Anyone used the Fostex FE83e

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Fostex FE83E

I just finished building a pair of double bass reflex enclosures using FE83E's and the sound is surpsrisingly good. I am not suggestion that a small 3.5" drive can reproduce good clean fast base but the enclosure makes up for it a bit. The mids and highs are beautiful, very fast and crisp. If you like jazz or piano music give them a try... definitley no jungle or house. The system can be found here
http://forum.audiogon.com/cgi-bin/fr.pl?vopin&1134928131&read&3&4&
 

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Neil

very good work, your double bass reflex DBR!

The FE83E is a very fine speaker for low levels, one of the best fullrange speakers out of the fostex line. I love this DBR box as nearfield monitor, just on my desk, not trying to fill a complete room with sound. Even at the European Triode Festival 05 some people where surprised about the reproduction quality!

The original plan comes from this link:

Fostex recommended enclosures

You easily can tweak them by linearizing the frequency response between 500 and 1500Hz. I do it very successfully by some accoustical gain, by conical front horns attached.

Inner diameter 72mm, outer diameter 21cm, horn "length" 7cm.

You will be surprised about the difference! It should be easy, to form such a horn by strong paper and to hold it just by hand in front of the speaker, for a quick trial.

Happy ears!
Franz
 

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Here, you see how I make them: out of some "Hartschaum" (sorry my limited english), some hard foam, made of poly vinyl chloride PVC.

I heat it in the kitchen oven to 90 to 110 degree celsius and form it by pulling it.

Cheap and you will not believe the difference!

Franz
 

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Hello all,

And congratulations Franz for the good work. I'm quite jealous ;)

Yet I'd like to know more about the way you build horns, I mean how do you shape them, do you have a special tool for that?

Plus I know there are various ways to calculate a horn, what is yours?
And what frequency do you achieve to reach with such a small driver? What other driver do you use for the bass range?

Sorry for these numerous questions.

Bye

PS: I own a pair of ACR FE130S
 
And congratulations Franz for the good work. I'm quite jealous

:cool:

Yet I'd like to know more about the way you build horns, I mean how do you shape them, do you have a special tool for that?

You see the tool in this picture.

Plus I know there are various ways to calculate a horn, what is yours?

Easy: the inner diameter is the upper frequency of the horn, the outer diameter the lower frequency. The hornlength is the increase in volume between both freqencies.

And what frequency do you achieve to reach with such a small driver? What other driver do you use for the bass range?

No other driver, as I am a fullrange freak, actually.

Sorry for these numerous questions.

No problem!

Franz
 

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Hi Kofi

First: are you really THE Kofi Annan personally, the friend from Adolf Ogi? If yes, I offer you two fronthorns for free but you should visit me at my home, next time you stay in Bern!

There is no secret but no exact recipe existing. Just try :D

It works best with small speakers, up to 10cm diameter. Bigger ones tend to "loose" too much highs, with this arrangement.

I used it successfully specially with Fostex FE83E and FE108Sigma.

The material is offered in the local hobby shop. It is easy to saw and sand it like soft wood.

Over 60 degree celcius it is getting soft and bendable.

Here another picture, same style horns attached to some Cornu Spiralhorns.

Link to Spiralhorns

Kind regards
Franz
 

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Franz,
Thank you for the fantastic suggestion. I thought that my next DIY would be a DAC but i am going to hold off and try the horn extensions. Your tool is ingenious.. simple and very effective. Have you tried to use a heat gun to soften the PVC?
Do you simpley sandwich the PVC between 2 sheets of 9mm ply and then guide the sheet over a stand that repressents the inner diameter and length of the horn?
And my double base relfex were heavily based on the design from the Fostex website. Just used a flared port to smoother lows.
Thanks
 
Have you tried to use a heat gun to soften the PVC?

Yes, first, I made my fronthorn experiments with a heat gun. But it is not easy to dissipate the heat well.

And another disadvantage: the heat is just applied from one side. The material is about 3mm thick and some kind of foam, so the other side will not get hot enough.

It is easier to use an oven. Maybe infrared from both sides could be an alternative.

Do you simpley sandwich the PVC between 2 sheets of 9mm ply and then guide the sheet over a stand that repressents the inner diameter and length of the horn?

Thats exactly the recipe!

Franz, looking forward for your enthousiastic report about the incredible improvement of the sound :)
 
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