Sorry!
I have redone these at a sensible size...
Please see below
Finally a sunny day!
Into the night
Port sub assembly
Dry fit (it does!)
Outside again
Just before lid was glued...
Glued and painted! Used Tuffcad with a textured roller.
Happy with the finish, going to have a life of luxury compared to my old speakers...
All fitted! Test day! Setup is Void Mycro 6 on top, Vs. a Void Venu bass for benchmark. Focusrite soundcard into DCX2496 then a Lab 2400q doing the duties. REW software with DBX measurement mic. UltrasoundTM lawn chairs (extra bass, y'know)
Good stand too
Beasty drivers!
SPL vs the Void. Please note, PPSL is +3dB higher than it should be, due to some incorrect gain settings. Happy with the +8dB @ 30Hz, seems to be a little happier lower down. Nastiness is kept above 200Hz, so with some sensible filtering at 100-120, it should be kept well under control.
And filtered at 24LR @ 25Hz and 24LR @ 100Hz
Stopped when the neighbours commented on doors rattling.. Oops..
Now we're inside. With some notches around room modes, its doing a bloody good job of exciting every door in the house. AB testing with the Void is looking promising. Very tight and controlled, effortless. Even if the woofers are going a little mental - lucky they have the Xmax.
After a couple of hours, here is full system integration. Blocked ports in Mycros and running PPSL upto 120. Super clean and absolutely loves some techno (even if I dont particularly)
Room has some difficult modes, I won't show the waterfalls. But it seems to finally behave around the listening position.
Distortion measurements from outside. (Void top, PPSL below). Not quite what I was expecting in harmonics reduction? Can anyone shed any light?
In summary, very happy with the little guy! PPSL seems to integrate extremely nicely with my tops, very much a lack of "anything extra added". Also seem to be a little 'faster' (sorry, I know that isn't a thing), perhaps due to the smaller cones. Loads of fun with HT too, explosions are fairly tactile now.
There is however a little more suspension noise than I would like (granted, that was with test tones), even if the port is whisper quiet.
Now I just want a little bigger, maybe a pair of BMS 15"s... Hmmm....
I have redone these at a sensible size...
Please see below
An externally hosted image should be here but it was not working when we last tested it.
Finally a sunny day!
An externally hosted image should be here but it was not working when we last tested it.
Into the night
An externally hosted image should be here but it was not working when we last tested it.
Port sub assembly
An externally hosted image should be here but it was not working when we last tested it.
Dry fit (it does!)
An externally hosted image should be here but it was not working when we last tested it.
Outside again
An externally hosted image should be here but it was not working when we last tested it.
Just before lid was glued...
An externally hosted image should be here but it was not working when we last tested it.
Glued and painted! Used Tuffcad with a textured roller.
An externally hosted image should be here but it was not working when we last tested it.
Happy with the finish, going to have a life of luxury compared to my old speakers...
An externally hosted image should be here but it was not working when we last tested it.
All fitted! Test day! Setup is Void Mycro 6 on top, Vs. a Void Venu bass for benchmark. Focusrite soundcard into DCX2496 then a Lab 2400q doing the duties. REW software with DBX measurement mic. UltrasoundTM lawn chairs (extra bass, y'know)
An externally hosted image should be here but it was not working when we last tested it.
Good stand too
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Beasty drivers!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
SPL vs the Void. Please note, PPSL is +3dB higher than it should be, due to some incorrect gain settings. Happy with the +8dB @ 30Hz, seems to be a little happier lower down. Nastiness is kept above 200Hz, so with some sensible filtering at 100-120, it should be kept well under control.
An externally hosted image should be here but it was not working when we last tested it.
And filtered at 24LR @ 25Hz and 24LR @ 100Hz
Stopped when the neighbours commented on doors rattling.. Oops..
An externally hosted image should be here but it was not working when we last tested it.
Now we're inside. With some notches around room modes, its doing a bloody good job of exciting every door in the house. AB testing with the Void is looking promising. Very tight and controlled, effortless. Even if the woofers are going a little mental - lucky they have the Xmax.
An externally hosted image should be here but it was not working when we last tested it.
After a couple of hours, here is full system integration. Blocked ports in Mycros and running PPSL upto 120. Super clean and absolutely loves some techno (even if I dont particularly)
Room has some difficult modes, I won't show the waterfalls
. But it seems to finally behave around the listening position.An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Distortion measurements from outside. (Void top, PPSL below). Not quite what I was expecting in harmonics reduction? Can anyone shed any light?
