Purifi PTT6.5W04-01A 6.5" midwoofer

[dc655321]

A decent report and measurements on this driver has appeared.
Disappointing, but expected, pricing appears around the $400 ea. mark.

 

[Wombat]

Start at the beginning. Try WinISD to get a feel for it. Then try these: https://listoffreeware.com/free-speaker-design-software-windows/

Read the text(ignore the math unless you understand it). Start at page 1. : Berenak

WinISD guide

 

[Audiocrusader]

A decent report and measurements on this driver has appeared.
Disappointing, but expected, pricing appears around the $400 ea. mark.

It can't be! It just can't be! No way a ferrite magnet driver can beat a Neo magnet driver! Would have been nice to see the 8 and 10mm excursion performance of the competing drivers though. I guess the reviewer was throwing them a bone as the results would have been devastating. Oh and yes very disappointing to see that this drastically increased performance comes at a reduced cost. Show me where a DIY'er can buy 7+ Illuminators at $230 a piece.

 

[Lorenzo74]

Use 2 of them and it will be more than a match. Ideal driver for a 2.5 way tower.

I had same idea. Wide baffle to get unidirectional down to as low as possible (300Hz?)

which Tweeter?:
1) seas DXT to control lateral dispersion and reduce early reflection (1550Hz LR4 via DSP?)
2) Bliesma 1.5” with lower resonance fs, lower xover point, lower distortion better off axis integration
3) Viawave GTR 145, excellent but need higher xcrover point, I’m concern on off axis integration.
Or
4) Which is your ?

My main concern is to reduce early reflection as much as possible (Kii3, Dutch&Dutch,...)

Looking for your opinion
Many thanks
Lorenzo

 

[Ilkless]

I had same idea. Wide baffle to get unidirectional down to as low as possible (300Hz?)

which Tweeter?:
1) seas DXT to control lateral dispersion and reduce early reflection (1550Hz LR4 via DSP?)
2) Bliesma 1.5” with lower resonance fs, lower xover point, lower distortion better off axis integration
3) Viawave GTR 145, excellent but need higher xcrover point, I’m concern on off axis integration.
Or
4) Which is your ?

My main concern is to reduce early reflection as much as possible (Kii3, Dutch&Dutch,...)

Looking for your opinion
Many thanks
Lorenzo

DXT handles 1.5kHz LR2 without a sweat, Mark K, the designer of the ER18DXT DIY design tested it and found it clean to 105dB/1m. Also the DXT would have wide top-octave dispersion (closer to constant directivity), while having wider vertical dispersion than the Viawave ribbon. I personally think the DXT is a much cheaper and proven driver. Plus Bliesma distortion increases below around 2kHz to slightly elevated levels for the size and price.

https://www.diyaudio.com/forums/mul...narrow-directivity-horbach-keele-filters.html

A Horbach-Keele design would be interesting and really give near-constant directivity vertically and horizontally.

 

[Audiocrusader]

I had same idea. Wide baffle to get unidirectional down to as low as possible (300Hz?)

which Tweeter?:
1) seas DXT to control lateral dispersion and reduce early reflection (1550Hz LR4 via DSP?)
2) Bliesma 1.5” with lower resonance fs, lower xover point, lower distortion better off axis integration
3) Viawave GTR 145, excellent but need higher xcrover point, I’m concern on off axis integration.
Or
4) Which is your ?

My main concern is to reduce early reflection as much as possible (Kii3, Dutch&Dutch,...)

Looking for your opinion
Many thanks
Lorenzo

I'm thinking this new BlieSMa tweeter crossed over at 1.8K would be ideal:

https://hificompass.com/sites/default/files/documents/Datasheet-T25B-6.pdf

And they're only 250 Euro each!

 

[617]

I had same idea. Wide baffle to get unidirectional down to as low as possible (300Hz?)

which Tweeter?:
1) seas DXT to control lateral dispersion and reduce early reflection (1550Hz LR4 via DSP?)
2) Bliesma 1.5” with lower resonance fs, lower xover point, lower distortion better off axis integration
3) Viawave GTR 145, excellent but need higher xcrover point, I’m concern on off axis integration.
Or
4) Which is your ?

