What would be a good tune for a 7ft3 SI18 - AVS Forum
Forum Jump: 
 4Likes
  • 3 Post By tuxedocivic
  • 1 Post By LTD02
 
Thread Tools
post #1 of 20 Old 06-18-2014, 01:43 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
What would be a good tune for a 7ft3 SI18

Looking for suggestions for a good tuning freq for a SI18 in a 7ft3 net box. I did some modeling in winisd and found 18hz with two 3 inch ports about 14 inches long looked pretty good. I could build a minimarty but I need a different shape. I also would prefer to stick with round ports unless the slot ports would allow me to achieve something the round ports couldn't.

I could go up to 8 ft3 but that didn't appear to offer a lot of gain over 7.
Samps is online now  
Sponsored Links
Advertisement
 
post #2 of 20 Old 06-18-2014, 04:41 PM
AVS Special Member
 
chalugadp's Avatar
 
Join Date: Jan 2013
Location: Vancouver, BC, Canada
Posts: 4,586
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 677 Post(s)
Liked: 908
I think you nailed it, 18hz. Would be usuable to 15hz.
chalugadp is online now  
post #3 of 20 Old 06-18-2014, 04:54 PM
AVS Special Member
 
tuxedocivic's Avatar
 
Join Date: Feb 2010
Location: Ladysmith, BC
Posts: 4,576
Mentioned: 4 Post(s)
Tagged: 1 Thread(s)
Quoted: 257 Post(s)
Liked: 510
You're going to have some serious port noise if you approach anything near xmax. Which is about 1kwatt. You could underpower it, but that seems pointless. Consider 4x3" ports that are 60cm long for a 20hz tune, or some a way to get that port working. That's still not really ideal either. I'd be thinking 4" ports. That's where slot ports are nice, you can extend them along the side of the box and get lots of mouth area. You might need elbows in your PVC.
Mfusick, LTD02 and Samps like this.
tuxedocivic is offline  
post #4 of 20 Old 06-18-2014, 05:02 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,200
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked: 948
+1


two 3" ports run air velocity up too high for that driver with full power.


three 4" ports is about what I would suggest as a minimum in your case.


that is one reason the slot works so well -- it is a cheap way to build a large port.

Listen. It's All Good.
LTD02 is online now  
post #5 of 20 Old 06-18-2014, 05:03 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
Thanks. How do you calculate first port resonance? I don't see any mention of it in winisd. If the port velocity is real low is that wasting something? If i can get the same tuning with two different port diameters and they are both under the acceptable limit for velocity is one better than the other?
Samps is online now  
post #6 of 20 Old 06-18-2014, 05:06 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
I must have entered a ts spec wrong in winisd because the velocity I got with the three inch ports was 14ms.
Samps is online now  
post #7 of 20 Old 06-18-2014, 05:10 PM
AVS Addicted Member
 
Mfusick's Avatar
 
Join Date: Aug 2002
Location: Western MA
Posts: 22,419
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 147 Post(s)
Liked: 776
17hz. SLot port.

-

"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
Mfusick is online now  
post #8 of 20 Old 06-18-2014, 05:28 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,200
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked: 948
"I must have entered a ts spec wrong in winisd because the velocity I got with the three inch ports was 14ms. "


did you have your power adjusted to 500-1000 watts or so?

Listen. It's All Good.
LTD02 is online now  
post #9 of 20 Old 06-18-2014, 05:36 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
I set 600 watts in the driver spec and 500 watts in the plot spec. I guess I wasn't pushing it hard enough to raise port velocity. What specs should I use?
Samps is online now  
post #10 of 20 Old 06-18-2014, 05:40 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,200
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked: 948
two 3" diameter ports in that configuration with 500 watts gives about 44 m/s air speed.


something is amiss.

Listen. It's All Good.
LTD02 is online now  
post #11 of 20 Old 06-18-2014, 05:46 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
I will have to double check my numbers. I must have made a typo somewhere. Are the data-bass numbers more accurate than the SI specs?
Samps is online now  
post #12 of 20 Old 06-18-2014, 06:28 PM
AVS Club Gold
 
AV Science Sales 5's Avatar
 
Join Date: Sep 2011
Location: A beautiful view of a lake
Posts: 7,475
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 239 Post(s)
Liked: 392
Quote:
Originally Posted by Samps View Post
I will have to double check my numbers. I must have made a typo somewhere. Are the data-bass numbers more accurate than the SI specs?
I would go by the Databass numbers.

Mike Garrett, AV Science Sales Call Me: 585-671-2968
Email Me: Mike@AVScience.com
Brands we sell: http://avscience.com/brands/ 
Call for B-stock projectors
Stewart, Seymour, SE, SI & many more.
Klipsch, RBH, Martin Logan, Triad, Atlantic Technology, MK Sound, BG Radia, SVS & Def Tech.
AV Science Sales 5 is offline  
post #13 of 20 Old 06-18-2014, 07:02 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,200
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked: 948
this is a test


[IMG]

[/IMG]

Listen. It's All Good.

Last edited by LTD02; 06-18-2014 at 07:05 PM.
LTD02 is online now  
post #14 of 20 Old 06-18-2014, 07:15 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
I re entered the specs from data bass and got the same results. I'm not sure what I'm doing wrong. Here is a screen shot of the ts specs I'm using and the port results I get for 7ft3 with a 18hz tune.
Attached Images
File Type: png SI18 Specs.PNG (92.3 KB, 10 views)
Samps is online now  
post #15 of 20 Old 06-18-2014, 07:24 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,200
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked: 948
mach 0.11 is 11% of the speed of sound at sea level, which is around 340 m/s, so mach 0.11 is about 37.4 m/s.
Samps likes this.

Listen. It's All Good.
LTD02 is online now  
post #16 of 20 Old 06-18-2014, 07:32 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
I thought when the number was green it was in the good range and when it turned red it was a bad number.

So what vent mach do I want to aim for? I can figure out the rest based on the math you posted. Thanks!
Samps is online now  
post #17 of 20 Old 06-18-2014, 07:48 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
How about three 3 inch ports at 22.5 inches. That gets me .05mach which should equal 17ms. That is alot of port though. The slot port is looking better now! How hard would it be to convert the minimarty design into a box that has a 22inch max width or depth for the bottom panel? I need it to fit between a wall and a floor register.
Samps is online now  
post #18 of 20 Old 06-18-2014, 08:17 PM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,200
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked: 948
how much power are you inputting?

Listen. It's All Good.
LTD02 is online now  
post #19 of 20 Old 06-18-2014, 08:31 PM - Thread Starter
Member
 
Samps's Avatar
 
Join Date: Feb 2014
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 46 Post(s)
Liked: 22
I put 600 watts in the driver specs. But if you're asking about how much I will actually be using, I'm not sure yet. An inuke probably or another pro amp with about 1000 watts. I need as much output out of this as I can get since I wont be able to add another. Large room. Already have a ported 12 to back it up. But it needs to fit around an air vent. I can't move the wall or the air vent. Otherwise I would just build the minimarty, or even the martycube. I probably listen to more music than movies,
Samps is online now  
post #20 of 20 Old 06-19-2014, 12:56 AM
AVS Addicted Member
 
LTD02's Avatar
 
Join Date: Oct 2003
Posts: 16,200
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 233 Post(s)
Liked: 948
i simply meant in winisd for the purposes of calculating the mach number.

Listen. It's All Good.
LTD02 is online now  
Reply DIY Speakers and Subs

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off