FE166E BLH problem

[hajame]

I have built the officially recommended back loaded horn enclosure for my Fostex FE166E drivers. I have placed sound aborbants and sand into it to tune the sound. I found that the sound changes a lot upon changing the amount of materials placed in it but I don't think it is the right sound this driver should produce.

The mid-high frequencies disperse and become muddy when the enclosure is empty. When there is sound absorbant just behide the driver, mid-high dispersion problem is improved a lot. However, the overall sound is still not clear. I started filling sand to where the official datasheet told me(the canal below the driver). It seems to be optimum when the sand is of a certain volume but the sound is still slow, especially the bass.

Is it the "right" sound from a BLHed FE166E? Is there any better tuning recommeded?

 

[Nelson Pass]

Try varying the density of the stuffing just behind the driver.

 

[Scottmoose]

There's no right or wrong answer here sadly. I suspect you're just going to have to experiment until you hit on the sound you like. I'm a little surprised you're finding the bass slow though. A few general questions / points to suggest.

Firstly, how long have you had the drivers? The FE166E takes around 300 hours before giving its best in my opinion. (unlike cables, caps etc, drivers do require break-in time.)

Next question -is the horn exactly as per the Fostex plans? I've known people have problems when they rounded off all the 'nasty' right-angles inside the cabinets, which is a big mistake -they're part of the design.

Third question: how are they positioned in your room -against the wall, in corners or pulled out?

Fourth; how are they coupled to the floor? If you've put spikes on them, try removing them, and using a large quantity of Blu-Tak or children's play-dough or something like those to completly cover the base, and then stand them on a couple of paving-slabs (you can always pretty them up later with some veneer etc, or splash out on some marble if you're feeling rich). This makes a HUGE difference to any speaker, particularly in terms of improving the bass-weight and general claity. Spikes are generally not A Good Idea in my view -you've instantly created an open acoustic cavity under the speaker, which is exactly the reverse of what you need.

Best & good luck
Scott

 

[weidok]

[Firstly, how long have you had the drivers? The FE166E takes around 300 hours before giving its best in my opinion. (unlike cables, caps etc, drivers do require break-in time.)


Best & good luck
Scott [/B]

Thats correct they have to burn in for a long time
I am playing with the Fostex FE 167 E and after 150 hours
playing the sound improved..

are you using a bsc network ??

 

[cantskienuf]

Did you use birch or mdf? I used birch and took the minimalist approach to deadening - plumber's putty on the basket and wool felt on the magnet. I like the sound, but I did several months of OB break-in while slowly building the cabinets. From the wording on the instructions I didn't get the feeling that they were recommending deadening as much as saying that if you felt you must do so, do it here and there. Figured I could always re-open them to insert more, but I haven't felt a need.

 

[hajame]

Try varying the density of the stuffing just behind the driver.

Firstly, how long have you had the drivers? The FE166E takes around 300 hours before giving its best in my opinion. (unlike cables, caps etc, drivers do require break-in time.)

Next question -is the horn exactly as per the Fostex plans? I've known people have problems when they rounded off all the 'nasty' right-angles inside the cabinets, which is a big mistake -they're part of the design.

Third question: how are they positioned in your room -against the wall, in corners or pulled out?

Fourth; how are they coupled to the floor? If you've put spikes on them, try removing them, and using a large quantity of Blu-Tak or children's play-dough or something like those to completly cover the base, and then stand them on a couple of paving-slabs (you can always pretty them up later with some veneer etc, or splash out on some marble if you're feeling rich). This makes a HUGE difference to any speaker, particularly in terms of improving the bass-weight and general claity. Spikes are generally not A Good Idea in my view -you've instantly created an open acoustic cavity under the speaker, which is exactly the reverse of what you need.

Best & good luck
Scott

1. I have had the drivers for a year. After 300 hours break-in time, I did notice the improvement--- better positioning, imaging and clearer mids and highs.

2. It is exactly that plan. Plywood is used except that the interior is lightly painted in case there is mould grown.

3. Both of the speakers are placed 1 feet in front of the back wall. One of them is a half feet away from the side wall and the other is 3 feets from the other side wall.

4. I did put spikes under the speakers. Before that, I cut some bouncing balls into half-spheres and used them as legs. Real spikes sounded better. I am removing the spikes and listening. I will report the result later.

The materials under the base that you mentioned is not avaliable to me. I think I will try using some magazines first.

 

[hajame]

are you using a bsc network ??

What is a bsc network?

 

[Josephjcole]

What is a bsc network?

Baffle step Compensation. I don't think you will need this, but if you want to read about it you can find it here:
http://www.t-linespeakers.org/tech/bafflestep/intro-bds.html
Joe

 

[johninCR]

The problem may be your room if you now have bass that was lacking before, and now it sounds muddy. Give them a listen outside with only a rear wall boundary. The room is often the most overlooked item but IMHO is one of the most important factors in obtaining good sound.

