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Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Tweeter
http://www.diyaudioprojects.com/Forum/viewtopic.php?f=11&t=7026
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Author:  Danny [ 02 Jan 2021, 10:36 ]
Post subject:  Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Tweeter

Hi,

I am planning to buy the Fostex BK-20 Folded Horn Kit (providing the enclosures and the 8” FE206NV full range drivers) & adding the T90A Super Tweeters from Madisound speaker store.

https://www.madisoundspeakerstore.com/f ... -kit-pair/

The FE206NV’s frequency response tops at 18KhZ while the discontinued FE206EN went up to 20KhZ. That is why I am thinking of adding the T90A tweeters.
Previously I built bass reflex enclosures with the FE206ENs and I am happy with the results.
But, now I would like to see how it sounds using folded horn enclosures with my DIY Vacuum Tube amps. One only produces 3 Watts/channel while another 20 Watts.

Any suggestions/recommendations or anyone with previous experience on these products?
Should I buy the super tweeters (they cost $215 each) or wait and see how it sounds without them first?

Thanks,

Danny

Author:  Suncalc [ 02 Jan 2021, 15:10 ]
Post subject:  Re: Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Twe

The difference between 18kHz and 20kHz is fairly insignificant. And only about 20% of the human population can hear at 20kHz. Unfortunately, I am not in that august group.

So, personally, I would save the $430 and additional acoustic work for the cabinet and just see how they sound. I have never known the FE series to be weak in the upper frequencies. But I have to trust my sound meter and spectrum analyzer because my ears pretty much give up on anything above about 15kHz (which is still pretty high, by the way).

YMMV. ;)

Author:  Gio [ 06 Jan 2021, 15:43 ]
Post subject:  Re: Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Twe

Looks like a fun speaker kit. I have the FE206E in a similar back loaded horn. I also later purchased the T90A to use with the horns. While they add a bit of air, there is not much going on at the top end musically. Proabbly their biggest advantage was you can point them, and at walls where you could help your room a bit. But they are very expensive for what would only be a very small contribution. But they do look great on the speakers! I would suggest trying the kit without the super tweeters to start and you can always add them later if desired.

Good to see there is a new driver version out, FE206NV. I'll have to go read the impressions about it.

Let us know how you make out.

Author:  Danny [ 06 Jan 2021, 21:08 ]
Post subject:  Re: Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Twe

Matt & Gio,

Thanks for the input. I’ll let you know what happens.
I will initially purchase just the kit and take it from there. So it will take several weeks.

Daniele

Author:  jororaitchev [ 09 Jan 2021, 08:24 ]
Post subject:  Re: Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Twe

The interior of the cabinet should be treated in a similar way / not just my personal opinion /keep this in mind, skills and tools are required.

P.S.
The photo is an example.

Author:  Danny [ 18 Jan 2021, 13:09 ]
Post subject:  Re: Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Twe

Well, I received the kit this past Monday and started assembling the enclosures. It only took 2 days to receive the kit from Madisound with free shipping.
The process is rather slow because, according to the instructions, you need to glue one piece at a time, clamp and then wait for the glue to harden. But, it’s ok. In a couple of instances I glued 2 pieces at the same time because I determined that it would not cause a problem. See pictures below.
The instructions are ok but not great. You need to make sure that some of the panels properly meet because they can be oriented in different ways and even though it may look ok, there is really only one way of placing them. When done right the panels interlock and meet precisely.
They did a good job at milling the panels. They fit nice and tight.
Now comes the sanding, pre-stain conditioning, staining and varnishing. I’ll use a red mahogany stain and give it 3 coats of glossy polyurethane.
I’ll keep you informed.

Danny

Author:  Danny [ 27 Jan 2021, 12:53 ]
Post subject:  Re: Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Twe

Yesterday finished the project and connected the speakers to my DIY OddBlocks KT88 Push-Pull Mono Blocks. I am breaking them in gently and most likely they will improve with time.
But, they sound great. They have a lot of clarity, definition and substantial bass compared to my previous Double Bass-Reflex enclosures using the previous version of the drivers (FE206EN).
Lot of work but a rewarding project.
See pictures below. Not sure why one of the pictures is shown side-way. I have tried to add it several times. But, I cannot get it straight.

Author:  tubelectron [ 17 Feb 2021, 12:36 ]
Post subject:  Re: Fostex BK-20 Folded Horn Kit (FE206NV driver) & T90A Twe

Danny wrote:
Yesterday finished the project and connected the speakers to my DIY OddBlocks KT88 Push-Pull Mono Blocks. I am breaking them in gently and most likely they will improve with time.
But, they sound great. They have a lot of clarity, definition and substantial bass compared to my previous Double Bass-Reflex enclosures using the previous version of the drivers (FE206EN).
Lot of work but a rewarding project.
See pictures below. Not sure why one of the pictures is shown side-way. I have tried to add it several times. But, I cannot get it straight.


Nice work @Danny 8-) - Congratulations !

-tbln.

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