Buck 5,000+ posts
little alien on campus
I was led to believe changing either port in a 6th would effect the other. Front or back.
So if I want to change the back port, shorten it for any reason, it wouldn't effect the front port? Also, would shortening to raise the tuning effect the port area for the rear chamber? I have no idea what the port velocity modeled to, but it's already small at a little over 6 in² per. Just being curious
In general, my experience says there’s very little effect on the front chamber tuning by changing the rear port, if any. I mean, it’ll make the front chamber pressurize differently when changing rear tuning, but if you think of the series 6th as a box within a box, you can take the whole rear section out, and the front will still be tuned to 50 hz; you can’t do that reverse and have the same results.
The biggest mistakes I see in series 6th’s, IMO, is too little rear port area or box volume. There’s not really a magical reason to make the rear chamber ports excessively small or rear airspace too small. I see that a lot. Idk what the airspeed on your rear port is. I’ve done upwards of about 14 in^2/cube rear before, and would’ve done higher, in some cases, if I could’ve. I’ve also done as low as 5-6 in^2/cube, and the port area is largely power and overall chamber air-space-dependent. Different sized woofers have different relative wattage/cubic foot inputs, so the relative energy density of the air charge can increase greatly with smaller woofers and high power, requiring huge ports. Tuning low, especially once you start getting into the mid 20’s, the port speeds can really fall off. So, you have to know how to balance all of that together, lol.
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