Finished horn modelled with MJK's analysis worksheet

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Just finished horn modelled with MJK's spreadsheet. The internals are similiar to Olsen's dual waveguide horn that starts out as a series of split manifold's which empty into a main horn section. It sounds as modelled (Definitely getting into the 30's) although I have not measured its response yet. Some design goals I had were nearly square mouth (438mm x 434mm), 1220mm H x 536mm D x 470mm W, .85xSd throat, Exp-Hyper flare T=.45. I even found a good deal at lowes for ply that is maple on one side and birch on the other and made the uppersection maple and the mouth birch.

One question I have though and it may be my error is that it seems the T/S parameters really don't effect the analysis in the worksheet. Am I doing something wrong? Iam using the FF225K now but want to try the FE207.
 

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I doubt you're doing anything wrong (although I'd have to see your inputs to be sure). If you want to run a quick check, stuff the Visaton B200 T/S specs. into your model. You'll be much more likely to see a difference with this unit, as both Vas and Q are relatively high. As a general rule, hybrid BLHs are often quite forgiving of moderate driver changes (though they'll usually work better with the unit they've been optimised for).
 
hi Andy - this one looks good - FWIW AJ-Horn would not show much difference betweeh 206 & 207

if 207 has more highs than 225 then that could make the bass sound better.

I'd like to know how BLH like this play dynamically vs my Karlson w. 15" coax or 18" + slotted - tube - I've got Super 10 in 70l reflex - nice nuff in 8x10 room but dynamically restricted even then compared to what I"ve used. Are FR BLh what I "need"?

Freddy

ps - no "low bass" with K15 or same size w. 18" but whats there is pretty good and low cone excursion is a good thing -- 200W input peak on odaiko sounds ok
 
Freddy,

The room I have it in now is about 20ft x 20ft with a 14ft ceiling. (Garage). I always hear horns need alot of room so 8x10... I don't know.

Here's how this modeled in MJK's worksheet. You should get alot of 'cabin effect' in that room.
 

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assuming half-space that looks pretty close to RCA Fan's 186 liter air-volume BLH sim.

my other rooms are somewhat larger - one ran K-horns and could run the old Edgarhorn 100 - also have FH1 and Sentry IV junkers but they're only midbass like La Scala

how powerful sound does this type get vs 15" coax in bass reflex? I need a rough reference for dynamics

Freddy
 
Thanks Scott. I think when I get home from work I am going to stick a FE208Z from one of my Fostex enclosures in it and see how it sounds. If it sounds good, I'm replacing my Fostex horns in my Family Room with these (After I build the second one.) Its a fairly easy build and uses a little less than two 4x8 sheets of ply.

Here's the split section prior to the convergence into the main horn body. I opened up the throat to .85xSd. One strange thing I also notice with this horn vs. my first horn is that the other horn seemed to suck the life out of the speaker. It lost alot of its midrange. Now these sound alive.
 

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I know this might sound like a woodworking question but I am looking for advice. This horn looked really nice when it was white maple with the birch mouth. Last night I put a black ebony stain on the white maple portion and I don't like it. Is there any way to get the stain off? I know if I sand too much it will probably remove the finish since it is ply. Or am I stuck with it?
 
I know this might sound like a woodworking question but I am looking for advice. This horn looked really nice when it was white maple with the birch mouth. Last night I put a black ebony stain on the white maple portion and I don't like it. Is there any way to get the stain off? I know if I sand too much it will probably remove the finish since it is ply. Or am I stuck with it?

If the maple is ply then you are probably stuck with it as the stain most assuredly penetrated the first ply layer. If it's solid maple you might be able to sand it out but you'll have to take off a fair amount of wood to get down to a consistent, clean level.
 
Since I couldn't turn back easily with the stain I decided to do the best I could and actually, it doesn't look that bad after the poly coat. These things are heavy (120+ lbs.) so I'm not lugging them out side to measure the response anytime soon. I have replace my FE208 enclosures and notice a significant difference. They seem to respond as modelled. I am definitely reaching the mid 30's. I have a question though and it wouldn't be possible without Scott's advice. I purposely made the throat and mouth so they could be tweeked. I am not precisely as modelled and was wondering what the best approach is to tweeking. Should I go back and remodel with what I really have and see how to improve? When I built the throat opening I made it a series of blocks with a bolt so I could increase or decrease the size. I also have the mouth low but could curve it slightly upward and dcrease the mouth. Any ideas?
 

