Here are the pics. Sorry for the blurry shots. I had only my lousy phone at hand.
I made it down ported just to test how it would work. I will make it backported if this won't work well enough. I might actually test it laid on side so it will be side ported and see if it changes anything
Also the port is few mills blocked by the amp and next to speaker wall but initial impressions are good though. I can't get much below 40 Hz but sounds quite good. I tested with my klipsch rf-52 sub crossed at 100 hz and rest from mains and also with mains all the way down.
If I have time, I will test it tomorrow with my rear speakers as mains to get a better idea (cyburg's needles with w3-871sc)
I actually used wood parts made for furniture 😀. They were free for me and had a nice finish on them so I couldn't resist. The sides are from glued timber (if that is the correct term). The rest is particle board. All sides are about 2 cm thick.
The port is pvc pipe that has 75mm outer and ~68 mm outer diameter. The port is around 35 cm long with few centimeters outside of the box and 45 degree angle part inside. The inner dimensions are about W 28 cm, D 26 cm and H 35 cm. The total outer height is around 56 cm.
I made it down ported just to test how it would work. I will make it backported if this won't work well enough. I might actually test it laid on side so it will be side ported and see if it changes anything
Also the port is few mills blocked by the amp and next to speaker wall but initial impressions are good though. I can't get much below 40 Hz but sounds quite good. I tested with my klipsch rf-52 sub crossed at 100 hz and rest from mains and also with mains all the way down.
If I have time, I will test it tomorrow with my rear speakers as mains to get a better idea (cyburg's needles with w3-871sc)
I actually used wood parts made for furniture 😀. They were free for me and had a nice finish on them so I couldn't resist. The sides are from glued timber (if that is the correct term). The rest is particle board. All sides are about 2 cm thick.
The port is pvc pipe that has 75mm outer and ~68 mm outer diameter. The port is around 35 cm long with few centimeters outside of the box and 45 degree angle part inside. The inner dimensions are about W 28 cm, D 26 cm and H 35 cm. The total outer height is around 56 cm.
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It looks not bad!
Ok, with this box size i would say you have around 16 liter - 2 liter for port and chassis = around 14 liter netto volume. Your tuning freq should be around 44hz with your given port size.
WinISD says against the 20 liter ported box 3db lower SPL with your box @ 40hz. Rear port air velocity around 20 m/s...do you have any port noise? Some saying 20 should be maximum, some others 15.
grey = 20l tuned to 40hz
yellow = 14l osssyvan's box
Ok, with this box size i would say you have around 16 liter - 2 liter for port and chassis = around 14 liter netto volume. Your tuning freq should be around 44hz with your given port size.
WinISD says against the 20 liter ported box 3db lower SPL with your box @ 40hz. Rear port air velocity around 20 m/s...do you have any port noise? Some saying 20 should be maximum, some others 15.
grey = 20l tuned to 40hz
yellow = 14l osssyvan's box
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Thanks. I tried to take a good angle for the shot. It doesn't look too bad if you don't look at it too close.
I can't figure out how you came up with that volume 😀. I guessing you mistook the dimensions as outer dimensions. Using the inner dimensions of the box: 2.6 dm * 2.8 dm * 3.5 dm = 25.48 dm^3 = 25.48 liters. From that the port (Is around 1.5l) and the speaker parts (max 2l I suppose) would get it to 22 liters.
I haven't noticed any problems with the air velocity. Don't seem to make any noise really. In the tuning frequency I tried to take notice with the hp that the amp has but not sure if I used correct filter and values.
I just noticed that I can't really try my needles as mains as it seems that my lovely cat had decided to perforate one. They still sound ok but I really have to fix it and hope it still works. Any hint on how to do it? I am thinking about hot glue.
I can't figure out how you came up with that volume 😀. I guessing you mistook the dimensions as outer dimensions. Using the inner dimensions of the box: 2.6 dm * 2.8 dm * 3.5 dm = 25.48 dm^3 = 25.48 liters. From that the port (Is around 1.5l) and the speaker parts (max 2l I suppose) would get it to 22 liters.
I haven't noticed any problems with the air velocity. Don't seem to make any noise really. In the tuning frequency I tried to take notice with the hp that the amp has but not sure if I used correct filter and values.
I just noticed that I can't really try my needles as mains as it seems that my lovely cat had decided to perforate one. They still sound ok but I really have to fix it and hope it still works. Any hint on how to do it? I am thinking about hot glue.
Ups, ok:
22 liters
80watt input
your tuning freq. 35,15hz
rear port air velotity 24,7 m/s
If you're choosing a HP filter around 30hz you should be able to use its full 80 watt input power. Between 30 and 40hz around -4db SPL.
22 liters
80watt input
your tuning freq. 35,15hz
rear port air velotity 24,7 m/s
If you're choosing a HP filter around 30hz you should be able to use its full 80 watt input power. Between 30 and 40hz around -4db SPL.
Seeing the photos has given me a renewed sense of determination to actually see this project through to completion! I'm rethinking the port slot idea, because I'm probably going to end up doing all of the cutting myself so I want the design as simple as possible...