In summary, very happy with the little guy! PPSL seems to integrate extremely nicely with my tops, very much a lack of "anything extra added". Also seem to be a little 'faster' (sorry, I know that isn't a thing), perhaps due to the smaller cones. Loads of fun with HT too, explosions are fairly tactile now.
There is however a little more suspension noise than I would like (granted, that was with test tones), even if the port is whisper quiet.
Now I just want a little bigger, maybe a pair of BMS 15"s... Hmmm....
How did you model this/come up with this design?
Design a box for two subs in a ported box, make a box to those specs and add a U slot for the 2 PP drivers?
I would like to do something similar for two of these,
Creative Sound Solutions | High End Speakers and Speaker Kits
Any hints?
David.
Design a box for two subs in a ported box, make a box to those specs and add a U slot for the 2 PP drivers?
I would like to do something similar for two of these,
Creative Sound Solutions | High End Speakers and Speaker Kits
Any hints?
David.
You have to take into account the space the slot takes up inside the box and increase the overall dimensions accordingly, so that the volume of air inside the box remains the required/desired volume for the drivers / the tuning of the box.
You also need to consider cone excursion (so the 'in' driver cone doesn't smack into the 'out' driver magnet because it's too close at full excursion) and whether you're going to fit the drivers into the box before sealing it or after sealing it (if the latter, you need port width to be wide enough to let you get the 'out' driver past the surround of the 'in' driver, and give space for screwing it in).
It looks like you've already found the PPSL thread:
A Thread for those interested in PPSL enclosures
I am sure there are examples (directly added or linked to) in there, it is worth a trawl, and there should also be hints and tips.
There may also be examples in the pictures thread at the top of the forum:
System Pictures & Description
Have a search of the forum for 'PPSL' and there should be various threads come up.
You also need to consider cone excursion (so the 'in' driver cone doesn't smack into the 'out' driver magnet because it's too close at full excursion) and whether you're going to fit the drivers into the box before sealing it or after sealing it (if the latter, you need port width to be wide enough to let you get the 'out' driver past the surround of the 'in' driver, and give space for screwing it in).
It looks like you've already found the PPSL thread:
A Thread for those interested in PPSL enclosures
I am sure there are examples (directly added or linked to) in there, it is worth a trawl, and there should also be hints and tips.
There may also be examples in the pictures thread at the top of the forum:
System Pictures & Description
Have a search of the forum for 'PPSL' and there should be various threads come up.
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Hey, ZeroKelvin:
I'm really intrigued by this. I'm thinking this could be the ultimate super-compact sub for mobile DJ's. (A PPSL horn would probably be too big)
Maybe even this design but with two 12"
1: Why did you opt for a conical port, as opposed to a slot?
2: I don't yet understand a lot of the graph info. (Still learning.) You wrote "110dB @ 30Hz" but that sounds impossible. How does that relate to "standard" efficiency numbers? (I would expect it to be well below 100bB.)
- Thanks.
I'm really intrigued by this. I'm thinking this could be the ultimate super-compact sub for mobile DJ's. (A PPSL horn would probably be too big)
Maybe even this design but with two 12"
1: Why did you opt for a conical port, as opposed to a slot?
2: I don't yet understand a lot of the graph info. (Still learning.) You wrote "110dB @ 30Hz" but that sounds impossible. How does that relate to "standard" efficiency numbers? (I would expect it to be well below 100bB.)
- Thanks.
ZeroKelvin has not posted on DIY since November 19, 2017, his last posting in this thread was 4/19/17.
1) The port is cylindrical, ZeroKelvin explains why he flared the ends and rounded them with references in post #12. He also mentioned previously that 3D printing is no problem for him. For most, it is easier to work with plywood for large and long port construction requiring bends and flared ends.
2) "110dB @ 30Hz" requires "600 watts" input, if I'm reading the right graph.
Not impossible for small long excursion drivers, but put it in perspective, 110 dB at 30 Hz sounds about the same level as 80 dB at 1000 Hz.
110 dB with 600 watts is around 83 dB with 1 watt.
With as much cabin gain at LF a car interior can provide in addition (+12 dB), still impressive for a small box.
If you are still looking for loud and small for your portable DJ use, don't bother to look too low
.
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If you are still looking for loud and small for your portable DJ use, don't bother to look too low
Thanks, and yeah I understand that.
I'm hoping to build something along the lines of Les Hudson's design, but with 12's to make it more portable, and tuned to maybe 38 Hz or so.
If I can get the shape right, I'd hope to use 4 of them. Using 4, but pushing them less hard means more efficiency and even lower distortion. Plus, you can use cheaper speakers, which tend to be more efficient to start with. - Yet more reasons to go with dual 12's instead of dual 15's.
