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Multi-Way Conventional loudspeakers with crossovers

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Old 21st September 2019, 05:50 PM   #101
hidjedewitje is offline hidjedewitje  Netherlands
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Quote:
Originally Posted by Zvu View Post
It is worth that kind of money only if you need that performance in a certain format. If not, using multiple drivers will leave Purify behind for less money. I never understood the ridiculous prices in hi-end audio.
I think with multiple drivers they still have a great product. If you look at the SEAS Excel Line, the Scanspeak illuminator or SB Satori, they all have distortion levels of around -40 to -45 dB. Which is already incredible. The purifi driver goes towards distortion levels of -60dB!
Doubling the amount of drivers would only decrease distortion by 6dB. You would need 4+ drivers for the same result, which is obviously much more expensive. And more drivers give more problems than you might think in the first place. They also create off axis problems and size problems.

Sure there is better drivers for bass, but that is not what the driver is aimed at. The driver is meant as a midwoofer with some bass extension. It would be an ideal candidate for a high end two-way system.
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Old 21st September 2019, 06:38 PM   #102
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by hidjedewitje View Post
I think with multiple drivers they still have a great product. If you look at the SEAS Excel Line, the Scanspeak illuminator or SB Satori, they all have distortion levels of around -40 to -45 dB. Which is already incredible. The purifi driver goes towards distortion levels of -60dB!.

To quote myself from other forum regarding Purifi:

Quote:
I'm quite reserved about Purifi woofers for now. Few awkward things about those measurements. One of them being at the bottom of the page (figure 6) where 3rd harmonic at 250Hz drops while woofer playing louder. I've seen so far that going from 80dB to 90dB distortion stands still or moves very little but going down in percentage when driver playing louder ? I'll just have to wait some independent measurements because it basicaly means that while 3rd harmonic may rise with level, it doesn't rise for the same amount of dB as amplitude, but less. I also want to see higher resolution for their impedance measurements. At least 0-10 ohms - i see some irregularity at impedance phase but because they wanted us to see the peak of impedance at resonance frequency (who gives a damn) we can't see anything else (possible surround induced and other resonances).
And:

Quote:
It models reasonably well in volume of 15 liters and tuned to 35Hz.

Click the image to open in full size.
https://i.postimg.cc/KzWH0hMs/image.gif

Port resonance problem can be seen and while it looks severe, it can be absorbed or mitigated to some extent by placing the vent on the back side. Other problem is port noise and at 18W when port diameter is 50mm and length is 26.7cm with two flares it looks like this.

Click the image to open in full size.
https://i.postimg.cc/k4wSxW2n/image.gif

For loudspeakers that i want clean bass from i keep port air speed bellow 14ms. Lets say that at 17m/s it becomes audible, and that you really don't want to go above 26m/s then maximum power you can let through these woofers is 39Watts. All this happens at 60% of Xmax, over that and chuffing becomes serious distortion source so the point of low distortion woofer with 10mm Xmax is lost.

If we make the port larger, let's say 68mm, to minimize port air speed, port resonance goes down to around 320Hz and good luck mitigating that.

Click the image to open in full size.
https://i.postimg.cc/8zRLp7hm/68.gif

Again, the port induced distortion is too large to be neglected in my opinion.

I'd say that passive radiators should be used with these woofers or closed cabinets with appropriate low frequency boost. Then there are some advantages of low distortion that can be put to good use. But it would have to be quite a boost to get these results in closed cabinets (6-8dB boost at 40Hz actually). Distortion levels rise as well.

Thing that really puts me off for two way is 30 grams Mms, more than double from Wavecor, Revelator, Satori, Seas Nextel, Excel and Prestige woofers. Although Cms is 1.3 i am doubtful how would it sound. I guess that we'll just have to wait and see.

These are distortion figures of one 8 ohm Satori that is doing 88dB at 2.83V/1m.

https://hificompass.com/en/speakers/...satori-mw16p-8.

Two Satori MW16P-8 in parallel will achieve 94dB at 2.83V/1m. The level Purifi is measured at.

They start to look cheap at 130 euros/piece.
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Last edited by Zvu; 21st September 2019 at 06:55 PM.
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Old 23rd November 2019, 04:58 AM   #103
iamjackalope is offline iamjackalope  United States
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Here is a review with measurements.

Purifi Audio PTT6.5W04-01A midwoofer | HiFiCompass

There is pricing at the bottom of the page. Looks like they will be going for $390.00 a piece. So not cheap but according to hificompass they are the cats meow. They will be setting up a web store some time this month if they haven't already.

They look like a good match to the peerless DA25TX00-08 in a two way setup, possibly with a passive radiator.
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Old 27th November 2019, 07:30 PM   #104
racingpht is offline racingpht  Canada
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Anyone cares a group buy?

The price is much cheaper this way.
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Old 27th November 2019, 08:33 PM   #105
Juhazi is offline Juhazi  Finland
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An expensive 6,5" woofer with high excursion and low distortion...

Hmm, it suits compact 2-way closed box speakers with dsp well. But who wants to make such as diy? I can only think about cloning KiiThree or D&D.
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Old 29th November 2019, 08:46 AM   #106
hidjedewitje is offline hidjedewitje  Netherlands
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Quote:
Originally Posted by Juhazi View Post
An expensive 6,5" woofer with high excursion and low distortion...

Hmm, it suits compact 2-way closed box speakers with dsp well. But who wants to make such as diy? I can only think about cloning KiiThree or D&D.
Fusion amplifiers are easily available and make DSP solutions very approachable for many people.

Sure you won't have full control over the digital signal path (for things like directivity control, limiters for increased bass extention), but it'd still be a DSP solution.

I'm currently working on a DSP solution with this driver starting off with a fusion amp, but will later move towards my own DSP + DAC solutions.
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Old 30th November 2019, 04:52 AM   #107
PKI is offline PKI  United States
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Purifi Audio by Bruno Putzeys and friends.
Quote:
Originally Posted by racingpht View Post
Anyone cares a group buy?

The price is much cheaper this way.


I’d be in.
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Old 21st December 2019, 09:41 PM   #108
HeadShake is offline HeadShake
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Well, it is game time: The shop is up.

Anyone doing a group buy?
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Old 23rd December 2019, 04:20 PM   #109
maty tinman is offline maty tinman  Spain
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Purifi PTT6.5 Woofer and 1ET400A Amplifier Technology Review by mitchco

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

Quote:
Here is a quick comparo of frequency response measured in the same location and 30cm away. I have offset the measurement pairs so it is easier to compare. Purifi SPK4 Demo Kit on top, KEF LS50 on bottom:

Click the image to open in full size.

Let’s look at the demo speakers step (timing) response. What we are looking for is the “right triangle” shape which denotes an ideal speaker’s minimum phase response:

Click the image to open in full size.
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Old 23rd December 2019, 08:17 PM   #110
racingpht is offline racingpht  Canada
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New driver, awesome Xmax for a 4 inch: PTT4.0W04-01A
TS parameters are not complete, sadly.

A missing parameter is QMS. I put 6.0 as imaginary QMS and get a BL factor of ~3.24. Which is much lower than that of PTT6.5W04-01A. Considering a similar size magnet and xmax, I assume this driver uses a 2 layer voice coil?


Click the image to open in full size.

Last edited by racingpht; 23rd December 2019 at 08:23 PM.
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