I will be starting the build process for the FE163en-s Recommended Fostex back loaded horn plans found PDF HERE (pages 2) at the Madisound site. I'm pretty sure I got the last pair in North America from Solen, Quebec, of these limited production run Fostex's. From translating the Japanese Sites, only 100 were hand made in Japan, of which only 20 pair imported to the west.
After exploring the many options for a back a loaded horn(thank you to those who contributed on THIS thread), and discussing it with some people who have experience with this driver, I'm sticking with the tried and true plans.
Please consider this thread an on-going progress blog as I post pictures of the build, and address any challenges for those looking to build a similar Fostex enclosure.
But first, I have attached my cutting plans. I managed to squeeze all the panels into 2x 5'x5' (5/8" thick) Baltic Birch for both enclosures! The Japanese cutout plans are for a weird size we don't have her in North America, so I figure 5x5 is the most common, and more importantly, the only size available locally for Baltic Birch. Also, on the cutout plans, I have show the table saw ripping sequence, which is pretty straight forward, but helps take the guess work out when in my friends commercial wood shop.
I have also attached a colour coded assembly sequence drawing, which is a visual way to see what Fostex had in mind according to the plans.
The only pieces I couldn't fit on the 5x5 sheets is the stacked 'waveguide' at the mouth. (20,21,22,23,24). I have some extra BB scraps I can use, so hopefully others will improvise or have an extra small piece around. This could also be a angled piece instead of stacked, but I'm sticking with the plans. **edit** there is enough scrap pieces left over to stack together for this.
Download link to:
PDF of Sheet #1 5x5 (panel numbers correspond to Fostex Plan below)
PDF of Sheet #2 5x5
Color Coded Assembly Sequence
Fostex FE163en-s Horn Plans
After exploring the many options for a back a loaded horn(thank you to those who contributed on THIS thread), and discussing it with some people who have experience with this driver, I'm sticking with the tried and true plans.
Please consider this thread an on-going progress blog as I post pictures of the build, and address any challenges for those looking to build a similar Fostex enclosure.
But first, I have attached my cutting plans. I managed to squeeze all the panels into 2x 5'x5' (5/8" thick) Baltic Birch for both enclosures! The Japanese cutout plans are for a weird size we don't have her in North America, so I figure 5x5 is the most common, and more importantly, the only size available locally for Baltic Birch. Also, on the cutout plans, I have show the table saw ripping sequence, which is pretty straight forward, but helps take the guess work out when in my friends commercial wood shop.
I have also attached a colour coded assembly sequence drawing, which is a visual way to see what Fostex had in mind according to the plans.
The only pieces I couldn't fit on the 5x5 sheets is the stacked 'waveguide' at the mouth. (20,21,22,23,24). I have some extra BB scraps I can use, so hopefully others will improvise or have an extra small piece around. This could also be a angled piece instead of stacked, but I'm sticking with the plans. **edit** there is enough scrap pieces left over to stack together for this.
Download link to:
PDF of Sheet #1 5x5 (panel numbers correspond to Fostex Plan below)
PDF of Sheet #2 5x5
Color Coded Assembly Sequence
Fostex FE163en-s Horn Plans
An externally hosted image should be here but it was not working when we last tested it.
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The build starts with 2 sheets of 5x5 Batlic Birch.
I'm lucky enough to have access to a friends commercial wood shop. On a side note, he is only a few weeks away from getting his CNC router up and running, and open the door for doing some amazing speaker enclosures!
An externally hosted image should be here but it was not working when we last tested it.
I'm lucky enough to have access to a friends commercial wood shop. On a side note, he is only a few weeks away from getting his CNC router up and running, and open the door for doing some amazing speaker enclosures!
An externally hosted image should be here but it was not working when we last tested it.
Even though the Fostex plans are quite straight forward, its crucial to have the right equipment to get straight and square cuts, otherwise when the last side panel goes on, there will be gaps/leaks effecting bass output.
