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-   -   Exploring Purifi Woofer Speaker Builds (https://www.diyaudio.com/forums/multi-way/352063-exploring-purifi-woofer-speaker-builds.html)

mainframe99 2nd April 2020 12:39 AM

Exploring Purifi Woofer Speaker Builds
 
3 Attachment(s)
With the group buys well underway the idea was bought up that a design thread be started to discuss build options.

Mine have arrived but I have no build materials and will not be able to get any until we come out of quarantine in (hopefully) three weeks time. I planned to start with a hybrid of purifi's SPK4/5 builds using the same AMT tweeter but maybe using a slot port with the 2.5khz crossover. That and I haven't done any AMT builds so it seemed like a good place to start.

I read of a guy in Aus planning on doing a line of passive and active speakers with the woofer so be interesting if he could chime in here.

So with no materials for the next at least 3 weeks, what better time to discuss build options! Fire away

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Norman Tracy 2nd April 2020 06:57 PM

(First response) Thanks for posting pics, looking forward to arrival of mine.

(Opens second pic with side view) Holy crap LOOK AT THAT MASSIVE VOICE COIL!!! I WANT MINE NOW NOW NOW NOW SOONER THAT NOW!!!!

Bill poster 2nd April 2020 09:20 PM

A 2.5way with 4 per side cd be very interesting, top 2 in mtm.

jasdiy 3rd April 2020 07:13 AM

For what it's worth
We have them in a dsp/active/4way stereo system between 120 and 600
Which is very modest range for this driver, they replaced a highly regarded seas driver.

Cheers

Paul Ebert 3rd April 2020 05:48 PM

I'm going to be using them with the CSS SDX12 (sub)woofer and an as yet to be decided tweeter. Tweeter contenders include the Aurum Cantus AST2560, the Bliesma T25A, the ESS Heil and the Transducer Labs N26MGR-A (which I already own).

I may go dipole on the Purifi and AST2560 or Heil if I go that route.

xyvyx 3rd April 2020 06:39 PM

lookin' forward for my woofers to ship. (haven't received any updates since my order confirmation on Mar.13)

I'm goinig to pair them w/ Peerless DA32TX with an xo point around 1500hz.... TBD!

Dave Bullet 3rd April 2020 08:20 PM

Hey fella. I'm in Kapiti. Whereabouts in NZ are you? I'm annoyed I missed out on a group buy. I would have definitely been keen.

I've not done any ribbon builds, but I don't know if I'd pick the AMT for this woofer.

The AMT has a lot of 3rd order HD:
Mundorf AMT21CM2.1-C | HiFiCompass

And will strain / be audible as the woofer can take it. Compare similar voltage levels and watch the AMT HD climb.

Also beaming of the Purifi at a 3.2KHz XO point of the SPK5 design will give some lumpy off axis behaviour.

The AMTs are very expensive for what they offer. In a 3 way, allowing a higher XO point from a dome mid would be a goer. But I would not combine with the Purifi in a pure 2 way.

Shipping to NZ would be a killer too (unless you already have the AMTs). Instead I'd recommend the following tweeter. You can get these from theloudspeakerkit.com and much cheaper. Check out the distortion profile. Has similar offaxis performance to the AMT too:
SB Acoustics SB26ADC-C000-4 | HiFiCompass

You could cross the above LR4 at 2Khz and address the beaming issue AND get lower distortion than the AMT.

The purifi provides a maximally flat vented alignment in a 15.5L box tuned to 35.1Hz (assuming average losses) with an F3= 38Hz. This is pretty good. If you can go active, this woofer could really shine in a 3 way with a 100Hz XO to a side mounted 12. Candidates that dig deep if you like sealed bass are the 12" SB34NRX75-6 (not the L version) or Dayton 15" RSS390HF. Both give a sealed box Qtc=0.71 in 122 litres with F3 ~ 32-33Hz.

Although an extra 6 Hz F3 over a vented Purifi might not sound like much, you really leverage the Purifi's midrange strengths and offload bass duty.

TimbreAudio 3rd April 2020 08:39 PM

Group buy? Noooooo

mainframe99 4th April 2020 10:21 PM

Quote:

Originally Posted by Dave Bullet (https://www.diyaudio.com/forums/multi-way/352063-exploring-purifi-woofer-speaker-builds-post6146641.html#post6146641)
Hey fella. I'm in Kapiti. Whereabouts in NZ are you? I'm annoyed I missed out on a group buy. I would ... ...and offload bass duty.

Hi Dave, Iím in the big smoke mate. Hope you doing okay down there. We have people punching supermarket managers in the face :eek:

Agree on the 3.2khz crossover being too high. In the other thread I explained the spk5 build seems to be more about showing off the woofers ability vs. smooth off axis response.

For now I already have the AMTs as I havenít used them or heard them so I am curious. Ive always used domes. Iíve got a mini dsp shd studio which also only allows me to do a 2-way so I will stick with a 2 way for now, probably with the spk4 cabinet or similar and the 2.5 crossover.

I have a pair of wavecor tw030s on the way to get the crossover lower. But I wish Iíd seen that tweet you suggested first! Very nice tweet. I already have a big 4 way system with subwoofers that Is my reference and now Iím all about making something small with big output.

Dave Bullet 5th April 2020 08:10 PM

Quote:

Originally Posted by mainframe99 (https://www.diyaudio.com/forums/multi-way/352063-exploring-purifi-woofer-speaker-builds-post6148228.html#post6148228)
Hi Dave, Iím in the big smoke mate. Hope you doing okay down there. We have people punching supermarket managers in the face :eek:

Agree on the 3.2khz crossover being too high. In the other thread I explained the spk5 build seems to be more about showing off the woofers ability vs. smooth off axis response.

For now I already have the AMTs as I havenít used them or heard them so I am curious. Ive always used domes. Iíve got a mini dsp shd studio which also only allows me to do a 2-way so I will stick with a 2 way for now, probably with the spk4 cabinet or similar and the 2.5 crossover.

I have a pair of wavecor tw030s on the way to get the crossover lower. But I wish Iíd seen that tweet you suggested first! Very nice tweet. I already have a big 4 way system with subwoofers that Is my reference and now Iím all about making something small with big output.

Yeah it's crazy times all right. Plenty of muppets out there doing stupid things.

I'm sure those AMTs will sound sweet and if these 2 ways are predominantly for on-axis / sweet spot listening, they will sound wonderful. At least with the wavecors you have options and the miniDSP makes it super easy to switch.

Are you going vented with the Purifi?

Also - what drivers have you got in your 4 way out of interest?


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