question: will my 2 x 50mm x 160mm ports perform the same as a 65mm x 190mm port? Did I miscalculate???
Two 50mm ports have same crossection as single 70mm port.
So, you have to make them longer than single 65mm port for same performance. According to Hornresp 53.10 version, they have to be 229 mm long. But, you may get slightly different result with some other calculator.
Sorry for bad news.
So, you have to make them longer than single 65mm port for same performance. According to Hornresp 53.10 version, they have to be 229 mm long. But, you may get slightly different result with some other calculator.
Sorry for bad news.
Are you bracing that box? How big? What do you plan on using up top?
The FF225 reponds to some standard tweaks.
dave
The FF225 reponds to some standard tweaks.
dave
Best to make an Av = Sd shelf vent [k = 2.227]: https://www.diyaudio.com/community/attachments/effective-port-length-jpg.327847/
I thought that the volume of my 2 ports of 50 mm should be equal to the volume of a single port of 65mm x 190 mm long.
6.5 cm ÷ 2 = 3.25
3.25 × 3.25 = 10.56
10.56× 3.1416 × 19 cm = 630
5÷2 = 2,5
2,5 × 2,5 = 6.25
6,25 x 3.1416 x 16cm = 314 x 2 ports = 628
6.5 cm ÷ 2 = 3.25
3.25 × 3.25 = 10.56
10.56× 3.1416 × 19 cm = 630
5÷2 = 2,5
2,5 × 2,5 = 6.25
6,25 x 3.1416 x 16cm = 314 x 2 ports = 628
I owned a pair of FF225WK some years back and did build a roughly 1cu.ft (28 liters) reflex for them, though not to Fostex plan. I believe I tuned slightly lower as well. It sounded good, if a bit dry in a 'hi-fi' way. Increasing Vb or Fb could make for a livelier sound, but that's up to user preference. You should be fine with your box tuned in the 35Hz-45Hz range. The FF225WK really does need help above ~8kHz (IIRC), so plan on something there.
Good drivers, kind of wish I'd kept them now.... 🙂
Whenever I simulate this, the length of the vent naturally becomes very long. I have never built strictly to this, but did put together a couple of ad-hoc BVR/Daline hybrids that might come close to this. Is the half-wave resonance bothersome in your experience? Can I assume that you critically damp such a vent?
Good drivers, kind of wish I'd kept them now.... 🙂
Whenever I simulate this, the length of the vent naturally becomes very long. I have never built strictly to this, but did put together a couple of ad-hoc BVR/Daline hybrids that might come close to this. Is the half-wave resonance bothersome in your experience? Can I assume that you critically damp such a vent?
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Even after subtracting out the end correction?
Not IME since the BVRs I did were all relatively large cabs [Vas/1.44] tuned to Fs, which in turn was with rare exception [prerecorded special effects RTR tapes, CBS, Altec, B0$3 test record] at/below a recording's source output, so its sheer inertance? damped it to a good in room blend [by then 'standards' anyway].
Regardless, we don't notice any deep notches down low till very broadband, so unless it combines with similar, much stronger room modes don't see it as an issue, but can make room positioning less flexible, though a corner is almost always my preference since it further shortens the vent unless wanting more sub/bass.
Damping wise, yes, used the 'click' test on BVRs, though better IME to loosely attach a 'blanket' over the back of the driver Vs typical box, vent damping.
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No, I'm curious to see what happens. If it's unlistenable, I'll change my 2 ports to
a single 65mm x 190mm.I should have done that at the start.
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I changed the lenght of the ports on my speakers. You’re right!
thank you very much. Now I listen to the ff225wk without the ff165wk.
