Have you taken the 2nd, 3rd and 4th graphs indoors or something? They all seem to have a lot more response below 300Hz than the 1st one does.
Is the rear facing midrange you talk about just the woofer in the cornerhorn's?
Did you run into problems with the edge of the cone in the midrange horn slamming into the mounting plate? This was a problem I found in my horn at high levels. It was clear as daylight to hear it when excursion was high at high SPLs, awful sound it makes. I had to add a ring between driver and mounting plate, and add another piece between cone and front chamber to bring the volume back down again that the ring displaced in the front chamber. Or you could just route a circle groove in the mounting plate where the edge of the cone meets instead.
Good job!
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The rear-facing midrange used in the 1980's seven π loudspeakers were JBL 2105's, which were also used as front-facing midrange drivers. They were a 5" cone midrange, and there were sets for the front and rear installed in that model. Two-way versions develop all midrange from the driver in back, so the addition of a forward-facing midhorn will cause the speaker to have front and rear midrange output unless the driver in back is crossed over lower.
A 1/4" or 3/8" mounting spacer ring is an excellent idea. The additional front chamber volume won't hurt and it will ensure that the cone can't strike the mounting plate. For those that have routers, it might be just as good to route out that much area around the driver on the plate, maybe even just at the edge and back towards the center for an inch or so. The only part that might strike at high excursions is the surround and maybe the edge of the cone.
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I need to do the correct crossovers still, it's just half done make-shift stuff at the moment.
It's well into Autumn now, temperatures are a lot cooler. But we had zero rainfall all last month, something which hasn't happened since a decade or two, show's the effects of global warming I guess. Not good for our water supplies, we have water restrictions in the summer each year and for the first time we now have them through winter as well.
I was rummaging through the storeroom today and found a pair of old 8" Rola vintage drivers I had forgetten about. Just for fun I threw them on the tractrix horns I'm not using. They sounded OK actually, but definitly no where near as clean as the Alpha 6 conical horn. I might take do some frequency response measurements for fun on it, cuz I got a pair of them doing nothing. If its anything interesting I'll post some pics of the drivers and FR curves, see what I can do with a driver with no TS parameters and about 25-30 years old :P
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John
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Discontinuity in the horn flare will probably rule out the 10CX in this application now that I think about it. If I had one I'd try it anyway though.
Once again, thanks for sharing your designs. Simple = Elegant, especially when the engineering is sound (no pun intended).
John
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Gar.
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What I mean is that upgrades won't require throwing away a bunch of stuff and starting over. You might toss a capacitor, or you might swap out something for an improved part. But in general, the improvements I'm working on are incremental.
In many cases, existing crossovers won't even need to be replaced; They will be reused almost entirely and with fairly little modification. That was an important design criteria for me. I like being able to at least allow for the possibility of using off-the-shelf assemblies, and re-use of existing components and assemblies where possible. So I think these upgrades are pretty cool.
I plan to merge the Professional and Audiophile Series, implementing the π midhorn with a JBL 2012 on Professional Series seven π and seven π-18 cornerhorn systems. Essentially, the Audiophile Series seven π and the Professional Series seven π-18 speakers will become one and the same, using a JBL 18" woofer and a JBL 10" mid.
I intend to introduce a π cornerhorn family based on the Eminence Magnum Series woofers; These will use the midhorn and will probably adopt the Audiophile Series name. Both Audiophile and Professional Series lines use drivers with flux stabilization, and that was always key in my mind for these designations.
The rest of the π cornerhorns will take advantage of the π midhorn, using an Eminence Delta 10 driver. This is the way the π cornerhorn was originally intended, and while I like the performance of current models, the extra cost and complexity is not all that great. It will increase the cost of each cornerhorn about $200.00, but I think the improvement is worth the price.
To look back, the π cornerhorn and folded horns were originally three-way designs. But some two-way variants were made a long time ago that proved quite popular. Then and now, they are really interesting, with that "where is the sound coming from" all-around-the-room magic. Wives love them because they sound great and they blend into the room. So I'll still offer plans to anyone who requests them (just like the Peavey CH-3 versions from a few years ago). But this year, the cornerhorns go back to being a three-way using the π midhorn.
In this configuration, the woofer becomes essentially a subwoofer, and the midhorn takes most of the load. The mid/high crossover is already worked out, and it can be implemented with existing off-the-shelf components making it a pretty good deal for everyone. So I think it's a winner.
Most people used the ten π purely as a midbass cabinet, as it was originally intended. The new π midhorn can be easily incorporated, and the combination makes an excellent system. My plans here are to leave implementation of the ten π up to the person assembling the system, as it really lends itself to a modular approach. It's a wide-bandwidth midbass horn, and is useful for a variety of applications.
All one π, two π, three π and four π speakers will remain as they are, but the four π-18 will be used only in it's subwoofer configuration, sans mid-tweeter. The box size and tuning of the π-18 speaker cabinet is identical to the subwoofer already.
And finally, there's the new eight π loudspeaker. Many people wanted a hot-rod two π, and this new loudspeaker design satisfies that desire. I think it's a pretty cool "little" speaker. It just sort of happened. You and others were looking at the two π design and wanting to soup-it-up a little, and the midhorn was in the works anyway. So kind of like the chocolate and peanut butter Reese's commercials, the two just sort of fell together in what I think is a really groovy retro-meets-modern design.
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Dont put any absorbing materials inside the throat or near the throat entrance or higher frequencies will be attenuated severly.
I'd add a mounting ring or route out a groove where the edge of the cone/surround meets up with the mounting plate to prevent it from slapping against it at high levels.
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...and are you packaging kits for this model ?
Thanks, Rodney
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