This is a new thread as suggested by Moray James. For Moray James: What I did was to simulate the enclosure with two speakers in Horn Response. I simulated it as you would an Altec A7 type of speaker but with a front chamber on the horn. This front chamber would be the plenum if I am doing it right. The plenum opening was the horn throat. I rounded the opening a couple of centimetres and used this as the horn. I did do the combined sim to take into account the vents. As I said in the other thread, I don't know if this is anywhere near accurate.
Any input from those who have done this type of design would be most welcome.
jamikl
Any input from those who have done this type of design would be most welcome.
jamikl
PPSL in Hornresp
Hi jamikl,
I think your model places the speakers at the throat of the front horn (e.g.: CH driver arrangement), I may be better to have them entering the horn from the side @ S2 as in the OD arrangement.
I posted in the http://www.diyaudio.com/forums/subwoofers/176729-klipsch-horn-woofer-designs-3.html thread, Post #30, that I would ask David McBean for help in his Hornresp thread: http://www.diyaudio.com/forums/subwoofers/119854-hornresp-147.html#post2377713 , and he answered in Post #1464. I posted a sample PPSL Hornresp Input Screen in Post #1463, and feel relatively confident, that that is the correct way to model a PPSL in Hornresp.
The OD driver arrangement allows you to position the drivers in a short horn of two sections, by keeping the areas S1-S4 the same you create the plenum, and by OD definition the driver is located @ S2.
You then use Vrc/Lrc/Ap/Lpt to define you back-chamber BR.
Be sure to use the Combined Response for the SPL and resulting Impulse Response.
Hopefully someone has some practical dimensions and measurements to compare to the models.
Regards,
Hi jamikl,
I think your model places the speakers at the throat of the front horn (e.g.: CH driver arrangement), I may be better to have them entering the horn from the side @ S2 as in the OD arrangement.
I posted in the http://www.diyaudio.com/forums/subwoofers/176729-klipsch-horn-woofer-designs-3.html thread, Post #30, that I would ask David McBean for help in his Hornresp thread: http://www.diyaudio.com/forums/subwoofers/119854-hornresp-147.html#post2377713 , and he answered in Post #1464. I posted a sample PPSL Hornresp Input Screen in Post #1463, and feel relatively confident, that that is the correct way to model a PPSL in Hornresp.
The OD driver arrangement allows you to position the drivers in a short horn of two sections, by keeping the areas S1-S4 the same you create the plenum, and by OD definition the driver is located @ S2.
You then use Vrc/Lrc/Ap/Lpt to define you back-chamber BR.
Be sure to use the Combined Response for the SPL and resulting Impulse Response.
Hopefully someone has some practical dimensions and measurements to compare to the models.
Regards,
Hi tb46. Yes I saw your question on the other thread and David's response. I thought I might be doing it wrong but it was quite awhile ago and I didn't know about the other facility in Horn Response so I tried what I tried!!!
Will do it David's way when I get a chance. I did try a la scala derivative with
two 12 Inch speakers and posted the result somewhere awhile ago. Its on this forum somewhere!!!
jamikl
Will do it David's way when I get a chance. I did try a la scala derivative with
two 12 Inch speakers and posted the result somewhere awhile ago. Its on this forum somewhere!!!
jamikl
Shape of plenum chamber
Hi guys,
When looking at some models in Hornresp I found a pronounced peak in the PPSL frequency response that does not seem to be easy to tame. This may just be something I'm doing wrong, or it may be typical for this type enclosure. I then changed the plenum from its rectangular form to a triangular form and the peak becomes much easier to control in the model.
Maybe somebody who knows something about PPSL enclosures (e.g.: djk 🙂) can shine some light on this; or maybe we're on to something.
Regards,
Hi guys,
When looking at some models in Hornresp I found a pronounced peak in the PPSL frequency response that does not seem to be easy to tame. This may just be something I'm doing wrong, or it may be typical for this type enclosure. I then changed the plenum from its rectangular form to a triangular form and the peak becomes much easier to control in the model.
