Very low budget sub. - Page 4 - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #31 of 54 Old 02-01-07, 01:50 PM
Senior Shackster
 
BoomieMCT's Avatar
Boom
 
Join Date: Dec 2006
Location: Fairfax, Va
Posts: 866
Re: Very low budget sub.

No prob. diysubwoofers.org is "da bomb".
BoomieMCT is offline  
Sponsored Links
Advertisement
 
post #32 of 54 Old 02-01-07, 02:49 PM Thread Starter
Senior Shackster
Mike
 
Join Date: Jan 2007
Location: Chattanooga, TN
Posts: 292
Re: Very low budget sub.

See my edit, I keep on getting some insanely large numbers.
mgboy is offline  
post #33 of 54 Old 02-01-07, 02:59 PM
Senior Shackster
 
BoomieMCT's Avatar
Boom
 
Join Date: Dec 2006
Location: Fairfax, Va
Posts: 866
Re: Very low budget sub.

Quote:
mgboy wrote: View Post
See my edit, I keep on getting some insanely large numbers.
I don't know. To be honest, I always just use Unibox and let the computer crunch the numbers. Without seeing your work the only thing I can suggest is that you double check that all your units match up (esp. for the density of air).
BoomieMCT is offline  
 
post #34 of 54 Old 02-01-07, 03:10 PM Thread Starter
Senior Shackster
Mike
 
Join Date: Jan 2007
Location: Chattanooga, TN
Posts: 292
Re: Very low budget sub.

Well, I did it for just one PR (instead of two) and came up with 1307 grams, which is like 2.88 lbs. That has to be way too much, I mean, they sample driver they used was like 280 grams, which is less than a pound.

Can it support ~ 3 lbs on the bolt? < Dumb question. I know it can, but it still seems like a lot.

Last edited by mgboy; 02-01-07 at 03:18 PM.
mgboy is offline  
post #35 of 54 Old 02-01-07, 03:22 PM
Senior Shackster
 
BoomieMCT's Avatar
Boom
 
Join Date: Dec 2006
Location: Fairfax, Va
Posts: 866
Re: Very low budget sub.

Quote:
mgboy wrote: View Post
Well, I did it for just one PR (instead of two) and came up with 1307 grams, which is like 2.88 lbs. That has to be way too much, I mean, they sample driver they used was like 280 grams, which is less than a pound.

Can it support ~ 3 lbs on the bolt?
Well, according to the spec sheet the stock mass is 200 grams and the maximum moving mass is 500 grams (total, I assume). So, if the tune you are trying for requires 1307 grams then you may need three PR's, buy a 15" Dayton DVC PR or a TC-Sounds PR or change the tune of the sub.

But first let me double check my math - I'll get back to you in a few hours (since I have to wait to go home first).

BTW, what tune were you using?
BoomieMCT is offline  
post #36 of 54 Old 02-01-07, 03:27 PM Thread Starter
Senior Shackster
Mike
 
Join Date: Jan 2007
Location: Chattanooga, TN
Posts: 292
Re: Very low budget sub.

22Hz. >_> I really want it, but I may just stick iwth a port if I'm going to have to get multiple PR's.
mgboy is offline  
post #37 of 54 Old 02-01-07, 03:35 PM
Senior Shackster
 
BoomieMCT's Avatar
Boom
 
Join Date: Dec 2006
Location: Fairfax, Va
Posts: 866
Re: Very low budget sub.

If you really want to keep this "very low budget" I saw somewhere that someone had made their own PR's from speaker surrounds and MDF. Apparantly it worked pretty well down to 20 Hz or so (when it started flapping).
BoomieMCT is offline  
post #38 of 54 Old 02-01-07, 03:37 PM Thread Starter
Senior Shackster
Mike
 
Join Date: Jan 2007
Location: Chattanooga, TN
Posts: 292
Re: Very low budget sub.

lol, No that's okay. But that's pretty ingenius.
mgboy is offline  
post #39 of 54 Old 02-01-07, 04:12 PM
Senior Shackster
 
BoomieMCT's Avatar
Boom
 
Join Date: Dec 2006
Location: Fairfax, Va
Posts: 866
Re: Very low budget sub.

Okay, here is a first stab at this. First off, I made the input power 200 watts as that is the most RMS power the driver's voice coil can take (don't max out your amp). I used 170 liters (6 cubic feet) as the size of the enclosure. Here is a plot of the EHQS-12 driver with two of the cheaper Dayton 12" PR's. One has no additional mass (which results in a 30 Hz F3), the other has 300 grams extra weight on each PR (the most it can take). That one is tuned too low and results in an F3 of 43 Hz.

As a note (not included), the low mass one barely exceeds driver excursion on the active driver at 25 Hz, but the PR exceeds it at 30 Hz. The high mass one had all kinds of excursion problems starting at 50 Hz.
BoomieMCT is offline  
post #40 of 54 Old 02-01-07, 04:26 PM
Senior Shackster
 
BoomieMCT's Avatar
Boom
 
Join Date: Dec 2006
Location: Fairfax, Va
Posts: 866
Re: Very low budget sub.

Here is what I mean. Some of these excursion problems go away by using a smaller box and/or adding a third PR. I haven't yet gotten the driver to not overexcurse below 25Hz no matter what I do (for PR or ported).

I'd almost be tempted to experiment with a sealed box with an aperiodic vent.
BoomieMCT is offline  
Reply

Bookmarks

Tags
budget , low

Quick Reply
Message:
Options

Register Now




PLEASE COMPLETE ALL REQUIRED FIELDS BELOW... THANKS!

REQUIRED FIELDS ON THIS PAGE
YOU MUST COMPLETE ALL OF THESE

Username
Password
Confirm Password
Email Address
Confirm Email Address
Random Question
Random Question #2




User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
PLEASE READ BELOW PRIOR TO ENTERING AN EMAIL ADDRESS!

ATTENTION!

YOU MUST ACTIVATE YOUR ACCOUNT!

Activation requires you reply to an email we will send you after you register... if you do not reply to this email, you will not be able to view certain areas of the forum or certain images... nor will you be able download software.

AN INVALID EMAIL ADDRESS WILL CAUSE YOUR ACCOUNT TO BE DELETED!

See our banned email list here: Banned Email List

We DO NOT respond to spamcop, boxtrapper and spamblocker emails... please add @hometheatershack DOT com to your whitelist prior to registering or you will get nowhere on your registration.


Email Address:
OR

Log-in










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



Posting Rules  
You may post new threads
You may 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 is not allowed!
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


For the best viewing experience please update your browser to Google Chrome