PureAudioProject - Trio15 Lowther DX3 with "Leonidas" crossover review
by Maarten van Druten UPDATED!
I had a very interesting second
listening session at Leon's studio, to read about it, see the end of
My loudspeakers are over 20 years old now,
they served me very well but now it's time for something new.
So currently I have started my quest to find new loudspeakers.
In the loudspeaker world, the choice is enormous, transmission line,
line array, dipole, bipole, full-range wide banders, or magnetostatic
I have listened to many different loudspeakers during my life, but there
was never one loudspeaker that really made me smile...
They all had concessions at some point, one speaker had a very nice
projection and sound-stage but was lacking deep bass, the other was
sounding very nice but has a sweet spot that was so narrow that if you
moved your head only a few centimeters the sound stage collapsed
On the X-Fi high-end show 2016 I heard the
W1” dipole loudspeaker, which is made in the Netherlands.
The sound of this loudspeaker really made
This loudspeaker has an “Mundorf” dipole
air motion tweeter hanging in the air with wires, and this tweeter was sounding very,
The music was transparent, it's was
everywhere, even if you turned your head all around it was if there was
a big cloud of music was hanging in the room, the bass was also very
good, with lots of definition, deep but certainly not muddy.
The only disadvantage was it's price for 17.500 euro a pair, this
speaker was too expensive for my budget.
One of the audio developers of "daudio" told me that they were working on a smaller
passive version of this speaker in the 5.000 euro range.
That sounded as music
in my ears, but then I have to wait...
I'm not sure if I want to wait so long because the release date of this
speaker is still unknown...
PureAudioProject: "Leonidas crossover"
Then I noticed a article on the Internet about
the “PureAudioProject” (= PAP).
They designed a modular open baffle design loudspeaker, that is very
According the few reviews on the Internet their sound was something
special, and they sounded much better than commercial high end
loudspeakers costing even four times more.
And they won many “Best of Show” awards.
They have multiple models, two caught my interest the Trio TB15 Voxativ
with Leonidas crossover and the smaller Trio 10 with an Mundorf air
I became very interested in this concept, and
I wanted to listen to this special loudspeaker.
After some searching on the Internet, luck was smiling to me, because
one of the crossover designers of the PureAudioProject loudspeakers
was living close to my neighborhood!
So I contacted him, I introduced myself and
asked if it was possible to listen to this
Pure Audio Project loudspeakers.
Leon Huijgen responded quickly and invited me to his design studio!
I was very excited, and I can not remember when the last time that I got
excited to listen to loudspeakers
Leon was already waiting for me at the door
when I arrived, I introduced myself, and Leon was very friendly and
showed me around in his studio where he designs and test his
loudspeakers and crossovers.
Leon Huijgen is an loudspeaker designer that designs loudspeakers not
from a technical starting point but from experience, and just to
This practical approach comes also back in his
For the PureAudioProject has Leon designed a very interesting
crossover that is adjustable.
It can be easily adjusted to some ones preferences or to the room or
The Leonidas crossover
The designer himself "Leon Huijgen"with his creation
the "Leonidas crossover"
If you are interested in a more technical information about "Fletcher
& Munson curves"
Leon sent me this document about "X-overing an Open Baffle loudspeaker"
that he was willen to share with us.
Link click here: "About
X-overing an Open Baffle loudspeaker" (PDF)
Note: this document is NOT about the "Leonidas crossover", but an
variation of it.
When I entered his listening room two Pure
Audio Project Trio 15's were already warming up.
I was very excited to listen to them, because I have never heard them
Leon explained that he used the “Lowther DX3” widebander loudspeaker
unit in this TB 15 setup.
The Lowther DX3 widebander in the PureAudioProject Trio 15
The Lowther DX3 from the back, and of the
Of course the “Leonidas Crossover” was also
present in this setup
For this listening session Leon used a Marantz SACD player SA15 mk2 and
a Jungson JA-88D Class
A Integrated Amplifier.
We played many different music numbers from a compilation CD
How does the PureAudioProject Trio 15 sound?
First of all, after reading reviews of others I was a little afraid that
the bass would be absent.
This was absolutely not the case, bass was certainly there, and it was
fast, tight, and well balanced.
The sounds was very
transparent en the projection into the room was very good.
One thing became clear to me right away, the quality level of this
very high, this speaker delivers everything without any trouble, at this
this loudspeaker is a “steal” (in Dutch we say “geheim tip”) a insider
that this loudspeaker preforms at an remarkable high level
Another very important
thing I learned that day was, that every speakers needs a minimum power
level to work optimal.
The PureAudioProject Trio15 can also play very loud.
Before listening to this dipole loudspeaker I was used to a “boxed”
loudspeaker were the sound comes only from one side, but by this dipole
concept the sound comes from everywhere!
Because of this the music sounds much more realistic, “more live” and
also it sounds like if the music is played much louder than normal
Then Leon played Pink Floyd at a very high level
The music sounded amazing, without any trace of distortion!
Every instrument was very
detailed and available without any sharpness
Leon's preferred setup was a little bit different than my preferred
I personally like the music to be played a little quieter.
I also found that the mid
tones were a little too dominant
But this is about personal taste.
And this exactly were the amazing Leonidas crossover comes into place!
With this adjustable crossover the decibel settings of each loudspeaker
can be adjusted in absolute phase to the preferred level!
So Leon told me, for example
that he could adjust the both PAP A15
NEO woofers with + 6dB so that the full range Lowther DX3 still could
play on it's preferred level, and that total sound balance would more to
my personal taste.
