Sealed...the slot is the vented section, so it is essentially 4th order bandpass.
I placed a board across the top, to take measurements, above. The midwoofer enclosure will be that baffle in application
Theres no damping material in it either. Taken in my living room I'm sure the the room is in there somewhat. 90 and 70 hertz is the room I think.
Theres also some screws not in place in the back wall, if that matters...
I placed a board across the top, to take measurements, above. The midwoofer enclosure will be that baffle in application
Theres no damping material in it either. Taken in my living room I'm sure the the room is in there somewhat. 90 and 70 hertz is the room I think.
Theres also some screws not in place in the back wall, if that matters...
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Camplo,
Considering how closely your measured response matches the Hornresp simulation, I'd think the small dips around 70 and 100Hz are in the actual driver response, since the measurement was taken "maybe an 1inch in front of the slot in front of the drivers".
Group delay is a fraction of a wavelength for most of the response, other than the narrow slot resonance dip, where it increases to over 10 wavelength duration, fortunately we can't hear what has been canceled ;^)
Art
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Late to the party on this, but I built my first PPSLs nearly 20y ago. Mine did not have the rods across the plenum because that would have made them a motel foxtrot to build. As they were built as PA enclosures in the first instances, the plenums had tops and bottoms, and after the plenum dips/peaks were obvious in the first measurements, the rear wall of the plenum was made rounded. There was the vertical rear wall and then up and down from 9 o'clock 2 short walls each side at 30* then 60* from vertical. This braced the plenum very well and meant I could load drivers through the plenum, but it wasn't a job I relished and only did it to check drivers that may have been overdriven when rented out. Otherwise they remained in situ until the PA was sold maybe 7ya. In the final versions, the plenums were made as shallow as possible, yet still practical and the plenum mouth being >2x total Sd. Mine were also narrower and taller as I had to move then through doorways.
Most of mine were built with JBL2226s (some had RCF 18P300s which were heavy as expletive) and none of the ports were loaded into the plenum, rather exiting through the front baffle.
With the rounded rear plenum baffle, the response peak/null was much lower than sims I did later. At the time my measurement suite was not as good as today and I lost the old measurements, but they were mild and easily EQ'd. With the 15's they were crossed 4th order active about 200Hz, I think 175Hz from memory and high passed at 40Hz, again LR24. If I needed more SPL, I stacked multiples. Got lots of compliments on how clean the system was.
A bit later, I'd built 4 LABsubs and used these for bigger gigs, which meant no subs in the living room.
PS: I'm moving back to the same small town in the next couple of months, and as I still have a bunch of 2226s, will probably build 2 or 4 more if for no other reason than I have almost all the parts to hand including amps, mics etc to use for my Church and other community events.
Most of mine were built with JBL2226s (some had RCF 18P300s which were heavy as expletive) and none of the ports were loaded into the plenum, rather exiting through the front baffle.
With the rounded rear plenum baffle, the response peak/null was much lower than sims I did later. At the time my measurement suite was not as good as today and I lost the old measurements, but they were mild and easily EQ'd. With the 15's they were crossed 4th order active about 200Hz, I think 175Hz from memory and high passed at 40Hz, again LR24. If I needed more SPL, I stacked multiples. Got lots of compliments on how clean the system was.
A bit later, I'd built 4 LABsubs and used these for bigger gigs, which meant no subs in the living room.
PS: I'm moving back to the same small town in the next couple of months, and as I still have a bunch of 2226s, will probably build 2 or 4 more if for no other reason than I have almost all the parts to hand including amps, mics etc to use for my Church and other community events.
Hi guys. If 70 and 90 are slot modes, I'll take it. I thought it was going to be worse. Call it my sacrifice to the vent gods, in order to receive the blessings of the slot. If Brett likes then it must be an acceptable configuration (PPSL)
I also have a 2nd order planned but hoped to not have to use a high pass....maybe Ill get lucky
I also have a 2nd order planned but hoped to not have to use a high pass....maybe Ill get lucky
It's still just a ported box, so I'd still be concerned with excursion below tune. I do it even in domestic systems so there's no issue at any SPL I wan to play at.
I can claim nothing re these as all I did was follow the advice of the late 'djk', here and initially on AA. 6th order porting used on all LF cabs in the PA and have used it on domestic speakers several times too, most recently the surrounds. And my bass guitar cabs.
You have no way to remove the drivers from the finished enclosures? Rolling the dice on that one my friend.
I've had to ship a large number of defective drivers back over the years including 3 defective TD18 Apollo's. Some of these were coil and or rubbing issues that appeared weeks or even months later under moderate use.
I've had to ship a large number of defective drivers back over the years including 3 defective TD18 Apollo's. Some of these were coil and or rubbing issues that appeared weeks or even months later under moderate use.
Depth of the manifold determines this so a baffle down the length (depth) of the manifold won't make a difference. I do have actual experience of designing, building and measuring these types of enclosures.
äeehm sorry you are totally right. I dont know what i was thinking. I have also just recently built a ripol but somehow i confused that.
edit: do you know btw any good sources about the nature of the resonance? when i was researching i figured that it actually must be a helmholtz resonance which would mean that also the volume of the cavity matters. But all i find are vague statements
edit: do you know btw any good sources about the nature of the resonance? when i was researching i figured that it actually must be a helmholtz resonance which would mean that also the volume of the cavity matters. But all i find are vague statements
I have a few (4) ODTLs that could be siamesed? I wanted to change everything to the dual opposed anyhow…
Do you guys see a benefit if slot loading these ? They already have a very brief ‘rear chamber’(An upright tall cabinet end fired. Combined Output of drive and vent exit is together and in a down fired position.
Do you guys see a benefit if slot loading these ? They already have a very brief ‘rear chamber’(An upright tall cabinet end fired. Combined Output of drive and vent exit is together and in a down fired position.
