Cheap driver/box combination to get low and loud

I would hugely appreciate views of the experienced forum members on the above "design".Driver specifications here http://www.ljudia.fi/Archive/ProductFiles/940209/P1800W%20-%20Specifications.pdf

Do you see possible problems/fups on the "design".?Can I trust my winisd on this one.?

Thank you very much!

Thanks!

What would be a "good" size for 2x18"?

Should I tune the box to 40hz and make a little bump on the 40-80hz range?

If Im mostly goin to play reggae and dub would there be any idea in boostin certain frequencies in the box design. For example 40-80hz?

Is there any tricks to make the enclosure smaller but make it appear larger than it is.Did that make sense :D Making the box smaller but boosting some frequencies to make it sound fatter.

app wrote: Thanks! What would be a "good" size for 2x18"?

Well if you can lift and shift it on your own that's a bonus! Probably about 200L although it has been ages since I simmed one so take that with a pinch of salt.

app wrote: Should I tune the box to 40hz and make a little bump on the 40-80hz range?

Sure, you could do. Delay will be large at that point but you'll get a little more output and it will suppress the movement of the driver which may help with power handling. Just remember to HPF under the port tuning properly to get the best power handling.

app wrote: If Im mostly goin to play reggae and dub would there be any idea in boostin certain frequencies in the box design. For example 40-80hz?

Maybe, but you can very easily do that in the small signal before amplification for testing. It'll all be about what sounds good to you really.

app wrote: Is there any tricks to make the enclosure smaller but make it appear larger than it is.Did that make sense :D Making the box smaller but boosting some frequencies to make it sound fatter.

Absolutely you can at the expense of power handling and headroom in the passband. There are a few good projects on ESP Audio relating to equalisation of subs and extension of LF at the loss of power handling, which for HT applications is a very viable design choice to get those cinematic 20Hz effects with a small amount of power and a decent driver in a smallish box.

Also maybe you have covered this earlier, but why a 2x18" box. 2 1x18" boxes would be a lot easier to shift around on your own, more versatile for placement etc.


Edited by odc04r - 10 November 2014 at 11:12am

odc04r wrote: Also maybe you have covered this earlier, but why a 2x18" box. 2 1x18" boxes would be a lot easier to shift around on your own, more versatile for placement etc.

That is a good valid point! Thanks! I have no Idea why ive been thinking about 2x18" all the time. :D

DMorison wrote: If you're familiar with any existing boxes of this type, then calculate their external volume and divide by 1.4 or 1.5. That will give you a fairly decent starting range for Internal volume, allowing for all the things djeddie mentions.

If I use only one driver to what should the dividing number be changed to? If I design a port which is 18mm long like the ply I suppose that would also make a difference in the number which I use to divide.Since it takes no space inside the box.

Thanks for your help!

Still taking suggestions on possible drivers which cost under 200euros and are able to outplay either one 2x18" box with the mgr drivers or 2 1x18" boxes with the cheapo mgr driver.

I think that at 170 euros a pair it would be quite hard to find a match for those drivers.

odc04r wrote: app wrote: DMorison wrote: If you're familiar with any existing boxes of this type, then calculate their external volume and divide by 1.4 or 1.5. That will give you a fairly decent starting range for Internal volume, allowing for all the things djeddie mentions. If I use only one driver to what should the dividing number be changed to? If I design a port which is 18mm long like the ply I suppose that would also make a difference in the number which I use to divide.Since it takes no space inside the box. You may be tempted to use the thickness of the wood as a port length to save on build complications, I have done it before and it worked ok (well I was 15 or so, I was happy to be making any noise). But before you do it, consider that an 18mm thick piece of wood is not going to be exactly that. Let's say on a good day it's +-0.5mm and that's from the shop, not taking into account moisture content etc. Plug those tolerances into a simulator and see how much that potential variation in thickness affects your tuning frequency. And that's not taking into account any end corrections etc, in practice for best performance ports always need a little bit of tuning. Your approach will make noise but it is very susceptible to error. Shelf or triangle ports are also good from the point of view of extra bracing.

True true!

Its actually a real pain in the ass dealin with 18mm port length,annoying as ef.Its super hard to make work. Much easier to just make a longer port in simulation.And its not that hard to build when its time for that.

Im tryin different simulations to give myself some sort of marginal in which I try to get the speaker to work.I dont need to get it just as I simulated, but if it works inside the margin I have, Ill be satisfied. Cause theres no way Im gonna be able to build the box just as simulated. But If its close enough and all the possible changes has been thought of Im quite safe.

It just takes a lot of time to think about different options to find the sweet spot which is in the zone to make the speaker work as close as possible to what I simulated.

edit.Im goin to use the best possible ply which is finnish birch ply of course No need to go russian or baltic here






Edited by app - 10 November 2014 at 2:15pm

Id like your opinion/help AGAIN! :D

I just simulated a box for 1xmgr p-1800w!

I got the following result.

Size: 250 l
Tuning freq: 34,08hz
Port size: 63x3x8,1
Signal: 250w
Max port air velocity @ 31,5hz 24,1 m/s
Cone excursion max 6,8mm @ 49hz (x-max is 6,5mm)
SPL: 119,5db @110hz/116,5@34,46hz

This might be the design Im goin for.What you guys think about the numbers?

Im also wondering how to correctly calculate the box size so that it is as close as possible with all the stuff inside the box.Is there any other way than to use the numbers in the previous post?

What would be a good ratio of the boxes sides if the front panel must be 63cm wide (because of the port)

Can someone say just from the numbers how this speaker would sound like?

Thanks!



Edited by app - 10 November 2014 at 9:11pm