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How does the ipal system work?

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Aleksander View Drop Down
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    Posted: 19 July 2022 at 8:37pm
The numbers are impressive. But how does it work? Anyone found a optimal compact design with frequency response suited for live rock, pop and EDM music? (where double 18"s are the most used cabs currently)

Ipal driver with ipal mod claims 6 db spl advantage vs "normal" drivers. To reproduce low frequencies loud the drivers need to move lots of air. How can a ipal system compensate to move more air and get louder than a normal driver with similar xmax? Or is the 6 db extra spl only on frequencies up where less xmax i required? 

After bulding a few designs(reflex, horn, BP++) with ipal I have come to the following conclusion:

Above 70hz - 1 x b&c ipal 21 with ipalmod in a 270L cabinet will get as loud as two double 18" cabs from the current market leaders on their standard presets. 
My "compact" single ipal designs struggle to keep up with double 18"s below 50-60hz. Ipal in big cabs is a different story. 

My quest is to get as high output as possible, frequency response that can be used for "all kinds of music" in a cabinet no more than 300 liters so its easy to move around. 
Now and then I take out my cabs to test them on live music- got lots of comments on how surprisingly loud they are but can´t say I´m quite happy yet, they get very loud on the wrong frequencies. 

Currently Im testing out ipal driver on a 5000w rms 1 ohm car amplifier made for spl competitions in a reflex enclosure. The plan is to test it against ipalmod and try to understand whats going on. So far it seems like there is more response on the low frequencies without the ipalmod but with less defined sound. Have not had the chance to do max spl tests yet.

I have also started on a 290 liter reflex box for the new PD 24" driver to test up against the ipal designs. The 24" should be able to move massive amounts of air from what I can see in the specs. 

If I´m not doing something very wrong it seems to me that there is no replacement for displacement;) 

Anyone with similar experiences? 





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airbell View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote airbell Quote  Post ReplyReply Direct Link To This Post Posted: 20 July 2022 at 9:18am

I've already shared some information and experience about this topic.
IPAL drivers have a lot of linear xmax and motor force and will outperform almost all other drivers in therms of spl/size.

That said, the combination of a very strong driver with low qts and a class d amp as the ipal mod with pressure sensor sounds very powerful, controlled and tight, but also has a steeper rolloff below tuning frequency and is missing the typical bassreflex "resonating" sound because of class d and especially because of the pressure sensor. 
It's like you can't have all from just one enclosure (controlled clean sound, strong punch, high spl, low box size, strong lowend with warm full subbass) 

Practical experience: Compared 18NTLW5000 in 165L net with 35Hz tuning against 18IPAL in 105L net 35Hz tuning: sine wave they are almost the same at tuning but the 18sound sounds lower and cleaner in subbass frequencies but the ipal sounds tighter with more punch, but still quite similar by the way.

If your goal is to archive more subbass you could turn the sensor off or set lower sensor sensivity, or as you said use another amplifier. I tested Lab Gruppen fp/plm14000 with ipal, it is in general nicer sounding with  "deeper or fuller" sounding bass but as i mentioned not as tight as the ipal mod.

some things you don't see with pn or sinewave measurements, music means impulses and some small changes in the waveform for example a higher group delay or "reverberation time" can cause huge difference in the subjective sound impression of a loudspeaker/subwoofer and make it sound deeper or louder even if you measure sine wave or pink noise and they seem to have the same response.

Don't forget ipal mod is made for professional subwoofers for touring. it has not as much continuous output power as a 5000w car hifi amplifier, but fits the ipal drivers and is very efficient and you can use several of them on a C16 circuit breaker with low average current draw.

Btw. 290L is way too much for the 21IPAL except you mean brutto/the total enclosure volume.
What is your tuning frequency, port area and geometry?

Last but not least, don't forget that the drivers could actually be used in a tapped, hybrid or front loaded horn enclosure, they have perfect parameters for it.

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smitske96 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 20 July 2022 at 9:31am
Did you both try playing around with the virtual speaker mode?
I personally have not heard or tested the Ipal system yet, but I have heard some great things about the PK Gravity 218 (which apparently does have that real low-end most people want).

I am kind of busy with a side project which could incorporate Ipal drivers and module.
Its a 2x18 6th order design but with a relative short horn instead of the higher tuned chamber (so comparable to something like the Skhorn, but much smaller). Still its a project that coming a long slowly and mostly due to the costs.

New 24" Neo PD is an awesome driver, good results coming from that one.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote airbell Quote  Post ReplyReply Direct Link To This Post Posted: 20 July 2022 at 11:33am
Havend listen to the PK Gravity 218 but from pictures it looks like it has way too much net volume (180-200L) for EACH of the 18IPAL drivers.
I tested the 18IPAL in 200l 35Hz and then 160L 35Hz tuned enclosure aswell.
It will give you a lot of output at tuning, which seems also quite low for the gravity 218
(maybe 30Hz?).
If that's the only thing you want, a lot of clean and big sounding sub <50Hz, maybe it's an option.
Comparable with the even way stronger M-Force solution.
But it's not made for a 1 bass solution imo, you need kick bins from 50Hz upwards then.

