Hello,
I'm new to the forum, but have been reading threads here and there for some time.
I'd like to build a pair of subs (that double as 30" stands) for my VMPS 626Rs.
I very much like the passive-radiator mentality of the VMPS subs, and while they are not exceptionally expensive, they are out of my budget. I would not be willing to spend more than $350 US (on the high end) on drivers and radiators.
This is a strictly 2-channel hi-fi music system, but I want to feel the low brass and low strings and rock percussion and synths. And it needs to be clean...not like a 17 year-old's Honda Civic kicker box.
Is what I'm asking for possible? Or am I better off spending my $350 on one VERY good single driver?
Thanks!
I'm new to the forum, but have been reading threads here and there for some time.
I'd like to build a pair of subs (that double as 30" stands) for my VMPS 626Rs.
I very much like the passive-radiator mentality of the VMPS subs, and while they are not exceptionally expensive, they are out of my budget. I would not be willing to spend more than $350 US (on the high end) on drivers and radiators.
This is a strictly 2-channel hi-fi music system, but I want to feel the low brass and low strings and rock percussion and synths. And it needs to be clean...not like a 17 year-old's Honda Civic kicker box.
Is what I'm asking for possible? Or am I better off spending my $350 on one VERY good single driver?
Thanks!
Hello.
I like the bass produced by a sealed box the best, and it sounds like you do too. You say 30" high , but how wide? How deep? How low do you want the bass to go? Not a lot of low bass in recorded music. What's the low freq. rolloff of your main speakers? Your budget is low, but do-able.
I like the bass produced by a sealed box the best, and it sounds like you do too. You say 30" high , but how wide? How deep? How low do you want the bass to go? Not a lot of low bass in recorded music. What's the low freq. rolloff of your main speakers? Your budget is low, but do-able.
The 626R dimensions are as follows: 13 1/2" deep x 10 1/4" wide x 23 3/4" tall, with 7/8" radius vertical edges (horizontals are square). Much like the one pictured in the attached image.
However, as long as it doesn't negatively impact the planer qualities of the 626Rs, I don't mind either going wider (than 10 1/4") with the subs or side-loading the drivers.
I'm pretty open to ideas, but I'd like to concentrate around the passive-radiator model (if practical). Also, my $350 budget is just for drivers.
VPMS rates the speaker at 42 Hz-25 kHz +0/-3 dB. I cannot verify this.
I'd like the sub to go down to 20 Hz or lower, but to also take some of the stress off of the woofers in the 626Rs and let them sing a bit.
Any thoughts?
Thanks!
However, as long as it doesn't negatively impact the planer qualities of the 626Rs, I don't mind either going wider (than 10 1/4") with the subs or side-loading the drivers.
I'm pretty open to ideas, but I'd like to concentrate around the passive-radiator model (if practical). Also, my $350 budget is just for drivers.
VPMS rates the speaker at 42 Hz-25 kHz +0/-3 dB. I cannot verify this.
I'd like the sub to go down to 20 Hz or lower, but to also take some of the stress off of the woofers in the 626Rs and let them sing a bit.
Any thoughts?
Thanks!
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torontodude said:
We all like the sub to go down to 20Hz, but thats expensive unless you resort to some allignments such as EBS or bandpass.
Here is a website with some good info on a sub construction with a passive radiator.
http://www.hardwareanalysis.com/content/article/1789/
Need to keep in mind that the cost of drivers and PR's for 2 of these exceeds your budget.
Another though is how you will drive them? 20hz at good spl requires a lot of power.
Here's a few kits that use PR's that could suit your needs:
http://www.solen.ca/sxxls.htm
What about Seas L26RFX/P?
I was thinking about the driving them with one or two Reckhorn A-400s, but I may change my mind depending on what's available on e-bay when it comes time!
Thanks for the links. I'm not so interested in kits themselves, but it certainly gives me some ideas.
Any thoughts on brands or models that offer excellent value? I've hears that Seas are better than one might expect looking at their price.
Thanks again!
I was thinking about the driving them with one or two Reckhorn A-400s, but I may change my mind depending on what's available on e-bay when it comes time!
Thanks for the links. I'm not so interested in kits themselves, but it certainly gives me some ideas.
Any thoughts on brands or models that offer excellent value? I've hears that Seas are better than one might expect looking at their price.
