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Old 26th April 2004, 12:57 PM   #31
Vikash is offline Vikash  United Kingdom
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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.
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Old 26th April 2004, 02:24 PM   #32
Stocker is offline Stocker  United States
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Quote:
Originally posted by MikeB

At this moment i don't know any software simulating this kind
of enclosure.

Mike
I have a VERY old DOS program that lets you model passive radiator boxes...IIRC it's called BPBOXSPC.exe...

if you don't mind not using a mouse, it's actually pretty versatile.
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Old 26th April 2004, 05:54 PM   #33
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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).
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Old 26th April 2004, 06:14 PM   #34
stee-b is offline stee-b  United Kingdom
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Bk electronics again! Look under modules and hybrids.Peerless XLS10P 32.90 + 8 delivery.
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Old 26th April 2004, 06:23 PM   #35
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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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File Type: gif pr response peerless xls 10 - 30l 2.gif (48.7 KB, 266 views)
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Old 26th April 2004, 07:38 PM   #36
Vikash is offline Vikash  United Kingdom
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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.
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Old 26th April 2004, 09:41 PM   #37
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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.
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Old 26th April 2004, 10:46 PM   #38
Vikash is offline Vikash  United Kingdom
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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
Room gain
Sand sandwich

Quote:
Anyway the one I have seen, which has a starting mass of only 265g...
I got mine from BK Elec and I thought it was 400g to start with. I'll have to check this out...

Quote:
Am I right though, in assuming that the extra mass that you can add will damp down the response...
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.
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Old 27th April 2004, 11:43 PM   #39
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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?
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Old 28th April 2004, 07:25 AM   #40
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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
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