And this is terrific news, a
speaker system that is adjustable to someone own preferred taste is a
very big welcome in the world of High-End.
No more concessions but tailor made musical presentations just how it
The modular PureAudioProject Trio 15 project is an very adjustable
system, were not only the loudspeaker units can be easily replaced or
changed, thanks to Leonidas crossover now also fine tuning is possible
in absolute phase!
Unfortunately Leon didn't had
a Voxativ speaker unit available for testing, because I was also very
interested how this unit would sound with his crossover.
After listening to the PureAudioProject Trio15, we listened to an TB
10 with two Morrel 10 inch woofers and a Fostex widebander.
Leon's own version of the PureAudioProject Trio 10 with Fostex
close-up from the front and back
After listening to the Trio 15 with the Lowther DX3 this was not an
especially the Fostex was no mach for the Lowther DX3.
In comparison the Fostex sounded flat, clean, even a little bit
Then Leon had a nice title surprise for me!
He placed two little MDF two-way tranmissionline loudspeakers on the
stands...and he played the same CD again.
I was impressed, seldom I had listened to such a musical,
well balanced loudspeaker,
these little speakers sounded very, very good.
Seldom I had listened to such a musical, balanced nice loudspeaker
After Leon told me that this little speaker cost only 199 euro's
I was totally amazed! He explained me that this was just a workshop
speaker for students to build it them self.
Unbelievable, this speaker sounded much better
(more musical, and better balanced) than many so called high-end
speakers I have heard in the shops.
Leon quality to use his own ears for his speaker designs rather than
just following theoretical rules really showed off here
For example the crossover in this little speaker contains only one resistor, this makes the
sound so very pure and well balanced sounding.
After listening to this amazing little
gem, we installed the Pureaudio Project TB15 with the Lowther DX3 again
Trio 15 listening session 2:
Remarkable was also the wideness of
the projecting of the music from the Lowter DX3
Normally a widebander has the effect to give the music al little narrow
projecting, but not this Lowter DX3, it had a better defined and also a
wider sound stage.
Sometimes I could hear a strong “S” sound by some recordings but I
cannot explain what was the reason of this, I only have listened this
I was very happy after this amazing demonstration of Leon Huijgen's
The PureAudioProject loudspeaker are really sounding amazing, and
thanks to Leon's “Leonidas crossover” the optimum result can be
Everybody has a different taste, the is no good or wrong, it's not a
fight who is better.
It is all about fine-tuning the music, so you will find what sounds for
you the best.
With this unique Leonidas crossover you are definitely on the right
Leon sended my an email that he discovered the
reason why the midtones were a bit dominant by the first listening
He explained me that the XO he was using was also used in the Trio 10
Only Leon forgot to adjust the components back for use in the Trio 15.
Therefore the midtones were 3 dB to loud, and that was what I was
hearing that day.
So problem solved, and luckily my ears are
still working :-)
Leon invited me for a second listening session, because he had something
special for me.
Of course I was more than happy to visited him, when I entered his
studio, I saw a glimpse of a new speaker he had build.
Leon had build in only two weeks time a scaled
down version of a loudspeaker that looked a little bit like the Voxativ
- Ampeggio Due.
Leon told me that this speaker was a one experiment only, just to test
Of course I wanted to listen to this small loudspeaker.
The sound was very good, remarkable was the deep bass, especially for a
loudspeaker this slim.
This speaker could also hang on the wall.
The units used in this speaker were just old one's Leon had laying
Later newer better units are going to be used
The sound-scape was also wide, but I was missing something. it looked
like the loudspeaker was missing some top end.
Then Leon came with surprise.
He placed something small on the speaker and connected it to the current
Then we started listening again...
Unbelievable, now the sound-scape was much better, better defined
Now not only the balance of the music was better, also the bass seemed
to go deeper.
What was it what Leon had done?
Leon had made a small wooden board with a dome
tweeter in the middle
A small wooden diffuser was placed at an angle above it.
For the XO only one capacitor was used.
So that the tweeter comes in at 10.000 Hz
Because the tweeter was pointed upwards, a very comfortable diffuse
cloud of sound
Because of the reflection a delay should be
present, but the fact was that in reality
this "delay" was almost inaudible
How is it possible that only one small tweeter could have so much effect
on the total presentation?
Not only the definition was better also the bass was sounding much
Leon told me that this was a common effect, when a super-tweeter was
added to the system.
I asked if it was possible to add this tweeter
to the PureAudioProject Trio 15
Leon laughed? are you sure?
I asked him why we laughed, He said this tweeter costs only 0,50 cents!
First we listened to the PureAudioProject Trio 15 without the
And then Leon installed this tweeter on top of the PureAudioProject Trio
I was amazed, also here the same dramatic impact was clearly audible
The definition became clearer, the sound-scape opened, and the
presentation of the total music became better balanced.
Also the bass seemed to improve by this amazing 0,50 cent tweeter.
After this listening session I was truly
convinced that the PureAudioProject Trio 15 will be my new loudspeaker
I have ordered the Voxactiv Trio 15 by PureAudioProject.
After my holiday I was do an extended review about my new loudspeakers
on this site.
I want to thank Leon for inviting me and for
sharing his experiments with me.
This "super-tweeter" was a very impressive one, I'm sure this experiment
will be continued in the near future.
Leon has allready made some newer prototypes, and he has send me the
following photos, he called them: "Leonidas 3D 2I" (= 3 dimensional
They look very promissing, I will write more
about them soon!
P.S: Many thanks to Leon Huijgen for
this hospitality and for this very impressive, and interesting listening session.
For more info about the "PureAudioProject":
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