Nested Sonotube tapped horn?

That's not really a horn but an aperiodic vent, or a stab in the dark at a trasnmission line. You're talking about nesting a skinny sono in a fatter sono, right?

IMHO that would sound like s%%t, but what do i know. I had some old motorolla speakers that had something like that going on, you know, back before people understood sound. What is all this going to achieve? Are you tuning the whole apparatus like a regular port for flatter response, or just have some acrylic sonotubes and want the pimp factor? I swear I'm not throwing hate, I'm just confused.

problem is there is no horn here tapped or not

You could build it, and then see if it really can do sensitivity of ard 100dB (or any appreciable gain against a vented box) for 1W. Or pump 100W into it and measure at 10m, GP. Then match the cu vol of yours against the appropriate model in the Danley line.

Surely... I have very little knowledge of both.. but I do have a decent grasp on the physics of speaker and enclosure design..... And what you have pictured offers up very little if any "horn".... crude at most and if any benefit gained is most likely not due to the properties of horn loading.

Actually this approach does work. There will be affects at higher frequencies that depend on the cross section of the internal area at the bends, but below 100Hz you can have a response that is akin to a horn.

Tom Danley himself had planned out some conventional horns and tapped horn designs using nested tubes, although I don't recall any of those coming to life recently. He did always note that long ago he built a BIG transmission line subwoofer in exactly this manner.

In operational terms, Tom liked to describe the straight segment approach as "digitizing the horn." The average area vs. length and total volume define the horn's operation, and the number of segments or steps needed is just a question of the upper bandwidth needed and the areas involved.

Wonderful... funny how everytime I open my mouth... MS isn't too far behind to kick me in the head.

Mark once again thanks for a tiny crumb (no matter how small) of your insight and knowledge base.

Now time to crawl back into the hole... maybe go clean some ice... I think I should stick to RF

So Chris can pick up where Danley left off. I'll stand by for pics and plots Or at least an explanation of why danley said "F%%k it" to these designs after some pot inspired back yard experimentation....

A big tube looks fugly in the pro audio world, can't stack/array? But perhaps something that's no good for us also, like it doesn't sound good esp when its pushed....bad freq response, not enough gain over appreciable BW so its not too far off from a vented sub of equal vol etc. Never know till you've built it and listened critically. There are many horn subs in the market, but from what one can read...some sound better than others.

I tried nesting tubes to make a concentric port.


Even went as far as to publish a calculator for tube sizes and endgaps.
I found that there was too much turbulence when the air had to change direction. Fun though...

So instead of explaining how your wonder tube works you call me dirty names and tell tales of a cut up trashcan and baking sand one spoon at a time back in the late sixties. I think you're insane, yes, even if we have it easy "these days" Good luck though. I don't have to build or prove anything any more than you do by the way

In fact let's take a look:


All that woodworking? Seems trivial to build a box for someone who rides a bike for 12 miles with 100 pounds of beach sand. Regardless, if that's the only 'advantage' there is then I can see why Danley didn't want any of it.


Oh man, order yours today, right? I'm sure it will "probably" sound okay.


Seriously, dude, you asked for thoughts, I gave some to you. Sure it looks like it ruffled your feathers, but you still haven't given an ounce of physics behind your concept other than mentioning that it's a horn system. Well great, hey, I invented a horn too. It does a million dB with one watt. Driver, dimensions and all? Oh, well uh obviously it can be scaled to fit. Yeah, just scale it to fit... It works by... you know, horn principles.

One big difficulty I see here is to get the right driver to fit the sonotubes after modelling (is there any horn sim software for the tubes anyway...), which i believe the tubes comes in fixed sizes/dia?

Interesting story. It brought back many memories and one I thought I should relate:

33 years ago, I got the idea to build 3-way speakers that had a separate woofer box, in which was contained the crossover and a 12" woofer in a ported box of 3 cubes, a separate 6" midrange cube and another separate (and pretty cool looking, slim box, if I say so myself) with 2 tweeters.

The mid and tweet boxes wired off the back terminals of the woofer box from the crossover and could be placed for maximum sound stage in any room.

I used sink cutouts from our counter top shop to build the woofer box, which already had laminate on one side, which I turned to the inside of the box. I then laminated the boxes with wood grain laminate.

