SPL of Horns

[Kofi Annan]

Does anyone know what the sensitivity of Fostex 206E horns in the 208EZ enclosure would be? The drivers themselves are 96dB and I know that the overall sensitivity of the speaker increases when mounted in a horn enclosure, but I don't know how much.

I've heard that the sensitivity can go up to 100dB in this enclosure, but I've also heard that it may only go up a few dB (say, to 98dB), so I'm confused.

I'd really like to know since I have some tube gear on the way, so if anyone can help I'd really appreciate it.

Also, if anyone can help me with a new UN resolution on Iran, I'd appreciate some help there too. I'm stumped.

Thanks!
Kofi

[GM]

Don't know, but from just looking at measured specs I can speculate that the FE206E is only ~94.4dB eff. Vs the FE208ES's ~95.5dB in the horn related BW, and that the filter chamber/throat is too large for the FE206E, so you may need more series resistance than your system has and you may also need to experiment with reducing the filter chamber's Vb for best in-room response once you find the optimum amount of added series R. This means that the final system efficiency will be <the driver's base efficiency and some digital EQ shaping may be required for best in-room performance.

WRT horn gain, it is dependent on a number of variables, and for a properly done BLH it is designed to be anywhere from 2-6dB higher than the driver's base efficiency, IOW just enough to make it ~flat in room ~an octave above the design Fc, so while they are technically horns due to having a LP filter/positive expansion, their gain is more like that of an unstuffed TL. Few achieve this though without significant EQ shaping unless designed for the specific app.

WRT the Middle East in general and radical Muslims in particular, I'm rapidly swinging to 180deg of politically correct, so can't offer you any peaceful suggestions.

GM

[BillFitzmaurice]

The overall sensitivity doesn't change in a rear loaded horn. Model the driver in a vented box in WinISD and you'll see that it has practically no bass response; this is due to the very low Qts, the price you pay for high sensitivity. What the rear loaded horn does is to tap the rear wave of the driver and use horn loading to add gain that will raise the bass response hopefully to the same level as that of the front wave.

www.billfitzmaurice.com

[Kofi Annan]

Thanks for the information! My next question (since there's always a next question) is will I get a reasonable response with a 3.5W SET tube amp? I'm not looking for arena rock sound level, mind you, but I would like to engage in moderately loud listening levels when say, Jacques Chirac and Gerhard Schroder drop by.

WRT the Middle East in general and radical Muslims in particular, I'm rapidly swinging to 180deg of politically correct, so can't offer you any peaceful suggestions.

Yeah, I get that a lot these days. What if we get all the Mideast leaders together to play a "winner-take-all" round of No-Limit Hold'em? Its a thought...

Thanks,
Kofi

[GM]

You're welcome! Beats me, I mean one man's moderately loud is another's TV viewing level. Figure in-room system efficiency is 93dB/m, then adding 10*log(3.5) = ~98.44dB/m. Factor in room dependent loss over distance and there's a good chance you'll be clipping the amp if other than chamber music is played. I don't care for it, but many folks find the clipping of tubes euphonic, so maybe this will be adequate.

Back when I was semi-serious about this stuff, I used to regularly clip a Mac2300 driving ~107dB/m eff. 70-500Hz midbass horns on selected organ an symphony vinyl/tape/CDs, though the average SPL was around 96dB/m, or ~'live', but heavily compressed/limited R&R, etc. should play plenty loud unless the room is large/open and you sit far away, so as always YMMV.

What if we get all the Mideast leaders together to play a "winner-take-all" round of No-Limit Hold'em?

LOL! I can't believe any of them would go for it! If held though, I imagine it would be just another 'shootout' (possibly literally) with no-one honoring their 'debt', so nothing would change. Hard to have a reputable game when all the participants are disreputable......

GM

[Kofi Annan]

I can't believe any of them would go for it!

OK-- Pot Limit Hold'em, then. Canasta, maybe?

Thanks for the information. I do listen enjoy the rock and roll, jazz and soul music, so hopefully these will perform OK. I sit (or lay down, or weave drunkenly back and forth) about 8' - 10' from the horns, so I'm thinking the volume output will be adequate.

Looks like you live near me (I'm in the Atlanta UN building) so if you hear an overall loudness in your general vicinity followed by a legal announcement in the AJC that Mrs. Annan is filling for divorce, that's me.

Thanks again.

Kofi

[GM]

You're welcome!

Whatever happened to the game of Warlords, chess? Seems to me this would be the obvious choice. Anyway, Some Jazz/Soul will clip the amp, so I guess it will be a matter of whether or not it's objectionable to you.

Looks like you live near me (I'm in the Atlanta UN building)

?! I have no idea what you're referring to. I live off Shallowford Rd near I-85. BTW, do you come to the annual AtlaDIY Meets under an 'assumed' name? Sure would be nice if you brought them. I haven't auditioned any Fostex horns or FE206Es.

GM

[Kofi Annan]

I've never been to the Atlanta DIY, but I'd like to attend. I'd be glad to bring the horns, only I made them out of 3/4" MDF (and they're not exactly works of art) and I would say that, without exagerration, they weigh approximately 75,000 lbs each.

I would, however, be glad to view others' stuff and make uninformed, completely ignorant comments: "What's that round thingee on top there?..."

I just started with this DIY Audio stuff only recently and while I have already built a fair amount of gizmos, I'm still learning and a bit intimidated by those in the know.

Let me know if and when you have a meeting and maybe that will give me the guts to finish my cabinets and properly damp(en?) them. Also, I will need to enlist the help of several pirates and / or professional wrestlers to move the damn things.

Kofi

[GM]

They can't be as heavy as some of the systems folks bring. My estimated 350 pounders ARE a bit much to haul around though, even with their casters/handles.

Many (most?) of the folks who show up are like you, IOW have only built either kits or copied on-line designs. Heck, every year I've been one of us 'experts' has had to tell someone to swap their tweeter polarity, fix a connection, or similar newbie mistake, so I wouldn't be too concerned about whatever level of 'expertise' you're at.

WRT level of finish, some bring unfinished or basic flat black primered, so even if you didn't finish them it's no big deal. I know how you feel though. The first year I went, all I had was some unfinished RS 40-1354 'fullrange' towers (ML-TL) I was building for a friend, and almost took them back home when I saw the professional fit/finish level of some.

Anyway, historically it's been up the street from me in Doraville the 3rd Saturday in October, but we vote on the date every year and there's been some talk of moving to a different location and possibly making it a two day event. There's a website set up, so sign up and get updated: http://groups.yahoo.com/group/DIY2004-Atlanta/

So what's the 'Atlanta UN building' you speak of? Your home?

GM

[Kofi Annan]

Many (most?) of the folks who show up are like you, IOW have only built either kits or copied on-line designs.

That's encouraging.

Heck, every year I've been one of us 'experts' has had to tell someone to swap their tweeter polarity, fix a connection, or similar newbie mistake

This was done with kindness, I hope.

all I had was some unfinished RS 40-1354 'fullrange' towers

Funny, I have a pair of those myself that I built for a friend. I know it sounds like I'm being a smart ***, but its true, only I built the 1354s in the standard Fostex FE-103 BLH. Cones are damped with damar and the frame is reinforced with modeling clay. That's the best looking thing I've built.

historically it's been up the street from me in Doraville the 3rd Saturday in October

OK-- I'll do it and I'll try and bring the 206Es. But if anyone asks you built 'em.

So what's the 'Atlanta UN building' you speak of? Your home?

Yes. Also known as Unfinished Speaker Depot.

I'll sign up for updates for the meeting and I guess I'll see you there. Thanks for the encouragement.

Kofi