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Howard Ferstler

Review of AR-303 by Julian Hirsch in June of 1995, He A/Bd the speaker against the AR-3a

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A mistake that more than a few US companies seem to have made over the years: you should never pay your vendors and subcontractors (domestic or overseas) with shares in your company.

I can pretty much guarantee that any company who is doing this is doing it because their back is against the wall, and they are trying to obtain a supply of products to re-start the cash-flow cycle. I speak from experience here.

In any event, it is better to raise capital from entities with a vested interest in a thriving business, rather than from entities who might prefer liquidation or sale of the brand during difficult times.

-k

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Well, at the very least, don't pay out enough shares to lose majority. Otherwise you might as well just close up now and go home. Even if the business thrives, it won't be yours anymore.

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Well, at the very least, don't pay out enough shares to lose majority. Otherwise you might as well just close up now and go home. Even if the business thrives, it won't be yours anymore.

I've been on both sides of the acquisition game several times. By the time an owner gets to the point of wanting this kind of deal, chances are good that they have little say in the arrangement. This is especially true with niche businesses that rely on specific entrepreneurs and broadly interpreted competitive advantages. If a key investor does not have a majority, they must find a way to mitigate the risk of dilution from the issuance and sale of new shares. For example, if the majority interest votes to double the number of shares, said interest will remain a majority, while a 20% stake will morph into a 10% stake. Repeat as necessary. So, if a serious recapitalization is required, the lender/investor will typically demand controlling interest. (For this, and various other reasons, it is generally easier to buy/sell a business outright than it is to invest in it.)

There is actually a deeper issue at work here: There is exactly one rational motive for an institutional investor to put money into a small manufacturing business: a transaction of the business. Otherwise, the rates of return of world-class manufacturers simply cannot effectively compete for capital. Risks are too high, best-case bottom line is too low, growth is too slow. Suppliers have a vested interest, but similarly need to be guaranteed of the relationship and the pricing, which brings a whole different set of problems.

-k

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I can pretty much guarantee that any company who is doing this is doing it because their back is against the wall, and they are trying to obtain a supply of products to re-start the cash-flow cycle. I speak from experience here.

-k

Also sounds like Snell in the early days. Audio Nord purchased drivers from Vifa (for Snell) in return for shares in the company. Eventually they had enough equity to leverage Dr. Osgood out.

It sucks being undercapitalized.

David

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I actually can check with Allison, and do so immediately.

How? Well, attached are three pages copied out of the catalog he produced during the years when he was going whole hog. It describes the Allison Boundary Effect, and even includes poop about the Allison tweeter and Roy's approach to speaker distortion.

Note that this boundary effect phenomenon is, as I pointed out in a different post elsewhere, from the 2-pi to 4-pi transition we get when wavelengths become long enough to no longer allow the front cabinet baffle to be seen as a 2-pi surface and the system works as if it were functioning in free space. The Allison cancellation suckout thing is different, although it is indirectly related to the 2/4-pi phenomenon. And the suckout effect has nothing to do with cancellations that occur at the listening position due to reflections getting to the listener at different times. It works at the woofer, period.

Howard Ferstler

You are better off reading Roy's 1974 paper. He refers to a model with the real and reflected source, as I had mentioned. He describes the effect in terms of the summing of source and the delayed reflection. No mention is made of the woofer cone motion being altered by the second (or reflected ) source, so changing the power "at the woofer" is an incorrect interpretation.

We are used to seeing the pressure effect of the Allison dip from a single boundary. The effect can be quite dramatic. Yet when viewed in terms of radiated power from a single boundary, the effect is quite mild. This is because the effect frequency changes greatly with angle and you can move fully to the sides where there is no cancelation at all. This is also why the maximum dip happens at about .35 wavelength off the wall rather than .25 wavelength (Allison's figure 4). As you start summing response curves around the system for a total power response, the on axis curve (only) would have a dip at .25 wavelength, all other angles will have the dip at progressivly higher frequencies. This leads to a milder composite dip at .35 wavelength. If something were going on "at the woofer" it would have to happen at .25 wavelength where the woofer and its virtual reflected woofer are 0.5 wavelength apart. Instead there is 0dB gain or loss at that frequency.

For the 2 boundary and 3 boundary case the dip gets dramatically worse, especially when the source is equal distant from the 3 boundaries. One way of looking at this is that you can't move very far around the source when constrained to 1/8th space. You don't have the case where you move to the side and the source and reflection(s) are in phase. Hence the power summation more dramatically shows the big cancelation that the individual curves would have.

David

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You are better off reading Roy's 1974 paper.

Considering how many times we've seen somebody refer to a published paper and somebody else pooh-pooh it as "outdated" or even claim it has since been repudiated by its author, I'd much rather Howard check with Allison now. Maybe we'll get really lucky and something will get said about that Villchur matter...

I know several people who went the "shares as operating expenses" route, and every single one of them have told me that in retrospect they wished they had just let their company die a quick and merciful death.

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Also sounds like Snell in the early days. Audio Nord purchased drivers from Vifa (for Snell) in return for shares in the company. Eventually they had enough equity to leverage Dr. Osgood out.

