A Thread for those interested in PPSL enclosures - Page 34 - diyAudio
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Old 3rd October 2012, 11:15 PM   #331
Scott L is offline Scott L  United States
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Default Angled (or tappered)

Quote:
Originally Posted by TG1 View Post
I'm also wondering, like LineSource, if an angled slot does have any major effects...?

Also, what is the optimum size for the slot (if there is any such thing)?

-tg
Opening is 1:2 of woofer's SD. These were made strictly for mid-bass. The dynamic impact is incredible! In the first picture you can see how the plenum is angled back. If I ever do another build, it will be that of a classic, shared volume, 6th order for SUB-woofer use only. I've come to the conclusion the ppsl is best utilized in the low bass only. The system in the picture uses them to 250 Hz, but my ears tell me 180 Hz and lower for best sonic quality. OR, it may just be inherint limitations of the drivers I used: Eminence 4012HO.
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Old 4th October 2012, 02:52 AM   #332
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Scott: have you tried them with a plenum which is as small physically as possible and no taper as shown in your first picture? Are your sections of sono tube sealed or are they vented? Thanks. Best regards Moray James.
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Old 4th October 2012, 11:55 AM   #333
kees52 is offline kees52  Netherlands
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Hi There

If I want to make a ppsl for this speakers, how to begin designing them and with what software this is possible.

visatons 10 inch polypropulene


Technical Data:
Rated power 110 Watt
Maximum power 140 Watt
Nominal impedance Z 8 Ohm
Frequency response fc - 7000 Hz
Mean sound pressure level 91 dB (1 W/1 m)
Excursion limit 22 mm
Resonance frequency fs 19 Hz
Magnetic induction 1 Tesla
Magnetic flux 1250 Weber
Height of front pole-plate 8 mm
Voice coil diameter 5 cm
Height of winding 1,45 cm
Cutout diameter 23,3 cm
Net weight 2,5 kg
D.C. resistance Rdc 5,7 Ohm
Mechanical Q factor Qms 3,19
Electrical Q factor Qes 0,38
Total Q factor Qts 0,34
Equivalent volume Vas 230 l
Effective piston area Sd 330 cm2
Dynamically moved mass Mms 42 g
Force factor Bxl 8,7 T m
Inductance of the voice coil L 1,2 mH


thanks
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Old 4th October 2012, 05:57 PM   #334
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Quote:
Originally Posted by kees52 View Post
Hi There

If I want to make a ppsl for this speakers, how to begin designing them and with what software this is possible.
Design for your speakers as you would any bass reflex cabinet, reduce the volume taken up by the plenum (slot) from the cabinet volume when calculating box size.
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Old 4th October 2012, 06:40 PM   #335
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Forgot to answer the second part of kees52 question, Hornresp is a good free software design program, it even allows the plenum to be considered as a stubby "horn" so you can determine what frequency it will cause a resonance at.
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Old 4th October 2012, 08:04 PM   #336
kees52 is offline kees52  Netherlands
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Hi there

Thanks, I now hornresp and have done tapped horns with it, I have to play with it again.

I have now the visatons in a acoustic resistance box where she doe very well there job, but as every audio freak we want to test everything ;-).

Designing amps is mare my thing but she need speakers and this is a little a start for me, ready made are very expensive sometimes, and with diy I can save a lot of mony.

The visatons did also very well in a H frame, I had very deep bas, I did really like it but it has to be located in the middle of the room for best bass, and bass was there only when present in music, that is like it has to be, so clean, normal boxes have sometime bas what is not in the music, (booming), that is what I don,t want. But we discuss here the PPSL.

Oke, PS plenum? (slot) my english is not that good, is this the space between the two speakers, opening, maybe a picture will help, I see these have efficienty like horns? because you are use horn for mid and high.

I go read google for more about it, it looks also like a OB dipole woofer woho has not so high efficienty.

Dipole Woofer

And here discussing about to use hornresp.

Hornresp

thanks again

Last edited by kees52; 4th October 2012 at 08:12 PM.
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Old 4th October 2012, 09:04 PM   #337
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Quote:
Originally Posted by kees52 View Post
Hi there
Oke, PS plenum? (slot) my english is not that good, is this the space between the two speakers, opening, maybe a picture will help, I see these have efficienty like horns? because you are use horn for mid and high.
A plenum, or slot, is the space between the two speakers.
The plenum does not increase efficiency like a large horn would, but does subjectively increase "punch" and "tightness", and allows for a smaller frontal area than if the speakers were front loaded, and is easier to build than a stepped baffle for push pull as is used with speakers requiring a higher crossover point.
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Old 4th October 2012, 09:50 PM   #338
Scott L is offline Scott L  United States
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Default ppsl mid-bass prototypes

Quote:
Originally Posted by moray james View Post
Scott: have you tried them with a plenum which is as small physically as possible and no taper as shown in your first picture? Are your sections of sono tube sealed or are they vented? Thanks. Best regards Moray James.
Hi Moray,

The plenum is indeed as small as physically possible. The magnet actually sits slightly inside the cone of the adjacent woofer. The taper goes from front to back, not side to side. It was also built to mimic the beginning of a horn throat. The horns I built for these were prototypes, too small, and not a sturdy enough construction, which is why I removed them. The sono-tubes are sealed, and of differing volumes to compensate for the fact one woofer is inverted. An interesting observation I discovered along the way is, while a single drivers' Fs is 46, when they are loaded in the slot, the fs dropped to 40 Hz. One can throw Thiel/Small calcs out the window in this type of build: the system Fc lies at 57 and the apparent low frequency limit is 36 Hz. Just imagine what a ppsl sub-woofer application can do !
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Old 5th October 2012, 03:15 PM   #339
kees52 is offline kees52  Netherlands
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Quote:
Originally Posted by weltersys View Post
A plenum, or slot, is the space between the two speakers.
The plenum does not increase efficiency like a large horn would, but does subjectively increase "punch" and "tightness", and allows for a smaller frontal area than if the speakers were front loaded, and is easier to build than a stepped baffle for push pull as is used with speakers requiring a higher crossover point.
Ahh I was right I see, oke now it get more clear, I have to play with the hornresp software, nice that this is a dipole source box, it sounds good and has high efficientie? SPL.

I try to find soms documantation on google.

Thanks for sharing with me.

kees
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Old 5th October 2012, 03:35 PM   #340
kees52 is offline kees52  Netherlands
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Join Date: May 2009
Location: Sprang-capelle Holland.
Quote:
Originally Posted by weltersys View Post
Design for your speakers as you would any bass reflex cabinet, reduce the volume taken up by the plenum (slot) from the cabinet volume when calculating box size.
Has I design the reflex cabinet with two speakers doubling vas and Sd because I see here two speakers also.

By the way, little offtopic but do someone now what tweeter this is? it sounds better then the magnat metal domes.


thanks
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Last edited by kees52; 5th October 2012 at 03:41 PM.
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