Exploring Purifi Woofer Speaker Builds

Surface area isn't everything. Remember that the Purifi has a huge linear Xmax of +/- 10 mm and an Sd of 133cm2.


The first 15" I pulled up was the Faital 15PR400 which has an Sd of 805 cm2 and an Xmax of +/- 5.8mm (FaitalPRO 15PR400 - 15" Subwoofer)


Displacement of the 15" at Xmax is 467cm3 whereas displacement of 4 x Purifi is higher at 532cm3.


Working backwards from that, you would need a 15" with about +/-6.7mm linear Xmax to match the linear displacement of 4 Purifis.

That is to easy. Why didn't you use Dayton PN395-8 (sd of 890cm2) as example or B&C 15DS115 with Xmax of 16.5mm and Sd of 855cm2 ?

It is easy to tweak the results if you want. Why are you using 15" midwoofer to compare it with something that will work as a pure woofer in "advanced" Kii three ?

I used Sd of roughly 850cm2 for a 15" and Sd of 120cm2 for 6.5" woofer - both are quite usual.

So let me correct myself - you need 6.3909 x Purifies to obtain Sd of one average 15" woofer. Precise enough ? :)
 
Surface area isn't everything. Remember that the Purifi has a large linear Xmax of +/- 10 mm and an Sd of 133cm2.


The first 15" data I pulled up was for the Faital 15PR400 which has an Sd of 805 cm2 and an Xmax of +/- 5.8mm (FaitalPRO 15PR400 - 15" Subwoofer)


Displacement of that 15" at Xmax is 467cm3 whereas linear displacement of 4 x Purifi is higher at 532cm3.


Working backwards from that, you would need a 15" with about +/-6.7mm linear Xmax to match the linear displacement of 4 Purifis.

The Purifi looks to be one of the best small woofers on the market, however the SB B42FHCL75-6 and AE TD15H edge it out below 100hz. I've yet to hear a small speaker sound as satisfying as a AE td15 in a normal household room. The integration, tactical feel and weight are hard to beat. Biamping from one of those 15s to the Purifi at 200-300 hz should be a interesting combination worth the cost of creation.

Now, if someone can find a worthy tweeter. Good luck!
 
While I have no doubt that a 15 inch driver is always going to best this woofer, I think everyone forgets that this is a 15L box. I can pick these speakers up with one hand. If you couldn’t go any larger with the box and had to make a speaker cost no object, this IS the mid bass driver you use. They are pricey. I feel like I got my money’s worth. I plonked these in the lounge (cue wife running out of the kitchen) and the wife was complaining about the subwoofers being on. When I told her they weren’t, she took a closer look at the speakers and started asking questions about why they could make so much bass - for the first time she was genuinely intrigued about my hobby rather than rolling her eyes at it. These 15L boxes can make the house rattle, without making vocals sound like they are underwater, it is quite something to behold...
 
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Here's my quick and dirty uncalibrated REW measurement. Woofer BW12db slope at 1550 and tweeter BW18db at 2500 - this is a work in progress.
If they do an 8" and you used the 4" as a mid, pick your tweeter to taste, you would have one hell of a monkey coffin/tower.
purifi woof+mundorf amt 2.5khz cross SPL.jpg
 
Congratulations mainframe99 for having the first running speaker with PTT6.5W04-01A woofer on the diyAudio thread about them.

Pleased your reaction joins the chorus “bass these things put out is quite simply jaw dropping” and “I can’t stop shaking my head in disbelief of how loud, clean and clear these woofers are”. With my drivers a couple of weeks out not sure if this report makes the wait easier or if its just why can’t Christmas arrive NOW.

The quantity of bass vs. enclosure size is the headline but I note also the quality comment “clean and clear”. To me this speaks to the stated goal of PuriFi to dramatically lower distortion, especially when the woofer is operating at the extreme Xmax displacements it is designed for.

And for the 3rd, no make that 19th time the comments suggesting why not just use a 12” or better yet 15” woofer. Sure go for it, generally more Sd more better and max out Hofmann’s Iron Law while we’re at it. The best sound I have built were 1970s vintage 15” JBL co-axials in 14 cubic foot enclosures (yeah, odd TS parameters). Absolutely did it all, deep bass, very low apparent distortion, so much information retrieval and transparency. Loved my 2A3 amp like a couple of hormonal teenagers. Good times, best times. But eventually my dear wife asked if the monster boxes could please exit the living space. And now they reside in the storage locker. And not just because I do whatever she says. I am also house proud and eventually some of us decide the stereo does not need to be an object of shall we say ‘curiosity’. I coined the term ‘bachelor insurance’ for such systems because they will insure the owner remains (or becomes) a bachelor. If you have space and a budget check out Pi speaker kits (Pi Speakers - unmatched quality and state-of-the-art performance) or a big Bigger BIGGEST budget Kenrick Sound (??????????KENRICK SOUND? - JBL????? 43XX???? ?? ???????????) ships resto-mod 43xx speakers from Japan worldwide. They are very shiny, so shiny. Sooooooooooo shiny and 12” mid-woofers over proper 15” woofers.

