OK, so I did some simulations,
If you use a 12L box (dunno that in cuft) which could be made approx 10 inch square I get a response -3dB at 20 Hz with a Q=0,577 box.
Components:
C1=2,7u
C2=0,068u
C3=0,42u
R1=7,22k
R2=108,5k
R3=47,2k
There you have it. Not impossible values and they should work just fine. Of course you could modify it a bit and put in standard E12 series values.
/Frez
If you use a 12L box (dunno that in cuft) which could be made approx 10 inch square I get a response -3dB at 20 Hz with a Q=0,577 box.
Components:
C1=2,7u
C2=0,068u
C3=0,42u
R1=7,22k
R2=108,5k
R3=47,2k
There you have it. Not impossible values and they should work just fine. Of course you could modify it a bit and put in standard E12 series values.
/Frez
That would be great
That kind of response would be great, and the size would be even better. However, a few questions, is that with a ported box, and would i need to stuff that box? That combination sounds like a winner. Anyways, i figured out the bass blockers, so its all good now. I think i will start to draw up plans over the break, purchase the stuff before the break ends, and have it finished by The end of january at the latest. Ill keep you guys posted.
Greg
That kind of response would be great, and the size would be even better. However, a few questions, is that with a ported box, and would i need to stuff that box? That combination sounds like a winner. Anyways, i figured out the bass blockers, so its all good now. I think i will start to draw up plans over the break, purchase the stuff before the break ends, and have it finished by The end of january at the latest. Ill keep you guys posted.
Greg
simple bass blockers
scroll down to the bottom of this page, and enter in your Impedence (4ohms?) and the freq. you want, and it'll tell you the value(s) you need.
http://www.soundillusions.net/modules.php?name=Content&pa=showpage&pid=51
I've got a Santa Cruz turtle beach and go digital out to my Musical Fidelity D/A, sound better than the CD's D/A for sure! (althoughI haven't A/B'd it vs. the Santa-Cruz's D/A's which are supposed to be decent....)
kingfootga said:
scroll down to the bottom of this page, and enter in your Impedence (4ohms?) and the freq. you want, and it'll tell you the value(s) you need.
http://www.soundillusions.net/modules.php?name=Content&pa=showpage&pid=51
I've got a Santa Cruz turtle beach and go digital out to my Musical Fidelity D/A, sound better than the CD's D/A for sure! (althoughI haven't A/B'd it vs. the Santa-Cruz's D/A's which are supposed to be decent....)
oh yeah...
back on topic:
with those $30 subs, have you considered going sealed, and with a clam-shell isobaric? the clam could be on the 'top' panel of the box... like a pyramid.
such a small cube- you're not likely to use it as an end-table anyway...
iso'ing will cut the Vas in 1/2, so you can get really small (or stay the same w/ a bigger perceived volume for a flatter curve and lower Qtc for your transform circuit)
I built a clam-shell iso w/ a pair of Image Dynamics drivers (a few years back when I drove a CRX and before I had a digital camera 🙁 ) and you can get the box- very very small- so small that you have to plan ahead on how to get yer tools in to secure the driver(s)!! (my gross box volume was .175 ft^3 for a Qtc of .65, or 4.95 L)
back on topic:
with those $30 subs, have you considered going sealed, and with a clam-shell isobaric? the clam could be on the 'top' panel of the box... like a pyramid.
such a small cube- you're not likely to use it as an end-table anyway...
iso'ing will cut the Vas in 1/2, so you can get really small (or stay the same w/ a bigger perceived volume for a flatter curve and lower Qtc for your transform circuit)
I built a clam-shell iso w/ a pair of Image Dynamics drivers (a few years back when I drove a CRX and before I had a digital camera 🙁 ) and you can get the box- very very small- so small that you have to plan ahead on how to get yer tools in to secure the driver(s)!! (my gross box volume was .175 ft^3 for a Qtc of .65, or 4.95 L)
What is the advantage to isobarik?
What is the advantage to making a system isobarik? what does the vas mean, and wont it decrease efficiency? Is there any way to compensat for it when planning a linkwitz transform? I just dont see the advantage to doing it that way.
Greg
What is the advantage to making a system isobarik? what does the vas mean, and wont it decrease efficiency? Is there any way to compensat for it when planning a linkwitz transform? I just dont see the advantage to doing it that way.
Greg
Re: What is the advantage to isobarik?
