funny sub challenge

[CAS]

A buddy of mine wants me to put together a sub for him for around $50. Seems Parts Express has a 25 watt amp for around $31.00 and a dayton 10" for $25, but it's a DVC so I'll have to look for a single voice coil.

I've got the other materials so I'm mostly looking to see if I can improve upon a sad sony HTIB sub for $50.00.

Any compnent suggestions? Can't find anything on radioshack.com

[michael hurd]

E-bay?

[michael hurd]

$50 is a little cheap, can you stretch the budget at all?

http://cgi.ebay.com/p1000-JBL-10-SUBWOOFER-P-1000-POWER-SERIES_W0QQitemZ5827221579QQcategoryZ3291QQrdZ1QQcmdZViewItem

I have 3 of these, not bad, a little over 7mm x-max, I would build a vented enclosure to wring the maximum from them.

[sfogg]

"but it's a DVC so I'll have to look for a single voice coil."

Why? You can just wire the VCs in series or parallel to run it from the amp.

Shawn

[michael hurd]

Yep, what shawn said, or you could wire a resistor across the one voice coil, and drive the other.

http://www.adireaudio.com/Files/TechPapers/RDOOperation.pdf

[michael hurd]

Modelling the JBL p-1000 in Win-ISD, came up with a 4 cubic foot ported box, tuned to 28 hz. Assuming a drive level of 25 watts ( this is a 4 ohm nominal load ), in this box, and tuning it does not exceed xmax until 22 hz, with an output ability of 95 decibels at that frequency.

With a tuning point of 28 hz, the -3db point ( anechoic ) is 25 hz, with room gain probably a bit lower like ~ 22 hz or so.

95 db at 25 hz, 99 db at 25 hz, 102 db at 30 hz and above.

EDIT: took a look at the PDF for that small sub amp, and it develops 25 watts into 4 ohms, and only 15 watts into 8 ohms.

To wring the maximum out of the amp, look for a woofer that has a 4 ohm coil, rather than an 8 ohm coil.

[Scp53]

if i were you, tell him to up the money to $100 and buy a dayton 10inch

-

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-632

i dont even think a $100 DIY sub could touch this sub, much less $50

dollar 25 watter 10 in sub. i think in the long run this is the best

option.

peace, scp53

[michael hurd]

Scp53: I'd tend to disagree, running the numbers for the dimentions, ( subtracting 3/4 inch from all dimentions to account for the internal volume ) came up with 1.63 cubic feet.

Without taking into account the volume displaced by the woofer, the amplifier and the port, this is still a small enclosure, likely tuned quite high. After subtracting the rear displacement of the woofer, amp, port and any bracing, i'd be suprised if the actual volume was more than 1 cubic foot.

[CAS]

"but it's a DVC so I'll have to look for a single voice coil."

Why? You can just wire the VCs in series or parallel to run it from the amp.

Shawn

Yeah, I used to series parallel my 2 DVC's from a bridged 2 channel amp. I wanted to keep it nice and simple for him, but this will work, too. I guess he's not going to care either way is he.

Thanks.

[DrWho]

I think your friend should not upgrade his sub yet, save his pennies and purchase a real sub later on down the road. Heck, $100 now could turn into quite an investment later on down the road....so he could end up with his $100 sub and lots of money []

[CAS]

I think your friend should not upgrade his sub yet, save his pennies and purchase a real sub later on down the road. Heck, $100 now could turn into quite an investment later on down the road....so he could end up with his $100 sub and lots of money []

The only problem with that is he isn't interested in quality sound. I would imagine his ultimate HT budget may break the $300 mark including all audio components. No use convincing him to buy a quality piece if he's not interested in such.

[DrWho]

I just see a $100 sub as more of a lateral movement from the sony he's

running right now is all...so I'm not sure what he would be trying to

achieve. Nevertheless it certainly would be a fun project.

Have you spec'd out any "car audio" subs? You can get some decent noise

makers for pretty cheap, and they'll already be built for going in a

small cabinet. So if he's using the kind of mains I'm thinking of, the

low sensitivity should have no problems keeping up []

[DrWho]

I was just modelling some drivers and you should see if your friend

can't swing an extra $10....The Dayton 12" Classic woofer models up

rather nicely actually:

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=295-320&ctab=2#Tabs

($30)

In a 1.5 cubic foot sealed cabinet it will do 102dB with that amp

you're looking at and have an F3 of 50Hz. Or in a 3 cubic foot cabinet

tuned to 33Hz, it will have an F3 of 32Hz and be able to pull 103dB.

The distortion levels for this driver are extremely low too.

For a little bit more money he could also go with the Dayton 70W

subwoofer amp and be able to do 108dB, which is actually starting to

push being a real nice subwoofer.