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Purifi PTT6.5W04-01A 6.5" midwoofer

Lbstyling

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hardisj

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Do you have any thoughts on the Distortion Vs the current crown holder (at any size) the TD15M or ,TD10M? (I appreciate its much bigger driver)
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.
 

yourmando

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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
 

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Matias

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AnalogSteph

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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

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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

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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:
 
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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/



Here is directivity of L16 and Purifi 6,5


 
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Juhazi

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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...

 
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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

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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

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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

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Lorenzo74

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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
 
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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.
 
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