Nelson Pass: The Slot Loaded Open Baffle Project

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#402
Measure what you want, I always question measurements that are taken only at close range, or 1 meter, I personally do not ever listen that close, unless I think I have a driver out :0

I find that measurements from the listening position make more sense to me. I also understand that the classical measurements are done so for a reason, repeatability...and comparing to other drivers measured similarly.

A tone disc, and the rat shack meter should suffice for ballpark measurements, it's just time consuming to do 🙁

I'm looking at some of the PE buyout 10" woofers, since I am going to XO low due to my large cone top ends. I can still XO below the OB peak. It seem that the ones you bought are all gone 🙁 Using only 4 drivers will keep the sub low enough that the acoustical center of the various 12" drivers I have will be at the right height for seated listening.

let us know how it goes, and thanks for the reply.

John
 
#403
Hi gents,

below you can see my take on the topic "slot loaded sub". It is a merge between a Linkwitz style Phoenix or Orion Speaker and a slot loaded open baffle by Mr. Pass. The idea to combine the parts this way came up when I had a Linkwitz system with seperate W-Baffle Sub and the rest of the speaker system standing on top of it. I wanted to have a more compact design similar to the Orion speaker. As I wanted to realize my own ideas I went the way described. The drivers used are: 8 Mivoc AW2000 for the subs, 4 Usher 8137K for the mids and 4 Usher 9950 for the highs. Crossover fequencies are 120Hz and 1.4kHz as in Mr. Linkwitz designs. Later on I`ll decide if I go for a slightly lower crossover frequency in the lows (90Hz). As you see, woodwork has almost been finished and the speakers need sanding and painting. I hope to fire up the complete system during the summer months.

Enjoy, Jürgen
 

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#404
Pozo1992 ... just a quick comment before I make a fool out of myself. That should be a great sounding speaker system, congrats.

It may have been covered but what about one woofer in a Pass Slot baffle? Not the one he commented on with woofer flush with front panel.
Reason, I have a pair of great 15" woofers (now discontinued). I thought about making slot up to 50% Sd and could then slide in spacers to tune. Corner loading may really make it shine.

Thanks gang, Zene
 
#406
Zene Gillette said:
Pozo1992 ... just a quick comment before I make a fool out of myself. That should be a great sounding speaker system, congrats.

It may have been covered but what about one woofer in a Pass Slot baffle? Not the one he commented on with woofer flush with front panel.
Reason, I have a pair of great 15" woofers (now discontinued). I thought about making slot up to 50% Sd and could then slide in spacers to tune. Corner loading may really make it shine.

Thanks gang, Zene
Click to expand...

I think NP made comments about doing that in his original article????

John
 
#408
hi Vince - way cool build - does the plenum's rear need to be curved for smooth operation or could it be simplified with rectangular spacers in that area? all I've got is a jigsaw.

is slot width ~ 3 inches?

I think your woofer tester may show the composite system Q plus any outstanding cavity resonances.

can it hit a good bass drum? - (you don't have much cone area on top)

278638d1335184807-nelson-pass-slot-loaded-open-baffle-project-slobspeaker7.jpg
 
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#409
Instinctively, I would say rounded, just because I think it would act as a better guide and not have as much turbulence. Also the mouth of the slots should be rounded for the same reason.

Use a blade made for scrolling and set the speed to medium, that would have been a "5" on my jig saw. Let the blade do the cutting and don't rush it. If you go all out like I did, you'll use up 1 blade.
 
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#411
All are 13x33-1/2. Figured out even spacing for the three drivers, marked it and drilled a small hole through all 5 panels. The front Baffles are 33-3/4wx30h. the woofer baffles are 3.5" higher so there is some space the fasten the upper baffle, that is the same dimension of the bottom baffle. The upper front baffle will need a brace, like in the article.
 
#412
what's a good jig saw blade to do this speaker? some of the last I bought won't "steer" - also what cutout diameter for those Peerless? I ordered enough to do something but have had nearly full blown vertigo for well over a week (40 years of the problem so far = no mobility)
 
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#413
Try harbor freight. *They had a 15 blade set by Portland, but I will double check.
My jig saw is a tool-less type. To be safe, find a scroll blade for your scroll saw.

I believe the cutout is 7-5/8. Parts-express.com will tell you.
Search "peerless India 12ohm shielded".
 
#415
thanks again - do these look like the scroll blades from that 15pc set? http://www.harborfreight.com/5-piece-3-20-teeth-per-inch-t-shank-jigsaw-blades-for-wood-68071.html

since I ordered enough to do 6/side plus a spare or two it'd be cool to know the ballpark parameters - - had drivers with qts double what they should be and fs a half octave or more higher than spec.

had 21" Madison on Ob=seemed unable to sound right on bowed bass viola - GW1858 on H-baffles = not bad - maybe a bit sluggish - Karlson are my fave toys.
 
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#416
#418
mine got a ding form the side but might straighten - -re:Vas - don't think that affects the gathering of Qs and fs - - if interested you can add mass or mount one driver in a sealed box to calculate Vas.

we'd like to see the system resonance and Q for your S.L.O.B. - just run it to measure parameters and take a screen shot

I'll get ill a lot - vertigo can last months - reflux/apnea have taken a toll, teeth rotten too - ugh
 
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