Although I co-owned a kitchen/bath company and had access to table saws, routers and saber saws, I used fairly rudimentary tools and built them at home in my spare time. I based the design on ideas gathered and sifted from the book 'Hi Fi Loudspeakers and Enclosures' published in 1947 (IIRC). It had all of the theory for horns, ported, drone-cone inverters, folded horns, sealed, infinite baffle, etc., and had designs from Bozak, Klipsch, Jensen, Altec, Lansing (JBL was signed Jimmy B Lansing on the back of the box of one of them), University, Wharfdale, etc.

I built a couple dozen sets and sold them back in 1975-76, allowing the purchasers to select their own wood grain. I fondly remember my wife and I, newly married, in a tiny apartment with saw dust up to our ankles in the living room from me routing the laminate trim, while she soldered all of the connections.

I recently was contacted by one of the purchasers who told me that his basement was recently flooded in a storm and his speakers were destroyed. He asked if I would build him another set like he had. I explained that technology has made leaps forward and that it would be more economical and offer more design choices to just buy a pair from any number of manufacturers.

He asked if I would draw plans for the speakers so that he might try to build a set himself because he wanted those speakers in that design. He used them in his shop and placed the woofers in niches and had built shelves for the mids and tweeters so that the sound was good anywhere in his shop (according to him).

Well, I decided to rummage through my attic and sure enough, I found an old set that I had used myself and saved (I save EVERYTHING).

I decided to blow off the dust and ship them to this guy so that they'd have a home and he'd be happy to get what he wanted, free of charge.

In the process, I noticed and remembered the hand wound coils in the crossovers that we made ourselves with a drill, spool and wire, as well as the clever little things I would write inside the boxes for posterity I calculated the box size and port with a slide rule because I couldn't afford the exorbitant price of a calculator when they first came available, etc.

We hooked them up and measured them. Since the components are separate, they were easy enough to measure separately and then as a whole.

I must say how stunned I was to see the accuracy of the overall FR as well as the slopes and points of the crossover. The ported box was flat to 28Hz and they had a slightly rising response from 10K to 20K. In fact, I am amazed that the rubber surround (a rarity 35 years ago vs cheap foam or corrugated, impregnated accordion-type surrounds) of the woofers was still intact and that everything was in near-perfect working order.

The speakers were delivered last Saturday to a very grateful guy who will have them until the next natural cause of their demise, which is pretty cool to me.

I bought the drivers from a high school friend who was a stateside distributor for Phillips. He went on to have many amazing experiences in pro sound, including a long meeting with Paul Klipsch who explained to him that those old timers had discovered, discussed and written about things like digital, fiber optics and solid state in the late 40s, and then proceeded to prove it by pulling articles from his vast library, which was adjacent to his office.

Sorry for the ramblings, and apologies to the youngsters who are somehow put off by these sorts of stories, but I wanted you to know that I always enjoy the old war stories like yours. I appreciate your input, even though I'm not up on horns and other larger solutions like PK, et al.

Please continue...

Bosso

Actually, I know for a fact that Tom designed and built an experimental avalanche control device using stepped pipe segments of increasing size. This wasn't a music reproducer and operated mostly in sine wave mode, but it was light and efficient for the huge package size that sat on a flat-bed trailer pulled by a semi. That device actually ran off a gas powered motor turning a crank to drive the horn at 12Hz which I'm told was enough to make the leaves on surrounding trees quiver.

Ironically, Tom often suggested and wanted to build a horn out of the nested pipes as he appreciated the elegance and economy of the implementation, but generally the package wasn't conducive to the application, market desires, or those who would ultimately produce the final speaker. One of the wacky designs that led to the Tapped Horn (actually one of the first tapped horn designs), was conceived and designed to use pipe segments, but the potential client's project was delayed or sidetracked for reasons not related to the acoustic device. Yes, this was a wider range device using more conventional drivers and some of the designs I am referring to were intended for pro or home audio.

As I explained above to those who actually read through the response, pipe segments work just fine so long as you understand and reasonably account for the limitations. The hurdles are very similar to those encountered in folding a horn. Come to think of it, a handful of the tapped horns which have been built as well as those Danley Sound Labs sells do in fact use some straight profile segments. So long as you account for whatever changes that imparts on the behavior, it can function just fine, and sometimes it even works better for the use. Whether the straight segment has a rectangular or circular cross section is of minor consequence until higher frequencies, with both having benefits depending on the use and dimensions involved.

