Fostex Hp16 diffusers and damping.

[adejacko]

Hi all,
My Fostex 208E Sigma flat-pack will be arriving in a week or so. This is my first build and I want to do the best job possible.

I cannot find the HP16 diffusers that go in the bottom chamber. I found outdated links to Madisound or TeamAudio in France, who no longer sell them. Nor does Wilmslow Audio. Even the Japanese Fostex site does not stock them.

Can anyone help? Do you know of someone who has a pair lying around and wants to sell them? Or a shop that has old stock?

Also, what damping material is best to use;
a) on the back of the driver
b) on the back wall of the cc.
c) on the bottom and front lip of the enclosure (as in diagram)

One more question for the moment - is the T900A tweeter really worth it?? It costs more than the drivers, flat-pack and everything else together. If I do get the urge to splash out, I want to know that my money has been spent wisely.

Thanks. No doubt I'll have more questions as I start building them.

[Scottmoose]

I wouldn't worry about the diffusors; they were very expensive for what they were.

a, b & c: 'Best' doesn't mean much. All materials have slightly different damping properties but there's nothing mystical about any of them. BAF wadding, ultratouch, wool carpet underlay or similar work fine.

Re the T900a -it depends what you consider to be 'really worth it.' I can say that of this type supertweeter it's the one I like the most, & it measures better than the more expensive T500a. Whether it's worth the difference in outlay over the T90a is another matter. Only you can decide that, which I grant you isn't easy when you can't hear & compare before hand. The T90a is very good, the price difference is not minor, and the law of diminishing returns kicks in. Once you've established a high quality baseline, incremental improvements cost a lot. It therefore becomes a question of whether you can afford it or not. If you can, then I would say yes. If you can't, or it would be a significant stretch that would impact other areas of your life, emphatically not.

[adejacko]

Thanks Scott,
I've seen photos of felt on the back of the driver, covered in duck tape. I thought about using carpet underlay in the bottom of the cab. I have no idea really, as I've never done this before. I like to get as much info from others with the same speakers, who've already spent hours of tweaking, so I don't have to.

Does the amount damping change if the room size is different?, or have owners found that these enclosures all need the same amount of damping in more or less the same places. Sorry if it's a daft question.

A few weeks ago, I would not have dreamed of buying the T900A's, but everyday I feel more and more inclined to get them, so I probably will. If a pair ever come up on ebay, they'll be grabbed straight away.

Speaking of ebay... I wonder if these are any good?
Bespoke Horn Super Tweeters - Perfect upgrade for Tannoy Fostex Lowther Speakers | eBay

[Scottmoose]

Damping requirements vary according to room acoustics, partnering amplification, and personal inclination / preferences. So no, there's no fixed amount per se. As a minimum, ensure the driver chamber is lined on the back & one sidewall. You can adjust to your heart's content from there.

Regarding the ePay tweeters, without knowing a manufacturer & model number, I'd avoid like a dose of botulism.

[planet10]

Originally Posted by adejacko

Bespoke Horn Super Tweeters

Built-in XO would disqualify them. These have no pedigree, no telling how good it is... it could well be a cheap goldwood, cleaned up and mounted into a cyclinder with a cap.

I'd get T90, they are superb.

What flat-pak did you get? From where?

dave

[Scottmoose]

I would imagine the fell Wilmslow audio.

[adejacko]

Hi Dave. Yes, Wilmslow. I chose them cos the kit is rebated. which will make it easier for me to build, and stronger construction.
So it looks like a toss up between the T90A and T900A. It'll depend on how rich I'm feeling.

[planet10]

Are the flat-paks made of plywood? And one would assume the factory 208 horn?

dave

[adejacko]

dave,
If you go on the wilmslow site, you'll only see then in MDF, but I emailed and Neil who works there said they'd do them in birch, £335 (more or less). I know it's more than I'd pay at the timber yard, but I'd rather have someone who's done this before, and have the pieces rebated too. I haven't done woodwork since school.... a long time ago.

[adejacko]

Oh.. they are the new 208 enclosure, not the BK201 (which u can get in birch from teamaudio.fr). I was originally going to buy the old BK flatpack from France, as I preferred the design. Then I read that the new design was far better, and I've grown to like it.