Some of the pieces layer out, each one numbered according to the plans.
An externally hosted image should be here but it was not working when we last tested it.
Some of the pieces layer out, each one numbered according to the plans.
An externally hosted image should be here but it was not working when we last tested it.
The first sections for glueing are pretty straight forward. The Fostex plans show the assembly sequence, and its obvious they start out easy!
4 Hours later and a lot of glueing, things are taking shape. I used plenty of glue, with very light clamping. I used no brad nails or screws.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
4 Hours later and a lot of glueing, things are taking shape. I used plenty of glue, with very light clamping. I used no brad nails or screws.
An externally hosted image should be here but it was not working when we last tested it.
I have seen many designs where builders have attempted to smooth the folded sections of the horn in an effort to improve efficiency. However, the Fostex plans are designed to act somewhat as a low pass filter. Lower frequencies tend to not be bothered by the folds, where higher ones get absorbed. So, expanding on that concept, I figured it would be ideal add absorbing material in the folds.
The tricky thing with these enclosures is that I only have one chance to add any sound absorbing material beyond the compression chamber. From what I have read, adding material to the throat (smallest part of the horn) can hinder efficiency, so it's best to leave it alone and add material at the 2nd and/or third bends where things start to open up more, and the material thickness has less of an effect on constricting things. I'm glad I did, as I still needed to add more later on.
The tricky thing with these enclosures is that I only have one chance to add any sound absorbing material beyond the compression chamber. From what I have read, adding material to the throat (smallest part of the horn) can hinder efficiency, so it's best to leave it alone and add material at the 2nd and/or third bends where things start to open up more, and the material thickness has less of an effect on constricting things. I'm glad I did, as I still needed to add more later on.
An externally hosted image should be here but it was not working when we last tested it.
For the compression chamber, I wanted to avoid early reflections, so I added material on walls close to the driver. I can daily remove this later on, if I find that its too much. Also, when I cut out the speaker hole, I set the jig saw on 45deg and cut it out again to open it up more for the sound.
An externally hosted image should be here but it was not working when we last tested it.
Clamping the last panel is the most critical step in the assembly. I only had about 5 minutes before the glue set. Prior to this, I had to figure out a way to get the clamp pressure down the middle of the cabinet, as my clamps can only go around the outside. So I made braces that put pressure down the centre to ensure no air gaps between the baffles.
So at a minimum, there are 12 clamps total. Remember to wipe the glue off with a wet cloth at every stage!!
An externally hosted image should be here but it was not working when we last tested it.
So at a minimum, there are 12 clamps total. Remember to wipe the glue off with a wet cloth at every stage!!
An externally hosted image should be here but it was not working when we last tested it.
After assembly, I added poly fill (pillow stuffing) to the bottom of the mouth. I also added fill to the compression chamber (light amount).
An externally hosted image should be here but it was not working when we last tested it.
The finished product! I'm very happy with how the project turned out. It took about 10 hours from start to finish. The sound was a bit 'boomy' until I added the polyfill. The fill didn't reduce efficiency, it just deepened the bass.
Compared to the bass reflex enclosures I had the Fostex's in before, the bass is so much better. Not just in output quantity, but quality as well. The texture, and speed (bass notes start and stop instantly, that is what I mean by speed) is amazing. Listening to music late last night, a song with piano stood out. I have never heard a piano sound so real. The lower register keys moved air in the room with authority.
It's also beyond physics to watch the little 6.5" cone barely move, yet produce bass output that feels like a 12" woofer. Very cool.
It's also interesting how the midrange and highs have improved as well. I'm not sure if this is because the load has shifted the impedance effecting other frequencies, but overall it sounds flatter, and more refined.
An externally hosted image should be here but it was not working when we last tested it.
Compared to the bass reflex enclosures I had the Fostex's in before, the bass is so much better. Not just in output quantity, but quality as well. The texture, and speed (bass notes start and stop instantly, that is what I mean by speed) is amazing. Listening to music late last night, a song with piano stood out. I have never heard a piano sound so real. The lower register keys moved air in the room with authority.
