TQWT with Fostex FE206E - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 26th June 2006, 07:57 PM   #1
Morfeus is offline Morfeus  Germany
diyAudio Member
 
Join Date: Feb 2006
Location: Berlin
Default TQWT with Fostex FE206E

Hi,

I am playing a little bit with the FE206E. I had built the bass-reflex enclosure from the Fostex PDF with the recommended horn. That was quite ok, but I wanted to try a TQWT.

Click the image to open in full size.
(port facing to the floor, therfore the stands)

The few Excel sheets to simulate a TQWT gave quite promising results, telling the enclosure could go down to arround 30Hz with the Fostex.

As the enclosure is quite easy to built, I gave it a try:

Click the image to open in full size.

Baffle width: 24,4 cm, port diameter 8,1 cm, lenght 12,1 cm.

The result was terrible. Mids and heights where wonderful, but no bass at all. Even male voices sounded thin. The BR enclosure was better in any way.

How can that be? What is wrong?

The reason why I'm playing with the 206 is, that bulding the Fostex recommended horn is to time consuming for me. I know Bob's design, but that needs a contour filter and I am loosing 3-4 dB of the 96dB. I need the 96dB (at least) for my 300b SET that I am building.

Thanks for you help,
Heinz
  Reply With Quote
Old 26th June 2006, 08:38 PM   #2
hlj is offline hlj  United Kingdom
diyAudio Member
 
Join Date: Apr 2006
Location: Oxfordshire, England
Definitely some thing grossly wrong, all the tqwts I have built have produced loadsa bass and low with it.

As you have built them I would cut out the bottom (terminus) completely and experiment with different heights until you find the right result.

Start at about 20mm and work up.
__________________
Experimentation maybe hit & miss, but it's sheer enjoyment!
  Reply With Quote
Old 26th June 2006, 09:01 PM   #3
weidok is offline weidok  Netherlands
diyAudio Member
 
weidok's Avatar
 
Join Date: Jan 2004
Location: dkm
hi Morfeus

You need a baffle step circuit

read this article from MJ King

http://www.quarter-wave.com/Project05/BSC_Circuit.pdf
__________________
There is NoBox like NoBox
  Reply With Quote
Old 26th June 2006, 09:43 PM   #4
Morfeus is offline Morfeus  Germany
diyAudio Member
 
Join Date: Feb 2006
Location: Berlin
Quote:
Originally posted by weidok
hi Morfeus

You need a baffle step circuit

read this article from MJ King

http://www.quarter-wave.com/Project05/BSC_Circuit.pdf
Hi weidok,

yes, but that reduces SPL to 90dB and this is what I definately don't want.

Grettings,
Heinz
  Reply With Quote
Old 26th June 2006, 09:52 PM   #5
Dumbass is offline Dumbass  British Antarctic Territory
diyAudio Member
 
Join Date: Mar 2003
Location: British Antarctic Territory
Quote:
Originally posted by Morfeus
Hi weidok,

yes, but that reduces SPL to 90dB and this is what I definately don't want.

Grettings,
Heinz
Unfortunately, some series resistance is all but required of the FE206E in a vented enclosure. In Martin King's project 5, it is 3 ohms, so you could start with that.
  Reply With Quote
Old 26th June 2006, 09:53 PM   #6
diyAudio Member
 
Join Date: Apr 2004
Location: Costa Rica
Send a message via AIM to johninCR Send a message via MSN to johninCR Send a message via Yahoo to johninCR
Take the port tube out completely, leaving just the hole, MJK's worksheets say that port is way too long for those cab dimensions. Also you need to stuff the line to smooth the response.
__________________
Everyone has a photographic memory. It's just that most are out of film.
  Reply With Quote
Old 26th June 2006, 09:55 PM   #7
diyAudio Member
 
Bob Brines's Avatar
 
Join Date: Jan 2003
Location: Hot Spring Village AR
Default Re: TQWT with Fostex FE206E

Quote:
Originally posted by Morfeus
...The reason why I'm playing with the 206 is, that bulding the Fostex recommended horn is to time consuming for me. I know Bob's design, but that needs a contour filter and I am loosing 3-4 dB of the 96dB. I need the 96dB (at least) for my 300b SET that I am building.