Thanks again!
torontodude said:
The Seas is a beautiful driver. It's a woofer, not really a sub, that would give superlative preformance is a sealed 3 way. T/S specs say it's better in a sealed box. Could be used in a vented box ~ 140 litres with an F3 at 26Hz. That's pretty big, and vented(yuck).
Also fairly expensive at $160.00.
For $70.00 you could get equal bass response with a smaller vented box(85 L) from the Peerless S263SWR3908. The SWR stands for subwoofer. Higher efficiency by 2dB, higher power handling, longer excursion, not as pretty though
Another option is to use a small long throw with a bigger passive radiator. This could keep your cost down, get the box size down, and give good performance. I have been thinking about a sub arrangement where the woofer is mounted behind the passive radiator in a compound type configuration. Would be interesting to try.
torontodude said:
Congrats! Are they new? How much were they?
Did you read Sanders article that I posted earlier? It details a sub using those drivers:
http://www.hardwareanalysis.com/content/article/1789/
Pay particular attention to what he says about the weight of the PR versus freq. response. You can play with box dimensions up or down by a small margin to get the right size you are looking for.
Are they new? How much were they?
They're not new, but are fairly new and fully working (or so I'm told). They cost me $97 US each. So not cheap, but much less than new.
I did read (although not thoroughly yet) the link you posted previously. That's what prompted me to get these drivers.
Are there any disadvantages in side-loading these drivers, so that they face each other (maybe with the passives facing outward), so I can maintain the width of my 626Rs of 10 1/4"? Or am I better off making the boxes wider and front loading or down firing.
VMPS has their subs with the driver on the front and the passive down firing, but the Seas catalogue says that their passive should be mounted vertically. Would this also apply to the Peerless?
Also, has anyone ever replaced the dust-cap on a XLS10 with a phase plug? Or is that a topic in and of itself?
Thanks again!
I did read (although not thoroughly yet) the link you posted previously. That's what prompted me to get these drivers.
Are there any disadvantages in side-loading these drivers, so that they face each other (maybe with the passives facing outward), so I can maintain the width of my 626Rs of 10 1/4"? Or am I better off making the boxes wider and front loading or down firing.
VMPS has their subs with the driver on the front and the passive down firing, but the Seas catalogue says that their passive should be mounted vertically. Would this also apply to the Peerless?
Also, has anyone ever replaced the dust-cap on a XLS10 with a phase plug? Or is that a topic in and of itself?
Thanks again!
I am wondering about using these drivers for two t-line subs to save myself $200 for the passives. Something like these (but with single drivers):
http://www.teresaudio.com/haven/subs/subs.html
But I have never heard a t-line sub before. Any thoughts/comparisons to the PR idea?
http://www.teresaudio.com/haven/subs/subs.html
But I have never heard a t-line sub before. Any thoughts/comparisons to the PR idea?
torontodude said:
A good choice for different drivers, I'm afraid. The ones you have are recommended suitable only with passive rads. IMO the way a well made PR sounds is similar to a TL.
The t-line is a good allignment for a sub giving clean deep bass if done correctly. Here's a pic of an experimental one I built from a toilet partition divider that I got from one of my sites for free. It's 1 inch thick particle board with formica on both sides. It sounds amazing, really getting everything possible out of the 12" sub.
PS: It's the big ugly thing in the corner.
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I find that really interesting (and slightly disturbing), that a speaker can be better suited for a PR or t-line. I would have thought that if your diver has to move a 400 g passive, then it would be a simple task of figuring out the column of air required to equal 400 g.
A quick search shows that air is ~ 1.3g/L, so (if that's right (I've also seen 1.19g/L)) I would need a column that is 307.7 L, or 0.3077 cu. meter. Which would have me building a r=0.15m x h=4.35m cylinder, or some other combination that also adds up to 400g of air.
I guess the problem comes in when you need a 1/4 wavelength in tube length...so if I were going for about h=1.5m , I would need a tube that's r=0.255m. Not too hard to find or make...
So where does the problem come in, or am I totally backwards about this stuff?
Wow...don't you love the stupid questions of a newbie who knows just enough to be dangerous?!?!?
Thanks again!
