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Multi-Way Conventional loudspeakers with crossovers

Is there a Golden Ratio?
Is there a Golden Ratio?
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Old 14th September 2018, 09:47 PM   #11
system7 is offline system7  United Kingdom
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Originally Posted by nigelb63 View Post
+/- 1mm? Surely a deviation that small can't be audible to the human ear? Especially considering the subjectivity of listening. Some people like to EQ, some like flat, some like bass heavy, some like sibilance. I'm no expert but I can't agree with your statement.
Just quoting because we are turning the page. FWIW, a mm on a tweeter just shifts the sweet spot slightly. Not worth worrying about.

I think this Volt 8" polycone plus SEAS 25mm tweeter project of yours really shouldn't be too hard. I have no idea why you think an 18mm aluminium baffle is a good idea though. No-one does this stuff. How you going to machine it?

And bracing a hugely heavy box is just not my idea of easy to build. Is it even necessary? The BBC didn't think so. Damping panels won't do anything on heavy rigid panels except add mass and stored energy which you will hear.

The only listening approach that makes any sense is to compare to live sound. That is the real yardstick. If that leads you to use classical music which you have heard live, so be it. But TBH, most people don't listen to anything other than an unreal studio sound, so are clueless.

This is how you do your Volt/SEAS speaker:
Rogers Loudspeakers › LS5/9

Not hard to flesh that one out for your particular drivers once you understand what it does well.
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Old 15th September 2018, 01:17 PM   #12
nigelb63 is offline nigelb63  United Kingdom
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I’m learning all of the Steve, The reason for an aluminium baffle? My ocd, I like the look of silver anodised aluminium paired with a dark veneer- palisander or we get .I work in manufacturing so getting the baffle machined isn’t a problem.
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Old 15th September 2018, 08:14 PM   #13
system7 is offline system7  United Kingdom
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Yeah, but it's a major speculation that an 18mm aluminium metal front panel will be any good. It might ring like a bell! I just don't know really.
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Old 15th September 2018, 10:46 PM   #14
nigelb63 is offline nigelb63  United Kingdom
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It won't be in free air so no chance of it ringing but we will see.
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Old 16th September 2018, 12:58 AM   #15
AllenB is offline AllenB  Australia
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Originally Posted by nigelb63 View Post
for baffle width over woofer diameter?
I can almost see where you are coming from, but the question isn't lending itself to an answer. What specifically do you think is at stake here?
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Old 16th September 2018, 01:01 AM   #16
AllenB is offline AllenB  Australia
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Bear in mind most drivers are designed to work in a cabinet a bit wider than the driver.
Sorry Steve, but I can't see a point here in the current context.
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Old 16th September 2018, 01:36 AM   #17
planet10 is offline planet10  Canada
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Is there a Golden Ratio?
Quote:
Originally Posted by system7 View Post
Yeah, but it's a major speculation that an 18mm aluminium metal front panel will be any good.
18mm would be severe overkill. It might ring if you tap it with a hammer, but music is not going to excite it.

Golden Ratio is not better than other non-coincident ratio boxes that are based on irrational numbers.

It is pretty thou. Iíve done quite a few boxes that are close to Golden Ratio,

Root 2 works, but donít use it twice.

dave
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Old 16th September 2018, 03:42 AM   #18
nigelb63 is offline nigelb63  United Kingdom
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Seriously, take my word for it. The baffle I have designed for my project will not ring. It will be completely inert once its fastened to the cabinet. If someone can provide a reasonable argument as to why my aluminium baffle will be inefficient I'll continue with it.
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Old 16th September 2018, 07:28 AM   #19
AllenB is offline AllenB  Australia
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Efficiency may be another subject, but fastened to the cabinet... will it transmit sound to the other panels?
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Old 16th September 2018, 08:19 AM   #20
system7 is offline system7  United Kingdom
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Time to get back on topic. This aluminium baffle may or may not work, time will tell.

The Golden Ratio, 1.618... or 0.618... , is one of the more interesting algebraic numbers:
Golden ratio - Wikipedia

Ramanujan found it particularly interesting as the simplest irrational constant to express as continued fractions. It is the limit of the ratio of successive Fibonacci numbers: 1,1,2,3,5,8,13,21,34,55,89,144, ...

FWIW, it is not a transcendental like Pi and Exp e.

It has a deep relationship with 5-fold symmetry, which in turn has a deep relationship with the 6 equal angle lines that can be constructed in our 3D space:
A New Path to Equal-Angle Lines | Quanta Magazine

And you thought that there were only 3 axes at right angles in 3D space that have equal angle symmetry!

Should we incorporate it in our rectangular monkey coffins? Probably does no harm. The idea is the vibrational nodes are in an irrational ratio, so overlap and reinforce as little as possible. No particular frequency is then overly emphasized.

However, does it really matter? Plenty of loudspeakers break the rules while sounding spectacularly good. Like this Spendor S100 example owned by Vrystaat:

Click the image to open in full size.

Lot to like there. Vibration and damping is generally spectacularly misunderstood. It's why bridges fall down and buildings topple. Time really does tell.
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Last edited by system7; 16th September 2018 at 08:32 AM.
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