MoonBassAlpha Posted June 16, 2014 Share Posted June 16, 2014 Now I have got batteries for my jigsaw again, I'm going to revisit my 10" cab idea. I was going to make it sealed this time (I think I got the porting a bit wrong last time!) I was going to use 12mm ply but only have (loads of) 6mm. I'm thinking of doubling it up glued together but perforating the inner layer with 1" holes to lighten, and provide anchor points for stiffening dowels if necessary. Speaker is Celestion bn200x, Thinking of making the cab taller than the previous trapezoid shape. I seem to remember the volume needed to be about 1 square foot, is this right? or different for sealed? I have no real woodworking tools, so fancy joints are out-ish, but thought the 2 layer walls would open up the option of simple mortice & tenon joints. Might incorporate a handle/Shuttle 3.0 holder again too. Can you see any problems with the ideas here? Cheers MBA (Jules) Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted June 16, 2014 Share Posted June 16, 2014 [quote name='MoonBassAlpha' timestamp='1402919831' post='2477834'] Speaker is Celestion bn200x, Thinking of making the cab taller than the previous trapezoid shape. I seem to remember the volume needed to be about 1 square foot, is this right? or different for sealed?[/quote]Have you modeled the driver using speaker modeling software to determine required cab volume, and to compare both response and maximum SPL of sealed versus ported? That is the first step in designing a cab. Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted June 16, 2014 Author Share Posted June 16, 2014 No Bill. It's just a cloud of ideas at the moment. I've not used WinLSD, but I guess that should be my first stop. A sealed cab of appropriate dimensions will give a gentle bass roll-off, yes? Quote Link to comment Share on other sites More sharing options...
charic Posted June 16, 2014 Share Posted June 16, 2014 I think you should make a cab into the exact shape to half of your car boot and then an opposite to match Quote Link to comment Share on other sites More sharing options...
Matt P Posted June 16, 2014 Share Posted June 16, 2014 ooh, i'm watching this with interest, i think i have the exact same speaker sitting in a box at home, i bought it with the intention of making a cab but then read up on cab building and bottled it. i could still do with a tiny cab for home practice so if you come up with something that works i might have to finally give it a go. Matt Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted June 16, 2014 Author Share Posted June 16, 2014 [quote name='charic' timestamp='1402927622' post='2477942'] I think you should make a cab into the exact shape to half of your car boot and then an opposite to match [/quote] I like your thinking, but drive a Meriva, so it would be mahoosive! Quote Link to comment Share on other sites More sharing options...
charic Posted June 16, 2014 Share Posted June 16, 2014 [quote name='MoonBassAlpha' timestamp='1402930026' post='2477976'] I like your thinking, but drive a Meriva, so it would be mahoosive! [/quote] Bad think? How about a modular 4x10 I have loads of stupid ideas for cabs. Wonder if I can make one out of lego Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted June 16, 2014 Share Posted June 16, 2014 [quote name='MoonBassAlpha' timestamp='1402923497' post='2477892'] A sealed cab of appropriate dimensions will give a gentle bass roll-off, yes?[/quote]Yes, and no. The roll off is lower slope but the f3 is much higher, so you don't get better low end, you get less. On average a sealed cab only works better than ported below 30Hz, which is of no benefit for electric bass. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted June 17, 2014 Share Posted June 17, 2014 Bill is right of course but there are some other advantages to a sealed cab. The gradual roll off is easier to eq, especially if your cab is well damped (with Q=0.7 or less). I'm also finding a lot of cleaning up your sound is about avoiding exciting room resonances, ie rolling off the bass. If the cab does this as part of its design then it can be very effective. The problem with the loss of 3-6dB of bass below say 80Hz that you'll get is that you need more power and your speakers can easily end up running out of excursion if you start to eq extra bass. You can improve the 'bassiness' of your sound by rolling of a little treble and maybe adding some upper mids to add a little brightness. Many cheap drivers have this midrange peak anyway so pack, say, eight of these into a sealed box and you solve the excursion problem, roll of the treble, oh wait a minute...... Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted June 17, 2014 Share Posted June 17, 2014 Just looked at your speaker, it isn't really ideal for a sealed box as Q=0.31 is really too low for a sealed box design. It's going to roll off from quite high up and sound really thin in any practical sized box. Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted June 17, 2014 Author Share Posted June 17, 2014 Cheers Phil, good info. Us muggles need these things pointing out by those who know stuff! Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted June 17, 2014 Share Posted June 17, 2014 If you've got it in a ported cab already try stopping up the ports and see how you like the sound - Phil's right about the roll off but with micro amps packing hundreds of watts, you can just boost the bass to compensate and it might give you a good practice cab. That speaker should take it. The good thing about this approach is it's free, quick and fully reversible Quote Link to comment Share on other sites More sharing options...
