Maelstrom-x 21" 15cu Sealed Build! - Page 7 - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #61 of 225 Old 11-20-09, 09:53 AM Thread Starter
Senior Shackster
Raven
 
Join Date: Aug 2008
Location: Bolingbrook, IL
Posts: 511
Re: Maelstrom-x 21" 15cu Sealed Build!

Quote:
sub_junkie wrote: View Post
Wow...very nice build. Great work
I'm even anxious to hear how you think it sounds. Its going to shake everything in your house
I get that now with my small folded horn! What I want, is stuff broken!
Lonely Raven is offline  
Sponsored Links
Advertisement
 
post #62 of 225 Old 11-20-09, 09:56 AM
Shackster
Mike
 
Join Date: Apr 2009
Posts: 32
Re: Maelstrom-x 21" 15cu Sealed Build!

Quote:
Lonely Raven wrote: View Post
I get that now with my small folded horn! What I want, is stuff broken!
haha
I'm sure you can't wait to see this 21" monster moving some serious air.
Gelinas is offline  
post #63 of 225 Old 11-20-09, 10:45 AM
Elite Shackster
Mike
 
Join Date: Nov 2007
Location: San Dimas, CA
Posts: 1,633
My System
Re: Maelstrom-x 21" 15cu Sealed Build!

Since you asked about not many questions I have one.

Will you be permanently gluing down the front baffle once you are satisfied with the performance?
I would figure the gasket tape will yield a very good seal but that 21" monster will test it's limits.

Glad to hear about the good HR experience.

Great sub, can't wait to hear how you like it.
sub_crazy is offline  
 
post #64 of 225 Old 11-20-09, 10:57 AM Thread Starter
Senior Shackster
Raven
 
Join Date: Aug 2008
Location: Bolingbrook, IL
Posts: 511
Re: Maelstrom-x 21" 15cu Sealed Build!

Quote:
sub_crazy wrote: View Post
Since you asked about not many questions I have one.

Will you be permanently gluing down the front baffle once you are satisfied with the performance?
I would figure the gasket tape will yield a very good seal but that 21" monster will test it's limits.

Glad to hear about the good HR experience.

Great sub, can't wait to hear how you like it.
I've used this same rubber-foam tape on my folded horn, which is a complex build, and had great results.

Considering the the baffle is "stepped", and nearly press fits in, air would have several solid panels to snake around. I'm pretty confident the insulation tape will hold considering the physical loads I have on it. And if I do detect leaks (which I'm honestly not sure how to "detect" leaks on this), I have plenty of surface area to add a second line of insulation.

See the steps in the baffle. Two of those layers will sit flush on the box. I could easily add a second tape line.




All this is to insure I can "service" the box or driver should it need it. Granted, I have a 19.5" hole I could crawl into if I really had to, but it's been standard practice for me to be able to open up any boxes I build...even if it's just to try out different damping methods. (or to look at the drivers because it's been so long I couldn't remember what model they were! LOL)


Lonely Raven is offline  
post #65 of 225 Old 11-20-09, 11:02 AM Thread Starter
Senior Shackster
Raven
 
Join Date: Aug 2008
Location: Bolingbrook, IL
Posts: 511
Re: Maelstrom-x 21" 15cu Sealed Build!

I should probably add, if I don't feel the 2.5" stainless deck screws I'm picking up today will do the job, or they pull through the wood (which I wouldn't be surprised considering this paneling), I'd rather upgrade to bolts and T-nuts on the baffle then glue it all down.

Once I'm sure I have everything sealed and working well, I'll be "finishing" the box by rounding over the corners, and either using a roll on bed-liner type coating, or wrapping the whole thing in leather. It would make a nice ottoman.
Lonely Raven is offline  
post #66 of 225 Old 11-20-09, 11:07 AM
Elite Shackster
Mike
 
Join Date: Nov 2007
Location: San Dimas, CA
Posts: 1,633
My System
Re: Maelstrom-x 21" 15cu Sealed Build!

I like the leather idea, that sucker would take up a whole cow!
sub_crazy is offline  
post #67 of 225 Old 11-20-09, 11:08 AM
Elite Shackster
Mike
 
Join Date: Nov 2007
Location: San Dimas, CA
Posts: 1,633
My System
Re: Maelstrom-x 21" 15cu Sealed Build!

