• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Purifi PTT6.5W04-01A 6.5" midwoofer

Lbstyling

Senior Member
Forum Donor
Joined
Jan 2, 2019
Messages
390
Likes
318

Lbstyling

Senior Member
Forum Donor
Joined
Jan 2, 2019
Messages
390
Likes
318
I don't have any data or insight in to those woofers. But I do have a good relationship with John so maybe I can ask him for a test sample.

The ultimate showdown:cool:
 

yourmando

Active Member
Joined
Aug 14, 2020
Messages
132
Likes
158
I'm not so sure about that. One of the most important speaker parameters is dispersion characteristics. If you want to have even dispersion with frequency, there is no beating a smaller midrange crossed over to a (smaller) tweeter, which necessitates a three-way design. Unless you want to put the drivers inside a waveguide, but that brings new complications to the table. This driver starts struggling off-axis already at 1500 hz. It's good compared to many other drivers of the same size, of course, but it's not good - when it comes to off-axis response in the midrange - compared to many 3- or 4-inch drivers.

If one wants to keep the speaker small, though, it would have been exciting to see an active DSP based 3-way with this as the woofer, crossed over to a 2- or 3-inch driver around 1000 hz, crossed over to a really small wide-dispersion tweeter around 6 or 7 khz. Something like that (this is just a guess as to what would work out). Now we're suddenly talking about a speaker which has deep bass, is slim and small, has no crossovers in the most sensitive region, and probably could achieve very wide and even dispersion over the whole frequency range (way beyond what a 2-way could achieve in terms of dispersion). Pretty neat!
(ping @March Audio - I have no idea whether this would work out or not, but given that you're already making an active speaker with this as the woofer...)

It works!

I’m very late to this thread, but I was nodding in agreement about the driver sizes and crossover points to control dispersion.

Then I realized these are the exact crossover regions in the top baffle used by Linkwitz in his final LX521 design.

He chose the sizes, baffle widths and crossover points for the same reason—to keep dispersion wide and smooth across the frequency range. He crosses over the 8” and 4” at 1000hz, and the 4” and 1” tweeter at 7khz (and at bottom 120hz to dual seas 10”)

It seems like the Purify woofers could be used in place of the 8” to take the top part even slimmer.

I’m currently contemplating a 2 way dipole to be used as height speakers directly above my Linkwitz Orion dipoles

To keep it small, I could use these Purify mids, but cross over to a tweeter such as the new Bleisma’s at a lower crossover point down to 2khz if possible where the Purify dispersion is still wide. Bass would be crossed over to the home theater dual 12” subs.

http://www.linkwitzlab.com/LX521/Description.htm
 

Attachments

  • 57978E12-1C67-44E0-AE4C-65B12842F1E6.jpeg
    57978E12-1C67-44E0-AE4C-65B12842F1E6.jpeg
    3 MB · Views: 158

Matias

Major Contributor
Forum Donor
Joined
Jan 1, 2019
Messages
2,616
Likes
4,289
Location
São Paulo, Brazil

AnalogSteph

Major Contributor
Joined
Nov 6, 2018
Messages
1,721
Likes
1,589
Location
.de
Cool. Funny how at 105 dB the Purifi has less distortion than the 12" PA midwoofer (which, mind you, is likely to be optimized for high efficiency @ 101.5 dB nominal and only costs about half as much either, but does enjoy the advantage of almost 4 times as much Sd).

I only noticed now that his distorton products are plotted on a different scale from the fundamental. So his limit is at about 0.01% = -80 dBr, or noise floor as low as 15 dB SPL.
 

briskly

Active Member
Joined
Jul 10, 2019
Messages
108
Likes
143
New Purifi PTT6.5W-NFA (medium-stroke) driver announced. 4-ohm and 8-ohm models. Also from Purifi, alphabet soup.
The W-NFA has more conventional parameters than the renamed PTT6.5X-NFA (long-stroke). Easier to use with a vented cabinet and slightly higher efficiency. It seems to reuse the cone and surround from the long-stroke model.
 

Lbstyling

Senior Member
Forum Donor
Joined
Jan 2, 2019
Messages
390
Likes
318
New Purifi PTT6.5W-NFA (medium-stroke) driver announced. 4-ohm and 8-ohm models. Also from Purifi, alphabet soup.
The W-NFA has more conventional parameters than the renamed PTT6.5X-NFA (long-stroke). Easier to use with a vented cabinet and slightly higher efficiency. It seems to reuse the cone and surround from the long-stroke model.

Just need a 10, 12 and 15 inch one now. Could you imagine the sound quality of below 0.1% THD at 100db?:eek:
 

gingerbeer

Member
Joined
Jun 30, 2018
Messages
32
Likes
39
I'm considering an LX mini build - apart from the difference in diameter, if the purifi woofer was to be used would other dimensions need to change (lower tube diameter/ height/ volume) and any requirement to add a passive radiator? Speaker design isn't my strength!