I would have to check, but I recall finding almost exactly this design patented or simply branded by one of the computer speaker companies, likely Creative or Logitech. Their embodiments are usually molded plastic which affords some added flexibility in the 180 deg bending. A port and a horn have some similarities, but also some important differences. At the 1/4 wavelength loading point, you generally have simultaneous low velocity with high pressure at the throat, while having high velocity and large air displacement at the mouth. Obviously this will have different requirements for the pressure coupling/quarter-wave resonance than is present in a port where we are concerned with smooth air-flow and end termination to reduce air flow noise. How the bends and turns are handled becomes critical, as any expansion and contraction of area inside the port would be very detrimental to air flow.

While not the same, a look at Polk's Power Port design is another interesting twist. Way back when he designed it, Mathew Polk actually posted a spreadsheet to calculate such a port for DIYers. Not a bad idea, but hard for most to build efficiently without custom molding/tooling or owning a lathe.

Much of my own work in the past few years has involved going back to good ideas which we weren't able to implement correctly at the time, or didn't understand all of the variables at work. Bandpass subwoofers and horns are but two easy examples.

Great story Bosso!

Chris, all we've learned here is that this design was used by someone as a non-musical device, I'm young, you're crazy and that's about it. At least you're blowing steam off by pulling the age card. Better in my opinion than just flat out calling me rude to defend your thread and whatever else is on the line in your mind

As for long winded stories about the good old days, they are fine - I for one come here to read, learn and get up to snuff on all sorts of oddball ideas like this one for instance. It's a bit out of place when someone asks for the magic behind the claims though. Surely a good follow up to a good explanation, but more of a side dish. FIY I've read all of it, Marks posts, Bosso's, all of it. Meybe if Chris posted here more than 7 times per year he'd understand I'm not here to flame anyone - just to learn. Hard to learn anything when we go off talking about the late 60s and bicycles in a thread about a bass horn though =]

So far this is an interesting thread. I'm enjoying the stories from Bosso, and Chrisbee. Collo is throwing out some interesting port designs and Mark is discussing the powerport and the plausibility of this nested horn idea. I'm enjoying all of it.

AlexE,
Chill man. Maybe if you quit attacking Chrisbee we will get down to the underlieing principles that may or may not make this nested horn suitable for a subwoofer system. Just because someone only has a few posts does not mean that they are a newb or some kind of audio moron.

Wow Chris.

There is a lot of effort on your part to discredit me, and yet nothing at all about sizes, proportions, or much at all about the nestled sonos. Would it kill you to say something like "the backwave reiforces the sound pressure like a ported design, but the stepped diameters provide a horn system at the mouth?" The S in AVS stands for science, not s%&t talk.

You made a thread where you present an unusual design in order to "avoid all that woodworking" and resort to calling the nonbelievers all sorts of things and start talking about goverment investments. I get it, Chris.

I'm seriously cracking up over here. ESPECIALLY at your feeble attemtps to argue ad hominem.

http://en.wikipedia.org/wiki/Ad_hominem

Read it and weep buddy, my age has nothing to do with an abstract idea that you refuse to explain yet so feverishly defend against all questioning.

"Guys i have a bass horn design! Just scale it to fit, it's better than ported cabs. Trust me here, I made one out of a trash can in the late 60s. No, don't ask what sizes anything should be, or in what proportion. Tapering is probably not needed. You youngsters wouldn't understand! Rude Grasshoppers can't learn by asking."

Laughter really is the best medicine. That's your posts in a nutshell. I feel much better! Thanks.

Honestly speaking, this thread would have gone down the toilet if I didn't say what I thought and drew attention to it. I think I'll leave it alone now, and let this thread sink to it's proper home. When even Mark S. can't come up with some solid guidelines for such a design, I doubt many others will have anything to add. You personally got squat other than that MSPaint drawing. Most new poeple here looking to build a working sub will have the brains to stay away from shot-in-the-dark designs, so no harm done - carry on with the BS...


Thanks,
-Alex

I'd like nothing more than information from this man. Post count has nothing to do with it. I doubt we'll get to understanding any principles, as there are none. When even Mark S. can't come up with any proper guidelines for such a design, I doubt many others will have a lot to add. Chris seems lost in his own thoughts too