My main concern is to reduce early reflection as much as possible (Kii3, Dutch&Dutch,...)

Looking for your opinion
Many thanks
Lorenzo

If you're trying to limit early reflections I'd recommend an actual waveguide of some sort; a large tweeter or a tweeter with a faceplate waveguide will be a step in the right direction though.

You may want to look at the wavecor unit with a large waveguide, very robust:
https://www.audioxpress.com/article...W030WA12-30-mm-Cloth-Waveguide-Loaded-Tweeter

 

[HammerSandwich]

I had same idea. Wide baffle to get unidirectional down to as low as possible (300Hz?)

which Tweeter?:
1) seas DXT to control lateral dispersion and reduce early reflection (1550Hz LR4 via DSP?)

Wide baffle? DXT? 1550Hz XO? Sounds like you already want to make a mini-Grimm!

Per Hificompass, PTT6 has the same sensitivity as W22EX. FR/breakup are flatter & easier to work with. Dispersion & distance to tweeter will be better. And the Vas is a lot lower, though I think you'll run into other problems if you try to make the cabinet smaller.

You don't even need 2 woofers. The PTT6 looks to move (a little) more air with significantly less distortion.

 

[Killingbeans]

which Tweeter?

3) Viawave GTR 145, excellent but need higher xcrover point, I’m concern on off axis integration.

I've sort of got the hots for the Viawave right now. The 'w' version GTR 145W has a waveguide built in.

Looks really good?

EDIT: On second thought, a ribbon tweeter might not be the best choice for my preferred music genres.

 

[Lorenzo74]

DXT handles 1.5kHz LR2 without a sweat, Mark K, the designer of the ER18DXT DIY design tested it and found it clean to 105dB/1m. Also the DXT would have wide top-octave dispersion (closer to constant directivity), while having wider vertical dispersion than the Viawave ribbon. I personally think the DXT is a much cheaper and proven driver. Plus Bliesma distortion increases below around 2kHz to slightly elevated levels for the size and price.

https://www.diyaudio.com/forums/mul...narrow-directivity-horbach-keele-filters.html

A Horbach-Keele design would be interesting and really give near-constant directivity vertically and horizontally.

/////

Hi
thank you for your valuable reply.
You have serious knowledge on hifi.

I’m targeting to reduce back waves and flor- ceilings early reflections But keep lateral energy if properly delayed at least 10- 20ms respect to direct sound to “fool“ my brain.

lateral reflections according to many research are positive from a psycoacoustic point of view if properly delayed respect to direct signal more than 10-20ms. they add liveness to sound reproduction without affecting articulation index and intelligibility.

Referemce floyd E. Toole and Herr Eng. S. Linkwitz.

the difference between listening into anechoic room and our home is the time between first arrival and second reflections (3rd 4th are fine since low in level)

listening with our ears at 36” height (T. J. N. and J. Atkinson, stereophile) from floor at 3 meters (sorry mixing Imperial and S. I. ) generates a floor bounce less than 1 ms after first arrival. That’s not good. Ceiling soon after. Bad too.
Lateral (if 10ms delayed) is fine, do not blur images and might help.
(That’s why lateral response have to be correlated to on axes!)

I’m remembering incredible exercise fron AR MGC1 speaker. See stereophile archive.

Let’s our brain capture the information cristal clear and eventuality be surrounded by positive lateral (never on axis) delayed 20ms coherent reflection. it makes the trick.

Summing up:
Kii three + BXT is sounding superb since BXT reduces ( it’s a vertical array) ceiling and floor bounce ((20-midrange) and (but not only for that) boost high SPL low-THD below 80Hz.
Mr. Putzeys clearly explain this to J. Darko on June 2018, youtube

I’m glad to be here. Looking forward to your feedback
My Best
Lorenzo

 

[Lorenzo74]

I'm thinking this new BlieSMa tweeter crossed over at 1.8K would be ideal:

https://hificompass.com/sites/default/files/documents/Datasheet-T25B-6.pdf

And they're only 250 Euro each!