It's also beyond physics to watch the little 6.5" cone barely move, yet produce bass output that feels like a 12" woofer. Very cool.
It's also interesting how the midrange and highs have improved as well. I'm not sure if this is because the load has shifted the impedance effecting other frequencies, but overall it sounds flatter, and more refined.
An externally hosted image should be here but it was not working when we last tested it.
Thanks ChrisB, and thanks for your helpful input in the previous thread on deciding enclosures. I think Fostex knew what they were doing when recommending this design.
Well all I can say is what a great project to share with all of us here on the fullrange driver forum. You did a super job. I like how you got to listen to your drivers in a bass reflex and then you have them in this back loaded horn. That gives me hope in the back loaded horn designs. Well again enjoy and if you do anything other projects please share them with us. Mr. Daniel
Did we ask yet how many hours of playing time these guys have on them?
If less than the typical 200+ hrs that any Fostex I've ever used needs for full break-in, you haven't heard them at their best yet.
If less than the typical 200+ hrs that any Fostex I've ever used needs for full break-in, you haven't heard them at their best yet.
I'm familiar with the typical break in period of fostex drivers. In the past i broke in a pair of fe103's, then fe206e and later a pair of fe126en for frugal horns. With those, i ran a 60hz tone at fairly high levels over a weekend. Right or wrong, they loosened up signifigantly. But recently i have been reading and hearing the importance of a gradual break in and with normal music. This was regarding the Alpair 12p drivers, and i think applies to this situation. So, currently, they have about 40 hours of normal listening on them, and out of the box, they sounded amazing, so even more of a reason to not mess with a good thing. Which is more than i can say for the previous fostex drivers i've owned( am radio anyone?!). I suppose i could run a radio station on them, facing each other, out of phase, with a blanket thrown over top. I'm going away for a 3 day conference and can do it then.
Thorens and Sansui, not bad friends to go along with your DIY. Congratulations to beautifully built horns! If I measure the time domain response (water fall) of drivers mounted in pipes and horns, I see a large inpact by damping material in the chamber behind the driver. The lighter the cone the more affected it is by reflections from the inside. I would try to add some more damping materia from the driver downwards. One option would be to do a circular low "pot" for the magnet and cover the back and side of the magnet structure with felt. With such a magnificent driver I would hesitate to use silicone glue to stick the felt to the driver 😉
With more damping material in the chamber you might have to remove some of the damping material in the bottom of the cabinet.
With more damping material in the chamber you might have to remove some of the damping material in the bottom of the cabinet.
Thanks DrBoar.
The sansui sounds really tube like with the Fostex with no hint of Solid State sound. From what I understand it was built in the 60's right at the turn from tube to SS and still maintains a similar tube archecture but with mosfets instead(combined with point to point wiring). I only paid $120 for it and it sounds fustratingly better than my tube amp at 10x the price. Do you know if it's possible to upgrade to a bigger Sansui yet maintain that tube sound? Don't we all want the best of both worlds? The Fostex really belts out the dynamics with only 20wpc, but runs out of steam pretty quick in my larger room.
The sansui sounds really tube like with the Fostex with no hint of Solid State sound. From what I understand it was built in the 60's right at the turn from tube to SS and still maintains a similar tube archecture but with mosfets instead(combined with point to point wiring). I only paid $120 for it and it sounds fustratingly better than my tube amp at 10x the price. Do you know if it's possible to upgrade to a bigger Sansui yet maintain that tube sound? Don't we all want the best of both worlds? The Fostex really belts out the dynamics with only 20wpc, but runs out of steam pretty quick in my larger room.
Didn't know Sansui was using mosfets so early on. What model is your amp? Kinda looks like an AU-555A.
jeff
Nicely Done! I wonder if you added any window treatment to reduce the glass resonances and the reflections? It should help with the sound a lot.
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