Horn Enclosure for Fostex 206

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Scottmoose said:


Scott, once again I see your response graphs are showing actual bass on the horn. What are you doing to get these results. Are you scaling up the horn to 1/2 space to see what the potential response is? As you saw with my 1/32 space response. It shows a highly inaccurate response as towhat the bass region will actually produce. Thanks!

P.S. the first AN Super Eight prototype horn is almost done. I will have it going by tomorrow afternoon! This is the horn that I sent you the numbers to to have a look at. It is a monster. 15.5 inches wide by 40 high by 25 deep. Large and heavy. Just like I like em. 🙂

Tom
 
Hi Tom

Please accept my apologies for not getting back to you before. So much on in the run-up to Christmas. However, I have looked at it, and I reckon you're onto a good design there that'll be well worth pursuing. Over the enxt day or so, I'll try a few variations on the theme that I've got lurking around my mind & let you know the outcome.

Best
Scott
 
Scottmoose said:
Hi Tom

Please accept my apologies for not getting back to you before. So much on in the run-up to Christmas. However, I have looked at it, and I reckon you're onto a good design there that'll be well worth pursuing. Over the enxt day or so, I'll try a few variations on the theme that I've got lurking around my mind & let you know the outcome.

Best
Scott


Thanks Scott! I do appreciate it. We had some rain here over the last few days and seeing that I work out back of my house, I have not been able to finish the assembly. Hopefully, I will be able to finish it over the next two days. I will keep you posted as to the results. Man I wish I lived closer to most of you guys. Down here in Washington, D.C. I don't know of any folks envolved in this pursuit. Maybe one day a road trip to your guys neck of the woods for a gathering. (Long trip, but, sounds like it would be worth it).

Tom

Merry Christmas Everyone!
 
Hope I'm not diverging to much, but I decided to do the 206 in a the208 sigma horn as a holiday project, here's the progress so far. The drivers should be in the mail tonight, I'll post the results soon.
 

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So the results...

I just got the 206's and dropped them in a few hours ago. The gear I'm using is as follows

Technics stereo receiver
Nad C542 CDP
Monster cable 14g copper speaker wire

Not the most high end equipment, but it does the job for me
So far I'm somewhat pleased with the midrange (which I'm absolutely a freak about), there was plenty of pop and was really articulate

The high end was decent, a little bright but not in a bad way

The bass was good, but I was hoping for a little more. It was not as tight and defined as I'd hoped it would be. I wasn't expected true sub sonic boom, but it seemed to me that I could hear the low low end in a kinda artificial way (like listening to headphones). I couldn't quite feel it like I thought I would.

These speakers really sung during acoustic guitar and banjo recordings. Similar results with my Jazz CDs.

Listening to more complicated stuff like rock and orchestral music they seem to get a little lost, but I guess that can be expected from a speaker covering the entire audio spectrum.

On the note of full range, I've never had a full range speaker system before and was quite impressed with their holographic portrayal of the music. Aligning them up was bit of a chore as they are like focusing laser beams.

Overall I like them. They still have a bit of breaking in to do though. Plus I have to still add the additional side panels. Once I add these will they help tighten up the bass more?
 
Partly: it'll tighten it up by increasing rigidity, but if you want to know why you're not getting bass, it ain't the speakers you need to look at. It's the amp.

The FE206E is a very low Q driver, i.e. the motor is very powerful, and it has an extremely light cone. That's great, but it also means that it's very easy to overdamp it with the amplifer. What you need is a low DF (Damping Factor) amp to get them singing. Valves are usually the way forward, but a T-amp, or one of Nelson Pass's Zen amps will also work well.

No money? OK, junk that 14AWG Monster wire in favour of something thinner, and preferably solid core. Like magnet wire. Get down to the local electronics suppliers, and get a spool of ceramic coated wire. Costs very little -about £3.50UK for example gets 25m of the stuff. In your case the largest I'd look at is 20AWG. An alternative is a pair of 24AWG twisted conductors extracted from a run of Cat5. The extra series resistance will help. You can get good results too in these cases from 30AWG magnet wire, but it scares some people, using this hair-fine wire as speaker cable. Not surprising, :bigeyes: but it does work.
 
Ya I figured the amp was the major contributor to the less than amazing bass response, what I heard was contrary to the reviews I had read. I've been considering building a Gainclone if I get enough time too. I've read that they have anything from a low to high damping factor. Not to sure what to think. How do you think they would mate with these speakers?:scratch:
 
It took my 206's almost 2 months before they threw in some decent punch. I've got them hooked up to a Gainclone thru Wirewizard Spelbinder cable.

So i guess you will have to wait before you will hear the full force of the 206's, just don't expect them to go really low.
Once they're all played in (is that the way to say that?), they can even handle rock or pop music to your liking, you'll see (hear) !
 

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In that box (BK something or other?) they won't go especially low. They will in the 208ESigma cabinet though. 🙂

Gainclone? Yup, a low DF one should do the trick nicely. If I'm being completely honest though, I've never been a fan of gainclones. Oh, I know they can work well, but out of preference, if cash is tight, I'd save the time and money, and buy a Charlize T-amp from www.diyparadise.com + external power supply. Big upgrade over what you have at the moment. If you've more to spend, then the Zen V9 with its power JFETs will cause your eyes to pop out. See Nelson Pass's DIY site: www.passdiy.com
 
Now considering the gainclone has a suitable DF I probally end up building one, to start off with. I'm still a bit weary of the T-amp. I've heard everything from high praises to absolute disguist. I think stereophile did a review of them once, and they didn't seem to hold up very well, but thats stereophile anyways. A buddy of mine said he lend me his 300b monoblocks for a while, so I'll see how that goes. More results to follow🙂
 

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Hi, I hope that the cutting plans promised recently for reducing the 3 sheets on the Fostex web site, to two for the 208 cabinet (to use Baltic ply) are now attached. You will need 4 sheets for two cabinets. One thing I soptted the night before it was due to be cut was that piece 8 could not be cut from Sheet 1 and it was moved to sheet 2 (in the corner) There is plenty of spare room.


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Excellent. Thank you, Puffin.

You should have a large smile on your face with 300b amps. I'd still suggest a good T-amp over a gainclone. Remember, a large number of gainclones have circuit designs of deeply dubious merit. If you must, I'd advise Rod Eliot's. Rod is an engineer, and knows what he's doing. As a bonus, you can buy a dedicated PCB for the project from him, for not a lot of money. http://sound.westhost.com/project72.htm
 
I think the reference to the 300B is probably meant for someone else. However I am curently running-in the 206's in the specified BR box recommended by Fostex. I have several modified Tripath Amps and an Autocostruire 2020 amp. My favourite is a heavily modified Sonic Impact amp, used as a power amp with a Valve Pre Amp. At 96db the little S.I is a power house !
 
I dont know Scott. I designed my GCs around a minimum cap effect and let the batteries do the work. There is already a natural cap effect in a battery P/S. I only run 30 mf between the pins and have been critized for that, but my outlook is just to prevent ossiclation of the chip and not provide filtering.
I have amps from a powerhouse ( or what i consider a powerhouse) yahama surround reciever and marantz 2238 to GCs and SET and still perfer the battery P/S GC.
I am not an EE like Rod ( just a substandard ME). The major problem with GCs is the P/S ( like many other amps) and not the circuit design. If you use the minimum cap value it will work well.

ron
 
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