I tested only a little bit the Virtual speaker mode, yes you can change the sound, make it sound slower or muddier, but not really make it sound and behave like a decent typical low mms bassreflex driver in a big box. but maybe i didnt spend enough time with it, anyway, I always prefered it with the pressure mode (you can only pick one at the same time) with harder more precise sounding bass.

Btw. the topic headline "how does it work" is a different actually very interesting topic, i think the math behind it is quite complicated, so far I know its a "current driven amplifier". Sounds similar to a thing that is used to control electric motors, its called FOC (field oriented control) that keeps the current in a spinning motor constant or better "sine wave". with constant voltage you will get a torque rippen because when the windings are at the nearest position close to the magnet the magnetic force is the highest. This can cause the typical annoying hf noise of an rc car or cheap ebike.

I think the princip about the ipal system is not the same but kind of similar, it controls the transducers calculated position according to the input signal.


Edited by airbell - 20 July 2022 at 10:34pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 20 July 2022 at 11:47am
"warm full subbass"

what are we talking about here? harmonic distortion?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote airbell Quote  Post ReplyReply Direct Link To This Post Posted: 20 July 2022 at 5:43pm
that's the question. I just tried to express what I heard from a subjective point of view.
If you think about distortion as something that is not part of the original signal, then yes. But I think its not all about harmonic distortion but also a matter of "after ringing" (sorry I maybe dont know the exact English therm).
Take a look at this at page 2
without the dpc sensor activated the loudspeaker still produces some subbass even after the input signal disappeared. I think this is normal for most loudspeakers, some more some less, and makes the typical "ported subbass sound".with the dpc activated the whole bass sounds more tight but also less "full and warm"...


Edited by airbell - 20 July 2022 at 11:16pm
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Aleksander View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aleksander Quote  Post ReplyReply Direct Link To This Post Posted: 20 July 2022 at 7:25pm
Originally posted by airbell airbell wrote:

https://forum.speakerplans.com/anyone-using-partial-or-full-bc-ipal-solution_topic104576. - Anyone using partial or full B&C IPAL solution? - Speakerplans.com Forums - Page 1



Btw. 290L is way too much for the 21IPAL except you mean brutto/the total enclosure volume.
What is your tuning frequency, port area and geometry?

Last but not least, don't forget that the drivers could actually be used in a tapped, hybrid or front loaded horn enclosure, they have perfect parameters for it.


Thanks for the link! Seems like we have similar experience. I have also done some tests with horns, bandspass ect but they have not proven optimal for my goal so far. I might try a tapped horn just for fun later.  

The boxes I have for the driver now are ranging from 180-220 liter, with 45-70 liter port. The ports ranges 50 - 60 cm wide and 9-16 cm tall. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 20 July 2022 at 9:25pm
Originally posted by snowflake snowflake wrote:

"warm full subbass"

what are we talking about here? harmonic distortion?

Mmmm... warm and snuggly like a big Celestion Ditton.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 21 July 2022 at 8:29am
Originally posted by airbell airbell wrote:

that's the question. I just tried to express what I heard from a subjective point of view.
If you think about distortion as something that is not part of the original signal, then yes. But I think its not all about harmonic distortion but also a matter of "after ringing" (sorry I maybe dont know the exact English therm).
Take a look at this at page 2
without the dpc sensor activated the loudspeaker still produces some subbass even after the input signal disappeared. I think this is normal for most loudspeakers, some more some less, and makes the typical "ported subbass sound".with the dpc activated the whole bass sounds more tight but also less "full and warm"...


it could be that also. but whether it is harmonics or ringing, any clean sounding amp could be changed into a warm sounding amp with some signal processing if that's what you want. Better to start with an amp that is capable of low distortion and high output.

Edited by snowflake - 21 July 2022 at 8:48am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aleksander Quote  Post ReplyReply Direct Link To This Post Posted: 22 July 2022 at 3:53pm
Originally posted by smitske96 smitske96 wrote:

Did you both try playing around with the virtual speaker mode?
I personally have not heard or tested the Ipal system yet, but I have heard some great things about the PK Gravity 218 (which apparently does have that real low-end most people want).

I am kind of busy with a side project which could incorporate Ipal drivers and module.
Its a 2x18 6th order design but with a relative short horn instead of the higher tuned chamber (so comparable to something like the Skhorn, but much smaller). Still its a project that coming a long slowly and mostly due to the costs.

New 24" Neo PD is an awesome driver, good results coming from that one.

Tried to play around with the parameters, going to work more on that. 

What kind of cabinet did you make for 24" PD? I like the sound from it. Not sure if I got the port and box perfect but it gets pretty loud probably not far from a double 18" box from 30-80hz on my bridged K3 amp. More testing during the weekend and next week. 
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