[LHD21]

A buddy wants a new sub and I suggested we build one to fit his budget. He's got enough room for an 18x18x36 box which comes out to 6.75 ft^3. Ive been plugging driver information into winISD pro and I think I found a good match. I had initially tried unibox but there seems to be no margin for error there. I figured I'd cut my teeth on ISD and then move to unibox once I had a better grasp.



I was told I should enter as few variables into winISD as possible. I followed the instructions in the app and entered VAS, QTS, FS, Xmax and QES. The app calculated QMS, SPL and NO.

The chart looks pretty good. We'll have to fine tune the size to account for driver volume and port volume but its a great start. I'm having trouble getting winISD to display excursion. When I select the driver excursion chart it shows a blank graph. I'm also having issues with port air speed calculations. It will let me do rear ports but not front ports. Front ports just show an empty graph.



Are there any glaring errors here? Is the port speed issue due to the type of box I selected when starting the project? I believe it was c4\\sc chebyshev.

 

[lennon_68]

Maybe I'm missing it but did you say what driver, tuning, and port diameter the chart displayed is for?


Edit: Oops, looks like the driver is a Dayton QT385-4. It also looks like it's tuned to 20hz. What sized port are you planning on using? Also how many watts are you planning on pushing it with?

 

[Looneybomber]

Looks fine, but out of curiousity, do you need to know about the content above 100hz?

 

[LHD21]



Quote:
Originally Posted by lennon_68 /forum/post/15474646


Maybe I'm missing it but did you say what driver, tuning, and port diameter the chart displayed is for?

Its the Dayton QT385-4 15" chosen because its inexpensive and we were able to get it to model so nicely. Of course thats going to go all to hell when he puts it in his very oddly shaped living room.


The port is 8" of 4" diameter port without flares.


Our goal was low 20s tuning which we got. Some arbitrary between 20 and 21hz.

Quote:
Originally Posted by Looneybomber /forum/post/15475065


Looks fine, but out of curiousity, do you need to know about the content above 100hz?

Not at all. I just forgot to change the graph limits when I snapped the screenshot. Its going to be crossed at 80hz.

 

[Zardnok]



Quote:
Originally Posted by LHD21 /forum/post/15474075


A buddy wants a new sub and I suggested we build one to fit his budget. He's got enough room for an 18x18x36 box which comes out to 6.75 ft^3. Ive been plugging driver information into winISD pro and I think I found a good match. I had initially tried unibox but there seems to be no margin for error there. I figured I'd cut my teeth on ISD and then move to unibox once I had a better grasp.



I was told I should enter as few variables into winISD as possible. I followed the instructions in the app and entered VAS, QTS, FS, Xmax and QES. The app calculated QMS, SPL and NO.

The chart looks pretty good. We'll have to fine tune the size to account for driver volume and port volume but its a great start. I'm having trouble getting winISD to display excursion. When I select the driver excursion chart it shows a blank graph. I'm also having issues with port air speed calculations. It will let me do rear ports but not front ports. Front ports just show an empty graph.



Are there any glaring errors here? Is the port speed issue due to the type of box I selected when starting the project? I believe it was c4\\sc chebyshev.

You need to add system input power (amp size in watts) on the signal tab for the driver excursion to show up.


If you are using a standard vented enclosure, you will have only rear port velocity regardless of where it is actually mounted to the enclosure. Front port velocity is used for band-pass enclosures.


Also, what driver are you modeling and what port size? Also what budget is your friend trying to stay with? Perhaps the gurus here on AVS could suggest an application or speaker you have not considered.

 

[LHD21]



Quote:
Originally Posted by Zardnok /forum/post/15475813


You need to add system input power (amp size in watts) on the signal tab for the driver excursion to show up.

Thats already in there. Its required to see port speed. The driver excursion graph is still blank.

Quote:
Originally Posted by Zardnok /forum/post/15475813


If you are using a standard vented enclosure, you will have only rear port velocity regardless of where it is actually mounted to the enclosure. Front port velocity is used for band-pass enclosures.

Makes perfect sense.

Quote:
Originally Posted by Zardnok /forum/post/15475813


Also, what driver are you modeling and what port size? Also what budget is your friend trying to stay with? Perhaps the gurus here on AVS could suggest an application or speaker you have not considered.

He's trying to stay as close to $200 as possible with power to the low 20s. So far we're looking at the PE 240w plate amp and the driver I mentioned above. For just driver and sub he's looking at around $250 plus shipping. I have some extra mdf and wire he can use to fill in the rest. He'll have to dig up a port too.

 

[lennon_68]

Excursion looks good down to 18hz. You're probably going to get some port chuffing with a 4" port though. Attached is what Unibox is modeling for that setup with the full 240W. You'll probably never get all 240W though so I modeled it out with 100W and it's still peaking at 32m/s around 18hz.


I'm not that familiar with how audible that would be though.