It sucks being undercapitalized.

David

Interesting. Do you know who put up the seed money for the founding of Snell? Was it a "friends and family" effort?

Indeed, as we have talked about, the undercapitalization of small- to mid-size US manufacturing is a very serious and very long-term problem. It is hard to see that changing without some serious policy help.

-k

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Interesting. Do you know who put up the seed money for the founding of Snell? Was it a "friends and family" effort?

Indeed, as we have talked about, the undercapitalization of small- to mid-size US manufacturing is a very serious and very long-term problem. It is hard to see that changing without some serious policy help.

-k

Yes, I think it was the family. Peter's father was a nobel prize winning biologist, if I recall correctly. After Peter died Dr Osgood, a local business professor, convinced the family to let him run the company for stock. Cash flow was so dodgy that driver suppliers would put them on hold and they would either have to do a quick redesign or let a distributor buy a batch of drivers in exchange for product!

Audio Nord picked up a significant share of the company that way. When they realized that Osgood was draining the company they figured out a way to maneuver him out. Soon after they sold to Boston Acoustics. I came in for a second interview and road up the elevator with Andy Kotsatos. "And who are you?" I asked, "We just bought the company." said Andy.

David

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Well, at the very least, don't pay out enough shares to lose majority. Otherwise you might as well just close up now and go home. Even if the business thrives, it won't be yours anymore.

If you shut down:

- All your existing investors lose everything. And are not happy. Some might even sue you for breach of fiduciary duty for not accepting the money to allow a going concern, just so you can keep control.

- The vendors who have worked with you, probably extended terms, are screwed.

- The employees who joined your new venture, worked long hours at less than market salary, sometimes for free, have no job.

- You are now on a downward career spiral, since you have pissed off all the constituencies you need to start your next biz, so the terms will be tougher, less slack will be cut, etc.

If you stay open, but lose control:

- Everyone but yourself is definitely happy. You are >probably< happy, at least because your name and ideas can reach the market.

- Investors are particularly happy, since the company succeeded, they got a larger share than planned. Your ability to finance your next effort goes up exponentially.

If you stay open, but don't lose control:

You are Bera Soma, Dead Villian, Frandy Peed or one of the other two or three true business savants in all of audio history.

-k

http://www.audioheritage.org/images/jbl/co...d130-magnet.jpg

(For the record: I do >NOT< recommend the way Jim Lansing eventually is allegedly to have attempted to fund his struggling biz.)

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If you shut down:

Probably why I've never started a business except for sole proprietor consulting. In the scenario you describe, I think I'd hand over my shares to my employees and just go. Obviously, I was never destined to be a "captain of industry."

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Dave, the feedback signal hasn't anything to with it bouncing towards the listener at any angle. The reflected signal returns to the woofer and partially nulls the woofer's output. The thing that you hear disappearing when you move to the side and approach the wall is the interaction between the direct signal and the bounce off of the wall that are getting to your ears and cancelling or not cancelling at that point. However, the Allison boundary effect happens everywhere, because it interacts with the woofer and not the listener. The artifact is not listener-position dependent.

In his 1992 interview with David Ranada in The Audio Critic, we have: [Allison] ".... reflections from room surfaces or hard boundaries really do reduce the output of a woofer in the frequency region where those woofers are a quarter-wavelength from the surface.

[Ranada] "This is not merely a listener-position phenomenon, the output of the woofer actually decreases."

[Allison] "Yes, it actually does decrease where one or more room surfaces are a quarter of a wavelength (approximately) from the center of the woofer. The effect is mild where only one boundary is concerned. But when more than one boundary - and in the worst case three boundaries - are equally distant from the woofer, the woofer is effectively operating in a partial vacuum, which reduces its output by 10 dB or more."

[Ranada] "That's because the reflected sound waves alter the emission from the speaker?"

[Allison] "Yes, they are reducing the pressure on the surface of the woofer and reducing the radiation resistance because of that. On the other hand, when the woofer is a very small fraction of a wavelength from one or more boundaries - then the output is actually increased, doubled, quadrupled, or multiplied eightfold, depending upon you have one, two, or three room surfaces."

[Ranada] "So this is the origin of the famed 'Allison dip,' which is a midbass decrease in output."

The Allison boundary effect involves out-of-phase interactions at the woofer and NOT interactions at the listener, and Ranada understands this as one can see by his own responses.

PS: you do not see a cancellation dip with those two woofers on the same baffle that you mention, because they are close enough together for any cancellation artifacts they might generate to be above their operating range. They add together coherently, just as wall-reinforcement does with boundaries that are a very small fraction of a wavelength from the woofer, as Allison noted above. Moving woofers close to boundaries is one solution to the Allison boundary cancellation, provided any potential notches at higher frequencies (due to the close proximity to the boundary) are above the woofer's operating range.

Howard Ferstler

Still not buying it. His math and description in the paper both pertain to the simple sum of the source and its reflection, or virtual source, behind the plane. Nothing includes a woofer model as would be required if the air load on the woofer were causing it to modify its velocity profile. Secondly, none of the 1,2 or 3 boundary cases have the null at .25 wavelength. This is because they are averages of multiple curves that all have their nulls at various frequencies, due to the path difference varying as observed from different angles.

