The way that you simulate the box response with a passive radiator is just pretend it's a port, i.e. change Fb. Then when you actually build the box you add weight to the passive radiator until you get the same Fb (you can tell by the impedance curve).
However, this is all a bit much for a 1st project and like a lot of the others I would suggest going for a sealed box. Adding EQ will give very good results.
My tip is to check out 8 inch and 10 inch car sub-woofer drive units... good performance and in small boxes... but do your research well, there's a lot of naff car subs out there.
However, this is all a bit much for a 1st project and like a lot of the others I would suggest going for a sealed box. Adding EQ will give very good results.
My tip is to check out 8 inch and 10 inch car sub-woofer drive units... good performance and in small boxes... but do your research well, there's a lot of naff car subs out there.
Ok, as people have mentioned above, it does look like I will most likely be building a small sealed box now and putting in some circuitry to help get a decent response at low frequencies. I have included graphs below for the box response for a sealed enclosure of around 9 liters (I reakon this should measure up to about 26 x 26 x 26 cm on the outside, fi I use 22mm MDF for constructuion, and take into acount the volume of the driver and a littel buit extra for the elcetronics).
If some one who knows a bit more about these things than I do (looks like just about anyone at the minute) could verify that these are close to what I should be able to achieve (in terms of the responses of the speaker and the size of the box, giving the neccessary internal volume) that would be great.
If some one who knows a bit more about these things than I do (looks like just about anyone at the minute) could verify that these are close to what I should be able to achieve (in terms of the responses of the speaker and the size of the box, giving the neccessary internal volume) that would be great.
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If you want a small sub, you should go for a twin coil woofer and put it into a 4th order bandpass box. You could go for a 6½-8 inch woofer from Monacor - look for the SPH TC series (twin coil).
I have a small sub (ca 45 l with a SPH 250-TC from Monacor and it is superb.
I think you could run it on WinISD
I have a small sub (ca 45 l with a SPH 250-TC from Monacor and it is superb.
I think you could run it on WinISD
Hi, I can't seem to find much information on the Monacor drivers in english anywhere unfortunately (just a few of their drivers at wilmslow audio, but nothing suitable, and my german is far from useful these days), but I think that if they would need a bandpass enclosure then they would probably go the way of the peerless driver and be a littel too complicated for what I am looking at now, but thanks anyway.
I agree with Mike. Don't be afraid to look into the XLS10 + passive (PR) combo. It is easier than building a ported enclosure. You will find that your f3 shoots much lower compared to a sealed enclosure and it's as easy as cutting a hole in one side for the PR (the enclosure size changes very little).
If you want to model a PR enclosure, then use Unibox (requires Excel). It's free and I'm also using it for my current XLS10 and PR design
Matt (Fifth Element) is using an XLS10 in a sealed config with eq, and he praises the XLS10. Also Macky888 has used the XLS10 with PR. It will be more expensive, but most people regard them as exceptional value.
You can build an enclosure with a PR in 25l if you wish! Which is in the same park as the REL unit mentioned earlier I think.
You can also put the PR on any side. Placing it opposite has a slight advantage, and two PR's opposite each other has even more potential for cancelling vibration although costs go up.
Do a search for XLS10 in this forum and you will find a lot of discussions about this driver.
If you want to model a PR enclosure, then use Unibox (requires Excel). It's free and I'm also using it for my current XLS10 and PR design
Matt (Fifth Element) is using an XLS10 in a sealed config with eq, and he praises the XLS10. Also Macky888 has used the XLS10 with PR. It will be more expensive, but most people regard them as exceptional value.
You can build an enclosure with a PR in 25l if you wish! Which is in the same park as the REL unit mentioned earlier I think.
You can also put the PR on any side. Placing it opposite has a slight advantage, and two PR's opposite each other has even more potential for cancelling vibration although costs go up.
Do a search for XLS10 in this forum and you will find a lot of discussions about this driver.
bigparsnip said:
Information:
in english
this was a search on subwoofers - you could search for high-tech subwoofers too.
buying possible from:
here
Hi, what I meant by this was that I didn't have any idea of how the passive radiator would model, and how the parameters for it would compare to a port in any given enclosure, so I would have had no idea what the sub would be like befre I built it. But, I guess the unibox link that Vakesh kindly posted helps me out there and will make this worth looking into a bit more as I will be able to see what effect the PR will have.
And medum, thanks for the links, I will have another look at those drivers in a bit as well and see what I cna possibly achieve with them.
Ok, I have just had a quick look at the XLs 10 using unibox and the passive radiator designs and it looks like in a small ish enclusure you can get 12dB down at about 25Hz, but the -3dB is all the way up at 74Hz. And although it does look possible to get down to about 20Hz at only -6dB with a cabinet volume of around 30L I'm not sure how the overall thing will sound, as the response isn't particurlaly flat over the whole of the range I would expect to be using it on.
Any suguestions on what this may sound like, or if there is any way to get round this?
Any suguestions on what this may sound like, or if there is any way to get round this?
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At first glance the predicted FR doesn't look too appealing, but...
f3 is calculated as 3db down from the peak, which in this case starts dropping at ~300Hz (which is much higher than you wil probably xover), so don't worry about the figure too much - The shallow roll off rate illustrated in the graph tells a better story. Then factor in room gain and you will have an in-room response much closer to flat (and probably much better than systems designed with anaechonic flat FR) with maybe 106+db SPL at 25Hz within xmax. That's not too shabby for a 10" driver.
f3 is calculated as 3db down from the peak, which in this case starts dropping at ~300Hz (which is much higher than you wil probably xover), so don't worry about the figure too much - The shallow roll off rate illustrated in the graph tells a better story. Then factor in room gain and you will have an in-room response much closer to flat (and probably much better than systems designed with anaechonic flat FR) with maybe 106+db SPL at 25Hz within xmax. That's not too shabby for a 10" driver.
