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Purifi PTT6.5W04-01A 6.5" midwoofer

GelbeMusik

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... passive radiator will be a necessity. Tomorrow I'll optimize my BMR crossover ... see whether all these great measurements really make an audible difference.

The B/S400 I think was a design that reportedly exhibited some shaking, when driven hard. The rattling would not sound that good, so I expect two impulse-cancelling passives at opposing sides to be necessary.

Regarding listening tests, I expect the 50..60Hz region to be most critical. If You find some time and are interested too, a dedicated IM test would be nice.

Due to my own anecdotal experience the Doppler, which is Frequency Modulation could possibly transform into Amplitude Modulation in-room, making it more objectionable. Maybe because of the very rough sound-field in-room (before visual smoothing).

I also had the feeling, that the FM became quite unpleasant, when the sound wasn't just bass (e/g 60Hz) plus one single, modulated tone. A mix of a bass modulated tone, plus some other clean tone--from the midrange--could reveal more.

Thank You anyway.
 

dwkdnvr

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Does anybody have one? Asking because that is my way of thinking as well. But I am not very knowledgable about drivers.

If you can go a bit bigger the L16RN-SL used in the LxMini does well in as little as 7L sealed (f3 63Hz in 7L), although you probably want to cross it a bit lower than other drivers of similar size. Crossed to a waveguide tweeter around 1500Hz would make for a good combo.
 

DDF

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I don't have a firm opinion on this, but I'm having trouble figuring out what question the 4" is an answer to. It isn't suitable as a dedicated midrange--the bass capabilities would be wasted and the sensitivity is really too low for commercial purposes. You can't use them in parallel because the system impedance would be too low. It would make a pretty expensive and low-sensitivity passive computer monitor. Maybe it would make sense to use it in an active mini where sensitivity wouldn't be an issue and the long stroke could make bass equalization viable That might make particularly good sense if it could be used sealed. The Qts is borderline for that (.37), but I haven't modeled it.

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.
1592006351324.png
 

headshake

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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.

Thanks for the review.

I've been toying with the manufacturer and hificompass spl traces inside of virtuixcad. I was wondering how 3rd party data looked compared to what a manufacturer provides. It is sort of an sb acoustics vs purifi using hificompass for the control. Looks like SBA is closer to hificompass with my fuzzy test by tracing. I now expect the 4" to be a little messier than they show.

Maybe it would make sense to use it in an active mini where sensitivity wouldn't be an issue
This is what I was thinking (but I am a newb at speaker design). I've been focussing on the sb12cac, sb15cac, and 4" purifi. What I like is that I can cross it to a sub lower than the 4"cac but not need a big enclosure like the 5"cac requires. I've never made a speaker before so there is that. :p



...


So I have a question about the purifi vs sb15cac: Would the distortion difference be audible? Is this like a high end dac vs a mid-range dac- neither one will have audible distortion I am just paying for specs?

I attached some random internet user pics of measurements.
 

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Selah Audio

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Excited to see what you think of them

The measurements look good. I've done some testing of a 2-way with a BZ Labs CQ76B tweeter. The midrange is very clean and detailed. Pairing up the woofer with driver combinations that make sense is probably the biggest challenge. Any number of 1" domes could be used for a 2-way. In a 3-way there are some options depending on what size of cabinet you want. Going active opens up more possibilities too.
 

Matias

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Dennis Murphy

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The measurements look good. I've done some testing of a 2-way with a BZ Labs CQ76B tweeter. The midrange is very clean and detailed. Pairing up the woofer with driver combinations that make sense is probably the biggest challenge. Any number of 1" domes could be used for a 2-way. In a 3-way there are some options depending on what size of cabinet you want. Going active opens up more possibilities too.

The Purifi's are superb speakers for a 2-way in a .5 cu ft box or a little less, although finding an appropriate port is a challenge. I ended up using the passive radiators, but even without weights they tune too low for use in a larger 3-way. I had to give up on them for my BMR's, and I don't have any plans to introduce a full range 2-way. Bottom line: a beautifully engineered but highly specialized driver.
 

tuga

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A small closed box is possible using active EQ to extend the bass. If you don't want to do that you'll need to add a subwoofer.

Why not 3-way (and a sub)?
 

HooStat

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Have any DIY plans been published for the woofer (other than the one from Purifi)?

I would be really interested in an active, DSP cross-over monitor with the Purifi woofer and Purifi passive radiator. Just not sure what the right approach is for the tweeter (or how to model this to get the proper cabinet size). I have read that the Bliesma T34 tweeter is great, but Purifi used a ribbon tweeter.

I know nothing, but this project interests me. Maybe beyond my skill set. Trying to do it as simple as possible would be great.
 

Selah Audio

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Have any DIY plans been published for the woofer (other than the one from Purifi)?

I would be really interested in an active, DSP cross-over monitor with the Purifi woofer and Purifi passive radiator. Just not sure what the right approach is for the tweeter (or how to model this to get the proper cabinet size). I have read that the Bliesma T34 tweeter is great, but Purifi used a ribbon tweeter.

I know nothing, but this project interests me. Maybe beyond my skill set. Trying to do it as simple as possible would be great.
The Purifi design uses a Mundorf AMT tweeter. I'm working on a DIY design with a ribbon/planar tweeter. I also have some DSP units on hand which I plan to use.
 

Ilkless

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The Purifi design uses a Mundorf AMT tweeter. I'm working on a DIY design with a ribbon/planar tweeter. I also have some DSP units on hand which I plan to use.

Hi Rick, Dennis just commented on the issues he had with implementing the PTT6.5 on AVSForums:

I've given the Purifi woof every opportunity to prove itself in the BMR, including running it with two of the Purifi passive radiators, and I finally gave up. It's a very specialized animal. It performs about as well as the Scan 8545 in a smaller cabinet, which makes it a prime candidate for a premium 2-way in a cabinet of .5 cu ft or less. But even in that application the port has to be too long to fit without bending it and introducing even more port noise. The passive radiators solve that problem, but in a larger cabinet the bass response falls off below 100 Hz and the midbass is thin. Given how much more expensive the woofer + PR's are compared with the Scan, it doesn't make sense to reduce the volume of the BMR cabinet to achieve essentially the same results.

Not sure how far along development you are, but have you encountered anything similar? Or have you found a box size/alignment that allows the Purifi to realise its potential?
 
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