Allison is correct to agree that the emission from the speaker is altered, that is what the power sumation shows. Calling it a decrease in midbass output is equally true. It still doesn't mean that the pressure response being created is independent of angle as you imply when you state that the null is formed "at the speaker". The null remains a function of observation angle and is purely a reflection phenomenon.

Points to ponder: If the Allison dip is quite strong with a woofer in front of a single boundary, when measured straight out from the system, why does it diminish in the power average? (Because it varies strongly with angle.)

Why do ground plane measurements not have aberations related to the distance the woofer is from the ground? (And I have done this in cases where the woofer spacing would have been 1/2 wave apart within the passband. Read Gander on ground plane measurements, no mention of it.)

Why do none of the dips in the power response happen at .25 wavelength off the surface? (.35 for the single boundary case. Even the 3 boundary case is closer to .3 than to .25. Answer: because we are averaging something that varies with angle.)

Where is the woofer modeled in Allisons math? (It is a model of the geometry of two independent sources. The sin Theta term creates the variation with observation angle.)

Why don't side by side sources have a null at a frequency equivalent to a 1/2 wavelength spacing? (because the mechanical impedances, primarily mass, greatly diminish any effect one woofer could have on the other.)

Not quibbling with anything Allison said, just how it is being paraphrased.

David

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Probably why I've never started a business except for sole proprietor consulting. In the scenario you describe, I think I'd hand over my shares to my employees and just go. Obviously, I was never destined to be a "captain of industry."

I laughed out loud at the "captain of industry" image! Yup, that's us audio guys.

More like the Captain on Gilligan's Island. All the fun is in trying to be rescued...

-k

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I laughed out loud at the "captain of industry" image! Yup, that's us audio guys.

More like the Captain on Gilligan's Island. All the fun is in trying to be rescued...

I think I always used to identify more with Gilligan, but since taking on the moderator role in these forums, the captain probably is closer...

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It really makes no sense for me to repeat what I have said before.

Please, don't let that stop you.

(Roy Allison) I never claimed that the cone velocity was altered significantly. It is altered, but negligibly.

As I had said. It is not about the woofer velocity profile but about the pressure sumation of the source and its reflection.

To sum: the power output of a low-frequency speaker is altered at some frequencies in predictable manner and amount by typical room boundary reflections. Q.E.D.

Yes it is can be modeled simply as a reflection effect, as cone velocity is negligibly altered.

I will say that a formula Roy came up with to calculate the suckout formula does use 0.3 instead of 0.25, simply because the woofer center cannot be a true quarter-wavelength away from the whole boundary surface at the same time.

The 0.3 multiplier is a compromise to get a working frequency. For the front wall, that would be to the cabinet edge and then straight back to that wall, of course. Other walls would probably work with straighter measurements.

Nope, the theoretical 1, 2, and 3 boundary power response curves shown are calculated for an ideal point source case and have nothing to do with cabinet width or energy spilling over the edges, or varying distance to the "whole boundary". The discrepency between the dip frequency and the "expected" .25 wavelength null is inherent in the power averaging of a function that changes with observation angle..

I'm off on vacation but will take some measurements that illustrate my point when I get back.

David

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Uh oh, here comes an audio engineer wannabe. :P:rolleyes:

I admit 1) I haven't read this entire thread and 2) am only an audio amateur and only understand about half of what is being posted here by those on both sides of the argument.

That being said........

Reading the comments about woofer/boundary issues made me think of subwoofers and how they are usually located for best performance. To expand on that: in my experience, the majority of subs sounded best (best = non-boomy quality; and compared to a pair of conventional floorstanders using woofers with a combined radiating area equal to the sub's driver, capable of producing higher levels of bass that also extends much deeper) when located very near a wall, inches in other words, and especially near or in a corner.

Obviously this only works for the really low stuff, because when I've played around with my conventional full range speakers and placed them right up next to the wall but especially in a corner, the level of low bass increased significantly and was more extended (I know the speaker itself remained the same - I just mean the lowest frequencies it did produce were now more obvious), but everything above ended up sounding boomy and just plain ugly.

And there's that series of Boston Acoustics loudspeakers sold in the 80s, the "A" series, that IIRC were designed to be operated with their backs against the rear wall. I think their very broad front baffles helped them to "blend" with the wall...or am I confused? But they and some other brands at the time were the only speakers to use such a design and I've never seen any imitating that design since then, so I guess they didn't perform as well as originally thought?

That's all I wanted to say - thanks for reading! :)

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... Soon after they sold to Boston Acoustics. I came in for a second interview and road up the elevator with Andy Kotsatos. "And who are you?" I asked, "We just bought the company." said Andy...

I meant to reply to this sooner, but anyway...

Great vignette! There are all kinds of potential snappy retorts, none of which would have come to mind in the actual situation.

I think I remember that big freight elevator. There was a cabinet floor, a driver/crossover floor, a warehouse/inventory floor, an office floor? Am I even close, or mis-remembering?

-k

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