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-   -   Fostex 206E ML TL (http://www.diyaudio.com/forums/full-range/79893-fostex-206e-ml-tl.html)

panord 20th May 2006 01:15 PM

Fostex 206E ML TL
 
I am planning to build the 206E ML TL from Martin King's Quarter Wave website. It looks like a good beginner project for my father in law and I. I have gotten some good insight from Martin, especially regarding the BSC, but I would love to get opinions from anyone that has built these. Any additonal insight on cabinet construction? The plans on the website are pretty straight forward (that's what I like!), but I'm wondering if their should be some additional bracing? Any other info would be greatly appreciated. I've seen some of the comments regarding damping the stamped metal frame on the drivers. This makes sense to me and seems pretty simple. Any other (simple) tweaks?

Bob Brines 20th May 2006 02:58 PM

The very first bit of advise is if you intend to to Martin's MLTL, use the FE207E, not the FE206E. Unless you totally kill the efficiency of the FE206E is series resistance, you will wind up with a harsh, fatiguing speaker.

Martins MLTL is indeed straight forward -- 6 pieces of plywood and that's all. Those who have built it appear to be pleased with the results. I did a similar MLTL, marginally smaller, but made of MDF, lined with cement board and fiberglass and braced with three internal X-braces and an additional stiffener on the baffle. All a matter of style, I suppose.

Bob

panord 20th May 2006 09:14 PM

Well, I've already got the 206's in hand. I was concerned about the reduction in efficiency, but other conversations I had indicated the impact may not be that great. Oh well, I figured this was a learning project (to build the cabinet, experiment with the BSC, etc...) as much as anything. I'll be running these speakers off an old Hafler amp which should be able to handle them if they wind up too inefficient. I'll aim for more efficiency in the future as I'd also like to try a SET amp project. But that is down the road.

Bob Brines 20th May 2006 10:09 PM

Since you aready have the 206's, go a head with Martin's project. It should be a no-brainer to built. But, by all means, use Martin's contour filter. You will not like the results without the filter.

Bob

lovechild 21st May 2006 07:01 AM

Hi Bob,

in the last weeks, I have talked to several people in german forums, they all use the fe206e for their MLTLs.

When I asked why, they actually refered to your and Martins site as you both seem to mention the 206e and the 207e as equaly suitable for this design. They read that and then go for the 206 because of it's higher efficiency and better(?) treble.

Maybe a little note on your site might help folks finding the better driver, I know it's not your fault when they go for it without making their own simulations or at least asking s.o. - but hey, you are the 'big names' in MLTL design and it seems like people just relly on you.

just a thought...

best,
martin

Bob Brines 21st May 2006 08:42 AM

Martin,

I guess you are right about needing a note about driver applications. The LT-2000 MLTL cabinet was designed specifically for the Lowther DX2. Because MLTL's are not as picky as BR's and BLH's, a number of other drivers can be forced into this cabinet. Both the FE206E and the FE207E can be made to work. The FE207E actually works pretty well in the LT-2000 cabinet. The FE206E only works with 4 ohms of series resistance. Therefore the efficiency of the LT-2000(FE206E) is LOWER than the efficiency of the LT-2000(FE207E). Also, once you take care of the rising response of the FE206E, the high frequency performance becomes pretty much the same. If you look at the FR graphs of the FE206E and FE207E, the performance is almost identical out to 2k Hz or so, then the FE206E rises 10 dB by 10k Hz. When you are doing a BR or MLTL, you have to do something about that rise or you will wind up with a harsh, fatiguing speaker.

Bob

MJK 21st May 2006 11:29 AM

I will state right up front that I have not heard either the FE-206E or the FE-207E drivers. But I do have the Lowther PM2A and the PM6A drivers which present a similar set of trade-offs in my ML TL enclosure. Both drivers use the same frame and cone but the strangth of the magnets is much different which effects the Qts values.

A friend and I spent an evening comparing the two Lowthers in my ML TL enclosures. We started with the PM6A drivers and listened for about an hour to the standard test CDs I use, the sound was very good. Then we switched to the PM2A drivers which took about 10 minutes, adjusted the BSC circuit by increasing the resistor a few ohms, and went through the same set of music selections. There were differences in the sound, the bass of the PM6A was stronger but the midrange of the PM2A was much more detailed and revealing. At the end of the evening we both prefered the PM2A. We also agreed that we could easily live with either driver in the ML TL.

I think the decision to go for the FE-207E or the FE-206E comes down to personal taste and the music you intend to play. The bass will probably be better with the FE-207E but I bet the midrange is much clearer with the FE-206E. The FE-206E will require more correction using a higher value resistor and the efficiency will suffer. But if I were making the choice, I would use the FE-206E. Either way, I think both will sound very good for the money.

Bob Brines 21st May 2006 04:23 PM

Quote:

Originally posted by Bob Brines
...The FE207E actually works pretty well in the LT-2000 cabinet....


Quote:

Originally posted by MJK
...But if I were making the choice, I would use the FE-206E....
There's your consensus for you. You put your quarter in the machine and pull the handle. Of course, if you really want to do it right, you buy both drivers and make your pick based on your room and your music.

One thing that didn't get mentioned, both Martin and I use pretty strong SS amps, so efficiency is not an issue. If you are running under 10w/ch, and particularly if you are running a flea-powered SET, you might want to consider the final efficiency of a speaker bases on a huge magnet, very low Qts driver. But then, that's one reason so many members of this forum use BLH's.

Bob

Pendergast 21st May 2006 09:13 PM

Hello,

I am new in these fora, but I have read a lot about other people's experience. Thank you all for sharing! I am posting this here, since it is slightly in topic.

I purchased 2 Fostex 206es-r and have a project to buil enclosures with my father.

At first, I thought of going ahead with the suggested enclosures by Fostex. My father even figured a way to reduce the number of plywood sheets to cut. However, I believe the suggested encolsure is an ambitious project for newbies, so I thought of using John Rutters TQWP excel spreadheet to design an enclosure that would be easier to make.

The internal dimensions give the following (in cm):

height: 116.5
width: 20.3
depth: 36.7

Speaker should be at 26.2 from the top and a the pipe lenght calculated at 204.8

Here is an image.

Now, I am a total newbie at this, and I welcome any comments. I wished I had been able to use Martin King's MathCad templates, but I have no access to a PC so I had to make do with what I found.

Some feedback would be great!

Thank you.

planet10 22nd May 2006 01:32 AM

Quote:

Originally posted by Pendergast
Now, I am a total newbie at this, and I welcome any comments. I wished I had been able to use Martin King's MathCad templates, but I have no access to a PC so I had to make do with what I found.
Forget about Rutter's TQWT. Way more often than not you end up with something far from optimum.

The 206seR really wants a horn.

dave


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