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Exploring Purifi Woofer Speaker Builds
Exploring Purifi Woofer Speaker Builds
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Old 26th April 2020, 12:17 PM   #21
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by jamesblonde View Post
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 ?
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Old 26th April 2020, 12:29 PM   #22
jamesblonde is offline jamesblonde  Italy
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Originally Posted by Zvu View Post
That is to easy. Why didn't you use Dayton PN395-8 (sd of 890cm2) as example

Even the woofer you mentioned here has a linear displacement of 579cm3, only 9% more than the 4xPurifi combination (i.e. not a meaningful difference). I stand by my generalization but of course there will be exceptions.

Last edited by jamesblonde; 26th April 2020 at 12:39 PM.
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Old 26th April 2020, 12:34 PM   #23
scholl is offline scholl  United States
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Quote:
Originally Posted by jamesblonde View Post
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!
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Old 26th April 2020, 05:55 PM   #24
Paul Ebert is offline Paul Ebert  United States
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I haven't heard one (yet), but I would think that the Bliesma T34B would be worthy.

I wonder if Purifi will come out with a tweeter of their own. Would be interesting to see what they come up with. Same with a large woofer.
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Old 26th April 2020, 11:21 PM   #25
mainframe99 is offline mainframe99  New Zealand
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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...

Last edited by mainframe99; 26th April 2020 at 11:45 PM. Reason: wife running out of the kitchen :D
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Old 26th April 2020, 11:35 PM   #26
mainframe99 is offline mainframe99  New Zealand
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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
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Old 27th April 2020, 04:53 AM   #27
Norman Tracy is offline Norman Tracy  United States
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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.
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Old 27th April 2020, 05:05 AM   #28
yoke is offline yoke  Croatia
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Quote:
Originally Posted by mainframe99 View Post
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.
Attachment 838204
Could you please write something about over all sound ? Do you like AMT or would you change it with something else ?
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Old 27th April 2020, 06:35 AM   #29
dewdrop is offline dewdrop  Singapore
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I am also itching if we should do a GB in Asia.

A couple of questions:
1/ Apart from the AMT, any other possibilities?
2/ What sort of crossover will we need for a 15L 2-way?
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Old 27th April 2020, 08:13 AM   #30
jmpsmash is offline jmpsmash
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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.
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