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jwc

Bass horn ideas again. A possible build. Need criticism.

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The losses are mainly I^2*R, since the Edcor part is rated at 300W, at less than 75W the losses will be on the order of 0.25dB and declining even more at lower power.

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djk

""The losses are mainly I^2*R, since the Edcor part is rated at 300W, at less than 75W the losses will be on the order of 0.25dB and declining even more at lower power.""

Makes sense

I like the edcor line due to the various power rating options.

These things work pretty well, ideal for multiple woofer (2 or more, 4, 8, and 9 would'nt need an aufoformer) and mix-matched mid and tweeter driver senerios (using 8 if 16 was called for and vs versa).

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Considering the uniform interest in dual woofer setup, I will spend a little time reworking another horn option. Tonight, I will need to post some diagrams in order to ask the right questions about the throat for the dual woofer setup. Dana has explained it to me before but I'm not 100% confident with it. Once I have the throat worked out "in a splitter", I do pretty well with the rest.

jc

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Gil brings up some interesting points. I have a few more to add...

The one thing I think he left out was that the consideration that single driver front-loaded horn designs were used in the past because of size (or footprint) constraints in the home audio market. In the "old" days, drivers needed fairly large back chambers which makes a demand on the design, of course, and doubling that was out of the question except for the threatre versions. Reflex horns were/are also going to be quite large due to the even larger back chamber requirements for large drivers.

The trend in modern drivers is a small volume equiv. compliance, so now we literally can but 2x 15" drivers in 3 cu. ft of space and have them work quite well (provided we select the drivers carefully) in front-loaded horns.

There is going to be a price to pay, though, if you do dual drivers - and that is selecting and designing a top-end that can "keep up" with the bottom end. Extreme efficiency on the mid and high frequency units is quite difficult to control WELL (or easily [or cheaply]).

Designing and building a dual large-driver bass horn is relatively easy - the hard part comes later as a consequence... believe it or not! and it will be the most expensive part, too.

So what you gain, you also give up other things. Frankly, I think I'll pass on it - I already have a very good idea of what it will take to get there.

Interesting dilema, isn't it?

BTW, If I was going to build a Jubilee, I think I'd go with the Eminence Kappa-Pro 12. Looks like a pretty good fit.

DM

Kappa-PRO_12A.pdf

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An excerpt of the Carlson patent (EV)... dual or quad driver horn...

DM

post-13458-13819304745996_thumb.jpg

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One particular thing I want to point out as can be seen in a general glance at bass horn designs as a whole... And that is one of the design elements that you are seeing in the previously posted front-loaded horn patents.

Bifurcation - when and why

The whole point of bifurcation is to keep the horn channel dimensions relatively small compared to wavelength (remember the width < 1/6 WL "rule" I posted earlier?), allowing for folds to naturally occur relatively close (in travel distance) to the throat where the dimensions are smallest, which helps to prevent standing waves from forming in the respective channels. If you are not employing FOLDS in the horn design, then there are literally no benefits to be realized by bifurcation. If you ARE bifurcating any where along the way, the bifurcated channels must be symetrical and of equal length.

Not that some bifurcated horns split at the tailboard (ala Hartsfield) and some at the throat (most of the PWK designs). Which is a better approach? UNKNOWN. What about a UNITARY hornpath?

Unitary Pathways

Some respectable people here report that the well known unitary horn designs folded or not, such as the University "Classic" and "Dean", have a different and preferable performance compared to the bifurcated horns well known here. As those horn designs are not as drastically folded, it has been speculated that gentler folding (or bends) could be the cause, but it is hard to determine which element gives them the difference in performance, different drivers, different wave propagation characteristics due to mouth shape and position, or phase-related differences enherent in the single horn path, and/or all of the above, of course. The simple fact that it is REPORTEDLY different is enough to apply some thought and experimentation to the possibilities afforded by other designs.

