Exploring Purifi Woofer Speaker Builds

[Haze Head]

^^^^^ Here's the non potato pixelated concept BTW. Need to get the camera put back together. (Whoops, posting this bumped the page. Check out page 84 for the actual piece and context)

 

[lrisbo]

Hi Lars,

Personally I hope there will be a Alu version of 5.25, same magnet but with 2 layer voice coil?

Probably loses 30% BL with a lighter cone, but that would made the lowest midrange distortion small midwoofer. Needs larger box for reflex, but will make a super slim floorstander friendly. Or, for us DSP speaker builders it didn't matter at all..

Even better, that hyperthetical driver would make a 7L sealed "LS3/5A" killer, with 40hz -6db (I assume 20g mms and 5.4 N/A) and 95db max SPL >50hz thanks to its long stroke.

Best,

hi, we plan for a an alu cone 5.25 version and we will have a look at the motor options. The alu cone will likely be heavier than then paper cone.

cheers Lars

 

[lrisbo]

Hi Lars,
I wondered if you had any info regarding where you would consider the acoustic centre of your 8" driver (or any of your drivers for that matter) is in relation to the mounting face, I am not sure if this varies with frequency but an approximate distance at useable crossover frequencies would be useful to builders.
My active build is coming along slowly, 24db LR crossover and four way Purifi amps are ready, the spherical bass cabs part done (45l volume will be reduce with a smaller sphere offset internally so I can play around with final volume and reduce standing waves)

View attachment 1072046 View attachment 1072049 View attachment 1072047 View attachment 1072048 View attachment 1072050

My Viawave tweeters will be mounted in a close coupled pod and hopefully set back to align the acoustic centres.
The final crossover frequency will probably be 2k2 but will depend on the 8 ohm driver specs (any update available?)

Cheers Steve

hello Steve,

First of all, congratulations with your amazing spheres!

What will be the center to center distance between tweeter and woofer using a separate tweeter pod?

Acoustic center: it’s on my list to provide data but we have not yet settled on how to measure it. I tend to separate the response into its minimum phase response and excess phase response. the latter expresses the fixed delay part which represents the acoustic center. In other words, the delay if you EQ the response flat using a minimum phase filter (we normally EQ the response to match a target such as a LR4 filter as part of the system design).

Cheers Lars

 

[racingpht]

hi, we plan for a an alu cone 5.25 version and we will have a look at the motor options. The alu cone will likely be heavier than then paper cone.

cheers Lars

Great news, it's in my list then!

Sorry I should say less MMS regarding 2 layer option, not lighter cone.

Cheers!

 

[spresto9]

hello Steve,

First of all, congratulations with your amazing spheres!

What will be the center to center distance between tweeter and woofer using a separate tweeter pod?

Acoustic center: it’s on my list to provide data but we have not yet settled on how to measure it. I tend to separate the response into its minimum phase response and excess phase response. the latter expresses the fixed delay part which represents the acoustic center. In other words, the delay if you EQ the response flat using a minimum phase filter (we normally EQ the response to match a target such as a LR4 filter as part of the system design).

Cheers Lars

Hi Lars,
Thanks for your intrest, I think this extra info will be useful to builders in general.
Center to center distance from my cad drawing will be 225mm.
Some progress for my build.
Cheers
Steve

 

[lrisbo]

Hi Lars,
Thanks for your intrest, I think this extra info will be useful to builders in general.
Center to center distance from my cad drawing will be 225mm.
Some progress for my build.
Cheers
Steve

almost hypnotizing to look at these spheres!
I agree that the the acoustic center info is very useful. My concern is just if the interpretation of such a data point is clear enough etc.

 

[lrisbo]

Hello Lars

Sorry to bother you again with this but have you been able to complete the 8 ohms version of the PTT8. I would need the TS parameters to check that it will fit in my project.
Thanks in advance
Jean-Claude

Here is the long awaited prelim 8" 8R data sheet.
@tigeranand

 

[cowanaudio]

Lovely plots for a driver with so much linear excursion. Your team has done good work!

 

[jcga]

Thank you very much Lars

 

[thinbLue]

Here is the long awaited prelim 8" 8R data sheet.
@tigeranand

Looks so sweet. Cu coil <- 100% yummy!

 

[thinbLue]

Anyone looking for aluminum baffles? I'm working out a process for making custom baffles and the first go was to make one for the six inch Purifi with waveguide. The main tweaks I'm planning are some minor changes to the rear panel seal geometry and some faster machining strategies. Dialing in the anodize procedure is the other main objective. Note the exaggerated mounting holes; on the rear side they have a deep well chamfer and the idea is to have custom chamfered nuts with a rubber gasket seal. So the mounting bolts don't contact the baffle, and because the driver is essentially free floating the chamfered nut geometry actually handles the centering problem. Dunno whether it's a good or bad design feature, but making tweaks on the overall design is a fairly negligible fix.

I'm thinking I can do em from about 400-1200$ per pair depending of the level of finish. Also working on the flush mount bolts specific to Purifi, as can be seen in one of the mounting holes. So I was thinking to do a baffle plus hardware package for convenience. This was just a proof of concept so if there is any need for this sort of work give me a shout.

View attachment 1076555 View attachment 1076557 View attachment 1076558

Awwww

It's sexy as the Edge of Purifis

 

[Benno1988]

Whilst I dig through 85 pages, is anyone aware of a compact Purifi build? Bookshelf speaker, good close to a wall, not too deep.

 

[neutrino_th]

https://www.diyaudio.com/community/...ifi-woofer-speaker-builds.352063/post-6996303

 

[Benno1988]

https://www.diyaudio.com/community/...ifi-woofer-speaker-builds.352063/post-6996303

Just been reading up! Wonder if it goes ok close to a wall behind.

Looks killer.

 

[kims]

Just been reading up! Wonder if it goes ok close to a wall behind.

Looks killer.

Benno1988 - SPK8 can work fine close to a wall - you do gain some bass-responce, and could compensate for this by increasing the box volume form 4l to 5l

you can model the response in VituixCAD and see what change it gives.
rgds, kim

 

[Benno1988]

Benno1988 - SPK8 can work fine close to a wall - you do gain some bass-responce, and could compensate for this by increasing the box volume form 4l to 5l
View attachment 1077565
you can model the response in VituixCAD and see what change it gives.
rgds, kim

Thanks Kim!

I assume the Tweeter specified "B25B-6" is meant to read "T25B-6" ? Beryillium ones, 500 Euro a pair afaik?

Just need to source parts to Australia, no-one here seems to sell them?

 

[Benno1988]

Benno1988 - SPK8 can work fine close to a wall - you do gain some bass-responce, and could compensate for this by increasing the box volume form 4l to 5l
View attachment 1077565
you can model the response in VituixCAD and see what change it gives.
rgds, kim

Do I increase volume by adding depth? Would 4.5L work too?

 

[kims]

Do I increase volume by adding depth? Would 4.5L work too?

yes - changing depth is prefered, as the front baffel diffraction due to XY is handled by the corss-over

 

[Benno1988]

Maybe give it a little nudge in depth. Or just embrace the bass.

 

[jcga]

I assume the Tweeter specified "B25B-6" is meant to read "T25B-6" ? Beryillium ones, 500 Euro a pair afaik?
Just need to source parts to Australia, no-one here seems to sell them?

Yes, it is the Bliesma T25B-6, excellent tweeter by the way