A quick search shows that air is ~ 1.3g/L, so (if that's right (I've also seen 1.19g/L)) I would need a column that is 307.7 L, or 0.3077 cu. meter. Which would have me building a r=0.15m x h=4.35m cylinder, or some other combination that also adds up to 400g of air.
I guess the problem comes in when you need a 1/4 wavelength in tube length...so if I were going for about h=1.5m , I would need a tube that's r=0.255m. Not too hard to find or make...
So where does the problem come in, or am I totally backwards about this stuff?
Wow...don't you love the stupid questions of a newbie who knows just enough to be dangerous?!?!?
Thanks again!
torontodude said:
There's logic in your thinking: mass of air=mass of PR cone. The problem is, in an open ended TL the column of air is not being driven like piston. In a closed ended TL the column of air is not driven at all. The XLS subs were purpose designed for PR's.
That's not to say they will not work in another box type, just that performance will suffer.
I will quickly run a sim with Martin King's TL models and see what the results are. Will check back with the results.
PS: 300 litres is over 10 cubic feet! thats a closet!
If my calculations are right, a 1.5 m x 0.51 m tube would do the trick.
But I was unaware that a t-line was closed at the end. Are they all like that?
That would certainly change everything...
It might be just too big anyway, but I'm still interested! LOL
I'd be very tempted to go out and buy a 1.5 m x .5 m length of Sonotube, mount the driver to one end and see what happens!
But I was unaware that a t-line was closed at the end. Are they all like that?
That would certainly change everything...
It might be just too big anyway, but I'm still interested! LOL
I'd be very tempted to go out and buy a 1.5 m x .5 m length of Sonotube, mount the driver to one end and see what happens!
torontodude said:
Isn't that EXACLTY how it's being driven?
Air is not dense enough to act as a piston. It expands and contracts, it is easily compressed.
Example: As the cone moves forward, it sucks air with it. The air in the column, not being a cohesive mass, shows less movement at the end. As the woofer move back, the air directly behind the cone gets compressed. It then expands and acts on the column of air, again with less effect at the end. The column is acting as a cushion, a shock absorber, for the cones movement.
The XLS drivers were specifically designed for passive radiator enclosures. They have rock bottom Qts. On the other hand, a driver with a high Qts is best suited to an open box or infinite baffle arrangement.
I ran a TL simulation with less than great results: Line length of 110 inches, 2 x SD cross sectional start, 4 to 1 taper. This gave a 5 dB peak above Fs. Of course, this is a large box, even with 2 folds.
If it were me, for the extra $200.00, I'd take full advantage of all the benefits this driver has to offer: excellent low bass response, small box size, and the knowledge that you didn't cheap out and settle for less than best results possible.
Good luck.
If it were me, for the extra $200.00, I'd take full advantage of all the benefits this driver has to offer: excellent low bass response, small box size, and the knowledge that you didn't cheap out and settle for less than best results possible.
Good luck.
I agree completely!
Thanks for running that for me.
Something that I asked earlier that must have been missed in all the clutter was about driver placement. Are there any disadvantages in side-mounting these drivers, so that they face each other (maybe with the passives facing outward), (or vice versa) so I can maintain the width of my 626Rs of 10 1/4"? Or am I better off making the boxes wider and front mounting or down firing them. VMPS mounts the active on the front and the passive on the bottom making a it a down-firing slot-loaded passive.
Thanks for running that for me.
Something that I asked earlier that must have been missed in all the clutter was about driver placement. Are there any disadvantages in side-mounting these drivers, so that they face each other (maybe with the passives facing outward), (or vice versa) so I can maintain the width of my 626Rs of 10 1/4"? Or am I better off making the boxes wider and front mounting or down firing them. VMPS mounts the active on the front and the passive on the bottom making a it a down-firing slot-loaded passive.
torontodude said:
Gee, I could have sworn I made a reply to that post. Maybe I posted it somewhere else, in my confusion
I had a sonosub a few years ago, that down fired. I hated it. There's something that does not sound right about it, maybe to much "ground effect" or maybe my own biases. Also, some drivers can suffer from sag over time, especially the ones with heavy cones.
Side firing is good when there are no obstruction too near the drivers(or PR's).
Solid box construction is crucial, as it contains the fluid that makes this mechanism work - air.
For good tips on box construction (modest bow), see this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=98592
I'm in there, with one of my creations.
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