Exploring Purifi Woofer Speaker Builds

[Boden]

@lrisbo nr II: maybe a daft question, but: why is the SPL graph not totally flat (purely pistonic behaviour) in the 100 to 700 Hz band, but instead shows a number of minor dips?

What is the (electro-mechanical?) mechanism behind that?

 

[lrisbo]

@lrisbo

And following what tktran303 wrote above, could you correct datasheet name when downloading ? It's written PTT8... instead of PTT10 ...
Otherwise 10" looks very promising !

hi, I dont see the problem when I download?

 

[lrisbo]

@Boden : I believe most of the dips are from baffle resonances and some reflections in the chamber. There might be a tiny blip from the spider resonance and surround resonance. But yes, the true response is expected to be rather flat and smooth in that range

 

[tktran303]

@lrisbo nr II: maybe a daft question, but: why is the SPL graph not totally flat (purely pistonic behaviour) in the 100 to 700 Hz band, but instead shows a number of minor dips?

What is the (electro-mechanical?) mechanism behind that?

It’s a baffle effect.

The same phenomenon exists in other manufacturers data sheets.

To avoid baffle effects you need to take a nearfield eg. 15mm measurement, or a truely infinite baffle.

 

[lrisbo]

@lrisbo

The updated website looks great!

Here's a screenshot for datasheet on the 10" woofer:

View attachment 1185533

Zoomed in:

View attachment 1185529


I think we all appreciate manufacturers releasing FRD and impedance data for direct download:

https://ptt.purifi-audio.com/shop/p...,6022,6023,6024,6025,6026,6027,6028,6029,6030

When I imported into a viewer- here's what is shown:

View attachment 1185528


The sensitivity for the Frequency Response Data for the PTT10.0X04 zip file for download on the website seems too low:
This difference also exists for the PTT8.0X datasheet. (not shown)

For people unable to take their own measurements, this may be a little confusing. Can you please advise?

Thanks! I am investigating why the sensitivity is different from the 2.83Vrms graphs

 

[lrisbo]

It’s a baffle effect.

The same phenomenon exists in other manufacturers data sheets.

To avoid baffle effects you need to take a nearfield eg. 15mm measurement, or a truely infinite baffle.

Our chamber has infinite baffle in the sense that you take a full 4pi chamber and cut in half and put a wall/baffle in the cut plane

 

[jcga]

hi, I dont see the problem when I download?

When clicking here:
https://ptt.purifi-audio.com/web/content/product.template/1950/x_studio_data_sheet?download=1
you got a pdf with the following name: "PTT8.0X04-NAB-02" instead of "PTT10...."

 

[lrisbo]

The file name is correct when I download. There was an error that has been corrected a while back. maybe there are still old versions in a cache somewhere?

 

[jcga]

strange, still there here (a few minutes ago) with 2 different browser (Chrome & Firefox)
Also, I checked with a VPN through french and German node I got the same result

 

[hifijim]

In any case, the level of 2nd and 3rd HD below 60 Hz is really impressive. It would be impressive on a 18" pro subwoofer, but on a 10" it is amazing.

 

[stretchneck]

The file name is correct when I download. There was an error that has been corrected a while back. maybe there are still old versions in a cache somewhere?

Definitely cache issue - works fine for me.

 

[lrisbo]

strange, still there here (a few minutes ago) with 2 different browser (Chrome & Firefox)
Also, I checked with a VPN through french and German node I got the same result

very strange indeed. I can try from home

 

[newbieForever]

The same issue also for me, from Android mobile phone, firefox with and without VPN.

I'll check also from home.

 

[newbieForever]

From Windows 11 & Firefox 115 the file naming is correct.

With & without VPN...

But from Microsoft Edge we have the wrong file name again.

 

[jcga]

Just for information,

I just tried from Edge too and got the wrong filename so whatever browser (Edge, Firefox, Chrome) with or without vpn I got the same pb under Windows 11 latest version

 

[Onslo]

Big hiatus but I am back. Way back (around posts 700) I built a pair of closed aluminium enclosures as mini monitors and housed a pair of 8 ohm 6.5" Purifi's with electronic crossovers and 15" subs. Remember them? The subs are slot ported and the integration is not perfect. I love the little monitors though. I now wish to build it into a good 3 way system and thinking sealed sub enclosures. Any recommendations for drivers? Any of the larger Purifi drivers candidates? My knowledge of the recent releases is pretty limited and there are thousands of posts since I was active. Ant info ideas appreciated.

 

[stoneeh]

Here is an appetizer of the new tweeter with ultra wide controlled dispersion. in-box measurement at 1m (gated).

Would you be interested in sending me a sample for distortion measurements?

Test procedure / program would be the same or similar to my recent evaluation of the Bliesma T25B-6 in 6,5" waveguide - which it would also be a good comparison object for: https://www.diyaudio.com/community/...r-cnc-3d-printing.318190/page-91#post-7412243

 

[tktran303]

I had planned to visit Purifi HQ in Denmark in April, beg/borrow/steal a pair, then ship it to Ukraine ATTN: @HiFiCompass.

But damnit I was thwarted by logistical disruptions. Hopefully it will enter mass production in 2024 and we can all get our grubby paws on them.

 

[lrisbo]

we dont have prototypes to spare at the moment (all four assembled are in the spk16 boxes). The parts for mass production are getting tooled now so we all have to be patient for a while 😀 We will of course send samples to @HiFiCompass

 

[DualTriode]

Here is an appetizer of the new tweeter with ultra wide controlled dispersion. in-box measurement at 1m (gated). Will demo next week at the High End Show in Munich. See our FB/LinkedIn for more details. Our web is also updated to a brand new version in the coming days. There will be a white paper about the new demo box View attachment 1172586

Hello @lrisbo,

Why did you select "Ultra Wide" coverage for the tweeter? Is it the nature of the beast or a design target?

With a wide coverage tweeter the crossover frequency to the mid-woofer will be relatively low if the coverage angles of the drivers have a smooth Directivity Index transition.

The listening position will need to be close to keep the direct sound louder than the room surface reflections.

I have a pair of BlieSMa T25A-6 Aluminium-Magnesium Dome Tweeter Matched Pair being delivered in a couple of days for a test drive.

Thanks DT