Ok, seen as this seems to be heading away from the little tangband now, can people please tell me where I can get the XLS 10's from at a decent price. I have seen the drivers at one place for about £90, but I can't seem to find the passive one anywhere in the UK and have no idea how much it will cost at the moment.
Also, I take it from your commet above Vikash, that things should be fine with the slightly rissing response towards the higher end of the subs range (as most of this will be gone after the crossover anyway).
Also, I take it from your commet above Vikash, that things should be fine with the slightly rissing response towards the higher end of the subs range (as most of this will be gone after the crossover anyway).
Thanks for that, I was obviously being a bit stupid not to be able to find that one. Anyway, the spects on this are a little different from the ones on the peerless page, so I have included an updated response plot below, which does look prommising, I guess.
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Are you thinking one or two passives? Now this is the question that's got me stumped at the moment...
And don't forget to play around with the passive mass (mmp parameter) to change the tuning. The XLS10 PR has a m5 thread on the back for you to add more mass if you wish. Off couse the standard 400g will suffice in many situations, but it's something else to play around with. I think you can safely add up to 200g making 600g total weight.
You can see my results of running-in and T/S measurements of the 830452 here.
And don't forget to play around with the passive mass (mmp parameter) to change the tuning. The XLS10 PR has a m5 thread on the back for you to add more mass if you wish. Off couse the standard 400g will suffice in many situations, but it's something else to play around with. I think you can safely add up to 200g making 600g total weight.
You can see my results of running-in and T/S measurements of the 830452 here.
Hi, if I do go with the XLS 10 it will just be with one passive; this was supposed to be a little sub project after all, and I'm sure the XLS 10 will push it past what I was aiming for. But I guess you can't argue with a useable response down to 20Hz when it should still come in at only about 30L. Anyway the one I have seen, which has a starting mass of only 265g (I will probably have a bit more play about with this, but I don't have a huge amount of free time right now, as I'm right in the middle of sitting my finals at uni) will brobably be the starting point from which I can build on.
Am I right though, in assuming that the extra mass that you can add will damp down the response of the passive unit a bit, as well as lowering the frequency at which it will be opperating? So, by adding the mass, the system as a whole may start to roll off a little sooner, but go down that bit further because the region where you get extra gain from the passive will be lower down?
edit:
Just a quick nose, but it doesn't state on your site yet what sort of enclosure size or shape you are aiming for with this yet, and I was just curious on what your take on a decent cabinet design for this would be.
Am I right though, in assuming that the extra mass that you can add will damp down the response of the passive unit a bit, as well as lowering the frequency at which it will be opperating? So, by adding the mass, the system as a whole may start to roll off a little sooner, but go down that bit further because the region where you get extra gain from the passive will be lower down?
edit:
Just a quick nose, but it doesn't state on your site yet what sort of enclosure size or shape you are aiming for with this yet, and I was just curious on what your take on a decent cabinet design for this would be.
I'm toying with ideas at the moment, but will probably go for 25 to 30 litres if I settle on one passive (with 400g mmp), or up to 40 litres with two passives. Enclosure will be a cube regardless (most probably) with drivers on opposite sides.
The following threads may be of interest
http://www.diyaudio.com/forums/showthread.php?s=&threadid=30038&highlight=
http://www.diyaudio.com/forums/showthread.php?s=&threadid=30314&highlight=
I'll have to check this out...
The following threads may be of interest
http://www.diyaudio.com/forums/showthread.php?s=&threadid=30038&highlight=
http://www.diyaudio.com/forums/showthread.php?s=&threadid=30314&highlight=
I got mine from BK Elec and I thought it was 400g to start with.
I'll have to check this out...In the models I've done so far, I haven't really needed to add mass if there's only 1 passive (again, I'm assuming my PR is 400g to begin with). Only when I model with two do I find it useful to add mass to get a tuning I like.
Well, after a bit more ponedering it looks like I will be ordering up one of these drivers and a single passive radiator at some point in the next month or so to try my hand at building something that will probably end up being fairly similar to Vikash's description of his own project. A cube of about 20-30L with one driver, one pasive and a built in amp and low pass filter circuit to match up to me main speakers.
One this point (after all of the quick advice I have recieved so far) are there any special types of matching filter (to cut off the high frequency response of the driver) that can be constructed that allow easy variaton of the cut off frequency? Or should I just build myself a variable VCVS filter with variable gain to attempt to do the job?
One this point (after all of the quick advice I have recieved so far) are there any special types of matching filter (to cut off the high frequency response of the driver) that can be constructed that allow easy variaton of the cut off frequency? Or should I just build myself a variable VCVS filter with variable gain to attempt to do the job?
I made PCBs for a 2nd-order and 4th-order variable low-pass filter. The 4th-order one uses 2 dual pots (or 1 quad - hard to find) and you can select between 2nd-order or 4th-order with a switch.
I think I have a spare board of each type laying around if you want it. Maybe even with components already on (and suitable for your application), too.
I'd be interested in what you propose for a VCVS filter
I think I have a spare board of each type laying around if you want it. Maybe even with components already on (and suitable for your application), too.
I'd be interested in what you propose for a VCVS filter
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