Go Back   Home > Forums > >

Is there a program available to help with design of a FAST/WAW?
Is there a program available to help with design of a FAST/WAW?
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools
Old 13th January 2021, 09:06 AM   #1
Tony D. is offline Tony D.  Canada
diyAudio Member
 
Join Date: Feb 2001
Location: Vancouver Island, B.C., Canada
Default Is there a program available to help with design of a FAST/WAW?

This is the first time I've attempted to build a FAST and I am wondering if there are any hard and fast rules? For instance how does one determine the placement of the drivers on the baffle, is it similar to mounting a mid-bass and tweeter? The FAST builds I have looked at seem to be crossed over in the 200 to 500hz region so any help with the crossover point and other parameters would be much appreciated. I will be using a MiniDSP 2x4HD for crossover and tuning and I have a UMIK1 for measurement.

This project is an evolution of the Nautilus tapered transmission line for full range driver idea I had. The drivers are a Wavecor FR090WA02 3-1/2" Aluminum Cone Full-Range 8 Ohm: Wavecor FR090WA02 3-1/2" Aluminum Cone Full-Range 8 Ohm and a Scanspeak Discovery 18W/4434G-00, 7" Midwoofer, 4 ohm: Scanspeak Discovery 18W/4434G-00, 7" Midwoofer, 4 ohm

Thanks for any replies.
  Reply With Quote
Old 13th January 2021, 10:06 AM   #2
Scottmoose is offline Scottmoose  United Kingdom
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
They're just 2-way speakers, for all the acronyms that get bandied around. So once you eject those and look at them in that light, you see that for optimum results you approach them like any other multiway: measure the on & off axis FR curves, impedances, and design your filter based on that data, based on whatever frequency you may wish to cross at.

Being wideband drivers, you have the option in many cases of crossing lower than you can do with a regular dome tweeter, and there is typically less offset on the Z-axis so (especially if you cross relatively low) there is often less need for asymmetric slopes or physical offsets, which can make life easier. Otherwise it's just straightforward engineering / design process.
__________________
www.wodendesign.com (commercial site)
www.frugal-horn.com www.frugal-phile.com (community sites)
  Reply With Quote
Old 13th January 2021, 05:06 PM   #3
waxx is offline waxx  Belgium
diyAudio Member
 
Join Date: Apr 2014
Location: Wodecq, Belgium
Indeed, they are just 2 ways, but with a much lower crossover point than the classic 2 ways with a midwoofer and a tweeter. So you follow more or less the same rules as with multiways.
  Reply With Quote
Old 13th January 2021, 06:47 PM   #4
planet10 is offline planet10  Canada
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Is there a program available to help with design of a FAST/WAW?
As Scott & waxx have already said.

A 2-way with a very low XO.

One does have to look at a WAW with a bit different perspective. The wavelengths at the XO frequency are much longer and ideally one wants to take advantage of that.

First of is that you now have the possibility of getting the drivers close enuff that the centre-to-centre is less than the quarter-wavelength.

As well one needs to also consider that this frequency is also in the same range as the transition from 2∏ to 4” space, so one gets the opportunity of placing the XO where it can be used to deal with this transition as well simply by having a more sensitive woofer.

As well it is often quite possible to choose drivers and design boxes that allow as little as a 1st order XO.

The bass is designed the same way one would use that midbass but without the worry of how they do at the top end of theire bandwidth — it is nice to have a midbass with an extended and well behaved roll-off at top.

The midTweeter enclosure follows the same route as a midrange, it is just extended enuf fthat one can ditch the XO.

The miniDSP will give you lots of verstaility in terms of quickly playing with XO options, and then if you find the ADC/DAC limitinf you can look at converting the scheme sorted out with the miniDSP into analog form. If you have found a 1st order XO that works this can often be implemented as a PLLXO with only 3 small passive parts per channel in the “XO”.

dave
__________________
Stay safe. Stay home. Respect the 2m bubble.
  Reply With Quote
Old 13th January 2021, 08:48 PM   #5
oon_the_kid is offline oon_the_kid  Malaysia
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
I had a quick look at your choice of drivers. I have one comment on the choice of discovery as the bass driver. By utilizing something that goes down to such low frequency, you can have more freedom in bass driver now that it doesn't have to do any mid work.

The discovery has a Fs of 47 Hz, I think you can find many drivers to will have Fs cliser to 30 Hz, this will give you lower bass.

Oon
  Reply With Quote
Old 14th January 2021, 04:32 AM   #6
Tony D. is offline Tony D.  Canada
diyAudio Member
 
Join Date: Feb 2001
Location: Vancouver Island, B.C., Canada
"The discovery has a Fs of 47 Hz, I think you can find many drivers to will have Fs cliser to 30 Hz, this will give you lower bass."

Right, but I am now living in a townhouse with neighbours on one side who will appreciate my choice of F3 and I have the 18W/4434G-00 in hand. This will also allow me to keep the enclosure at a reasonable size which will keep my wife happy so all in all I think I'm on the correct path for my needs.

Thanks for the thoughtful and relevant input though.

Last edited by Tony D.; 14th January 2021 at 05:01 AM.
  Reply to this post

Reply


Is there a program available to help with design of a FAST/WAW?Hide this!Advertise here!
Thread Tools

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
a FAST / WAW speaker design for sale johnnycamp5 Swap Meet 2 16th July 2017 06:03 PM
FAST /WAW Speaker Design harvylogan Multi-Way 11 21st April 2017 01:53 AM
Woofer placement vs xover point in WAW / FAST design ollieimpossible Full Range 2 8th January 2017 11:06 PM
Cross Over design and Woofer choices for FAST / WAW tuxedocivic Full Range 20 15th January 2013 09:39 PM
Compact FAST / WAW design rho Full Range 13 23rd March 2011 07:38 PM


New To Site? Need Help?

All times are GMT. The time now is 09:03 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki