Pioneer B20 in vented boxes...

[Godzilla]

>> Larger ports are supposed to sound better than smaller ones, right?

I don't see why that is true. Why do you think that's the case?

[Kensai]

Mainly because I've read statements to that effect over and over. Also, if tiny ports sounded okay, why wouldn't we all be using short half-inch ports on everything? Then, of course, there's the fact that WinISD shows widely varying first port resonances depending on size (the real life effect of which I am entirely uncertain of at this point).

I would think (and this is unsupported on my end by exeriential data), that the larger port diameter would decrease port noise (which I have been able to hear, regularly with many ported units, none of which I have owned). What are your thoughts on the subject?

Kensai

[holdent]

Let's see if I get this right --->

The good thing about small ports is that they load the woofer really well and (mostly) help control the excursion. The bad thing is that at higher listening levels the port air velocity becomes too high and you can start to hear them "chuffing". All ports big or small will unload the woofer (bad) at very low fequencies.

[Kensai]

Finally got around to trying these in my old Yamaha NS-6390 cabinets (really the same as the NS-6490 cabinets in the living room except for the costmetics, and even then . . .). Been putting it off because I was too lazy to cut, strip and terminate some wire for the internals.

Anyway, put up on stands so they were nearly identical height as they were in OB, lets just say they sounded funny. Sealed, they sounded a bit congested through the mids and then far too resonant in the bass, though not really reaching much deeper than OB. Pulled the tweeter (which I wasn't using, just left in to keep the cab sealed), and slotted an ~2"x8" tube for a port (tuning to the high 20s, I believe). That gave me flabbier bass, same congested mids, but really only slightly more extension than sealed (pretty much the same sealed or ported). Main thing that I really didn't not like was that the bass seemed to over energize the room(s). I could get up and leave the room and by the time I was far enough away for the bass to start rolling off due to distance or walls, that was all that could be heard. This means that even a little bass was basically full level in both of the bedrooms sharing the same floor as the office ;-p Anyway, this is a very nearfield setup, and there's really no way to negate all the "bad" this generated. Think I'm addicted to/stuck with OB or possibly BiB sound for that room.

So, since I was on a roll, I went ahead and swapped them out into the NS-6490 cabs in the living room (again having to strip and reterminate wire). These cabs had already been modded to contain B&G Neo3PDR tweeters (with back cups removed) which were running from a 2.2uF cap above the Yamaha 8" woofer running full range (which in OB rolls off a full octave lower than the B20 on the high end, and even with massive EQ could never be full range). These cabinets are laying on their sides in the outer lower compartments of my large oak entertainment center so centered about 10"-12" from the floor. Not ideal as we'll see.

First impression was very, very disappointing. Just didn't sound right at all. So I turned off all the limited EQ on the old Pio 411 receiver down there (Loudness control, Tone control, etc.). Got the bass right pretty quickly (very similar to the Yammie 8"er, which is plenty low for us in this setting; we get a ton of room gain here), but there was a hole in the lower treble. This was Zilla's admonition that the B20s are dull off axis come to roost. My only option was to hook the Neo3s up to 4.7uF caps that originally ran the mids for the NS-6490. This got the hole filled, but now there is congestion in the upper mids/lower treble. This isn't that bad, so we're living with it for the moment, see how it grows. The next step would be to find a cap value inbetween and try that out.

On more extended listening, the congestion up high is less noticeable when you're not listening critically, but the B20 is definitely more detailed than the Yammie 8"er. Just passing through the room while my 4-year-old was watching Madagascar, and there was a scene that I thought was just dialog, but there was some music playing very softly in the background, as if from some PA system in the scene itself, that I had never heard before, and that detail grabbed me. Also listed to alot of Pirates of the Carribean music over the weekend, too, and cello sounded fantastic.

This setup is just probationary. In the living room, all the issues I had nearfield are either good things (cabinet resonance, which activates resonance in our entertainment center giving us good bass down to 35Hz or so) or are much less noticeable (midrange congestion). We'll see how it goes.

One point this brings up in my mind is the issue of whizzer cones and off axis listening. The Yammie 8"er is just a standard cone with an inverted hard paper dustcap, yet I'm perceiving higher frequency extension at the listening position than with the B20 which is a solid octave better up top when at ear height in the sweet spot. Does this mean that non-whizzered drivers will generally give better off axis performance in the upper octaves? Would something like Fostex FE206/7/8 or FF225K give better performance up top in this situation? What about if the B20s were to be phase plug modded or possibly de-whizzered entirely?

Kensai