 

[Nelson Pass]

Baffle step Compensation. I don't think you will need this, but if you want to read about it you can find it here:
http://www.t-linespeakers.org/tech/bafflestep/intro-bds.html

Joe

Many of the full range / high efficiency drivers, even when they
don't need BSC as such, often benefit from some of this type
of correction. The simple truth is that a lot of them have a hot
and/or peaky upper mid and top end that is improved through
step attenuation. The FE166E is not a big offender in this
area, though.

 

[smf]

Hajame

I also live in HK and want to try a Fostex 166E/BLH, but have not found anywhere that sells birch plywood. Could you let me know where you bought yours please (and had it cut to size)? Did you buy your Fostex speakers here too?

Many thansk

Stephen

 

[hajame]

Hello!
i am not sure whether mine is brich plywood or not. It is sold in large pieces. I cut the shape myself. It's such a piece of hard job...

 

[hajame]

I have removed the spikes and listened for a whole day. The instruments are less harsh but the images are sharper. The bass changes a little. It is less boomy. The sound I want is almost there.

 

[Scottmoose]

I have removed the spikes and listened for a whole day. The instruments are less harsh but the images are sharper. The bass changes a little. It is less boomy. The sound I want is almost there.

Excellent. Removing spikes and isolating the speaker / coupling it properly to the floor in this manner almost invariably brings positive results. I suspect now all you're left with is a little fine-tunig of the damping material, and you'll be there!

Best
Scott

 

[johninCR]

At the risk of being repetitive, you're still playing around with the speakers when it's very likely that your room is the problem.

 

[Josephjcole]

At the risk of being repetitive, you're still playing around with the speakers when it's very likely that your room is the problem.

I would agree that this probably is the case. However quite often the room is not something that can be changed. In which case the only option left is to tweak the speaker until you get something close to what you want.
Joe

 

[johninCR]

I would agree that this probably is the case. However quite often the room is not something that can be changed. In which case the only option left is to tweak the speaker until you get something close to what you want.
Joe

While changing the room itself usually isn't practical, there's never a case where acoustical treatments isn't possible. For bass treatments, you can even use the corners formed by the ceiling and walls and they can be virtually invisible making WAF a non-issue. You can tweak everything else until you are blue in the face, but if you ignore the room, you may be just spinning your wheels.

Plus it's easy enough to find out. Just take your speakers outside or stand a mattress or cushions and pillows in a corner and see what difference you hear. What are the room dimensions, layout, and construction ?

 

[Josephjcole]

While changing the room itself usually isn't practical, there's never a case where acoustical treatments isn't possible. For bass treatments, you can even use the corners formed by the ceiling and walls and they can be virtually invisible making WAF a non-issue. You can tweak everything else until you are blue in the face, but if you ignore the room, you may be just spinning your wheels.

Plus it's easy enough to find out. Just take your speakers outside or stand a mattress or cushions and pillows in a corner and see what difference you hear. What are the room dimensions, layout, and construction ?

Yeah, some how room treatment did not cross my mind . Do you have any links for room treatment ideas? I've always had a problems in the 80Hz region in my room, maybe room treatment would do me some good.
Joe

 

[johninCR]

There's a wealth of info online. Do a search for "room acoustics" and "bass traps" and do some reading. Stick to the sites not trying to sell you something. Having a problem only at 80hz will be quite easy to fix. To see the practical effects before you do any work, just play some bass heavy music and listen in the corners for which collects the most bass. Prop a mattress straddling that corner and listen to some music. It won't be ideal but it will give you an idea of how room treatments make a real difference. I consider the room to be second only to speakers for importance in the audio chain. Changing components, cables, etc. is a waste of time if you haven't already addressed the room.


Here are my bookmarks for bass treatment research. You should also research diffusion and absorption if you want to create an excellent music room:

Room dimensions and acoustics theory
http://www.silcom.com/~aludwig/Room_acoustics.html

Easy and very effective tube traps if you have the space.
http://www.teresaudio.com/haven/traps/traps.html

John Risch's DIY tube bass traps, if you can't find large pipe insulation locally.
http://www.geocities.com/jonrisch/basstrap.htm

Information and theory about panel absorbers.
http://www.mhsoft.nl/Helmholtzabsorber.asp#PanelAbsorber

Panel traps for a home studio.
http://www.ethanwiner.com/basstrap.html

Helmholtz resonators theory and practical design. May have an incorrect formula check below.
http://www.saecollege.de/reference_material/pages/Low Mid Frequencies.htm

Correct formula for Helmholtz resonators. Apparently an incorrect formula in a textbook is floating around on the net, so use this if you want to build a slat type trap.
http://forum.studiotips.com/viewtopic.php?t=94

A list of companies and prices for commercial sound treatments,
likely to be a cheaper sources than boutique operations than can be very expensive.
http://images.emusician.com/files/33/SONICTREATMENT.pdf

 

[Scottmoose]

Don't forget the room acoustics article on www.linkwitzlab.com either. Everything there is a good read.