Sweet folded horn
sub_crazy is offline  
post #68 of 225 Old 11-20-09, 08:54 PM Thread Starter
Senior Shackster
Raven
 
Join Date: Aug 2008
Location: Bolingbrook, IL
Posts: 511
Re: Maelstrom-x 21" 15cu Sealed Build!

EDIT: OK, after taking a breather I got an idea and it seems to have resolved my low output issue. I'll report later after I have some time with this.

Last edited by Lonely Raven; 11-20-09 at 09:11 PM.
Lonely Raven is offline  
post #69 of 225 Old 11-21-09, 12:17 PM Thread Starter
Senior Shackster
Raven
 
Join Date: Aug 2008
Location: Bolingbrook, IL
Posts: 511
Re: Maelstrom-x 21" 15cu Sealed Build!

Mini-Update: Last night I had some frustration with the sub and amp. I came home from a bad day at work, ran out to buy some 2.5" screws to put the baffle on, got the whole beastly thing upstairs by myself (it's actually lighter in two pieces, then my folded horn was!). And when I set it up, the output was...well, not impressive at all. I figured I had done something wrong, because the old pair of 10" had easily double the output of this 21". I was heartbroken, and just too tired and frustrated to look at it anymore, so I went out to dinner. When I came home, I remembered that I had been running the old setup with two inputs and two outputs. So I crawled back behind the rack and pulled the 1/4" plug out of input two, and the whole system came to life. So basically, the sub was probably only seeing half the sign wave, and I was only getting about half it's output.

This morning I did a few sweep with REW. I haven't yet pulled my microphone and mixing board out of storage, nor have I run my Audyssey XT on the Onkyo 805. I just wanted to run some sweeps now that I had a good nights sleep and time away from the frustrations of yesterday. I ran REW from 5 to 120Hz, noticed my rear speakers had somehow got set way too low, made some quick adjustments, and....WOW! This beast turns electrical energy into physical energy!

Apparently my DIY projector screen wants to jump off the wall at 15Hz, so I'm going to have to damp the screen and probably velcro it in key places to keep it from walking off the wall.

Overall impression...I have to say, I miss the horn. It just couples with the air better then anything else. It seems to excite the whole room, airspace wise. While the M-21" seems to press more mechanical/physical energy into the room. I'm getting the feeling that I'm going to need to decouple the box from the floor somehow, because the feeling of energy passing through the floor overpowers what the box passes through the air...or maybe not overpowers so much as I feel it before I hear it? So I think making myself a giant sub decoupler might help out here, though that would make it taller yet again, and it's already a bit obtrusive.

Again, all of this is without tuning and without trying out different placement options nor measurements. These are just my first impressions. I have a movie night planned with my friends tonight, so I have to get the sub at least setup enough where Star Trek won't bottom it out or clip the amp. But over this weekend I'll work on re-learning REW and taking some proper measurements.
Lonely Raven is offline  
post #70 of 225 Old 11-21-09, 12:51 PM
Elite Shackster
 
SteveCallas's Avatar
Steve
 
Join Date: Apr 2006
Posts: 2,398
Re: Maelstrom-x 21" 15cu Sealed Build!

A few posts back you said that sliding the baffle into place caused the cone to puff out slightly. You don't want that to happen. With a sealed sub, heat will build up inside the enclosure, and heat causes air to expand - now you will have even more pressure inside the enclosure pushing against the cone. That can mess up the suspension over time.

The trick a lot of people use to counteract this is to place a small pin hole somewhere near the top of the enclosure. This will prevent a buildup of pressure in the sub over time, but should be small enough as to not lose pressure from the backwave while the sub is in use. Someone who uses sealed subs and such a method may want to chime in to give him exact details, as I've never actually done it myself.

As for mechanically exciting the whole room, in my opinion, that the best part I used to have one of my subs in a 3rd floor apartment and it would cause my whole floor to bounce. Now I have two such subs in a one floor townhouse over a concrete foundation and the effect just isn't as good without feeling the ripples of bass run through the floor. The floor still imparts some bass energy, but not nearly to the same level as the wooden floating floor did. In real life, if there is a big explosion, you will feel it through the ground - therefore, a sub that mechanically excites the floor offers a more accurate respresentation of that explosion.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.
SteveCallas is offline  
Reply

Bookmarks

Tags
15cu , 21" , build! , maelstrom-x , sealed

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