Small subwoffer questions
Hi, I have recently been looking at building myself a small sub to go with my bookshelf speakers untill I move into somewhere I can fit some propper speakers. However, I have mainly just managed to confuse myself with all of the options (or lack of) for trying to find an eight inch sub that would be suitable for music (obviously it will get used for films too, but most of the time it would be my music playing through it). The nicest looking driver I have come up with so far is the Tang Band W8-740c which I should be able to get shiped to the UK for about £70.
I put the basic specifications for this driver into WinISD this afternoon and it produced a nominaly 9 litre box (about 0.33 cu ft. I think) with a -3dB point of around 44Hz (see the graph below). Whilst this is obviosly going to be an improvement over my curent bookshelves, I would appreciate it i someone could confirm that this would be an achievable goal with the unit in quiestion.
What would be even better though, is if someone out there knows of another driver (I did see a pearless model, the X:S10 I think which people have be talking about, but haven't modeled it yet) of around the same size, which I could put into an enclosure of no more than 30cm square on all sides (about 1cu ft.) to get a better low end response (possibly down to around 30Hz if this is achievable in such a small box without going for big drivers).
Anyway, any ideas people out there have, or links to information about similar projects then I would love to know.
Anderw.
Hi, I have recently been looking at building myself a small sub to go with my bookshelf speakers untill I move into somewhere I can fit some propper speakers. However, I have mainly just managed to confuse myself with all of the options (or lack of) for trying to find an eight inch sub that would be suitable for music (obviously it will get used for films too, but most of the time it would be my music playing through it). The nicest looking driver I have come up with so far is the Tang Band W8-740c which I should be able to get shiped to the UK for about £70.
I put the basic specifications for this driver into WinISD this afternoon and it produced a nominaly 9 litre box (about 0.33 cu ft. I think) with a -3dB point of around 44Hz (see the graph below). Whilst this is obviosly going to be an improvement over my curent bookshelves, I would appreciate it i someone could confirm that this would be an achievable goal with the unit in quiestion.
What would be even better though, is if someone out there knows of another driver (I did see a pearless model, the X:S10 I think which people have be talking about, but haven't modeled it yet) of around the same size, which I could put into an enclosure of no more than 30cm square on all sides (about 1cu ft.) to get a better low end response (possibly down to around 30Hz if this is achievable in such a small box without going for big drivers).
Anyway, any ideas people out there have, or links to information about similar projects then I would love to know.
Anderw.
Attachments
Hi, I have just tried to model a speaker with the Peerless XLS 10 driver, and either I have put the deatails of this into WinISD wrong (very likely, as this is only the second time I ever tried using this program) or this driver isn't quite as prommising as I though (have a look at the response I got out below).
If someone could please tell me where I have gone wrong here, or tell me why this driver isn't quite up to what I was expecing that would be great
If someone could please tell me where I have gone wrong here, or tell me why this driver isn't quite up to what I was expecing that would be great
Attachments
Regarding the Tang Band read this thread http://www.diyaudio.com/forums/showthread.php?s=&threadid=26845
Post #10 is by RAW who builds these subs for CSS. http://www.creativesound.ca/
Post #10 is by RAW who builds these subs for CSS. http://www.creativesound.ca/
Hi, I did see those earlier on whilst searching, however, they are a little bigger than I would idealy like mine to be. I guess my ideal comparison would be the REL quake which comes in at a fairly tiny 10 x 11.5 x 10.5 inches (including the feet) with a selaed 8 inch design (with a claimed in room response of -6dB at 24Hz?). The only probelm is when I try sealed boxes, I seem to get a very high roll off frequency which I'm not too sure how to cancel out easily.
I guess I could try and go for some sort of electronic equalisation to boost the output at lower frequencies, but I'm guessing that this is quite difficult to do right (It would be nice if I was proved wrong though).
I guess I could try and go for some sort of electronic equalisation to boost the output at lower frequencies, but I'm guessing that this is quite difficult to do right (It would be nice if I was proved wrong though).
You are using WinISD which does not take into account room gain which can add quite abit in the bottom end. As far as boosting the bottom end of a sealed sub, there is a circuit called a linkwitz transform. Basic explaination is here.http://www.trueaudio.com/st_lkxfm.htm
I guess this is a bit of an easy (dumb) question, but what values do I need to put into the sheet on that page for f(0), Q(0), f(p) and Q(0)? (and K as well I guess). Also, is there anything out there that will help me look at the effects of room gain on the sub (although, I will probably be moving again in a few months, so this may not be all that useful as I'm not sure on the size of the room I'm in next year yet).
Mikey p said:
I think the true problem is the tiny volume given by WinISD: 5.2 liters for a 10" sub! (Port dimensions must be unreasonably large.) Remember, by default WinISD attempts to model the enclosure with the *deepest* bass, not the lowest F3. Have a look at Peerless application notes for XLS subs to get started.
This is what the LDSG has to say about the XLS 10: "Most who've used it have had success using its matching 830481 10", 400 gram PR in a 35 liter (1.24 cu.ft.) box. This yields an EBS alignment with F3=78 Hz, but which is only 7 dB down at 20 Hz."
Good luck.