Like you said above: "and the size would be even better." (referring to another item, but states a design bene.)
the efficiency (assuming your amp can double when you add cut the Ohms in 1/2 via a parallel wiring structure) is null, b/c you're NOT doubling the Sd (or cone area) even tho you're throwing twice the power at the drivers. but w/ 8" subs, having to little power is usually not an issue.
The other disadvantage is 2x the driver cost, but $60 for 2 drivers ain't so bad.
so the benefits are: an even smaller box; the face-to-face arrangement uses a smaller air piston than the 'in-phase' when facing in the same direction; and some folks report that when face to face, the drivers can cancel some physical-movement induced distortion b/c when one is going back, the other forward, vice-versa.
About the Vas doubling, it's just a shortcut if your software doesnt' have an isobaric 'setting' just use one of the driver's sample specs, and cut the Vas in 1/2 (unless my memory is faulty)
kingfootga said:
Like you said above: "and the size would be even better." (referring to another item, but states a design bene.)
the efficiency (assuming your amp can double when you add cut the Ohms in 1/2 via a parallel wiring structure) is null, b/c you're NOT doubling the Sd (or cone area) even tho you're throwing twice the power at the drivers. but w/ 8" subs, having to little power is usually not an issue.
The other disadvantage is 2x the driver cost, but $60 for 2 drivers ain't so bad.
so the benefits are: an even smaller box; the face-to-face arrangement uses a smaller air piston than the 'in-phase' when facing in the same direction; and some folks report that when face to face, the drivers can cancel some physical-movement induced distortion b/c when one is going back, the other forward, vice-versa.
About the Vas doubling, it's just a shortcut if your software doesnt' have an isobaric 'setting' just use one of the driver's sample specs, and cut the Vas in 1/2 (unless my memory is faulty)
bought one sub.
alright, ive purchased only one sub🙁 (thats all the money i could spare) and a 150 watt plate amp ( the sub is rated at 120 rms, do you think i will be able to use more? cause i can easily use this amp for another project). Im planing to build a box that is 10" x 10" x 12.5" long out of 3/4" mdf. I think that will give me an internal vloume of about 10L? the amp is 2" deep. Now, how should i stuff the box? What is the best way to connect the linkwitz transform circuit? Im thinkin of unattaching the rca inputs, goin into the linkwitz, and then back into the amp. This will be so cool, a small box with (hopefully) big bass. Will the bass still be tight because it is in a sealed box, or will the linkwitz make it a bit looser ( it doesnt matter, i would just like to know)
Thanks so much, you guys have been a huge help.
Greg
Is that amp big enough?
alright, ive purchased only one sub🙁 (thats all the money i could spare) and a 150 watt plate amp ( the sub is rated at 120 rms, do you think i will be able to use more? cause i can easily use this amp for another project). Im planing to build a box that is 10" x 10" x 12.5" long out of 3/4" mdf. I think that will give me an internal vloume of about 10L? the amp is 2" deep. Now, how should i stuff the box? What is the best way to connect the linkwitz transform circuit? Im thinkin of unattaching the rca inputs, goin into the linkwitz, and then back into the amp. This will be so cool, a small box with (hopefully) big bass. Will the bass still be tight because it is in a sealed box, or will the linkwitz make it a bit looser ( it doesnt matter, i would just like to know)
Thanks so much, you guys have been a huge help.
Greg
Is that amp big enough?
You will find yourself running out of power. I would say use the 150-watt amp to drive a ported sub and use something bigger like the Parts Express 250-watt amplifier to drive a small LT like that. You need an amplifier that won't run out of power.
I am building a sealed 12" cube which will use the verson of the PE 250w plate amp that has the 6dB bass boost enabled to yield good low-frequency reproduction and an F3 of 25 Hz. Then I will save up to be able to put a 1-farad car-audio capacitor into the power supply for stiffening so it will have great transient response and as much reserve power as it will ever need. The Q of the closed box is right around 0.5 so it will be a transient-perfect subwoofer. I'm calling it "Presto". It should be able to deliver the right amount of bass to mate with my new MTM towers, whih will be assembled at about the same time.
As for the bass-blockers, PArts Express sells something called a bass blocker which is actually a capacitor which you wire in line with the speaker.
