A Thread for those interested in PPSL enclosures

[kees52]

Hi all

the build of a ppsl with 10 inch woofers I will start, I have some things read about it, but one question I have left, do I have to halve the Vas of the woofers and double the Sd?

when I calculate the box itslef as normal vented box it wil give a very long pipe, and in the slot the qts rise and Fs lowered and the woofer has already a low Fs of 19 hz, therefore will de ppsl box not very large, maybe someone has examples for hornresp to start with, I am a little curieus about this boxes and want to try it.

Maybe it is interesting to do the woofers in a samle slot without box around it and measure the thiele small parameters and use that for the calculation of the box around the slot like you all did.

Thanks.

kees

[Scott L]

Yes, the Fs will be lowered once mounted in the ppsl fashion. When I checked mine I did not check the Qts values. Would be interesting to observe what happens, BUT the Vas doubles, it does NOT cut in half.

[kees52]

Originally Posted by Scott L

Yes, the Fs will be lowered once mounted in the ppsl fashion. When I checked mine I did not check the Qts values. Would be interesting to observe what happens, BUT the Vas doubles, it does NOT cut in half.

In had read somewhere that in a closed box two woofers do cut vas in half, thus this not true for vented and ppsl?

if the fs drops and qts is higher do I have then include this in the first vented box calculation without the slot included? because then it is better to make a slot alone and measure.

thanks

[Scott L]

ONLY in an Isobaric does the required Vb drop to 50%. That is beyond the scope of this thread.

YES (!!) If I had to do it all over again (which I sure will someday) I would build the slot and then measure the paralleled drivers t/s parameters as if they were one.

[kees52]

Originally Posted by Scott L

ONLY in an Isobaric does the required Vb drop to 50%. That is beyond the scope of this thread.

YES (!!) If I had to do it all over again (which I sure will someday) I would build the slot and then measure the paralleled drivers t/s parameters as if they were one.

then afcourse I need two weights of for example 20 grams to use on both speakers? or a closed box for both, but I think weights are better.

thanks

I go sleep, and outside snowing, it is midnight here,.

[ßart West-VL.]

Originally Posted by kees52

then afcourse I need two weights of for example 20 grams to use on both speakers? or a closed box for both, but I think weights are better.

thanks

I go sleep, and outside snowing, it is midnight here,.

Yes, both cones need weights, then you ad them up. for example woofer1 + 20gr + woofer2 + 20gr = +40gr

I did the same thing recently.

[kees52]

Oke thanks, I go try that soon.

[kees52]

I have model a ppsl with the visaton wsp26 s these have a fs of 19 hz and a vas of 220 and a sd of 330, pretty big for a 10 inch.

The model trough bassbox pro 6 rae interesting if i do only closed box with slot, and the sound of a closed box system is good, my question is how low go the speaker when in a slot facing together, because it is already 19 hz how much lower it wil go, I have afcourse to test it but maybe someone has a idea.

I go then make a closed PPSL box with the 10 inchers, so it will have best impuls behavior and it go loud enough, the dipoles in my home is a problem because of my space here, a tapped horn is also possible but I do not now his sound quality, but people here have and I like to share.

I was always a horn fan, still I am, a tapped horn with a fostex horn will I think sound wel on tube amps.

But first these, I will try them all, the dipole do good, ver nice open sound, maybe the closed ppsl has a more closed character of sound.

[anubisgrau]

what will be upper range you gonna hit with it?

[kees52]

Originally Posted by anubisgrau

what will be upper range you gonna hit with it?

You mean where I go to mid bass? about 100 Hz, I talk then about the PPSL box.

the mid bas is open baffle 93 dB 2.83 volts from 90 hz to 20 khz.

I did read this, the plenum is a low pass filter, depth is important.

By mounting in a plenum several things change. The spacing becomes much tighter so the cancellation will work at higher frequencies, and a cavity is formed.

The cavity does several things, in no particular order:

The size, especially the depth, acts like a low pass filter. This can reduce 3rd harmonic distortion products near the top end of the passband, the effect is small, but audible. The cavity sizes I use have to be crossed in the 150hz~250hz region. It gives a slope of roughly 12dB/oct that must be taken into consideration in the design of the crossover.