Fostex FE203EN-S in a Sachiko?

[Rick R]

I have a pair of Sachiko’s that I bought from a DIYer locally that has FE206EN drivers. They sound pretty good. I also have a pair of the special FE203EN-S drivers that have been breaking in for almost a month in a storage cabinet. It seems logical to put the two together. I know I am going to have to adjust the stops behind the magnets, as the new drivers are deeper. I assume they need to fit snuggly so the back stops take some of the function of holding the drivers in a rigid manner. Any suggestions on gauge and/or type of wiring to use? The old drivers have very small diameter wires. Thanks for any other suggestions or cautions you might be willing to pass on to me.

I will be sure to post my opinion on the sound of the 203/Sachiko combo.

[planet10]

I would encourage you to do the experiment and report back. Some playing with damping in the air cavity may be needed. Given that FE206esr and FE208eSR have been successfully use i fully expect it to work well.

The driver magnet braces are optional, they are intended to draw reactional energy from the driver into the other panels to remove it from concentrating in the baffle. It is optional.

Here we avoid the whole wire controversy by just using single strands of 24 guage solid core plenum grade pulled from CAT5 wires. These drivers are so efficient, and will be drawing so little current that this size wire can be considered fat.

dave

[Rick R]

Thanks for the info and encouragement. OK, so I have removed the old drivers and the wiring. Now looking around I find that the only damping material is what appears to be wool or cotton mat about 1/2" thick on the back of the compression chamber. One speaker has more of that same material on the sides and bottom of the compression chamber, the other does not.

So, I am planing on installing the 203 drivers and not making any other changes, to be able to compare with the sound of the 206EN. But I have a couple of questions.

1. What kind of glue to use to stick the wool/cotton to the walls. How about Rubber Cement? I assume nothing that would be giving off fume that could damage the driver/cone.

2. For future tweeks, should the bottom, top, and/or sides of the compression chamber be treated with damping material?

3. I have seen past posts on UltraTouch Denim Insulation, which seems to be available at Home Depot in 2" thick pieces. Is that too thick for use in the compression chamber?

4. I have seen posts mentioning Acousta-Stuf Polyfill for use in cutting down unwanted high frequency sound by placing it in the first third of the line path. How does one go about that with the speaker completed?

[chrisb]

Originally Posted by Rick R

Thanks for the info and encouragement. OK, so I have removed the old drivers and the wiring. Now looking around I find that the only damping material is what appears to be wool or cotton mat about 1/2" thick on the back of the compression chamber. One speaker has more of that same material on the sides and bottom of the compression chamber, the other does not.

So, I am planing on installing the 203 drivers and not making any other changes, to be able to compare with the sound of the 206EN. But I have a couple of questions.

1. What kind of glue to use to stick the wool/cotton to the walls. How about Rubber Cement? I assume nothing that would be giving off fume that could damage the driver/cone.

depending on ease of access to the panel walls to which you want to attach, and the density of the material, you could try hot glue on the panels, or Weldbond white wood glue - neither will off-gas

2. For future tweeks, should the bottom, top, and/or sides of the compression chamber be treated with damping material?

The amount required can be a subjective & system related matter, and depends on the shape of the driver chamber and location of throat / aperture. Looking at the Sachiko plans (attached PDF) I'd suggest the panels labelled B, that portion of D that forms the top and bottom , and perhaps the sides of the chamber. IINM an early builder of Sachiko or Hiro also lined the horizontal panels A, with undesirable results.

3. I have seen past posts on UltraTouch Denim Insulation, which seems to be available at Home Depot in 2" thick pieces. Is that too thick for use in the compression chamber?

The particular UltraTouch insulation that we've been using is 1/2" thick with a bonded fabric backers that makes for very easy adhesion with white wood glue. It's also stiff enough that if cut to the right dimension it can friction fit, which makes experimenting with locations and quantities very simple.

The 2" batting that is designed as home insulation is certainly thicker and denser (much more so than normal fiberglass) than required for this particular application, and very tough to cut to size and peel to required thickness.

4. I have seen posts mentioning Acousta-Stuf Polyfill for use in cutting down unwanted high frequency sound by placing it in the first third of the line path. How does one go about that with the speaker completed?

In common with most of this type of manifold designs, the numerous corners (10 per path, not including the stepped deflector in mouth), and judicious damping of the driver chamber* should take care of much of the required HF filtering.


*just a pedantic note that I've read elsewhere - in a BLH the room would be the "compression chamber"

[superlian]

Hi. I have also bought this driver. BTW have you measured the TS parameters? I need The VAS value (Madisound doesnt have it, i have mailed Japan today).

Regards
Hans Erik
Norway

[Rick R]

chrisb

Thanks for the additional info and I will be judicious regarding the damping of the driver chamber.

One more question, the orientation of the drivers in the cabinet. I was going to install them with the wire leads down, in a manner that you can read the info on the back of the magnet. There is no info regarding this that came with the drivers, unless it was in Chinese.

superlian

I have taken no measurements. I am really more a listener than a measure'r.

[chrisb]

Originally Posted by Rick R

chrisb

Thanks for the additional info and I will be judicious regarding the damping of the driver chamber.

One more question, the orientation of the drivers in the cabinet. I was going to install them with the wire leads down, in a manner that you can read the info on the back of the magnet. There is no info regarding this that came with the drivers, unless it was in Chinese.

superlian

I can't imagine it makes any sonic difference, but I just like the aesthetics of the visible connections of tinsel leads to voice coil wire either below the dust cap, or horizontally in those with connections on either side.

I have taken no measurements. I am really more a listener than a measure'r.

The only thing I want to measure are the cut parts when I'm assembling a cabinet, otherwise I truly couldn't care less. Whether I do or don't like what I hear, the measures won't make any difference. Of course if I was designing or modifying something, that'd probably be a different story - luckily this community has lotsa folks that revel in the mathing and graphing - live and let live.

[Rick R]

I went ahead and replaced the 206EN's with the FE203EN-S drivers. I made no changes to damping, just put in the new drivers with the wiring that came with them.

Wow, what a difference. They are better in all respects. I am going to post a review here and on AA High EFF. People should know that these drivers rock and that the Sachiko is a great home for them.

[Rick R]

I was in error on the model of Fostex driver these speakers had. They were FE206E drivers with phase plugs. Sorry for the mistake and thanks to ChrisB for catching it. My Bad!!