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PostPosted: 03 Jun 2009, 12:17 
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Sorry for the lack of updates on this speaker - I've been too busy enjoying them. They have plenty of hours on them and I am much happier with the speaker since the mods. I'll try get a page together that documents the mods I made. I'm not totally sold on polarizing the chassis to the negative pole. I plan to install an on-off-on switch so that I can polarize to +, - or not at all. Then I want to try measure the difference. While it seems to have helped overall, there is a cost - some loss in dynamics and the efficiency drops a little as well (a dB or two).

Mark, keep us posted on your progress. This driver is a great match with small single ended amps.

Cheers

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PostPosted: 23 Jul 2010, 02:57 
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Hi Gio,

Do you have the list of mods you did for the speakers? Maybe I can try some of them for the Hemp 8''. They too have an annoying shout that is hard to eliminate. I once tried a 15Ohm + 6.8mH CHoke as BSC !! That just killed it LOL.

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PostPosted: 24 Jul 2010, 12:56 
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I have photos of the mods I did to the Fostex FE206E are similar to what is shown in the Fostex FE206E Speaker - Reversible Modifications / Tweaks post earlier in this thread. Most of the improvements are based around the stamped basket frame and the wide (reflective) spokes. Is the 8" Hemp speaker on a stamped or cast frame?
Cheers

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PostPosted: 25 Jul 2010, 05:57 
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Yes it is a stamped frame. I was thinking of an electrical solution though.

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PostPosted: 25 Jul 2010, 07:55 
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dtsup1 wrote:
Do you have the list of mods you did for the speakers? Maybe I can try some of them for the Hemp 8''. They too have an annoying shout that is hard to eliminate. I once tried a 15Ohm + 6.8mH CHoke as BSC !! That just killed it LOL.

You might have to implement a Parallel Notch Circuit, for your Hemp 8". Some drivers have unwanted peaks in frequency.

If you've got a frequency table of the Hemp 8" and you're able to find the peak, then try this: http://www.mh-audio.nl/ParallelNotchFilter.asp


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PostPosted: 25 Jul 2010, 08:20 
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Ye Kramme. Going to be really tricky =(
Big ol hemps need to be hammered in place @ 1500-5000Hz and 7Khz-10Khz, 4dB attenuation.
Whizzer may need to be surgically removed =p
Everytime I hear them, they keep saying "quack quack imma duck" lol

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PostPosted: 25 Jul 2010, 08:54 
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dtsup1 wrote:
Ye Kramme. Going to be really tricky =(
Big ol hemps need to be hammered in place @ 1500-5000Hz and 7Khz-10Khz, 4dB attenuation.
Whizzer may need to be surgically removed =p
Everytime I hear them, they keep saying "quack quack imma duck" lol


Sad :worried: You said surgery ...be my guest :mrgreen:

Image Image
After surgery it becomes look like a Visaton B200 ...and who knows, maybe sound as good as one.

Image


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PostPosted: 26 Jul 2010, 19:25 
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dtsup1 wrote:
Yes it is a stamped frame. I was thinking of an electrical solution though.

Here is a reversible mod that you can try. Ground the speaker negative OR the speaker positive to the speaker chassis. If you do it with a 3 position switch you can easily flip through all three settings.

Cheers

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PostPosted: 27 Apr 2011, 05:55 
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In the thread I would like to see builds, designs, comments and listening notes about speaker systems based on this driver the FE206xx. It is the biggest full range (as far as I know) driver which Fostex make. Not only that it is the most sensitive of all the drivers with a sensitivity of 96db for 1W at 1m. This is great for guys like me who like to build two stage SE tube amps. Most of my builds only produce 3 to 7.5W so very sensitive drivers are required.

To date I have built speakers using the smaller Fostex driver the FE167e and two pairs of boxes based on the FE206e and FE206en. I have built both the simpler two chamber boxes and back loaded horns. These designs come with the Fostex FE206xx drivers.

http://www.diyaudioprojects.com/Gallery/displayimage.php?album=search&cat=0&pid=176#top_display_media
http://retro-thermionic.blogspot.com/2009/11/fostex-fe206e-back-loaded-horn.html

But what I would like to offer here is my listening notes for the FE206e(s) in the back loaded horns. I have had these speaks for a while now but only played them on rare occasions. This time they are powered by my 3W 6AS7 SET amp. They will play quite loud with just 3W in a large room. When I originally set them up I had them about 3M apart. I am sitting back near 4M from them. I had them toed in and about ½ M from the back wall. The sound was good but sound stage crushed into the middle. Not well defined.

When it comes to listening I’m a little lazy. I set speakers up and leave them where I think they may sound best. But this time I decided to experiment with the horns. I pulled then another meter apart and aimed them straight ahead, no toe-in. I sat down not expecting much difference. But I was wrong, the whole sound stage spread very wide, the centre images focused and good depth and instrument positioning lifted. The sound appeared to improve too. Sometimes the Fostex can sound “honk”. Not anymore. Definition and detail sharpened and all of a sudden I was looking for a buyer for my everyday Osborn Eclipse. I have always liked the Fostex back loaded horns. Now I love them. I had heard that placement of these speakers is critical but I would never have guessed this critical. I’m still in shock.

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PostPosted: 27 Apr 2011, 21:38 
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I love mine too. So much so that I don't take them out of service to tweak them.

Yes, listening a little off the axis of the driver can help with that honky midrange. I also like to use a super tweeter (XO 10kHz+) - experiment with position.

Cheers

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