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Port assisted subwoofer design for PA |
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Crashpc 
Young Croc 
Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 539 |
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 Posted: 09 August 2024 at 6:51pm |
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By the way, my compact ported 21" design with 21DS115 that I am leaving have about 130l too.
This is not a coincidence I guess?
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Nikon and Canon people should not be married to each other. Why did you let this happen?
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bob4
Old Croc 
Joined: 29 February 2004 Location: Finland/Germany Status: Offline Points: 1924 |
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Posted: 21 August 2024 at 11:27am |
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The other day I saw a comment on fb, in a discussion about new celestion woofers. .....
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Crashpc
Young Croc
Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 539 |
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Posted: 21 August 2024 at 6:54pm |
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Yes? I am finding my ways. The experience and knowledge here is paid by wallet though.
Today I had a call with a friend, to which I recommended B&C 18DS115. He put em into X1s, and had some negative remarks on that. I had to explain that these might need some EQing to sound more familiar and warm compared to the speakers with less strong motor. He told me he did an after-party on the gig, and blew almost everything he had, except 18DS115s. It looks to me that newer 18DS115s with longer voice coils compared to older 21"s for whatever reasons might be tougher. I was pleasantly surprised. Hard electronic music, low dynamics, going hard in X1s with steady bass lines, the 18DS115 handled abuse with grace. My 21DS115s in the ported box didn't. The conclusion, although not very strong is that it takes only slight change on the same model of the speaker for the outcome to be different. Now I wonder if I shouldn't go with 18DS115s then. |
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Nikon and Canon people should not be married to each other. Why did you let this happen?
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Crashpc
Young Croc
Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 539 |
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Posted: 22 August 2024 at 6:01pm |
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So I redid the case I have. Sims in HR.
Compact ported box that goes straight to 40Hz, -3dB@ 35Hz, and then random roloff. RCF LF18X451, 96l, once tuned at 39Hz, once tuned at 30Hz. In both cases the port takes the same additional box volume.  Top row is the 39Hz box, bottom one is 30Hz box Thermal compression implemented as best as possible to keep SPL same. It might be usage dependent, but as can be seen, the 30Hz version has more cone movement and cooling in the majority of the range, and gets less power in the bass and deep bass region for less thermal compression. Also port flow is lower, and I guess HR does not take into account port losses. Maybe this can be neglected as longer port might have same high losses with lesser flow. Still this does not look like the undertuned solution loses at all. Yes you can up the power input on the 40Hz bersion, but wait the moment when the DJ pulls up that steady 40Hz bass line. Then either the limiter kicks it down 6-10dB or the thing is in fire in no time. |
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Nikon and Canon people should not be married to each other. Why did you let this happen?
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DMorison
Old Croc
Joined: 14 March 2007 Location: Aberdeen Status: Offline Points: 1740 |
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Posted: 22 August 2024 at 7:43pm |
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Hi Crashpc,
The forum shrinks images down to 1000px wide when we upload directly, this makes it really hard to see the axes on your graphs. Is there any chance you could split it into 2 images, or host offsite and link from your post so we can see full resolution please? Thanks, David.
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Sypa
Young Croc
Joined: 21 February 2013 Location: Croatia Status: Online Points: 953 |
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Posted: 23 August 2024 at 12:16am |
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And what do you mean newer 18ds115 with longer coils?
And compared to which older 21 ? |
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Crashpc
Young Croc
Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 539 |
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Posted: 23 August 2024 at 4:03pm |
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@Dmorison: here:
Sypa: Not enough experience, mixed opinions. The stuff suspension stands, the 18DS115 will burn quite some power on its suspension at and past Xvar, so it is not wise to run synthetic music with low dynamics to Xvar. On the other hand, compared to 21DS115, indeed, the 18DS115 has longer coil, so it will have good motor force still at these excursions, suffering somewhat less thermal compression. My colleague did an afterparty recently, with the rig made of various drivers, even in the bass portfolio, and only what survived was 18DS115. So yeah, sturdy awesome driver! I am looking for next gen drivers from RCF with Xmax of 18mm. Their suspension behavior is benevolent, so I would at least bet that some models wpuld regularly work with 20mm no problem. They are 16" and 19" though. There is always something on the horizon, and it is rarely worth the wait.
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Nikon and Canon people should not be married to each other. Why did you let this happen?
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