Exploring Purifi Woofer Speaker Builds

[thedesigner2011]

To my great shame, I didn't hear about this new woofer until now. Highly tempted to do a new "ultra low distortion" 2 way with these woofers and 4 prs. This thread is getting that old itch going again, maybe a Mundorf ATM to match this ugly beauty?

 

[xrk971]

You’ll need an ATM to make cash for the Mundorf and the Purifi with 4 PR’s.

 

[thedesigner2011]

You’ll get no disagreement from me, luckily this is my only hobby aka money pit! I forgot how expensive the big boy Mundorfs were, but it’d be a shame not to try finding tweeters to match these purifi. Gotta support R&D lol

By the way, love what you’re doing with your new build, really enjoying your progress posts.

 

[xrk971]

I have some RAAL's that I want to try too - they are obligatory 4th order though, so I can't do this transient perfect thing so easily with them, unfortunately. They are so pretty and would make the ultimate statement speakers.

By the way, love what you’re doing with your new build, really enjoying your progress posts.

Thank you.

 

[xrk971]

Hot off the press: Polar Data for PPT6.5 and RS28F in WG300 waveguide:

Same data with no FDW and in 1/24th oct smoothing:

 

[ScottG]

Nicely done with the waveguide integration. So important to have that treble production lowered compared to the average with a directive design.

3 kHz could be "dropped" a little though.

 

[Tron77]

If you look at the measured acoustical phase, it has the hallmarks of almost flat with the characteristic 55deg rise near the XO. This is as good as a Harsch XO gets. You won't see any LR2 or LR4 XO with inverted tweeter look anything like this.



This type of acoustic phase response gives this step response:

Thanks, brillianty explained, learned something that I never heard about before.

 

[xrk971]

You are welcome ! Always nice to see more folks seeing transient perfect designs as a goal to aim for.

 

[dewdrop]

Hi X,
When will you attempt the TL design? Can't wait to hear your impressions

 

[454Casull]

Hot off the press: Polar Data for PPT6.5 and RS28F in WG300 waveguide:

Wow, the high end looks superb. It almost seems like the waveguide is diffracting a little to keep the off-axis relatively constant.

 

[hallcon83]

I think I remember someone mentioned they were thinking of trying utilize them in an Open Baffle speaker - is anyone trying that?

 

[ABJensen]

I think I remember someone mentioned they were thinking of trying utilize them in an Open Baffle speaker - is anyone trying that?

You will neet alot of them to make any bass. At at their price No way.

 

[xrk971]

Maybe think of these as superlative powerful midrange with no breakup and low distortion?

Compare the curve to a VM752 and see which one is better (besides sensitivity).

 

[Paul Ebert]

I think I remember someone mentioned they were thinking of trying utilize them in an Open Baffle speaker - is anyone trying that?

I am considering doing so, but as a midrange, not a woofer. In that case, I'd only use it down to 400 hz or whatever works with the baffle design. I have a pair of CSS SDX12s that I would use for the woofers. They would not be open baffle, but sealed.

 

[jamesblonde]

I think I remember someone mentioned they were thinking of trying utilize them in an Open Baffle speaker - is anyone trying that?

That might have been me. I am planning a build (with AE Dipole15 and Beyma TPL150) but it will take time.

 

[fedde]

I hope a single Purifi could go to 250 Hz or so in open baffle. Alternatively two could be used. But for one Purifi you can buy two Satori, which may work better than a single Purifi.

By the way, apart from impedance is there any difference in using two drivers in series or parallel? You could put two 8 ohm parallel or two 4 ohm in series...

Fedde

 

[xrk971]

This driver makes a nice midrange but it was designed to be able to move a lot of air in a vented alignment. It would be a waste to use it on an OB. You couild use so many other drivers there as a midrange. Try Faital 6FE100 or 5MR450NDY. They have higher Qts and are also low distortion, and higher sensitivity.

 

[Tron77]

By the way, apart from impedance is there any difference in using two drivers in series or parallel? You could put two 8 ohm parallel or two 4 ohm in series...

Parallel is better when they need to play around their resonance (i.e. as woofers). Once they play only midrange, there is no difference

 

[jamesblonde]

This driver makes a nice midrange but it was designed to be able to move a lot of air in a vented alignment. It would be a waste to use it on an OB. You couild use so many other drivers there as a midrange. Try Faital 6FE100 or 5MR450NDY. They have higher Qts and are also low distortion, and higher sensitivity.

Thanks for the suggestions and I agree that the Purifi's Qts of 0.32 is not optimal for OB.



I find it difficult to get hold of CSD and HD info on drivers so that eliminates the vast majority of drivers, unfortunately, but without being able to hear drivers beforehand this is all I have to go on.



I did find some distortion plots for the Faital but it doesn't seem to be in the same class as the Purifi with H2 and H3 HD hovering around -30 to -40dB. (Purifi is -60 to -70 dB).



Both drivers you suggested seem to have a linear Xmax of around 3mm compared with the Purifi's 10mm. The extra Xmax should give me some extra crossover flexibility, so that's another plus for the Purifi.



I'm also not concerned with high sensitivity as I will have 250W available for the midrange from the Hypex FA253.

 

[fedde]

Parallel is better when they need to play around their resonance (i.e. as woofers). Once they play only midrange, there is no difference

Thanks, I suspected in case of resonances the setup would matter. In the case of Purifi this would mean that the 8 ohm model would probably be better suited, otherwise impedance gets under 2 ohm. Though the ncores could still handle it up to max current.

Pity of the higher fs though...

Fedde