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Old 26th April 2004, 08:32 AM   #21
Did it Himself
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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.
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Old 26th April 2004, 08:45 AM   #22
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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.
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File Type: gif sealed box - 1.gif (25.7 KB, 366 views)
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Old 26th April 2004, 08:47 AM   #23
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Oh, I forgot to mention that with the box and driver as they are, it would appear to give -3dB at 70Hz, and -5dB (the value that looks like it should be put into the linkwitz spreadsheet) at about 53Hz.
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File Type: gif linkwitz plot - 1.gif (15.1 KB, 346 views)
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Old 26th April 2004, 09:04 AM   #24
medum is offline medum  Denmark
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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
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Old 26th April 2004, 10:04 AM   #25
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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.
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Old 26th April 2004, 10:12 AM   #26
MikeB is offline MikeB  Germany
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Hi !

I don't understand what you mean with too complicated,
if you build the peerless, you just make 2 holes of the same
size, one for the slave and the other for the XLS.
Thats even more simple then vented...
Adding a linkwitz or stuff like that seems even more complicated
to me ?

Mike
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Old 26th April 2004, 11:02 AM   #27
Vikash is offline Vikash  United Kingdom
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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.
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Old 26th April 2004, 11:02 AM   #28
medum is offline medum  Denmark
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Quote:
Originally posted by bigparsnip
Hi, I can't seem to find much information on the Monacor drivers in english ........
Information:
in english

this was a search on subwoofers - you could search for high-tech subwoofers too.



buying possible from:
here
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Old 26th April 2004, 12:00 PM   #29
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Quote:
Hi !

I don't understand what you mean with too complicated,
if you build the peerless, you just make 2 holes of the same
size, one for the slave and the other for the XLS.
Thats even more simple then vented...
Adding a linkwitz or stuff like that seems even more complicated
to me ?

Mike
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.
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Old 26th April 2004, 12:45 PM   #30
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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?
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File Type: gif pr response peerless xls 10 - 30l.gif (48.3 KB, 281 views)
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