So, after my fling with big box big woofers I took quite a notice when Mitch “Mitchco” Barnett set aside his bi-amped big JBLs and about the PTT6.5W04-01A application note system said:

The PTT6.5 woofer is unique in being able to reproduce a prodigious amount of low frequency energy (i.e. in the 30 Hz range), yet remain absolutely clean sounding throughout the lower mids and midrange. The only comparison I have is using large, stiff cone, short stroke 15” woofers, which is what I use today in my JBL system, in addition to Rythmik dual 18” subs. The (major) disadvantage is that these cabinets tend to be the size of fridges, look fugly and cost more dollars. Further, the 15” drivers can barely make it to an 800 Hz crossover point, whereas the PTT6.5 is crossed over at 2.5 kHz in the demo kit, but can still hit 32 Hz, all delivered with low distortion. The PTT6.5 is a subwoofer, woofer and midrange to 2.5 kHz all in one unit.

Of course, it is all relative to size and SPL’s. There is no “replacement for displacement” and my large JBL’s with dual Rythmik 18” subs can easily outperform the PTT6.5 in sheer SPL’s. But, listening at “reference” level of 83 dB SPL, the PTT6.5 sounds unbelievably clean with good low frequency extension and outstanding clarity in the lower mids and midrange. A wide bandwidth, clean sounding, stand mount audiophile monitor it is.

Full review Purifi PTT6.5 Woofer and 1ET400A Amplifier Technology Review - Reviews - Audiophile Style

And that is why I am exploring the PTT6.5W04-01A to anchor my next design. A few years ago my wife and I were able to purchase my dream house. For me that is mid-century modern with a unified great room living space. The style cries out for small to moderate size speakers, If PuriFi can deliver some good percentage of the big woofer sound from a 15L box it’s mission accomplished.
 
Here's my quick and dirty uncalibrated REW measurement. Woofer BW12db slope at 1550 and tweeter BW18db at 2500 - this is a work in progress.
If they do an 8" and you used the 4" as a mid, pick your tweeter to taste, you would have one hell of a monkey coffin/tower.
View attachment 838204

Could you please write something about over all sound ? Do you like AMT or would you change it with something else ?
 
The possibilities are endless. But suffice to say for a pricey pair of woofers need to have decent enough tweeters to match.

Personally I have a pair of Focal Audiom TLR that was removed from a old build. It is in pretty bad shape but should be working after replacing the foam.
 
Congratulations mainframe99 for having the first running speaker with PTT6.5W04-01A woofer on the diyAudio thread about them.


I think that would go to @jasdiy who posted about having them in a 4 way doing 120 to 600 hz.. but yeah. A very veeery modest range for what this little guy is capable of. I’m in agreement with the decor thing. It might never satisfy the diehards or people who like the jolly’s of massive cones, but if you want (what I would argue) end game-ish hi-fi in a small box and just be done with it all, this mid bass driver is it.

The jury is still out on the AMT. Ultra smooth, maybe too much? Have a big listening session tonight. One small silver lining of these sad times.
 
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?

Sorry Dave I missed this. As above, vented. Box similar to purifi spk5 as its all I could manage with what I had lying around. Wanted to go front slot port and still might.

My ref system currently the atc scm40s with dual sb2000s. Currently.

The mini dsp feels like cheating with the speed you can change crossovers. Surely digital crossover is the future.
 
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).

Hi Paul, in the same cab or seperate cabinets? Be interested in your thoughts on the bliesma, a very admirable tweeter.
 
The jury is still out on the AMT.
As I said in another thread, the AMT is a poor choice to be paired with the Purify driver. This midwoofer is exceptional on many aspects, but can't fool the physics, and since it is a 6.5" driver, it starts beaming well under 2KHz, so I'd opt for a robust tweeter that can sustain a 1.5-2.0 KHz crossover point, if you want to avoid mismatched directivity. A tweeter on a waveguide would be even better. The AMT tweeter can't sustain such a low crossover point. I recently reworked a crossover for a 2-way with a Seas 27TBFC/G ending at an acoustic LR4 slope a bit under 2KHz, and it works very well.

Ralf
 
Hi Paul, in the same cab or seperate cabinets? Be interested in your thoughts on the bliesma, a very admirable tweeter.

Definitely separate cabinets for the SDX12 and the Purifi. I'm considering open baffle for the Purifi. The tweeter decision / purchase is indefinitely put on hold due to COVID-19 finances impact (unless I decide to go with the Transducer Labs).
 
Hi Paul, in the same cab or seperate cabinets? Be interested in your thoughts on the bliesma, a very admirable tweeter.

I agree about the Bliesma, though my current thoughts, influenced mostly by the review from HiFi Compass of all 4 T25 variants, are to lean more toward the T25B. They all look amazing and early impressions all seem exceedingly positive. I'd really like to hear the T25A and B (and, perhaps, S).

For my design, there are several possible directions that will require decisions to be made down the road. For example, if I go with open baffle on the Purifi, I may want to do so on the tweeter as well. In that case, I may go with the AST2560 and front and back waveguides. Or, I may decide to add a dedicated midrange which would allow me to move the Fc to the tweeter higher opening more options. Unfortunately, I'm not seeing a lot of good candidates for the midrange. The SB15CAC is being considered, as is the forthcoming PTT4.0.
 
Or, I may decide to add a dedicated midrange which would allow me to move the Fc to the tweeter higher opening more options. Unfortunately, I'm not seeing a lot of good candidates for the midrange.

..done right, a small array of the Peerless TC5FC00-04 might do just what you are looking for. ;)

The array will of course generate even less non-linear distortion for a given output level.

Best overall from 800-4 kHz with a good crossover. Excellent from 800-2 kHz.

Inexpensive (even in an array) as well! :)

If you don't mind metal, the the Peerless TA6FC00-04 is even better above 1 kHz.
 
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