Maybe somebody who knows something about PPSL enclosures (e.g.: djk 🙂) can shine some light on this; or maybe we're on to something.
Regards,
Attachments
Your first graph looks like what it does when both drivers face into the plenum, a cavity resonance.
When you flip one of the drivers magnet structure into the plenum the cavity resonance seems to disappear.
When you flip one of the drivers magnet structure into the plenum the cavity resonance seems to disappear.
Hi djk,
I spend the last week rebuilding my computer after a virus attack.
It makes sense that the volume reduction inside the plenum would make a difference, especially if the plenum is kept to a minimum.
Thanks for the additional information.
Regards,
I spend the last week rebuilding my computer after a virus attack.
It makes sense that the volume reduction inside the plenum would make a difference, especially if the plenum is kept to a minimum.
Thanks for the additional information.
Regards,
Ports?
This is another thread I've been looking forward to!
Am I mistaken, or do these subwoofer cabinet designs lack the ports that DJK had on some of his enclosures?
Regards, Ben
This is another thread I've been looking forward to!
Am I mistaken, or do these subwoofer cabinet designs lack the ports that DJK had on some of his enclosures?
Regards, Ben
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What are the benefits of PPSL vs Dual for an 18 inch, high powered amp build? Goal is low and clean and loud!
Cant find too much on PPSL...
Cant find too much on PPSL...
"Am I mistaken, or do these subwoofer cabinet designs lack the ports that DJK had on some of his enclosures?"
The basic idea behind PPSL is the plenum with the push-pull mounted drivers. The box could be sealed, vented, 6th order vented (most of my designs are 6th order vented), or even dipole (the Linkwitz sub).
"What are the benefits of PPSL"
Distortion reduction.
When I built the first model PPSL over 20 years ago it sounded so different (compared to a 'normal' speaker) that I didn't realize what I was hearing (lack of distortion). It was only when I compared it with a large corner horn that I realized what was happening, that the PPSL was cleaner, less colored, and more musical.
"Cant find too much on PPSL... "
Google
PPSL djk About 1,920 results (0.25 seconds)
1.
Push-pull Slot Loading (PPSL) sub drivers? [Text View] - AVS Forum
20 posts - 9 authors - Last post: Jan 4
Both SL and DJK are smart cookies. They chose this topology for very ... Maybe it would help if you explained how each would work in a PPSL? ...
AVS Forum › ... › Audio Related › DIY Speakers and Subs - Cached
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PPSL les hudson About 896 results (0.27 seconds)
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High Efficiency Speaker Asylum
Just completed a new experiment Push-Pull double 15" subwoofer. This is the best sounding subwoofer that I've ever heard after building sub cabinets for 33 yrs. Love it. Les Hudson
The basic idea behind PPSL is the plenum with the push-pull mounted drivers. The box could be sealed, vented, 6th order vented (most of my designs are 6th order vented), or even dipole (the Linkwitz sub).
"What are the benefits of PPSL"
Distortion reduction.
When I built the first model PPSL over 20 years ago it sounded so different (compared to a 'normal' speaker) that I didn't realize what I was hearing (lack of distortion). It was only when I compared it with a large corner horn that I realized what was happening, that the PPSL was cleaner, less colored, and more musical.
"Cant find too much on PPSL... "
PPSL djk About 1,920 results (0.25 seconds)
1.
Push-pull Slot Loading (PPSL) sub drivers? [Text View] - AVS Forum
20 posts - 9 authors - Last post: Jan 4
Both SL and DJK are smart cookies. They chose this topology for very ... Maybe it would help if you explained how each would work in a PPSL? ...
AVS Forum › ... › Audio Related › DIY Speakers and Subs - Cached
******************************************************
PPSL les hudson About 896 results (0.27 seconds)
*************************************************************
High Efficiency Speaker Asylum
An externally hosted image should be here but it was not working when we last tested it.
