hifi.slovanet.sk

[MaBat]

Otevírá to cestu k free-air verzi LittleBighorn, 70 x 50 cm.
Takových věcí, které by se daly postavit...

[jzagaja]

Can you post sim or point cloud Marcel? We could compare to my larger 300Hz waveguide (AiA Cinema model Black Swan).

[MaBat]

Still so much to do, no time for sims yet. Do you mean this? https://www.aia-cinema.com/active-speakers/black-swan.html
That looks very very good Jack.

I can give you MSH file which ABEC reads directly (I've tried, it works). Do whatever you want with it. Mesh elements are tagged already: 10=throat area ("drive"), 20=wall up to the front plane ("wg1"), 21=lip turover ("wg2"). Now I generate these files directly with a lot of params possible to set. This is just a quick try. In the end I would probably make it not so wide and maybe deeper. Also the lip can be scaled easily.

Do you have any measurements of the Black Swan?

[jzagaja]

I have requested measurements from them - xo is 350Hz/24dB. They are testing Axi 2050 (prefer over BMS) and BC DCX464. Mine is 60x40 and roundover to get smooth polar (by trial and error in Axidriver). But your has rollback and better changing cross section. Found company that can do thermoformed horns.

Currently I use Quadruple stacked Quad ESL57 but willing to try something "new" like Eminence KL3012CX in FH-JMLC-80.

[BlackBerry]

A na bass dať napriklad takýto pekný basák
http://www.loudspeakerdatabase.com/18Sound/18NTLW5000

http://www.eighteensound.com/en/products/lf-driver/18-0/8/18ntlw5000

https://www.lautsprecher-technik.de/eighteensound-18ntlw5000-subwoofer.html

[MaBat]

With ABEC you should be fine with only a quarter of it by making use of symmetry. This will greatly reduce computation time. I guess this shape could work pretty well. So far I have not tried any free-air simulations, only an infinite plane, so the model may need some modifications...

[MaBat]

I love the SculptGL, so convenient and effective...

[MaBat]

The termination could be probably improved significantly. This all would require some fine-tuning. Well, maybe not this way. I suppose this could be quite easily analyzed with just Circular Symmetric Coordinates in ABEC, if not in AxiDriver. I could export the profile to the respective formats.

[jzagaja]

Do you remember coverage, throat size and input angle of above waveguide?

[MaBat]

This was 100 x 80°, 39 mm, 0°. I can make this for any other values in a matter of seconds.

[jzagaja]

Looks like your waveguide keeps well much wider coverage and is much smaller.

[MaBat]

That looks strange. How did you do the sim and the termination? Is that AxiDriver? What is the wavefront at the throat? I can't see a reason for that bumps in SPL in the midrange, but haven't had a chance to try it yet. Now it might be interesting to see the same horn with different throat diameters.

Well if it would keep the beamwidth to 10 kHz, I would be satisfied. This is still only 20 cm deep and the coverage may be too wide.

[jzagaja]

It is AxiDriver, infinite baffle. I've opened STL in Solidworks and drawn 3D sketch/spline then exported points to Excel. Not sure if I can check wavefront in Axi?

[jzagaja]

[MaBat]

So you kept the terminating lip exceeding the baffle? That might cause problems I woudn't expect in free-air. For the infinite baffle you should cut the lip away first (the yellow elements). I think the wavefront is flat in AxiDriver by default, if you don't change it in any way. I just hoped for ABEC I will do that, sooner or later... Need to figure out how to do that in free-air (i.e. how to correctly define the back of the horn).

[MaBat]

[jzagaja]

Ok time to learn Abec

[MaBat]

Oh I thought you do it already... OK. I will prepare something.

[opa]

Hezky si s tou babou jagou povídáš, jenom zkus zvážit, jestli (česko)slovenské fórum je nejvhodnějším místem pro rozsáhlejší komunikaci v angličtině.

[jzagaja]

Pokud má skupina zájem o transparentní rohy, dejte mi vědět.

[MaBat]

Polsky neumím a Jacek neumí česky. Máš s tím problém, opa? Ber to prostě tak, jako že se bavíme o něčem, čemu nerozumíš.

[MaBat]

[jzagaja]

Asked several companies about thermoformed horns. One replied with something like 1800 pln netto for mdf mold and 500 pln netto per horn 5mm thick. Just asking if there is an interest in group buy. Personally I'm interested in FH-JMLC-80 with coax but listening to others.

[MaBat]

I don't think there is any real interest in building these kinds of loudspeakers here anymore, or any loudspeakers in fact. Maybe the last one marginally interested may be opa, but he doesn't understand what we are talking about right now

It may look really good, but for only a few pieces it would get a bit expensive (well, it depends). I don't have any plans to build and sell anything. Thanks for the offer anyway, would love to have some. Now I'm going to try to make my own.

[MaBat]

...the more I try to imagine, the more I like the idea. How would be solved the driver mounting?

[jzagaja]

I have 3D printer so rather glued adapter. Better make thermoformed part from diameter 15cm and below printed part for different driver. Also possible conversion to unity /synergy waveguide. Below example of slot adapter printed with PETG burgund from Rosa.

[MaBat]

ABEC to pro free-air simulaci zřejmě bude potřebovat jako hranici objemu, ne jako samotnou plochu. Takže takhle. Zezadu už by to snad mělo stačit hrubší, cílem je samozřemě ušetřit výpočetní čas, dá se to nicméně nastavit. Tohle celé tedy už teď generuju automaticky z programu.

[MaBat]

Tak na pokusy. Nestyďte se a klidně to v ABEC prubněte...
Kvalita té sítě na přední straně není žádná velká paráda, ale to je prostě dané způsobem, jakým to počítám, jinak to teď neumím. Asi by se s tím taky dalo ještě něco dělat. Zadní stranu už dělá gmsh svými algoritmy, ale to jsou jednoduché plochy, ty jdou snadno. Ideálně, kdyby se to celé povedlo aproximovat nějakými parametrickými B-spline (NURBS) povrchy. Ty pak gmsh zvládá taky dobře, na to jsou algoritmy už vymyšlené, ale to už je poněkud vyšší dívčí.

[MaBat]

Na samotné rozchození ABEC by to asi sneslo něco menšího a hrubšího, ono to jinak může počítat opravdu dost dlouho.

[MaBat]

Jinak i to malé pak půjde udělat libovolně jemně, až to někdo rozchodí. Je tam příklad pro BEM "Horn Robin", z toho se dá dobře vyjít. Akorát to zřejmě bude chtít rozdělit na dvě subdomény (vnitřek a vnějšek horny) a dodefinovat interface.