Hi Audiocrusader,
Thank you for your information. I’m wondering...:
to Bliesma or not to Bliesma, this is the question: Whether ‘tis nobler ...

why nobody has designed a DXT or similar waveguide (pls see Dutch & Dutch!) in front of T34A-4? 1.8-2kHz 2R 12dB octave and the trick is done!
We need “constant directivity” E2E:
(Kii, Dutch&Dutch, B&O,...)

the variable dome thickness is the bullet of “Quality” engineer S. Malicov and the killing app of this incredible tweeter.

the aluminium is 30% less beaming than beryllium at 10kHz (my poor 45years old ears are high freq. low pass filtered. 18kHz are for my kids, not to for me anymore. Why go beyond audible...? Apologize, this is another thread

Honestly I never tested it (mic and ear) but Troels was impressed and it happen very rarely.

looking forward to your posts, always insightfully.
my Best
Lorenzo

 

[Lorenzo74]

Wide baffle? DXT? 1550Hz XO? Sounds like you already want to make a mini-Grimm

You don't even need 2 woofers. The PTT6 looks to move (a little) more air with significantly less distortion.

hi Hammer, you are right.

4 Purify woofers are not needed at all.
I live with my family in a silent condominium. Traveling more than spending my time with them. I have a 1000watt sub and high end system in my BMW so why 2.5?

4 of such incredible woofers are not needed 99% of the time.

but you’ll regret that 1% when the music call for “ludicrous” SPL below 60Hz and you can’t crank the volume up. That’s why they sell x0k$ floorstanding high end speakers right?...

I’m with you, most of the times.
looking forward
My Best
Lorenzo

 

[HammerSandwich]

I’m remembering incredible exercise fron AR MGC1 speaker. See stereophile archive.

I've never even seen a magic speaker, but I'd definitely like to hear it. It was a brilliant design! Other than simply copying its narrow dispersion + integrated ambience speakers, you could emulate it with absorbers & surround speakers.

4 of such incredible woofers are not needed 99% of the time.

but you’ll regret that 1% when the music call for “ludicrous” SPL below 60Hz and you can’t crank the volume up. That’s why they sell x0k$ floorstanding high end speakers right?...

I meant only that a single PTT6 would fully match the Grimm's 8" for bass extension & SPL. Grimm sells a matching subwoofer for good reason, and I completely understand why you'd want the extra performance.

Rather than making a vertical array of PTTs, you could build 2-way, Grimm-like monitors & several subwoofers to distribute for more even bass. Use a thick rug & felt pad to tame the floor bounce in the mids. This should offer incredible performance more affordably. Or consider a 3-way (DXT, PTT, 30+cm) with the woofer mounted close to the floor, a la Allison. The Purifi massively improves distortion at high excursions, but big woofers still have advantages at low frequencies.

But if you don't mind paying for 8x Purifi drivers, do not let me discourage you. Whatever you decide, please link to your project.

 

[briskly]

I had same idea. Wide baffle to get unidirectional down to as low as possible (300Hz?)

which Tweeter?:
1) seas DXT to control lateral dispersion and reduce early reflection (1550Hz LR4 via DSP?)
2) Bliesma 1.5” with lower resonance fs, lower xover point, lower distortion better off axis integration
3) Viawave GTR 145, excellent but need higher xcrover point, I’m concern on off axis integration.
Or
4) Which is your ?

My main concern is to reduce early reflection as much as possible (Kii3, Dutch&Dutch,...)

The flange around the drivers needs to be made much larger to limit the driver's radiation pattern. That goal requires much larger drivers, larger horns, and/or the use of multiple sources, such as the Kii. The wide baffle of the Grimm is only used to move the cabinet diffraction effects down in the frequency band. This also requires a wide radius rounding or chamfer of the cabinet to effectively limit the effects of diffraction.

The DXT and other tweeters that use the faceplate as a horn (Wavecor, SB, etc.) are ready-made solutions optimized for mating to a 4-5" cone, though DXT can accept a lower x-over point than those cones would need. You will want to experiment with a larger waveguide to get a smoother match to the Purifi woofer. Here is just one example.

