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PostPosted: Mon Jun 05, 2017 1:18 pm 
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Emanuel Haumant wrote:
They don't understand that effectively.
Vent=Port= a hole (like in Sla pro, omnitop12) in french "event laminaire"
And a a duct is when ther is a "tube" in french "event"
It's confusing because originally a port was a simple hole in the cabinet. That dates back to at least 1930. The use of ducts was rare until the 1950s, and not commonplace until the 1970s. To differentiate between a simple port and a port with a duct the term ducted port was used. Over time the word 'ducted' was dropped, considered redundant, because almost all ports were ducted. The handle ports on the SLA Pro and Otop 12 are technically ducted, with the depth of the duct being the thickness of the cabinet panel, but according to the original definition you wouldn't call them ducted ports.

On the subject of what constitutes a tapped horn, this is the Danley patent.
https://www.google.com/patents/US8457341
Note in the pictures that there are no segments with constant area. If it's not tapered it's not a horn. As to how Danley got his patent, when prior art existed, it's all in the claims. The prior art from 1958 claims were related to the panel directly behind the driver, which is hinged at one end, allowing the size of the chamber behind the driver to be changed to tune the cabinet to the driver used. The claims later made by Danley were different, so the earlier patent didn't affect Danley.

As to what seems to be a serious lack of technical knowledge by some of your countrymen, it's no worse than here, where ignorance is often embraced with a fervor bordering on religious dogma. But Dr. Christian Heil would nonetheless be dismayed I'm sure.


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PostPosted: Tue Jun 06, 2017 8:28 am 
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Speaking of art, those who disagree with you are for whatever reason unable to see the obvious, or at least what's obvious to me. With one glance I knew what the MTH 46 is, but that comes with experience. Instead of seeing the cabinet as a whole I saw the four parts, two chambers and two ports. This diagram makes it easier for the layman to see what I see:

Image


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PostPosted: Tue Jun 06, 2017 2:58 pm 
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Very interesting read!
Welcome to the forum Emanuel :)

So often in the audio world you see people, at various stages, with various designs, simply accept what someone says, to be true.
Personally, I really don't like at all the way Mark O's design falls off so much below 50Hz.
Especially so in this modern age of EDM/doof doof, I'm surprised that a lot of the Mark O believers haven't discovered his design isn't much good for 30Hz.

Please don't quote me lol.

The answer is not to argue with them, but prove them wrong. Build some T48's. Or if your into EDM, some T60's...

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PostPosted: Tue Jun 06, 2017 3:17 pm 
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Grant Bunter wrote:
Welcome to the forum Emanuel
He's no newbie, he's an authorized builder.


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PostPosted: Tue Jun 06, 2017 3:26 pm 
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Bill Fitzmaurice wrote:
Grant Bunter wrote:
Welcome to the forum Emanuel
He's no newbie, he's an authorized builder.


Oops!
Apologies, haven't seen any other posts earlier...

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2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
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PostPosted: Wed Jun 07, 2017 1:58 am 
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Thank's Grant.

It' true i only post few times in the private chatroom these last 5 years.
Almost everything is already on the forum and Bills's plan are very complete !

I have built simplexx, Jack, Omnitop12, SLA PRO, DR, Tuba, Titan...

DR ! I love that design, not so easy to build but really impressive.

Jack light 12 for bass guitar, my personnal choice.

I begin a pair of David this week.

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PostPosted: Wed Jun 07, 2017 7:41 am 
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Looking through Marco's plans I see a commonality. The charts are all simulations, and only for SPL. It's very easy for a designer to fall into the trap of assuming that software modeling is 100% accurate, and that the data entry he used is also 100% accurate. You simply can't do that. You must build a prototype and measure the result, not only SPL but also impedance, comparing them to the simulation SPL and impedance charts to be sure that what you think you designed is what you ended up with. I can't say for sure that Marco never did that, but if he did there's no evidence of it on his site.


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PostPosted: Fri Jun 09, 2017 7:54 am 
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This is a real problem, they don't seem to have a lot of measured SPL charts of their designs.
On his thread about this controversy (tapped horn or bandpass) Marc.O only give simulations again.

Now, need to place an order for an RCF LF18G401 for an easy to buid box and ask my audiomatica clio pocket for the result.

Titan 48 make them laught a lot :mrgreen:
They thinks perhaps that's only old design for old people. We are in the 21st century now, we have 21 " !

One of them know the LAB Horn of Tom Danley (designed in 2000 or so as a free gift to diy'ers) and seems to appreciate it :
Marc.O about this design :

Quote:
Développé par Tom Danley (patron de DanleySoundlabs, designer des Servodrive et titulaire d’un brevet récent sur le Tapped Horn, rien que ça!), ce pavillon descend à 30Hz. Mais la complexité de ce caisson et le prix des HP en rebutera plus d’un.

Translated :
Quote:
Developed by Tom Danley (owner of DanleySoundlabs, designer of Servodrive and holder of a recent patent on the Tapped Horn, nothing else!), This pavilion goes down to 30Hz. But the complexity of this subwoofer and the price of the HP will reject more than one.


Measured charts from Bill :

Titan 48
Image

Tuba 60
Image

But "specialists" know in France that horn sound cavernous, have problem with close load and the warm-up faster HP and nothing under 60Hz as they say.
:mrgreen:

Very curious to see an MTH-46 against a Lab Horn.

