First post and DIY subwoofer questions...

[derekwwww]

Hello everyone, looks like a good board here! I just bought my first peices to my first home system last month. I have a Yamaha RX-V1500 receiver and a pair of Pro-Linear Euro Series PTX50T towers. I just ordered a 1000W plate sub amp from partsexpress:

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=300-808&ctab=4#Tabs

And I have two Image Dynamics IDQ v.2 DVC 2 ohm subs here that aren't being used so I am going to be using them for my home subs. Going to wire them into a 8 ohm load on the amp giving them about 250 watts each sub. The subs are going to each be in their own enclosure, with one sub in each corner of the room. So the amp will have its own enclosure built and it will go at my entertainment stand somewhere.

My questions concern my woofer enclosures... I downloaded WinISD, is this a fairly accurate program for finding out what size to build the best box size? I am going to be using sealed enclosures just for simplicity. Or should I just kind of go with what the specs that were given with the sub, even though it is a car audio sub. Next question is do I need acoustic foam inside my box or would polyfill work or could I do without? The feet I was going to get for the sub enclosures were these spikes:

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=240-725&scqty=4

or should I get the larger ones that are 1/2" instead of 3/8"?

Any help or suggestions appreciated! Thanks

 

[simon5]

WinISD is very accurate, but the volume they will tell you is internal total volume, you need to substract anything that's in the box, like the volume of the driver, the bracing, the plate amplifier, so don't just build a box with external volume calculations. If it's sealed, the impact won't be big, but in a ported box, the total internal volume is very important.

Since it's a subwoofer for a car, it's probably a good idea to not use the same enclosure that the manufacturer want you to do.

Also, a good thing to note is that WinISD measure the performance of your subwoofer in a anechoic space. So, under a certain frequency, you need to consider room gain that will lift the lower frequencies in SPL, especially in a small room.

 

[derekwwww]

Hi I am trying to use the WinISD program here and got a couple questions. In the area where you fill out all the driver data, my spec sheet has everything except Sd and Z. And I'm not to sure what to put in the Re spot. On my spec sheet it says: Re - .975/3.9. Should I use .975 or 3.9? The sub is DVC 2 ohm so what should I put in the Z blank 2 or 4? The subs will be wired in series. And should I just use the Sd that they use with the IDQ they have in their list?

Thanks!

 

[KEFMAN]

subs

The enviroment for car audio enclosures is so far away from the home situation as is the difference between headfones and real life. I can't advice you on the way to go except to say, ignore the car thing!!

 

[derekwwww]

Somebody correct me if I'm wrong but isn't there no difference between a sub made for car audio and a sub made for home audio other then the spec sheet for box building they give? There isn't actually a difference in the sub is there? There is no problem using Image Dynamics subs for a home application even though they are sold as 'car audio' subs? I am somewhat confused with your reply KEFMAN, please explain. Also, question still stand from my last reply... about WinISD.

Thanks

 

[simon5]

Since you will use it in series, write 3.9 in the Re spot. Z is not important and WinISD will estimate it alone.

Check if the measurements on your specsheet were taken with voicecoils in series or in parallel. That will change BL, Re and Le.

By the way, you don't need to enter a parameter in each blank. WinISD will calculate the missing ones. Enter each parameter one by one and let it calculate parameters.

If it's the same diameter driver, there's a good chance that's the same Sd.

 

[derekwwww]

Ok this is strange, according to WinISD my enclosure should be only 22.4 litres (or .79 cuft) for each sub. This is a little smaller then the 'normal' specs for using the sub in a car sealed. Does this sound right?
Thanks

 

[simon5]

I think it's a bit too small, but maybe you're not aiming as low as me.

I used 70 liters tuned to 18 Hz and it looks very well but you would need a passive radiator hehe!

This subwoofer likes a small box it seems.

Did you used the suggested enclosures or you tuned it yourself?

 

[Collo]

I've been using WinISD (0.50a7) for about a year now and I just love it.

When entering parameters into the database, make sure the "autocalculate unknowns" is unchecked when entering a new speaker otherwise you get compaints.

Sd is the effective cone area - if you don't lnow it, copy the figure from a similar sized driver in the database.

The authors run a forum at the website which is very useful
http://linearteam.proboards12.com/index.cgi?board=winisd

good luck with your sub....

 

[simon5]

It is better to have "autocalculate unknown" checked IMHO and to enter only some parameters in a certain order, then WinISD calculate the rest. WinISD complaints because the manufacturer parameters are not correct.

 

[derekwwww]

They will be used 80% music 20% movies so whatever you think would sound best for that. I dont have any restrictions on what size to build them. If they would be better with 1 cuft each then I would do that. I also have acoustic polyfill to put in the box too if it needs it? Thanks for the help so far!

 

[simon5]

Do you want to go sealed or ported?

 

[derekwwww]

I am going to be going sealed.

 

[simon5]

If you go sealed, do them as big as you can.