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Well,

I measured the response as best as I could while they are in the room I listen to them. I really don't know if this data is even of any use but I came up the attached. It has a measurement in the mouth, one meter away on floor, and at the listening position. What's really strange is the listening position graph since it seems to be level from 20-50Hz??? Is this useless data? I also know the mouth does not have that much midrange output. I'm guessing the most accurate of the three is the mic 1m away on floor which seems to have some similiarities to what was modelled. Should I lug this thing outside if I really want a useful measurement?
 

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Harry Olson would've been proud of you. :)

Well, given that you were measuring in-room, they actually agree pretty well with the 1/2 space graph IMO. As you say you're not precisely to the plan, I'd re-model the cabinet you have for interest. As it happens, I doubt that there will be huge differences, but it's always worth taking another look at things. You can check a few basic tweaks out in MathCad while you're doing it, but there are things you can do the software doesn't account for too -a run of damping material around the mouth etc. (something GM mentions).

FWIW, I'd say the plateau 50 - 20Hz is either a room-mode (probably), or a measuring glitch -depends how you measured them. Does it actually reproduce ~20Hz tones?

If you want a more accurate set of measrements in re their 1/2 space response, you'll have to lug them outside I'm afraid. Then again, it seems a bit back-breaking, and as you don't actually listen to them in 1/2 space (does anyone?) & AFAIK aren't planning to sell & market the things -why bother? Unless you're really into the science side, the important thing is how they sound in the environment you listen to them in, & those measurements look pretty good to me for that location.
 
Thanks Scott.

I did play around a little with the slight deviations I have in the build and it seems to be so subtle that I see no point it making major changes. One thing I did do which improved appearance and was on the advice of GM (I think it is along the lines of some his mouth tweaks.) was at the mouth I put a strip of 1/2 round oak so that the exit was smooth and flaring to infinity. I also in my haste to get them done forgot to fully dampen them as modelled and will need to go back and add a little more. I don't really hear anything that is audible below ~ 32Hz. but I do notice that the Sigmas excursion is alot less at these lower frequencies than when they were in the Fostex BLH. The room they are in is a little unusual too as there is a big opeining into the kitchen/Dinette area which makes overall dimensions around 40x14x9. (Although not the listening position, they sound really good when I am about 35ft away.)

Nothing commercial here. They sound really good to me and what a difference a tube amp makes! Probably won't lug them outside.

Now I have a pair of the Madisound NHT1259 woofers just sitting around doing nothing. (Don't need subs/WAF in red zone.) I know the Q is probably too high but I wonder how a BIB would stand up to the plate as a bass horn?
 
awhite1159 said:

Now I have a pair of the Madisound NHT1259 woofers just sitting around doing nothing. (Don't need subs/WAF in red zone.) I know the Q is probably too high but I wonder how a BIB would stand up to the plate as a bass horn?

Greets!

From a performance POV it's not too high, but combined with its Vas you're looking at a ~51 ft^3 Vb, ergo either a simple TL or MLTL is a better choice, though its designer Ken Kantor strongly recommends you only use it in a sealed app, so as always YMMV.

GM
 
hey GM - how about running NHT1259 through some BP4 sims? - might make nice sub to mate to small speakers - does your BP program support L, C + LC passive "boost" network analysis?

Madisound lists two versions (4 and 8 ohm) with very different specs - which one do U have Andy?

CSS has a little Reckhorn eq box which can be used fo fudge transforms and 6th order reflex and bump up little K

I've had BP4 play 'ok' - partly matter of matching up sub rolloff to sat rollon. Got giddy one day a decade ago with sine not realizing Dh200 was clipping - cone melted off former - just fried usb WT2 - al it takes is a ground with one lead to another device such a amp and smoke-time - guess that means wt3 next :^)

best,
Freddy
 
I have the 4 ohm. In fact these things are still in the closed box cabinets. Before I got into FR, I had these, Vifa 51/4 midrange and Vifa Dome tweeter 3 way with crossover externalized. Just the crossovers because I used air core inductors and solen caps cost me abot $500 bucks. They sounded good when I pushed about 3-4 hundred watts through them with my Adcom power amp. But hen I became a horn/FR guy but still listening to Zeppelin, Judas Priest, and Metallica. These horns and the tube amp can rock. I just don't need a seismograph to analyze the system.
 
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