You cannot avoid the baffle step with a single driver tall thin cabinet. BR, MLTL, TQWT, it makes no difference. A horn cabinet can be designed to boost frequencies below the baffle step, but to get to 30 Hz, the cabinet will be enormous. Mother Nature is a b, and Hoffmann's Iron Law prevails.

Second issue: Don't expect to get 96dB/w/m out of a 206E. Maybe in the ear-bleed highs, but not down where the music is. I wouldn't expect any more than 94dB/w/m best case. If you really need 96dB/w/m, you are going to have to make different plans.

Bob
  Reply With Quote
Old 26th June 2006, 10:25 PM   #8
Morfeus is offline Morfeus  Germany
diyAudio Member
 
Join Date: Feb 2006
Location: Berlin
Quote:
Originally posted by johninCR
Take the port tube out completely, leaving just the hole, MJK's worksheets say that port is way too long for those cab dimensions. Also you need to stuff the line to smooth the response.
I treid that this afternoon because I realised that I made a mistake with the length of the port and I wanted to shorten it. No difference at all...

Heinz
  Reply With Quote
Old 26th June 2006, 10:25 PM   #9
Morfeus is offline Morfeus  Germany
diyAudio Member
 
Join Date: Feb 2006
Location: Berlin
Default Re: Re: TQWT with Fostex FE206E

Quote:
Originally posted by Bob Brines


You cannot avoid the baffle step with a single driver tall thin cabinet. BR, MLTL, TQWT, it makes no difference. A horn cabinet can be designed to boost frequencies below the baffle step, but to get to 30 Hz, the cabinet will be enormous. Mother Nature is a b, and Hoffmann's Iron Law prevails.

Second issue: Don't expect to get 96dB/w/m out of a 206E. Maybe in the ear-bleed highs, but not down where the music is. I wouldn't expect any more than 94dB/w/m best case. If you really need 96dB/w/m, you are going to have to make different plans.

Bob
Hi Bob,

thank you for your email and your reply here.

To make my problem a little bit clearer: I am not talking about the lack of deep bass here. As I said, even the male voice was sounding totally thin. I would very much like to understand if I made a mistake in my project, as I am quite new in that field. If the answer is "no, you did not make a mistake, you just took the wrong way" this is ok for me, and I will try something else, like a horn i.e.

The 300b SET I am building will have about 8-10 W. The listening room is large. about 60 square meters, 3.7 meters high ceiling, parquet-flooring etc. One of those typical european houses arround 1900.

I am listening mainly to classics and jazz. Sometimes I like to hear the original sound level.

Ideas?

Heinz
  Reply With Quote
Old 26th June 2006, 10:46 PM   #10
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
If you designed this thing using an Excel sheet, I'm not surprised it's not optimal. You need Martin King's MathCad worksheets for that. But as Bob says, 96db 1w/1m from a 206 in a TQWT? No chance. Maybe ~92db. And you'd loose more with a circuit too. The only way you're going near 96db is to horn load the things. In a room that size, it's the way forward anyway IMO with FR units.

As you find the Fostex boxes (which aren't even genuine horns anyway) a bit over complicated, if you can cope with the size, a BIB is easy enough to build. I know you're not a fan Bob (forgive me), but they perform way better than they simulate, and it's probably the only simple option out there. Have a look here: http://www.zillaspeak.com/bib-fostex.asp The plot looks ragged, but that's because it's a 1/2 space sim, and doesn't really account for the room's infulence. Over 300Hz, they're actually pretty flat. Below that point, the room dominates anyway, so nothing is really clear-cut. They shift a lot of air, and unlike most horns, they are not exactly lacking in bass.
__________________
Community sites www.frugal-horn.com http://frugal-phile.com/
  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
Fostex FE206E gus6464 Full Range 4 13th December 2008 10:39 PM
WTD: Fostex FE206E woodturner-fran Swap Meet 0 22nd April 2008 01:19 AM
Newbe questions TQWT using fostex FE206E LazyJones Full Range 8 30th October 2007 04:27 PM
New FE206E TQWT Scottmoose Full Range 48 26th October 2007 04:05 AM
Zen amp and Fostex FE206E broadcast guy Swap Meet 3 10th June 2004 02:23 AM


New To Site? Need Help?

All times are GMT. The time now is 09:04 AM.


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