Hm, 7dB down at 20 Hz does sound rather appealing, but that is starting to push towards big box teritory, once you have the volume of the two peerless units in there as well as an amp and the port tubes. I guess I may have to just stick with the Tang Band for now, and see if I can come up with something to give it a good low end in a sealed cabinet with a linkwitz transform. I guess I will have a bit more play about in the next few days and see if I can come up with anything (but please if anyone can help me out with those values in the excel sheet, that would be great too).
bigparsnip said:
It's very easy what's going wrong:
WinISD can't simulate the peerless XLS, because the XLS is designed for a passive radiator.
Using the XLS for a vented/bandpass/closed does not work !
It has an extrem low QTS.
For the XLS-10 you need a 30Liter enclosure with the passive
radiator. Peerless calls it "Slave". This means you have two
drivers in the box, the XLS-10 itself and the slave.
Then you get frequencies down to 11 hz.
At this moment i don't know any software simulating this kind
of enclosure.
Mike
Ah, fair point I hadn't thought about that, but is there any particular way in which the two need to ba aranged, for example, would it be posible to mount them on opposite faces of a smallish cube to give a decent result, or would this cause problems with the waves in the box and be a bit of a waste of the slave unit?
MikeB said:
In fact, an XLS 10 with a port tube DOES work. But since the volume is too big for a small system...
I'd suggest the Apex Jr Super 8" subwoofer. This is what the LDSG has to say about this driver: "A recent addition is the Super 8" compact subwoofer. A high-Q design well suited to sealed box or dipole mounting, it's impressed all who've heard it."
I have seen a configuration with the 2 devices in opposite
directions, but it seems to be wrong.
A good example of how to implement the XLS is here:
http://www.lautsprechershop.de/hifi/bau_xa10.htm
Mike
directions, but it seems to be wrong.
A good example of how to implement the XLS is here:
http://www.lautsprechershop.de/hifi/bau_xa10.htm
Mike
How on earth would you model this as a port though, as surely, just matching up the volumes of the two won't help as there is the extra suspension and mass to think about? But, looking at the link from MikeB above, I do think that the peerless is probably a bit much for my first project, and will probably build into something a bit bigger than I want (or need) as the moment, as I'm guessing you will still need a fairly large volume to get the best from the driver, even if it were mounted opposite the slave in a cubed box.
Ok, it has to mate with 'bookshelf' speakers, and it has to be small. So I'd say it ought to be sealed, for two or three simple reasons...
1 - sealed may match the quality of bass from the small speakers better than ported (passive radiator)
2 - small size suggests convenient placement which means most potential room gain, which may perhaps match the roll-off of a sealed box speaker better
3 - it's harder to go wrong, easier and cheaper (no radiator or ports to buy and fit in)
4 - it probably doesn't need the extra several dbs of spl a ported design will give
5 - sealed may be about 1/2 the size of ported (I think that's normal)
1 - sealed may match the quality of bass from the small speakers better than ported (passive radiator)
2 - small size suggests convenient placement which means most potential room gain, which may perhaps match the roll-off of a sealed box speaker better
3 - it's harder to go wrong, easier and cheaper (no radiator or ports to buy and fit in)
4 - it probably doesn't need the extra several dbs of spl a ported design will give
5 - sealed may be about 1/2 the size of ported (I think that's normal)
Have a look at http://www.bkelec.com/
They claim to have a XLS10 in an 18 litre sealed box giving -6 dB @ 17 hz
Cheers steve
They claim to have a XLS10 in an 18 litre sealed box giving -6 dB @ 17 hz
Cheers steve
I recently completed a 12" sub in a sealed enclosure so far with good results.
For what you are trying to achieve an 8" driver in a sealed enclosure should work fine.
To get sub drivers to work below their resonant frequency read this http://sound.westhost.com/project48.htm , even though it applies to a 15" sub example.
As your box gets smaller you need to equalise the driver, feed it more watts and drive it harder to compensate for its natural rolloff. Using a Linkwitz Transform (LT) circuit achieves this. I have my LT PCB and will be trying it on my sub in the next few weeks.
If not an LT then choose a suitable long throw, low Fs 8" driver and model it using WinISD in the smallest sealed box that gives good response. Then put the box in the corner of your room and enjoy.
You could try modelling this driver.
http://www.adireaudio.com/diy_audio/drivers/adire/av8.htm
I have just used the adire DPL12 and it is great.
Howard
For what you are trying to achieve an 8" driver in a sealed enclosure should work fine.
To get sub drivers to work below their resonant frequency read this http://sound.westhost.com/project48.htm , even though it applies to a 15" sub example.
As your box gets smaller you need to equalise the driver, feed it more watts and drive it harder to compensate for its natural rolloff. Using a Linkwitz Transform (LT) circuit achieves this. I have my LT PCB and will be trying it on my sub in the next few weeks.
If not an LT then choose a suitable long throw, low Fs 8" driver and model it using WinISD in the smallest sealed box that gives good response. Then put the box in the corner of your room and enjoy.
You could try modelling this driver.
http://www.adireaudio.com/diy_audio/drivers/adire/av8.htm
I have just used the adire DPL12 and it is great.
Howard
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