in somewhat of a space constraint with regard to building, though I'd probably have to build one before others took the plunge so to speak. They are for people who wanted the efficiency and lower driver cost of horns with the simplicity (and lighter weight cabs) of bass reflex. I also think these will deliver more low frequency efficiency than most horns, but may not handle as much power due to Xmax limitations, but £110 for an 18 with 6.5mm of Xmax is a good deal. Super 18s with 13+ mm of Xmax cannot be had for £220.
If you've ever seen the multicoloured impulse spectogram charts on hornresp, the standing waves show up as a series of marks instead of a smooth decay. These were starting to encroach on the ~100Hz part of the graph. Shortening the box would shift these further up and away from the subwoofer's passband where they would be less problematic. This is one of the things I've had to watch out for with the large and low tuned boxes I modeled - making them too deep can affect the response.
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The trouble with thicker walls is it increases the total space the box takes up, say I was to build it with some 2" Polystyrene sandwiched between two sheets of 1/8" Ply. As it is an already large cab (which I've recently downsized to about 10 cubic feet internal), I don't want to make it unwieldy. Aluminium 1mm thick with open faced square cells would be ideal as it would be rigid, yet air could permeate right to the edges. However, I don't have access to such a material cheaply, nor the glue/welding to put together an airtight box with it.
No but a 18" driver with an X-max of 10.5 and a 5" voice coil can be had for £240 each when bought in pairs.
Void Acoustics V18-1000 18 inch 1000w AES Driver 8 ohms
Void Acoustics :: Void Acoustics V18-1000 18" 1000w AES Driver 8 ohms ONLY 245.00 IN STOCK (11 May 2014)
That's a mighty driver alright, but it shares more in common with high powered horn/tapped horn drivers like the B&C 18SW115 and RCF LX18X451. Although in a 120L box tuned to 40Hz, it'll do 127dB if you feed it 85 Volts.
Two P-Audios will best it in sensitivity and outright SPL in a bass reflex design of equal tuning, with less power compression, albeit using bigger boxes. Displacement volume for two is ~1600cc.
I'm sure the P-Audios would be abysmal tapped horn drivers though.
The volume reduction of 50 litres results in 5 1/2 inches being subtracted from the depth of the box. I.e. the 39" dimension is reduced to 34.5 inches, making the box just under 35" deep. The 35" dimension on the bottom is now 29.5". I will draw up the new hornresp soon. Upper bass sensitivity has increased, average sensitivity is now 99-100dB 2.83V 1m, handling increased to just under 40V at 6.5mm Xmax, Max calculated SPL 122-123dB. I'm sure they'll be some real world losses. This design will never take copious amounts of power but you can't have everything, that's what tapped horns are for! It should have fairly low power compression due to just 40V peak RMS to a 4" coil.
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