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PostPosted: Fri Jun 09, 2017 9:24 am 
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I wouldn't encourage anyone to build a LAB Horn. It has an inherent design defect. The driver chambers are too small, which leads to driver over-heating. That's not Danley's fault, but the fault of how the design was arrived at, which was by committee. Tom did the basic design work, but it was translated into the final result by others, and one of them made the chambers smaller than Danley specified. They ended up going to aluminum driver chamber covers as heat sinks, which helps, but it's still a flawed speaker.

Quote:
But "specialists" know in France that horn... have problem with close load and the warm-up faster HP
Chances are that whatever they think these problems are don't exist, but I still don't know what 'close load' and 'warm-up faster HP' mean. You would have to explain those terms, because they don't exist in my dictionary.


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PostPosted: Fri Jun 09, 2017 10:35 am 
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The driver chambers : "charge close" in french.

I say close for closed.

The driver chamber is a sealed enclosure.
warm-up faster is for "over-heating" as you say.
And it's really easy to think that over-heating come from sealed enclosure that not dissipating heat.

You give me the explanation i was looking for about over-heating and folded horn : the small chamber of the Lab-horn.

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PostPosted: Fri Jun 09, 2017 11:16 am 
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Emanuel Haumant wrote:
I say close for closed.
The driver chamber is a sealed enclosure.
warm-up faster is for "over-heating" as you say.
And it's really easy to think that over-heating come from sealed enclosure that not dissipating heat.
Having the driver magnet structure exposed to the air does help keep it cooler. It also results in higher THD and higher excursion. That higher excursion can lead to mechanical damage. The usual method of preventing mechanical damage is longer xmax drivers, which is also to say more expensive drivers. There's no such thing as a free lunch.


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PostPosted: Tue Jun 13, 2017 2:01 pm 
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Bill Fitzmaurice wrote:
Emanuel Haumant wrote:
I say close for closed.
The driver chamber is a sealed enclosure.
warm-up faster is for "over-heating" as you say.
And it's really easy to think that over-heating come from sealed enclosure that not dissipating heat.
Having the driver magnet structure exposed to the air does help keep it cooler. It also results in higher THD and higher excursion. That higher excursion can lead to mechanical damage. The usual method of preventing mechanical damage is longer xmax drivers, which is also to say more expensive drivers. There's no such thing as a free lunch.

Wood is a great heat insulator.
Isn't it wise to make aluminium doors on the Tuba's and Titans when used for a long duration like a 8h house party? I have seen a post with a measurement of 39C/102F for the coolribs of an 3012lf. The coils are probably allready a lot hotter by then.

I have lots of experience in computer cooling and overclocking and my experience is that cooling is very important to keep your stuff running for hours or longer, and a 102F temp in a computercase would allready be to high even thought the CPU and GPU can take temps of 190F / 88C before they lower the speed or burn.
The bigger the difference in ambient temp, and the more air movement, the more cooling. The more cooling the more watts or power can be dissapated and the lower the temps of the drivers stay.

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PostPosted: Tue Jun 20, 2017 7:42 am 
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Think wrote:
Isn't it wise to make aluminium doors on the Tuba's and Titans when used for a long duration like a 8h house party?


You don't need to do that with Titan and tuba.

If you stack cabs, aluminium acces cover doesn't change anything
Outside you need to protect aluminium access cover from the sun.

Furthermore in titan you can't do that because acces cover give acces to the horn, not to the chamber.

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PostPosted: Tue Jun 20, 2017 3:49 pm 
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Think wrote:
Isn't it wise to make aluminium doors on the Tuba's and Titans when used for a long duration like a 8h house party?


If it was something that was needed, it would be in the plans.


Think wrote:
I have seen a post with a measurement of 39C/102F for the coolribs of an 3012lf. The coils are probably allready a lot hotter by then.


In a Tuba or a Titan? I'll venture a guess, and say neither. In some other design? Why would we give a shit about what a driver does in another design?

Think wrote:
I have lots of experience in computer cooling and overclocking and my experience is that cooling is very important to keep your stuff running for hours or longer, and a 102F temp in a computercase would allready be to high even thought the CPU and GPU can take temps of 190F / 88C before they lower the speed or burn.
The bigger the difference in ambient temp, and the more air movement, the more cooling. The more cooling the more watts or power can be dissapated and the lower the temps of the drivers stay.


And this has no bearing on what we are doing here. CPU, GPU, RAM and HDD all rely exclusively on external cooling, via heat-sinks or water-blocks. They do not operate in a "closed" chamber. And, because they are silicon chips, heat affects their properties in a multitude of ways, not just resistance/impedance.

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PostPosted: Tue Jun 20, 2017 6:37 pm 
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If you're overclocking your Titans, you need to build more of them.

It's an ascension of Hoffman's Iron Law:

You can only have two of the three (low, loud, small).

If you're already low enough, but want to go louder, you must go bigger.

Go to a big concert lately? If there is a row of 16 dual 18's across the front of the stage, they are not just there for decoration. If you want that kind of volume from 4 Titans, it ain't happenin....

In the grand old world of speaker and enclosure design, if overclocking was a feasible means to an end, pro drivers would come with big braided copper tails on them to attach to a nearby heatsink.

It isn't, they don't.

If it was, they would've had them since the '50s.

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