I am building a sealed 12" cube which will use the verson of the PE 250w plate amp that has the 6dB bass boost enabled to yield good low-frequency reproduction and an F3 of 25 Hz. Then I will save up to be able to put a 1-farad car-audio capacitor into the power supply for stiffening so it will have great transient response and as much reserve power as it will ever need. The Q of the closed box is right around 0.5 so it will be a transient-perfect subwoofer. I'm calling it "Presto". It should be able to deliver the right amount of bass to mate with my new MTM towers, whih will be assembled at about the same time.
As for the bass-blockers, PArts Express sells something called a bass blocker which is actually a capacitor which you wire in line with the speaker.
Well, the sub will be here on the 30th and ive devoted the amp to a massive sub for our theater downstairs. Now, since im always short on cash, a friend heard what i was doing, and offered me a 250watt car amplifier for $20. Naturally, i bought it and am now trying to figure out how to power it. What power sources can i use for it? I have several computer style power supplies each with about 350watts each. Can i use those? I think they should have a very stable power output, so i doubt they will induce any noise. Will that be enough power for the amp? That's all of my questions for now, so thanks for your help.
Greg Lightfoot
If im online on AIM feel free to IM me at KingFootGA if u wish to.
Greg Lightfoot
If im online on AIM feel free to IM me at KingFootGA if u wish to.
pc powersupplies...
i use an old AT-stlyle one for 'bench testing' car amps just to make sure they work (AT's have the 'hard-on/off' switch)
the 350 watt ratings is at 5v and 12v (some at 3.3v)- so you won't get all of that wattage into 12v (ie: it won't do 29 Amps of current into the 12v lines)
there should be an amperage rating on the side of the PS- and it WILL dissapoint you.
I had a 500 watt old AST server PS that would power a CHEAP legacy 75w x 2 amp, reasonably well, but not my 200x1 Zapco (into a 4 ohm load) the amp wouldn't clip and the PS started making noises...
lotsa folks have these questions on car stereo boards- and the consensus is: an AC -> DC step-down transformer w/ the current capacity to handle any real wattage is more expensive than a /real/ home amp.
You can use it to play with, but don't expect to run a sub amp w/ one.
sorry
i use an old AT-stlyle one for 'bench testing' car amps just to make sure they work (AT's have the 'hard-on/off' switch)
the 350 watt ratings is at 5v and 12v (some at 3.3v)- so you won't get all of that wattage into 12v (ie: it won't do 29 Amps of current into the 12v lines)
there should be an amperage rating on the side of the PS- and it WILL dissapoint you.
I had a 500 watt old AST server PS that would power a CHEAP legacy 75w x 2 amp, reasonably well, but not my 200x1 Zapco (into a 4 ohm load) the amp wouldn't clip and the PS started making noises...
lotsa folks have these questions on car stereo boards- and the consensus is: an AC -> DC step-down transformer w/ the current capacity to handle any real wattage is more expensive than a /real/ home amp.
You can use it to play with, but don't expect to run a sub amp w/ one.
sorry
I have a 250watt AT PC suppy that will give 12amps on the 12volt rail.. highest you will get for a 250watt...
SkinnyBoy said:
so you're at about 58% efficiency on the 12v line.... (144/250)
if his supplies fare as well as yours (mine did not, I got at/under 50% of the rated 'max power') he can 'hope' to get ~203 watts...
KingF: who knows- you 'have a couple' lying around, blow one and let us know how much current it was putting out (w/ a 'peak' reading on your ammeter 😉 )
maybe i will.....
well, i got like 10 of them, i think, so what will it hurt😀 . but anyways, i think that after i build this sub, i might buy another of those drivers and put it into a tl sub, that would be cool. These subs seem to have lots of good applications, and they have 16mm of excursion while only costing $30, so its gonna be hard to resist..... I wonder what else these subs will be good for? any ideas?
Greg
well, i got like 10 of them, i think, so what will it hurt😀 . but anyways, i think that after i build this sub, i might buy another of those drivers and put it into a tl sub, that would be cool. These subs seem to have lots of good applications, and they have 16mm of excursion while only costing $30, so its gonna be hard to resist..... I wonder what else these subs will be good for? any ideas?
Greg
speaker in-box displacment
Hey guys,
I have also purchased the Peerless 831858 from madisound. Does anyone know what volume the speaker will take up inside an enclosure so I can add to the total volume of my box to use the linkwitz transform circuit?
Opie
Hey guys,
I have also purchased the Peerless 831858 from madisound. Does anyone know what volume the speaker will take up inside an enclosure so I can add to the total volume of my box to use the linkwitz transform circuit?
Opie
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