How does this design look? I've made the port 36mm wide rather than 12mm & bent it round the back of the box to accommodate the length. Volume after removing the port is still roughly 20l (I increased the overall depth of the box). 43Hz at -3dB.
How does this design look? I've made the port 36mm wide rather than 12mm & bent it round the back of the box to accommodate the length. Volume after removing the port is still roughly 20l (I increased the overall depth of the box). 43Hz at -3dB.
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Looks good.
What i know is if you 're building the port in the way your simulation shows the port is virtually longer (i don't know the calculationg factor) which you really need because your goal should be not higher than 35hz tuning freq.! In your simulation the port is around 3.6x23x60cm? This virtually is something maybe around 90cm which is good to receive the 35hz tuning freq. goal....you should use google about this port design to figure out the calculating factor for it, i can't find it at the moment.
What i know is if you 're building the port in the way your simulation shows the port is virtually longer (i don't know the calculationg factor) which you really need because your goal should be not higher than 35hz tuning freq.! In your simulation the port is around 3.6x23x60cm? This virtually is something maybe around 90cm which is good to receive the 35hz tuning freq. goal....you should use google about this port design to figure out the calculating factor for it, i can't find it at the moment.
Does it make a difference where I place the driver? I put it at the top just for aesthetics, but would it be better to place it further down so that part of it isn't directly in front of the internal mouth of the port?
Right, I'm actually going to visit my local joiner sometime later this week or at the weekend with a cutting list & a printout of this (or something similar if anybody flags up anything wrong).
I doubled the thickness of the front brace because I'm not overly confident of the strength of MDF & I added bracing through the slot port. It effectively makes it two smaller ports which in theory will play ~1Hz lower before hitting -3dB & have a lower mouth velocity but as they're right next to each other I suspect the difference will be negligible. Though it does also decrease the height:width ratio, so I doubt it will do any harm.
I've also got a lead on a dbx 233XL crossover going for £50 which I should hear back from on Friday, which will save me a bit of money 🙂
I doubled the thickness of the front brace because I'm not overly confident of the strength of MDF & I added bracing through the slot port. It effectively makes it two smaller ports which in theory will play ~1Hz lower before hitting -3dB & have a lower mouth velocity but as they're right next to each other I suspect the difference will be negligible. Though it does also decrease the height:width ratio, so I doubt it will do any harm.
I've also got a lead on a dbx 233XL crossover going for £50 which I should hear back from on Friday, which will save me a bit of money 🙂
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I noticed that my room has nasty room gain around 50 Hz. Any suggestions on what to do?
Also I will try higher tuning at some point and see how it changes the sound.
But right now my biggest problem is that I tried it with my avr. Now my gf won't allow me to use the sub for anything else 😀...
The satellites are on hold as I don't have time to go visit my parents and use their tools etc to make them. So now my 2.1 pc project turned into sub for main system and using headphones at desktop 🙂..
Also I will try higher tuning at some point and see how it changes the sound.
But right now my biggest problem is that I tried it with my avr. Now my gf won't allow me to use the sub for anything else 😀...
The satellites are on hold as I don't have time to go visit my parents and use their tools etc to make them. So now my 2.1 pc project turned into sub for main system and using headphones at desktop 🙂..
Build a second one and place it on the opposite or build 3 more for a DBA ....or use an EQ like miniDSP.
My local joiner has just quoted me £55 to supply & cut all of the MDF I need for my sub, which I think is fair. If I tried to do it myself I'd have to spend £30+ on a full sheet as well as buying some more tools & even then I'd probably do an awful job of it... So with any luck I'll have this in flat-pack form soon 🙂
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The bracing looks great. I don't know if the bracing through the slot port affects something? Haven't simulated it..maybe port noise?! All in all it looks very good!
I realised when I printed the design out for the joiner the first time that I had completely forgotten to put any bracing in, so I added some, but not too much because it's never going to be playing particularly loud. Of course I then had to make the enclosure larger to account for the loss of volume from the bracing, which meant I had to change the length of the port, etc. etc. etc.... I took the idea for the brace along the port from pro-audio subwoofer designs, particularly things like the x-sub (picture on the Speakerplans.com homepage).
The joiner called me to say the wood will come in on Monday, so hopefully I will have the pieces to assemble by next weekend. Things are finally coming together!
The joiner called me to say the wood will come in on Monday, so hopefully I will have the pieces to assemble by next weekend. Things are finally coming together!
Quick update, everything has gone better than expected so far!
The last pieces that I glued (the back & the base) are ~2-3mm off but I figure it's just due to small inaccuracies in all of the other joints adding up. I'll sand down the steps before I paint/cover it.
Just waiting for the glue I used for the wadding to dry before I put the binding posts in the back, then I'll crimp some cable.
The last pieces that I glued (the back & the base) are ~2-3mm off but I figure it's just due to small inaccuracies in all of the other joints adding up. I'll sand down the steps before I paint/cover it.
Just waiting for the glue I used for the wadding to dry before I put the binding posts in the back, then I'll crimp some cable.
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