 

[teddy27]

I am new on this forum and I see interesting topics here, so I decided to join. I agree with Wombat. BL modulation has nothing to do with Doppler distortion. Doppler is a acoustical wave modulation, BL is an electro-mechanical factor, not acoustical. Another thing that has been overlooked, is an Acceleration Factor issue with this driver. It has very high Mms, similar to 8" woofers like SB23...... Do you think that it doesn't affect the sound quality? I am sure it is. Ignoring that, is like saying that the mass of the car has nothing to do to it's handling. I always use the comparison between the Lotus Elise with Veyron. 900kg compared to 2.2T. No matter what you do, you can't overcome the Inertia! Some theoretics completely ignore that fact. So, the initial impulse won't be very quick, which will affect the reproduction of percussion or piano. From my experience, the heavy membranes (often metal or sandwich) always give slow, detached presentation. My personal experience with JBL123A proves that. I built the sealed 120l cabinets for them and all who listen agree that it is the most realistic bass they ever heard. Light 88g celulose membrane, which has some flexibility necessary to lead the initial transients and act as a point source. Pistonic, rigid membrane is good only on the paper. L123A is a full range woofer going to 6kHz flat. JBL used to know about drivers more that most theoreticians today. Sorry if I offended someone, but I use my (pretty good) ears to listen, not theories. We still don't know everything about sound reproduction. I still use my intuition. Remember THD wars?

 

[SIY]

I am new on this forum and I see interesting topics here, so I decided to join. I agree with Wombat. BL modulation has nothing to do with Doppler distortion. Doppler is a acoustical wave modulation, BL is an electro-mechanical factor, not acoustical. Another thing that has been overlooked, is an Acceleration Factor issue with this driver. It has very high Mms, similar to 8" woofers like SB23...... Do you think that it doesn't affect the sound quality? I am sure it is. Ignoring that, is like saying that the mass of the car has nothing to do to it's handling. I always use the comparison between the Lotus Elise with Veyron. 900kg compared to 2.2T. No matter what you do, you can't overcome the Inertia! Some theoretics completely ignore that fact. So, the initial impulse won't be very quick, which will affect the reproduction of percussion or piano. From my experience, the heavy membranes (often metal or sandwich) always give slow, detached presentation. My personal experience with JBL123A proves that. I built the sealed 120l cabinets for them and all who listen agree that it is the most realistic bass they ever heard. Light 88g celulose membrane, which has some flexibility necessary to lead the initial transients and act as a point source. Pistonic, rigid membrane is good only on the paper. L123A is a full range woofer going to 6kHz flat. JBL used to know about drivers more that most theoreticians today. Sorry if I offended someone, but I use my (pretty good) ears to listen, not theories. We still don't know everything about sound reproduction. I still use my intuition. Remember THD wars?

So, let's see- appeal to emotion, bad car analogy, dismissal of physics with the obligatory ignorance of Fourier, irrelevant anecdote, dismissal of physics again, then the usual "we don't know everything" fallacy. Very nice first post! You managed to pack it all in.

 

[Killingbeans]

I always use the comparison between the Lotus Elise with Veyron. 900kg compared to 2.2T. No matter what you do, you can't overcome the Inertia!

The data says otherwise:

Veyron, 0-10 kph = 0.1s

Elise, 0-10 kph = 0.5s

 

[Frank Dernie]

The data says otherwise:

Veyron, 0-10 kph = 0.1s

Elise, 0-10 kph = 0.5s

Data round zero is very inaccurate IME and the Veyron has 4wd which helps traction from a standstill.
It is still a 2 seat limo though.
I spent a huge amount of time measuring practice starts with Michael Schumacher when he was struggling with the small composite clutch.
The biggest difference in the initial acceleration is due to clutch and throttle pedal control.

 

[watchnerd]

The data says otherwise:

Veyron, 0-10 kph = 0.1s

Elise, 0-10 kph = 0.5s

Track times tell a different story.

Where even the cheapie Caterham beats the regular EB version, and the Dodge Viper beats the Super Sport.

The Veyron EB ranks #30.

https://fastestlaps.com/tracks/top-gear-track

 

[Killingbeans]

Just goes to show that it's a bad analogy

From the interview on HiFiCompass:

There are also people who dismiss our driver due to its approx. 26 g Mms and 4 layer coil because they think it is 'slow' - that changes of course when they measure or listen to it.