My big worry is if 12's will give enough "chest thump" or "fun" bass, or pick your own description.... Frequency response & lack of distortion don't seem to tell the whole story here. Something I'm having a hard time coming to grips with.....
1) Understood you want to reduce even order distortion, but do try to understand that the plenum area reduces cabinet volume, which reduces LF output per given enclosure size.
2) Cheaper speakers generally have softer cones, wider magnetic gaps and less effective magnet structures and coil winding schemes, and are less efficient (at least in the LF range) than better, more expensive drivers. That said, cheaper speakers also have more distortion, so push-pull arrangement will make more difference with them.
If you have room for 4 PPSL, you have room for a pair of decent size TH that could give you the same output with half the drivers and power.
3) "Chest thump" is primarily in the 60-160 Hz range, easily covered regardless of cone size. More linear displacement equals more output. That said, lower Fs drivers appropriate for low tunings are heavier and less sensitive in the upper range, a higher Fs/Fb will be more efficient in the "chest thump" range, less efficient in the "pant leg flap" range.
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Well, this pretty much sums up the main factors to be considered.
A dual 15" PPSL only makes sense if it's large enough for good bass extension, and I'm having trouble making that work. The perfect driver might get me there, but I doubt it. A "comfortably-sized" dual 12" works well for me, for several reasons, but will be far less efficient & since I might only be able to fit three of them, I worry about having enough oomph at outdoor shows.
So sure, a small TH15" is still on my list of possibilities. As mentioned before, I would make a pair, constructed so that TOGETHER they create a push-pull system. (Not PPSL, obviously.) This is why I previously asked if a TH Horn has the same ability to minimize" odd order distortion, the way a plenum does.
Seems to be a lot of disagreement on that one, though as best I can tell, the answer is no.
Still, I might not care about odd order distortion, in which case, the TH pair would be much easier.
Maybe I could even make FOUR 12" horns, but I's have to custom design them based on my critical dimensional requirements, and I fear that is a bit past my abilities. At some point, I also have to get back to my ACTUAL LIFE !
------------------------
AND NOW, thanks to lots of new info from the amazingly helpful Art Welter, I also have to consider a smallish Keystone sub. (Again, a pair built to be a PP system.)
My head hurts.....
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Mine too...So sure, a small TH15" is still on my list of possibilities. As mentioned before, I would make a pair, constructed so that TOGETHER they create a push-pull system. (Not PPSL, obviously.) This is why I previously asked if a TH Horn has the same ability to minimize" odd order distortion, the way a plenum does.
AND NOW, thanks to lots of new info from the amazingly helpful Art Welter, I also have to consider a smallish Keystone sub. (Again, a pair built to be a PP system.)
My head hurts.....
As I have said before, a plenum does not minimize odd order distortion.
Push-Pull loading reduces even order distortion, but may actually increase odd order distortion, making THD little different when drivers are pushed near Xmax and above, where distortion becomes evident.
Horns increase sensitivity, which reduces THD for a given SPL, but slightly increases THD for a given excursion- no free lunch.
Just recalled a 22.5" x 22.5" x 15" "smallish Keystone" 2x10" experiment from 2011. .
Banging response from Eminence Kappa Pro-10A (only 3.2mm Xmax, really a mid-bass driver).
The drummer that bought them liked them better than the larger (26.5" x22.5" x 22.5") LAB 2x12 BR which went a full octave lower, but were not quite as loud (and far less distorted)- the 2x10" had more "chest thump". I was glad to sell them, win/win
Art
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My head hurts.....
A PPSL box is still a ported box, though it trades a little extra cabinet volume in favour of reducing some even-order harmonics.
IMO, you really need to go and listen to see if a good ported box is the right thing for you - I'm getting dizzy from all of the jumping around to different ideas.
I'd set off by looking at the program material you intend to reproduce, and deciding on a suitable low-frequency cutoff. I went for 40Hz with the Tiny15s, but there are lots of users of the THAM12, which is just about starting to fall off at 60Hz. For them, the output levels from a cabinet that small was worth the sacrifice in low-frequency extension. For my use, there are a lot of PA systems that hit at 60Hz. I wanted something that'd drop a good amount lower, and I use multiples of the cabinets if I want more output.
All speakers represent a set of compromises. I get that you want some fairly compact boxes, but deciding how low you want to go will help put a design together.
Chris
PS - Art, those baby Keystones are very cute.
110dB @ 30Hz when placed in a car should be .. Interesting
Have you tested the enclosure inside your car?
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