Just completed a new experiment Push-Pull double 15" subwoofer. This is the best sounding subwoofer that I've ever heard after building sub cabinets for 33 yrs. Love it. Les Hudson
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I'm going to Google 'PPSL djk' as suggested; I would like to experiment with a pair of B&C 21SW152. I'll model both sealed and vented implementations.
Larry
Larry
The sealed PPSL is twice the size of the isobaric, and 3dB more efficient, with 6dB more maximum output.
"B&C 21SW152"
That looks like a nice driver, but it fits in a small box and the port required for the x-max the driver has may be a problem. Check the port size in your speaker program and see it you can make it work.
Most 18s don't look too bad, I have made a couple of different dual 18 PPSL for PA use.
"B&C 21SW152"
That looks like a nice driver, but it fits in a small box and the port required for the x-max the driver has may be a problem. Check the port size in your speaker program and see it you can make it work.
Most 18s don't look too bad, I have made a couple of different dual 18 PPSL for PA use.
Hi djk,
When I use the automatic alignment feature in Boxplot the isobarik configuration ends up 6dB down, and at 1/4 the volume.
Regards,
When I use the automatic alignment feature in Boxplot the isobarik configuration ends up 6dB down, and at 1/4 the volume.
Regards,
I am now deciding between a I) Dual Sealed Opposed build, II)multiple small sealed, and a III)PPSL Opposed Sealed. (Compound PPSL). DJK, most of the PPSL's you and Les online pictures of are Slot Loaded PPSL for PA. These seem harder to design and build than a PPSL Opposed Sealed design.
1. What is the advantage of having the plenum/slot loading manifold design in PPSL compared to a Dual Opposed PPSL.
2. Can you comment on the usage of PPSL for Home Theater? I've only seen you and Les building them for PA. Some users have commented that they won't work well down low??
Please correct me if I am wrong--
My current thoughts are to build a dual opposed PPSL. Why?
a) The design is easy, its like a Dual Opposed Sealed but with one driver and mount facing in.
b) In terms of modelling and building it, as long as I have enough internal space and amp power, what else should I worry about? Other designs have angles, horn length, port length etc. This design is a sealed box
c) This is better than 2 individual sealed 18's because of the ?even? harmonic cancellation. Right?
Thanks for the input, especially the parts in bold
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HI,My
:I would guess the PPSL shares similar SQ performance(= high) with a T-TQWT/T-TQWP if build sturdy, i.e. not letting any CSA:s larger than ~10”x 10” to be un-braced.
The differences when placed in a room would be : The PPSL sums sound pressures in the far-field thus shows directionality but the T-TQWT/T-TQWP acts like an omni pressure point-source and is not sensitive if placed jammed very close to other in room objects. Its like comparing in room performance using a closed sub to a corresponding ported.
Comparing a closed PPSL would be like to compare with a closed T-QPPSL( easy to simulate in HR): Both offering very similar performance: Internally the the PPSL behaves like an ordinary closed box but the T-QPPSL like an closed TL,i.e. Lambda/2 behavior. See the picture:
b 🙂
Attachments
Hi hawkson,
Sorry, but I don't get what you mean with: "...a dual opposed PPSL... its like a Dual Opposed Sealed but with one driver and mount facing in..." Could you, please, provide a sketch of that arrangement?
As to the design of the enclosure, keep the driver plenum(s) as small as practical, and follow the same general rules you would use for a sealed box (or for a vented (bass reflex) if you decide to go that way). It may be interesting to design the box with ports you can stuff, or close.
Regards,
Sorry, but I don't get what you mean with: "...a dual opposed PPSL... its like a Dual Opposed Sealed but with one driver and mount facing in..." Could you, please, provide a sketch of that arrangement?
As to the design of the enclosure, keep the driver plenum(s) as small as practical, and follow the same general rules you would use for a sealed box (or for a vented (bass reflex) if you decide to go that way). It may be interesting to design the box with ports you can stuff, or close.
Regards,
Oliver, your statement suggests there is no relation between (minimum) opening size versus Response.