Twin Avalanche 18", Sealed or PRs? - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #11 of 23 Old 12-29-09, 09:26 PM
Elite Shackster
 
SteveCallas's Avatar
Steve
 
Join Date: Apr 2006
Posts: 2,398
Re: Twin Avalanche 18", Sealed or PRs?

The website says one of the 10" drivers is for midbass and the other is for low bass - since they don't mention what the crossover frequencies are, it's hard to tell what specifically is happening.


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  
Sponsored Links
Advertisement
 
post #12 of 23 Old 12-30-09, 06:42 PM Thread Starter
Shackster
Brax
 
Join Date: Aug 2009
Posts: 41
Re: Twin Avalanche 18", Sealed or PRs?

So it looks like I will be building 2 sealed cabinets. WndISD calculates the cabinet volume at 280L for a Qtc of .703. This design has an -3db of 29 Hz and an output of 105 db @ 13 Hz. All of these calculations are for one sub so there should be another 3-4 db gain by adding a second sub.

These calculations do not include any fill in the cabinet. Is there any disadvantage in building a smaller box, then adding fill to bring the Qtc back to .7?
Brax is offline  
post #13 of 23 Old 12-31-09, 12:03 AM
Elite Shackster
 
SteveCallas's Avatar
Steve
 
Join Date: Apr 2006
Posts: 2,398
Re: Twin Avalanche 18", Sealed or PRs?

I would keep the enclosures as large as you are willing to accept.


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  
 
post #14 of 23 Old 01-08-10, 08:38 AM Thread Starter
Shackster
Brax
 
Join Date: Aug 2009
Posts: 41
Re: Twin Avalanche 18", Sealed or PRs?

As the design stands, I have only 3/8” clearance between a brace and the hole on the back of the magnet structure. Do I need to increase this clearance to ensure adequate cooling to the driver’s motor?
Brax is offline  
post #15 of 23 Old 01-08-10, 03:07 PM
Senior Shackster
 
Veltinorian's Avatar
Velti
 
Join Date: Dec 2009
Posts: 272
Re: Twin Avalanche 18", Sealed or PRs?

Brax, i dont want to dispute opinions of others but I have concerns with the limits of the enclosure type. I just simulated a good performer with a sealed enclosure, cause the parameters you gave are uncomplete, (theRSS390HF with Fs 18Hz, Qts 0,42, 87db SPL…) and that one with a ported enclosure simulates down to 18,8Hz F3 with a 264liters box. And guess, with a sealed one it is impossible to tune the thing below 39Hz ! I know the majority uses WinISD but I have done subs with BasBoxPro and the results are very close to what the program says. Just wanted to make mark here,

Regards,Veltinorian

(Also BassBoxPro seems to consider more driver parameters doing its math)
Veltinorian is offline  
post #16 of 23 Old 01-08-10, 05:35 PM Thread Starter
Shackster
Brax
 
Join Date: Aug 2009
Posts: 41
Re: Twin Avalanche 18", Sealed or PRs?

Veltinorian,

I welcome any advice since I am not a seasoned a sub designer like many on this board.

First are you saying, the T/S parameters for the Avalanche are not complete enough to model in BassBox? If so what is missing?

I filled out what I could in WinIsd and those were the plots I got, I did the same on Unibox and came up with identical plots. I did find it strange that the model with 2 passive radiators did not have a huge output advantage over the sealed design.

I am building two subwoofers, so I thought I could handle the drop in out put and still meet my needs with sealed designs. Do you think I would be better off going with the passive radiator design?
Brax is offline  
post #17 of 23 Old 01-08-10, 06:08 PM
Senior Shackster
 
Veltinorian's Avatar
Velti
 
Join Date: Dec 2009
Posts: 272
Re: Twin Avalanche 18", Sealed or PRs?

Bl, 1-W SPL and Cms are missing and they are important. (Cms can be calculated as there are Fs and Mms provided but there are still the Bl and 1-W SPL missing.)

Here is the answer to the question: Sealed give nothing over ported as long as the Xmax is not a concern, i.e. at for example at 300Watts to the driver you get the equal ouput from both as long Xmax is not reached, what is more the ported one extends even deeper to the lows, here is what i mean (done this with daytons RSS390HF):



The green one is sealed F3 is 40Hz box 58liters and orange one is ported F3 18Hz 260Liters. Even though i force the sealed enclosure above 58 liters, 158, 285, 585 it cannot go lower than 39Hz, thats it.

But here is one big but, if you choose to force the sub with more power the ported will reach its Xmax earlier and will not continue to produce an increase in power f.ex. when power is >300W with the volume going up, but but the sealed will increase its output, cause Xmax isnt reached yet and the outpuut from it will increase. And going on and on and on till it reaches say 400Watts. The power to the ported is also 400W but as SPL level it will be as there were only 300W to it. So for a SPL competition sealed wins (only if power > 300Watts), for low extension ported wins. Passive are not far than ported(drop a bit sooner 1 to 2 Hz) but have more flexibility to play tune the box, resolve problems with port noise and port displacement..but costs more for a passive to buy 50..80$

Last edited by Veltinorian; 01-08-10 at 06:43 PM.
Veltinorian is offline  
post #18 of 23 Old 01-08-10, 07:05 PM
Elite Shackster
 
SteveCallas's Avatar
Steve
 
Join Date: Apr 2006
Posts: 2,398
Re: Twin Avalanche 18", Sealed or PRs?

You guys are going to make me plug in my other computer to grab the original Avalanche 18 parameters

I will say that I'm 99% sure you can't get a flat response to tuning with this driver if you want a 15hz tune in only 260 liters. This driver likes large enclosures. I'll fire up the old computer sometime over the weekend and get the right parameters to test.


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  
post #19 of 23 Old 01-10-10, 02:32 PM Thread Starter
Shackster
Brax
 
Join Date: Aug 2009
Posts: 41
Re: Twin Avalanche 18", Sealed or PRs?

Steve,

In my modeling, I don't see a huge gain in low end output with a larger cabinet. I modeled all the way up to a 500L cabinet, and it didn't increase the low end out enough to justify the extra size or cost of the cabinet.

Unless there is something wrong with my models..............
Brax is offline  
post #20 of 23 Old 01-10-10, 02:53 PM
Elite Shackster
 
SteveCallas's Avatar
Steve
 
Join Date: Apr 2006
Posts: 2,398
Re: Twin Avalanche 18", Sealed or PRs?

I forgot about this.....don't really wanna hook up the other computer, but might have to.

Proper porting alone would dictate more than 260 liters for a 15hz tune - that's without even considering the shape of the FR.


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
18" , avalanche , prs? , sealed , twin

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