stoneeh

On 7/17/2023 at 12:47 AM, nerdoldnerdith said:

It's been down since April. You can use Wayback Machine to get archived versions of the site that work.

Not of the current website / database. Wayback Machine seems to have saved only the basic structure of the website, but can't load the data from the database.

When I click the image links:

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In the end though, you have to build & test to be 100% sure.

There are (also empirical, not theoretical) studies / papers on the topic, from the AES for example, that are freely available; the issue has been figured out for decades. The conclusion overall is that you should always use the maximum port size that you can possibly accomodate in a speaker box, because there will always be some compression. There are other concerns like port resonances (only relevant for full range boxes, not subwoofers), or cooling (only relevant for PA subs).. but generally, the larger the port, the better.

Flared ports reduce air turbulence at the port ends, which results in noise. So flared ports reduce noise. They do however hardly or not at all reduce compression, which is a result of an inadequate inner port cross-section area. Port noise and compression are / can be two different things.

Why guess (a simulation will always be a more or less elaborate guesstimate), when you can measure?

Since the NTLW5000 came up, here is one of mine in a 65l CB, maxing out on a 20 Hz sine signal. The measurement is taken at 1m half space; however, the measurement is C-rated, which means -6 dB @ 20 Hz. So you can equate these values to non-rated (flat) full space.

You obviously can't hear the 20 Hz signal, but it's quite easy to hear the (K3 dominated) harmonic distortion coming in above 100 dB.

I tried measuring with the CEA 2010 standard and got a passing result at 20 Hz of 103,5 dB; similar to your (Ricci) value of the BMS 18N862. I'm pretty sure I measured correctly; but it was my first CEA 2010 measurements, and different variables.. so I sure would be looking forward to you testing the driver as well.

What happened to the 2269H btw.? You listed it, but seems like you never measured it?

I have been a viewer of this site for a couple of years, find it very helpful, and greatly appreciate your efforts Ricci.