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8" 2-way project
I'm pairing the Peerless 830869 with the BeastMode in the Visaton 148R waveguide. I understand the WG doesn't have pattern control below 2.5K, but I'm trying it more to see if it helps with edge diffraction. A bonus might be slightly lower THD in it's lower regions. I made some test baffles to plop on some existing cabinets. The drivers play well together and I'm pleased with the blend. But the box (~.6 cubic feet) is too small for that woofer. It sounds lean - like someone put a dip in the upper bass with a parametric EQ. I cut all the panels to build some 1 cubic foot boxes this past weekend. I still need to decide where to put bracing, but I'm stuck on what to do about the ports.
Question: 3" is too long for the box. 2" will more than likely make some chuffing noise. Craig said he used 2.5" ports about 8 inches long. Menards wants $40 for a 10' section, which seems ridiculous to me. I do have a bunch of 1.5" flared port tubes.
I think 2 of these is around 24 m/s at 25W below ~30Hz. Box would be tuned to ~40Hz. SPL would be over 100dB at that level, so would it even be an issue?
Drivers in old box -
Comments
Model at your listening levels, see how things look.
Can't find the SPL meter I bought earlier this year. Might have wandered off in the boy's truck. Not sure what my usual listening level even is these days, but I do know it's far less than the front row at Ankeny. Now that I'm home, I checked what things look like at 10w. Looks like I should be fine with the 2 x 1.5" ports.
You say .6cf but then model 1cf? Not trying to be snarky. I tried modeling it myself and was confused for a bit when my results were way off from yours.
If you want more upper bass punch then tune it higher.
Seems Mike Choua wasn't impressed in a larger enclosure. Suggesting only slightly larger .7cf tuned 45hz
https://ampslab-spk.com/2023/06/06/8woofers-shootout/
No worries! Sorry - I should have said, I cut pieces for a pair of new cabinets that will be right around 1cf.
I talked briefly with Craig (PWRRYD), since I know he's had good success with this driver in a couple of different projects. I heard one of those in Ankeny a few years ago. I was impressed enough to try to pull off a 2-way of my own with it. I'm fairly close the same tuning in the same volume he used, so we'll see how it turns out.
Tom, in your model you are at 100 DB, can you lower power to hit say 80-85 db, the port velocity should reduce considerably... and 15 is good
Is that the expected listening level? Because WinISD defaults to 1meter distance (not typical 3-4meters at seating position), and does not factor in baffle step loss.
I generally have a goal of 100 bB/1m in my sims because my listening position is almost 3 m back. That said, even when I hear some significant port chuffing during track 3 (long sine sweep) I never seem to hear any port chuffing during actual music listening sessions. I listen at about 82 dBish at 3 meters. My listening room is not huge. 13 feet wide by 23 feet deep. The venue at Ankeny I would guess is 25 feet wide by 60 feet deep.
I think I'll be fine in my listening room, even at levels higher than I can usually tolerate. My space is only 12 x19 and door placement dictates that the "serious hifi" speakers fire across the short dimension. It should only be a problem if someone pulls up Barbie Girl in Sioux Falls or Ankeny.
Method or madness? My ports are a little too short and I want flares on both ends. They fit very loosely in a 1.75" hole - push them another .25" and they snug right up. Some scrap mdf should lengthen the ports just enough and add some bracing to the backs.
Well that worked out better than I had planned. There's a tiny step between the port and the hole in the larger piece of MDF, but it's less than what I've seen in the adjustable ports I've used.
But no good deed goes unpunished. After hogging out 8 holes in MDF, I thought I would clean up after myself like a good boy. I snagged the first assembly with the vacuum hose. It fell off the table saw with the ports in it and sheared off the smaller piece of MDF just above the glue joint.
It's back in the clamps again.
undersize the hole and then flush trim for next time, if you are going for perfect. But as you said, all the dayton ports that i have used have a bigger step going from the fixed length to the adjustable piece which goes over the fixed length.
You can also make a sleeve to wrap around the tube using a paper file folder, wrap with tape and adjust the length externally by poking a hole in the side of the paper tube & bending a coat hanger wire 90*
Yesterday was supposed to be glue-up day. Everything was marked and bracing was pretty much ready to go.
Glued up the 1st one - sides, top & bottom. That's when I learned that these shelf boards are not all the same width! I was pissed so I cut it apart, saving the sides. I headed back to Menards for a few more of the shelf boards. Their current stock is even narrower!! They’re just under 11.25”.
I'm hoping this is proof that the old adage about the best things in life is true.
. . . like, "Measure twice and cut once" . . . .
Sorry for your troubles, Tom . . .
Yeah - that's what I get for not measuring the width of all of them the first time. Just a minor setback - they’re in clamps after some trimming.
Yep, I got burnt once too. So now I go to their tool isle that has tape measures and borrow one to use. I've measured them anywhere from 11.125" to 11.625".
I now see they vary in thickness too. One cabinet is 10.5" wide and the other is 10.75". The interior measurements are same.
There's always Baltic Birch guys. Lol
Yeah - guess I can't complain considering the price. I have all of $12 in wood for this build, even after the mistake. The last time I bought cabinet grade BB, it was from an actual lumber yard probably 20 yrs ago. I think it was $55/sheet for the best stuff they could get. It was so nice to work with!
Ok there Mr richy pants
Yeah, at my Menards there is a stack of shelves marked with one thickness, I think 3/4". But they are 1/2", 5/8" and 3/4". I think the last time I got a 5/8" off the top and had to dig down 20 shelves to find the next one that was 5/8".
Same here. They can vary for thickness or width, even within the same stack. 1-1/4" stair treads, however, have always been consistent, though more expensive.