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Purifi PTT6.5W04-01A 6.5" midwoofer

Absolute

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Apologies I didn't mean to be harsh, just seeing a lot of thread derailing happening these days
No offense taken, I share your frustration. Sadly it's difficult to pay enough attention to what gets written where when all these windows are open at the same time and when you're spending time working in-between sessions.
I'll be better at it.

Let's carry on with Purifi midwoofer talk :)
 

q3cpma

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I looks like Genelec agrees with Purifi's idea concerning the surround as the Ones' woofer uses something similar:
index.php

 

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McFly

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I absolutely lost it at the part in that video when he’s taking his genelec for a row in his boat. I mean, I guess if you really love something...
 

Julf

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Yeah, their videos emphasize a bit too much the "hippie factory lost in Finland's beautiful nature" bit.

Especially as they are not that far from the centre of a pretty sizable city. :)
 

briskly

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@q3cpma
The stated reasons aren't a 1:1 match. As I had figured, Purifi's surround shape is about SD modulation.
The racetrack woofer wouldn't even deflect evenly with a conventional surround.
 

Ilkless

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@q3cpma
The stated reasons aren't a 1:1 match. As I had figured, Purifi's surround shape is about SD modulation.
The racetrack woofer wouldn't even deflect evenly with a conventional surround.

Yeah, the corrugations are much more regular than the Purifi one as well. The corrugation here probably compensates for the distortion/max SPL problem of the first generation.
 

q3cpma

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@q3cpma
The stated reasons aren't a 1:1 match. As I had figured, Purifi's surround shape is about SD modulation.
The racetrack woofer wouldn't even deflect evenly with a conventional surround.
In truth, I already knew it, but wanted to draw an interesting parallel. Quite obvious when the nervous guy said it was to equalize applied force at any displacement.
 

phoenixdogfan

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The coax is being high-passed to the woofer at 350Hz so excursion may still not be that big a problem. KEF themselves spec 111dB with pink noise. And yeah, factoring in baffle step, and the likely high sensitivity of the tweeter within the MF cone (acting as a waveguide), padding of the midrange and tweeter relative to the woofer is probably substantial to get a smooth response. All the more reason that these speakers should be active, but the market is clearly behind the curve...
Be really great to see the spinorama on the REF 1s.
 

Matias

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I looks like Genelec agrees with Purifi's idea concerning the surround as the Ones' woofer uses something similar
Yes, but they say that to distribute for force on the cone more evenly while Purifi is to keep the diaphragm area constant when moving.
 

Adam Bernau

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I ran the TS params for the PTT4 in unibox. They went for a small Vas at the cost of low sensitivity. Maybe they want to sell more amps ;).

For standard Butterworth sealed, need 1.5L box (too tiny to get decent amount of audio stuffing in there to quell the internal box noise) with 85dB 2.83V/1m, & low impedance (1W sensitivity is lowly 82 dB).

Xmax is hit ~ 60W (>40Hz, ~ 100dB 1m above Fc), and it hits its mechanical limits ~ 140W (> 40 Hz, ~ 103 dB 1m above fc). No idea if it'd be happy thermally but even a simple first order in front would let this take some power (as far as throw is concerned).

Higher Vas for more sensitivity would have been a nice trade off.

The 5 kHz peak and aggressive high frequency roll off off-axis wouldn't be fun to work with. The small box TS params don't jive with the abbreviated high end. If not for these, I'd be ordering a couple.

Let us know what you hear with the 6.5's reduced distortion.
View attachment 68590
Hi,
A freshly made pair of PTT4 has just arrived today at my door, so i will start building first test enclosure in the following days, but i was hoping to make it work in small ported box with 2 small passives perhaps, have you been trying to simmulate also ported enclosure?

Regards

Ondrej
 

DDF

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Hi,
A freshly made pair of PTT4 has just arrived today at my door, so i will start building first test enclosure in the following days, but i was hoping to make it work in small ported box with 2 small passives perhaps, have you been trying to simmulate also ported enclosure?

Regards

Ondrej

No I haven't, sorry, but there are many box modeling programs to choose from, I use an old but good one here for quick estimates http://audio.claub.net/software/kougaard/ubmodel.html
 

Mikk

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@Adam Bernau Looks great- nice work! Any problems fitting the Fusion amp, due to it's size? Or is it external? Which passive radiator did you use, and what crossover point/slopes did you go for? Have you played with the Fusion's EQ to boost bass/flatten the response much?
The cabinet looks great- looks totally professional.
Thanks,
Michael.
 
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ehabheikal

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I see no harm in interpreting the data and measurements that is already made public.



You are absolutely right. But restorer-john was probably mostly just responding to your hostility.

Keep calm and supply the data. No need to throw diplomacy out the window.


The measurements are for the part not it in a complete speaker i think, so problems introduced by frame/case and crossover etc still will reduce performance? right?
 
OP
Killingbeans

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Absolutely. Driver measurements are usually done in anechoic conditions on an "infinite" baffle (if I'm not mistaken) to get optimal readings.

The world's best drivers in a crappy implementation still gives you a (technically) crappy speaker. Unfortunately (..or fortunately?) the human ear often perceives many of these problems as "flavoring" or "lovely coloring", meaning that manufacturers, who sell their wares solely on the basis of exotic driver choises, won't go out of business any time soon.
 

Adam Bernau

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@Adam Bernau Looks great- nice work! Any problems fitting the Fusion amp, due to it's size? Or is it external? Which passive radiator did you use, and what crossover point/slopes did you go for? Have you played with the Fusion's EQ to boost bass/flatten the response much?
The cabinet looks great- looks totally professional.
Thanks,
Michael.
Hi, i am actually powering it temporarily with Hypex FA 122 plate amplifier, the Purifi ETA based plate amp with DSP is in the works. The DSP/crossover setting are still in works also, now the crossover is at 3 kHz at 24 dB/oct. I am now working on tuning the passive radiators, from my standpoint it really doesn´t look like it will need any "bass boost", exactly the opposite :)
 

hardisj

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