Balcro Posted June 19, 2014 Share Posted June 19, 2014 As Bill and Phill have said, porting is the answer. Picture 1 is the Celestion in a closed box. Picture 2 is the result when fitted in a small slot ported box. Balcro. Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted June 19, 2014 Share Posted June 19, 2014 Enlarge the thumbnails for a good insight into what we are all saying. that shallow roll off for the sealed box is almost a mirror image of the standard bass control. 12dB of bass boost at 80hz would give you a pretty flat response, boost the bass by 6db with the sealed cab and that lump at 100Hz will become embarrassing. With a parametric and patience you might be able to eq but it's not going to be something you do between songs shallow roll off and no lumps and bumps are a real bonus. However with this speaker the roll off is from much to high a point, 300Hz right in what I think of as midrange. Applying 12db of bass boost means demanding 16 times the power. If you are running at a conservative 50W then you are going to need 800w from that lightweight head which your little 10 isn't going to be very happy about.. Far better to let the ports do the work with this speaker and get something else if you want a sealed box. Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted June 22, 2014 Author Share Posted June 22, 2014 [quote name='Balcro' timestamp='1403174618' post='2480429'] As Bill and Phill have said, porting is the answer. Picture 1 is the Celestion in a closed box. Picture 2 is the result when fitted in a small slot ported box. Balcro. [/quote] What was the volume of the cab for that model? When I ran it in win|SD, the figure came out at 13 litres with a -3dB point at about 90Hz. I'm not looking for massive bass, so that seems ok, but I was a bit surprised at how small the volume came out. Not complaining though (unless I've entered one of the T-S parameters wrong!) Quote Link to comment Share on other sites More sharing options...
Balcro Posted June 22, 2014 Share Posted June 22, 2014 [quote name='MoonBassAlpha' timestamp='1403473715' post='2483100'] What was the volume of the cab for that model? When I ran it in win|SD, the figure came out at 13 litres with a -3dB point at about 90Hz. I'm not looking for massive bass, so that seems ok, but I was a bit surprised at how small the volume came out. Not complaining though (unless I've entered one of the T-S parameters wrong!) [/quote] Hi MBA, I checked again and the volume is surprisingly small. As you say, a volume of 13 litres gives a figure of around - 4 at 90Hz. The ported box in the second thumbnail was set at a net volume of 23 litres. Net volume accounts for the volume inside the box occupied by the BN-200x and the volume taken up by a slot port. I tweaked it up for purposes of illustration to give just a little more low bass. With the larger box, power handling is 200 watts all the way down to 65Hz, then drops to only 100w at 60Hz. 60Hz is also the point where "xmax" is reached with a 100w input, however with that input the system is producing a sound level in excess of 115db! Reducing the volume of the enclosure down to 13 litres will lower the 200w power handling down to 55Hz and the xmax point to about 51Hz. The trade off is a loss of about 3dB @ 90Hz. That should be good enough for many practice and small gig situations, but avoid huge inputs and the use of an octaver. Balcro Quote Link to comment Share on other sites More sharing options...
MoonBassAlpha Posted June 23, 2014 Author Share Posted June 23, 2014 Hi Balcro Thanks for checking that for me. I assume you got the power handling vs freq and xmax figures from a different simulator to WinISD? - I couldn't see where it would provide that info. My next checks will be about the port. I will go for a full width slot. I don't have the sizes to hand, so from memory it was about 268mm by 30mm giving a shelf length of about 90mm and mach 0.10. I did read somewhere that there should be at least 3" (76mm) gap between the end of the port and the rear panel, so with a box depth of 168mm it should be just about ok Quote Link to comment Share on other sites More sharing options...
Balcro Posted June 23, 2014 Share Posted June 23, 2014 [quote name='MoonBassAlpha' timestamp='1403523252' post='2483475'] Hi Balcro Thanks for checking that for me. I assume you got the power handling vs freq and xmax figures from a different simulator to WinISD? - I couldn't see where it would provide that info. My next checks will be about the port. I will go for a full width slot. I don't have the sizes to hand, so from memory it was about 268mm by 30mm giving a shelf length of about 90mm and mach 0.10. I did read somewhere that there should be at least 3" (76mm) gap between the end of the port and the rear panel, so with a box depth of 168mm it should be just about ok [/quote] Hello mba, No, the technical figures are all provided by winISD. Look for a tab or button marked "Transfer function magnitude". Click it and it will bring up various parameter options including port size; set it for a round, square or rectangular; the choice is yours. Set your chosen volume first, then work from there. Balcro. Quote Link to comment Share on other sites More sharing options...
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