The time-consuming research is in learning enough to understand the benefits AND drawbacks of a particular "solution" and then choose the best of those choices for your purposes design.

If you NEED to stay with bifurcation (i.e., a "W"-type horn design) as a design element, my question is WHY? There are probably thousands of W-type horns designs already available, why design another from scratch?

What are your goals?

Freq. response? Footprint (i.e., what - its got to be rectangular?), etc.?

DM

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D-MAN

I have listened to both types, and I like the Unitary types better, they seem wider in range. In my view, seems more robust and fuller.

The Bifurcation types seem to do well as true bass horns.

I certainly do not see any reason one should stick with w-bin designs.

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D-MAN I have listened to both types, and I like the Unitary types better, they seem wider in range. In my view, seems more robust and fuller.

That isn't the first time I've heard that said!

So much so, my current design is a unitary path.

DM

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50Hz square horn - I believe that this is the Turbosound "T50" with alot of internet fans.

DM

post-13458-13819304756224_thumb.jpg

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The only folded bass horns I've heard are bifurcated the best I can tell.

I want to reinterate my interest here. First of all, it is for education for me. I first need to understand some basics and see if I can follow through with making an entire design. I had to borrow a few "knowns" in order for me to do this. As such is the throat just like what is in the la scala.

The first few horns I followed through on were an ugly shape but I did follow through. I posted this last one to recieve criticism on a "finished" design in my head. Tis was an exponential 50Hz down to the centimeter. Doing a project design from the ground up MAKES me understand what is going on. I have a guy here locally that could put any design you guys throw at him for just a little cost to me. But I want to know what's up.

Granted...there is no way that I can catch up to sound engineers and think I can create a masterpiece. However, Pros and cons of horns already out there are chronicled here on this forum. Much like the networks of PWK. Yea...they are great and I spent a lot of time learning about them over the last 1 1/2 year. I then built about 12 networks last year and modified many in a way that MIGHT improve a weakness (that I percieve).

No different than the Cornscala I built just over one year ago. This was taking some known knowledge and improve something that I considered a weakness (scala-lack bass: CW-lack midrange).

So I have taken this a step further. Not to start a Klipsch Nazi war here but I'm not sure the Khorn is that appealing to me. I need to audition them some more to make my final decision. The Jubilee sounded great and I am torn between just getting a pair or continue my quest for knowledge and continue my stretch of DIY goals.

I have tried to hunt down bass horns on Ebay just to hear them out. It would be worth it to me just to buy em....listen and resell them if needed. However, bass horns just don't just come up everyday.

So what are my goals. Not set in concrete by any means. Everytime you guys post something as criticism I get a lot out of it. I have done this for a while on this forum and more than welcome to make myself look ignorant with the return of getting something out of it.

So in the end....bottom line.....just trying to seek audio heaven and being a DIY. I'm not a broke guy. I could easily sit back on my couch everynight, drink scotch and hear LP's on some Jubilees. It may come to that. However, would continue to get the itch to make something of my own.

All comments have been greatly appreciated. Will need to take some time and absorb the info somemore.

jc

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If I were you (or it were me in your place), I'd think about building a pair of Jubilees, you know, sooner or later, your going to HAVE to build them anyway, just to get it out of your system!

Why not now? It's as good of a straight-forward example of a dual-driver bifurcated corner horn as your going to find. And the plans are even free! It isn't going to get much better than that - I think that it would be an excellent learning example with the possibility of looking great, too.

Dana

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Hold it. There were a couple of goals that you inquired of.

I don't care about 2 way necessarily. It would be nice to have the bass horn go out to 300 Hz WELL. I was thinking of making my own tractrix or exponential mid horn later and getting a 2" compression driver such as the Altec 290L. I would need some tweeters too. I already figures out how to do this. I must say..the Altec 511 is hard to beat for the price and I have 902's right now. Very good combo. Comfortable going down to 400Hz.

