Fostex fe167e bookshelf design

[Tea42]

Hi all,

Right now I am also experimenting with the FE167E in a bookshelf enclosure. As a first experiment I did a small 9 litre BR enclosure. Fostex recommends two BR ecnlosures, a funny looking BR for the 167e that is even a little smaller (I calculated about 8.5 litres) and a larger 17 liter enclosure both tuned to roughly sixtysometing Hz. So I reasoned that a smaller enclosure would not hurt and built a pair.

Right now I am still experimenting with dampening a bit, but so far am quite happpy with the sound of the speakers.

I read a lot about how the Fostex drivers need breaking in. This certainly is the case here. Without altering the cabinet, the speakers are developing more and more bass every few hours.

Dimensions are (exterior) 20x29x23cm and made from 15mm birch plywood. The BR tube has a diameter of 5cm at the front and tapers down to 4.2cm at the back. Length is 11.5cm.

All the best,
Hans

P.S. Still I amm going to experiment with the driver a little. Will try to find an even better enclosure that fits my shelf space (29cm high and 23 deep). I would love to build one of the larger enclosures, but as I also collect pinball machines, my wife is reluctant to grant me another space consuming hobby.

 

[AmadeusMozart]

Calling Scotmoose

I posted something more detailed over on the WD forum, but I might as well add it here too.

Firstly, you need to be a bit careful here. The dimensions on Zillaspeak are actually for the discontinued FE167, not the current FE167E, which has different parameters. Jeff's copied them over from the Fostex site, for discontinued driver models.

If you want a good standmount / bookshelf for the 167, then I'd build something on these lines, if you didn't want to buy a set of plans from Bob (which IMO would be worth doing -Bob's a master at refining boxes). It has a similar volume to the Fostex box you mention, and a little more than the FB-16 apparantly has,but the alignment will probably be similar to Bob's (I don't know what the FB-16 internals are like, but I suspect we've got a similar take, though I usually prefer a narrower front baffle unless a full-blown WB box is wanted).

Internal dimensions 19in x 6.75in x 12in (HxWxD). Driver-centre 9.5in down from the internal top (i.e. at the half-way point). Port centre is 3in up from the internal bottom. Port is 2in in diameter and 2in long. Line the cabinet with carpet underlay or similar, top, bottom, rear and one side-wall, or stuff it 0.2lbs ft^3 of material in the upper 10in.

As you can see from the attached FR graph, this gives an EBS alignment, which should give decent extension without boom (which you'd get from a reflex box if you used a QB3 max-flat alignment. Impedance is steeper than an MLTL floorstander, but nothing to get worked up about. Driver excursion is fairly mild too. Should make a nice little standmount.

Scott - I have not been able to fit the XL FH3 into our living area and decided next to make the Fonken167 (thanks for the plans Dave!). However I am concerned about the 45 degree cut at the front being screwed up. (someone else has to make them for me so the Fonken will be quite a bit more expensive to build).

Regarding this BR design: How critical is the port location? Can it be moved to the back at the same height?

Similarly in page 2 you mentioned a 20 L version where the port is longer: Can the port be moved to the bottom ? And what are your thoughts about extending the port even more to something like 3 ~ 3.5"? (like Bob Cordell EQSS)

I never liked bass reflex but the metronome has been a revelation. I suspect the opening at the bottom has a part to play. Unfortunately the build is too tricky to commision to someone else.

Thanks in advance.

 

[chrisb]

Well, the Metronome is not really a "bass reflex", so your opinion of examples of that that class you've heard may be well deserved

I've also preferred the performance around and below tuning frequencies of resistive slot vented designs over the conventional BR designs I've heard myself .

 

[AmadeusMozart]

Well, the Metronome is not really a "bass reflex", so your opinion of examples of that that class you've heard may be well deserved

I've also preferred the performance around and below tuning frequencies of resistive slot vented designs over the conventional BR designs I've heard myself .

Thanks Chris - I will take a serious look at this design then:

http://p10hifi.net/FAL/downloads/Fonken167dtb-plan-030612.pdf