Fostex FE207E with Eminence Alpha 15 open baffle - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 Search this Thread
Old 25th April 2007, 09:32 AM   #1
diyAudio Member
 
Join Date: Oct 2005
Default Fostex FE207E with Eminence Alpha 15 open baffle

I am about to try out open baffle speakers for the first time (other than my Maggies). I have both a pair of fostex fe207e and a pair of eminence alpha 15.

My plan is to use a baffle about 600mm x 1000mm, sloping backwards slightly with 200-300mm side cheeks.

I am keen to keep things very simple initially, with a single inductor on the bass driver and the fostex running full range. I've played around with The Edge software but would appreciate some advice.

What inductor value would you recommend for starters? I have read about similar systems using from 3.9mH to 7mH.

Does the baffle size seem appropriate?

I don't want to get bogged down with BSC filter etc. as my next purchase will probably be a DEQ2496.

Any advice would be appreciated.
  Reply With Quote
Old 25th April 2007, 10:34 AM   #2
ttan98 is offline ttan98  Australia
diyAudio Member
 
Join Date: Apr 2006
Location: Melb
Martin King has developed a Mathcad program which allows you to determine baffle width and high required and also the roll-off frequency for the bass end.

Contact him, he is most helpful.
  Reply With Quote
Old 26th April 2007, 02:20 PM   #3
diyAudio Member
 
Join Date: Oct 2005
Many thanks ttan98 - I've ordered a mathcad model from Martin.
  Reply With Quote
Old 26th April 2007, 04:53 PM   #4
Ricky is offline Ricky  United Kingdom
diyAudio Member
 
Join Date: Sep 2005
Default Re: Fostex FE207E with Eminence Alpha 15 open baffle

Quote:
Originally posted by sharpi31
[B]I am about to try out open baffle speakers for the first time (other than my Maggies). I have both a pair of fostex fe207e and a pair of eminence alpha 15.

My plan is to use a baffle about 600mm x 1000mm, sloping backwards slightly with 200-300mm side cheeks.

Hi.

I've had a lot of experience with Eminence Alpha's in OB situ's.

I feel your choice is a good one. You may have to go to a 2nd order filter for the Emmy tho or else you might not be able to make it "shut up". A frequency of about 500Hz should do it. When you go to the DCX, using the same frequency, shut it off at 24dB/Octave or steeper and put a bottom limit on it of around 40Hz with a 2nd order roll.

You can also tame the top end of the Fozzie with a 6dB slope at around 8K.

Look forward to your results.

Ricky.
  Reply With Quote
Old 26th April 2007, 06:19 PM   #5
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

The Fostex run full range does not sound like a good idea due to xmax.

I'd say you should use a series 1st order crossover at least.
1st order series should work better than the normal 1st order parallel.

Click the image to open in full size.

4mH / 80uF are very ball park values.

/sreten.
  Reply With Quote
Old 27th April 2007, 07:57 AM   #6
felixx is offline felixx  Romania
diyAudio Member
 
felixx's Avatar
 
Join Date: Feb 2005
Location: in center
What do you think about this?

System Pictures & Description
__________________
"I'm glad I can build my own mistakes."
https://picasaweb.google.com/115586837612433686520
  Reply With Quote
Old 27th April 2007, 12:01 PM   #7
OzMikeH is offline OzMikeH  Australia
diyAudio Member
 
Join Date: Mar 2007
I have found my Fostex Fe207E somewhat flat in the extreme high end.
I may be doing something wrong for that result though, they only have about 50 hours on them.
  Reply With Quote
Old 27th April 2007, 12:12 PM   #8
diyAudio Member
 
Join Date: Oct 2005
Those are beautiful felixx.

How do you cross them over?

Did you use a BSC or equalization?

I think my first pair will look a bit less impressive than yours :-)
  Reply With Quote
Old 27th April 2007, 12:24 PM   #9
felixx is offline felixx  Romania
diyAudio Member
 
felixx's Avatar
 
Join Date: Feb 2005
Location: in center
I use Alpha15A for woofers and works very well.
The cross is active only for Alpha's.
The cuttoff is 250hz with Burr Brown OPA2134.
I have an active filter "a la Linkwitz" 3db and could be modified easy.
The Supravox is free of any components and it goes superb(xmax. is 4mm).

Here is an impressive work with Fostex into open baffle:
http://www.bd-design.nl/
Quasar.
__________________
"I'm glad I can build my own mistakes."
https://picasaweb.google.com/115586837612433686520
  Reply With Quote
Old 27th April 2007, 12:39 PM   #10
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Note that open baffles do not have BSC (baffle step)
as such, they have baffle roll-off at 6dB/octave.

You can use 2 bass units in a 0.5 way configuration to
compensate for 6dB of this roll-off, i.e. extend one octave.

/sreten.

Active EQ and bi-amping you can do anything with the lower unit.
You can reduce the Fostex amplifiers input capacitor to cut low bass.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
3 way open baffle with Eminence and Skytronic SimontY Multi-Way 452 16th September 2011 09:25 PM
newbie eminence open baffle mrthieme Multi-Way 13 6th September 2009 05:26 PM
Open Baffle Desktop - Fostex 4 angeloitacare Multi-Way 2 8th June 2009 10:49 AM
Eminence or P.Audio ? Open Baffle or Sealed Predator864 Multi-Way 0 23rd January 2009 11:51 AM
Eminence Kappalite 3015 as open baffle bass? EC8010 Multi-Way 4 29th June 2007 08:05 AM


New To Site? Need Help?

All times are GMT. The time now is 02:48 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2