 

[LHD21]



Quote:
Originally Posted by lennon_68 /forum/post/15476085


Excursion looks good down to 18hz. You're probably going to get some port chuffing with a 4" port though. Attached is what Unibox is modeling for that setup with the full 240W. You'll probably never get all 240W though so I modeled it out with 100W and it's still peaking at 32m/s around 18hz.


I'm not that familiar with how audible that would be though.

Below 18hz is it severe enough that I'll need to high pass it? I dont anticipate it being an issue but if its +90% of xmax at 15hz I'd look into it.


As far as the port speed is concerned, I wasnt too worried since he'll never use it above half volume. 120w puts it at a tiny bit under 34 m/s which hopefully wont be too loud. I believe that was peerless' cutoff. He's in an apartment and wont be turning it up loud anyway. By the time he gets some place he can blast it we'll probably change the amp at which time we can re-port it or build a whole new unit. Plus at half volume he should have plenty of headroom.


If this isnt a wise move let me know.

 

[lennon_68]



Quote:
Originally Posted by LHD21 /forum/post/15476624


Below 18hz is it severe enough that I'll need to high pass it? I dont anticipate it being an issue but if its +90% of xmax at 15hz I'd look into it.


As far as the port speed is concerned, I wasnt too worried since he'll never use it above half volume. 120w puts it at a tiny bit under 34 m/s which hopefully wont be too loud. I believe that was peerless' cutoff. He's in an apartment and wont be turning it up loud anyway. By the time he gets some place he can blast it we'll probably change the amp at which time we can re-port it or build a whole new unit. Plus at half volume he should have plenty of headroom.


If this isnt a wise move let me know.

You'll definitely need to high-pass it... but all ported subs should be high-passed. Attached is the excursion with 120W input.

 

[LHD21]

Just looking at my graph and driver specs, does it look like I have enough information in the parameters to do all the calculations I need? There seem to be an awful lot of 0s in those parameters.

I edited in the Pe and then took it out to try it both ways. I still get a flat line.

 

[lennon_68]

Not sure if it will make a difference but Re is 3.5 ohm and Sd is 131.76 in^2. I'm pretty sure the other 0's are fine.

 

[Zardnok]



Quote:
Originally Posted by LHD21 /forum/post/15475915


He's trying to stay as close to $200 as possible with power to the low 20s. So far we're looking at the PE 240w plate amp and the driver I mentioned above. For just driver and sub he's looking at around $250 plus shipping. I have some extra mdf and wire he can use to fill in the rest. He'll have to dig up a port too.

I was running a Qu4tro 15 with the PE BASH 500 amp, but I have since swapped out the BASH 500 for an EP2500 and have a single channel of the 2500 running the 15. When I can scrounge up some cash for wood and beer, I will build new end-table cabinets to fit the new Infinity 12s I bought before Christmas. Where does your friend live? I am trying to sell the BASH 500 and Dayton 15 now so I can afford the wood/stain needed to rebuild the new end-tables.

http://www.avsforum.com/avs-vb/showthread.php?t=899728

 

[LHD21]



Quote:
Originally Posted by zardnok /forum/post/15480346


i was running a qu4tro 15 with the pe bash 500 amp, but i have since swapped out the bash 500 for an ep2500 and have a single channel of the 2500 running the 15. When i can scrounge up some cash for wood and beer, i will build new end-table cabinets to fit the new infinity 12s i bought before christmas. Where does your friend live? I am trying to sell the bash 500 and dayton 15 now so i can afford the wood/stain needed to rebuild the new end-tables.

http://www.avsforum.com/avs-vb/showthread.php?t=899728

ygpm!

 

[skshepherd]

I know this is an old thread but it has a lot of what Im wanting to do already included in it. Especially the specs on the driver I'd like to use.


I downloaded the winisd but am not sure at all what I am doing. I entered the data from the driver but not sure what to make out of the data and the box.

I've tried to search for others experience using the Dayton QT385-4 and found this thread.


The Dayton QT385-4 is on sale now for $75. Id like to build a ported enclosure for HT with base I can feel as well as hear for as close to $250 as possible. I can fit a cabinet roughly 24 w x 24 d x 48 h maximum size. I can most likely afford a plate amp of 150 w or so. Can anyone help me figure out the dimensions and port size and length for the cabinet that will get as much output as possible down to 20hz with this sub? Thanks!

 

[LTD02]

a six cubic footer tuned to 22.68hz with a 36" deep slot port that is 3" tall x 16" wide and 3" from the back wall of the enclosure, will give you an effective tuning of around 20-21hz +/- a hair.


the rough overall dimensions (not counting wood thickness) would be 39" deep, 16" wide, 21" tall. with 3/4" wood, it would be roughly 41.5" deep, 17.5"wide, 23.25" tall.


a 250-300 watt amp with a high pass around 20hz should work well.