Using the K33 or Bob's driver would allow me to pretty much scrape up my own network.

Maybe the bass horn I have drawn out already would still work. Did my explanation of what the horn was doing fter the first 90 degree turn makes sense? Does that eliminate some of the concerns once the 45 degree fillets are in there? I tought I could make what I described above look good. But if there is criticism by noted a large compromise in low end sound......back to the drawing board.....or as you say.....build something elsealredy there. Speaking of that, Dana you posted one time a dual 12 inch woofer set up on a previous La Scala thread...Do you remember where that is.....Do you have enough info on it to build it?

The non bifurcated horns that I have seen schematics for may be difficult to "look good". My wife thought the University classic was just too "boxy". Not ruling them out with that statement.

jc

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Dana...you posted as I did. Maybe I should build a Jub. May need your help.

jc

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jwcullison

I read your post at thread 764394 in reply to 764356 and I wondered what happened.

So I go down stairs to my garage and unload an new table saw, 3 sheets of 7 ply birch from my truck, and as i replaced the blade on my wall mounted panel saw, it hit me. We hi jacked your thread. in the time you adjourned to review your plan and digest the info tossed around, we started talking about different horn concepts and personal preferences. This was just a side bar, and certainly not directed at you.

My apologies.

As far as your goals, anything I can do to help, you can count on it.

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If I were you (or it were me in your place), I'd think about building a pair of Jubilees, you know, sooner or later, your going to HAVE to build them anyway, just to get it out of your system!

Why not now? It's as good of a straight-forward example of a dual-driver bifurcated corner horn as your going to find. And the plans are even free! It isn't going to get much better than that - I think that it would be an excellent learning example with the possibility of looking great, too.

Dana

Dana,

You make a persuasive argument!

However, in terms of the plans I assume you are referring to the Patent along with the JAES article. What is not clear to me is the following

1) How close are the plans to what was ultimately produced (the prototypes). I assume that during construction some additional ideas & tweaks were incorporated.

2) Also what compromises were performed for the actual prototypes (or the theater versions). I assume some compromises were done to make the construction easier or because the extra benefit did not exceed some commerical or practical criterion. Those compromises would not need to be replicated if we make home versions. Although this thinking just initiates more tweaking at the very begining.

As an aside, folding the horn makes a otherwise long horn fit into the corner. However, Nature has also solved this geometric problem. In this case the horn is not bifurcated, rather it is coiled like a snail or conch shell (probably other examples also). Sure, the construction would be a bear and probably require building molds (which I know nothing about) but all the surfaces would be smooth and without corners or reflections (with the larger waveforms).

Thoughts & opinions,

-Tom

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There is going to be enough horn theory involved in selecting appropriate drivers and setting it up that heads could explode, let alone cutting and building 2 of them.

But the horn dimensions, Vb, flare rates, mouth size, path length, placement issues are already solved. Ample decisions still have to be made, like the throat layout, which is still somewhat up in the air (BigDnFays throat layout looks like what I think PWK would do, or at least, close enough).

It's certainly not a slam-dunk by any means. However, it could be successfully completed with some determination.

Doing it all from scratch is a bit harder, and is very time consuming as it is preferable, of course, to have all of the parts worked out and correct before you start cutting and building. It may be more personally satisfying, though. But that means alot of research, IMO, and that takes alot of time.

One reason that I recommended the Jubilee, aside from its reputed performance capability which should please any builder, is the fact that it is entirely symetrical. It can easily be understood, and therefore built without intricate instructions, once the design and layout is understood.

In general, start with the motor board, build the throat channels as seen in BigD's thread. It actually will flow from there, construction wise, almost intuitively.

Granted the LS would be the simplest build, but may lack on the performance end. Then there's the University Dean, which is also a reasonable build, but is not symetrical. Many options, but if your going to throw time and resources at it, why not go for a real big return on your efforts, better overall performance.

Your call.

Dana

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