I can't see any problems with using 6½" instead of 6" in LXmini. Directivity difference is minimal, hardly measurable at all in this application because xo is at 855Hz acoustically - and can be easily shifted/eq'd with the dsp unit.

https://www.linkwitzlab.com/LXmini/Design.htm
https://www.madisoundspeakerstore.com/2-way-speaker-kits/lxmini-linkwitz-lab-speaker-kit-pair/

LXmini-v3-xo-s.png


Here is directivity of L16 and Purifi 6,5
F_Seas_Prestige_loudspeaker_woofer_H1480_L16RN-SL.jpg


PTT6.5W04-01A-Data-Sheet-1.00-3.png
 
Last edited:

Juhazi

Major Contributor
Joined
Sep 15, 2018
Messages
1,528
Likes
2,420
Location
Finland
I wouldn't use passive radiator with Purifi, because it has hig excursion just for being able to handle high power and lots of equalization. A tube has always a disturbing longitudinal resonance that fits woofer's range. Putting lots of damping material on the low end of the tube is essential! Equalization will take care of low end response and crossover matching. The eq file provided by LX521 site is a good start, but understanding of things and ability to take measurements are essential for tweaks!

Diameter of driver frame must somehow match with the tube, but anyway one must make an adapter ring.

Esthetics of LXmini is "questionable". One might want to make a fabric hood for the midrange/tweeter...

LXmini-inroom-2.jpg
 

gingerbeer

Member
Joined
Jun 30, 2018
Messages
32
Likes
39
Thanks for the quick reply. Making the new dimensions and adapter is easy enough with CNC.

However does the volume of the tube need to increase to match the larger driver?
 

somebodyelse

Major Contributor
Joined
Dec 5, 2018
Messages
2,214
Likes
1,648
There's a fair bit in this thread on modeling the driver in a sealed enclosure, but later mentions here and in other places suggest there's a distortion problem when you've got that much driver displacement in such a small enclosure. I haven't found the post with the details though.
 

Selah Audio

Active Member
Manufacturer
Forum Donor
Joined
Feb 4, 2020
Messages
194
Likes
432
There's a fair bit in this thread on modeling the driver in a sealed enclosure, but later mentions here and in other places suggest there's a distortion problem when you've got that much driver displacement in such a small enclosure. I haven't found the post with the details though.
I'll be able to do some basic distortion tests soon on a sealed enclosure version. I'll be using a Bliesma tweeter and testing the design with both passive and active/DSP crossovers.
 

Rick Sykora

Major Contributor
Forum Donor
Joined
Jan 14, 2020
Messages
1,577
Likes
2,537
Location
Stow, Ohio USA

Lorenzo74

Senior Member
Joined
Nov 17, 2019
Messages
320
Likes
264
Location
Italy, Rome
I'll be able to do some basic distortion tests soon on a sealed enclosure version. I'll be using a Bliesma tweeter and testing the design with both passive and active/DSP crossovers.

did you read bliesma implementation at Hifi compass?

waveguide is key
Best
Lorenzo
 

Lorenzo74

Senior Member
Joined
Nov 17, 2019
Messages
320
Likes
264
Location
Italy, Rome
Have you seen the latest and greatest?

https://hificompass.com/en/projects/2-way-systems/puri-wave

Bye bye waveguide.

Hmmm
yes I did but is still Work in Progress...
Waveguide will be there. It’s needed to control > 1kHz dispertion. No way.
I wrote somewhere in ASR many months ago that the NEXT Speaker will be a compact cardioid (Kii3 like) with purifi 6.5, 4 and either bliesma (+low Xover point) or Viawave (waterfall, distorsion,...) fully DSPed.
waiting either B. Putzeys or someone else will make it.
thanks
My Best
Lorenzo
 

hollis

Member
Joined
Sep 3, 2018
Messages
51
Likes
30
I'm considering an LX mini build - apart from the difference in diameter, if the purifi woofer was to be used would other dimensions need to change (lower tube diameter/ height/ volume) and any requirement to add a passive radiator? Speaker design isn't my strength!

I am planning out this build as well. Bought all the large parts, but then that 6.5” definitely wont fit anywhere near that 4” pipe, was looking into 4” to 8” rubber pieces, but then we run into issues with the basket depth. Ultimately gave away all the parts just this week, and looking for a source for 6” pipe (or just break down and build a wooden hexigon/octogon tower of the same height.

The additional internal volume is a “plus”. The LXmini uses equalization for a low end boost, the larger internal volume will have less need of a boost.
 
Top Bottom