Purifi PTT6.5W04-01A 6.5" midwoofer

[Audiocrusader]

“The big Japanese players all built their own pulp and driver manufacturing plants, cast their own baskets and vapor deposited their own Beryllium/Titanium/Alumina domes. Many were all in house. These are facts, not hearsay.”

And in the case of TAD, they hired an American engineer to design them.

 

[restorer-john]

I agree with your pessimism towards the HiFi market, but there are rays of sunshine here and there.

Absolutely there are. And this driver may be the start of a whole range of superior loudspeaker products for OEMs to integrate into commercially successful products. I certainly hope so.

But let's not lump all the past into the irrelevant. There are plenty of truly 'cutting edge' drivers from 30+ years ago too.

 

[restorer-john]

And in the case of TAD, they hired an American engineer to design them.

Bart Locanthi was tempted to Pioneer to build a speaker just like the Century L100 to capture market share.

 

[Wombat]

First off I'd like to make it clear that transducers/drivers is a subject that my expertise doesn't cover very well. In other words, if I happen to ask some hopelessly trivial questions or get giddy about next to nothing, feel free to answer with something in the line of: "Read this book/article first, and then we can talk"

Anywho, with all the raving about the Purifi 1ET400A Class D amp, I couldn't help but notice their other product about to get launched, the PTT6.5W04-01A speaker driver.

More info here.

I've been meaning to build myself some new DIY speakers for ages, but never really get around to much more than dreaming and doing superficial research. I'd like some small bookshelf speakers with high WAF without sacrificing too much fidelity, and these drivers seem to be designed to address some of the problems pestering small long-stroke drivers. I must admit that I am ill equipped with the knowledge required to determine whether it's just hot air, or something worth extraordinary praise... or something in between. I trust the scrutiny of you guys to set me straight?

Purifi seem to be demoing it in a small (sealed?) encosure paired with a Mundorf AMT (as seen in this article):

It also seems that March Audio is going to use this driver in an upcoming active speaker? Maybe he would like to chime in?

BTW, feel free to use this thread for general talk about this driver.

Compare to this. http://www.seas.no/images/stories/prestige/pdfdatasheet/H1869-08_L16RNX3_Datasheet.pdf

Around $100 or less. https://www.madisoundspeakerstore.c...l16rnx-6-aluminum-cone-woofer-h1488-08-8-ohm/

Except for the acoustic suspension, cone type loudspeaker development has been slowly incremental from the original Rice and Kellogg effort(which included butyl rubber surrounds) of 1925.


What is the great leap forward with the OP driver? Why all the to-do?

 

[Audiocrusader]

It’s amazing how when a DAC comes out around here with 2dB better SINAD 20dB below the threshold of audibility we see a massive circle jerk. But when a driver is released that will have a massive impact on possible system sound quality for the money, in a much smaller form factor, nobody understands what the big deal is.

 

[Wombat]

Well that will probably be about 69-79% better than most other audio forums......

You are coming across very hostile. We all know there is a lot of BS and misinformed opinion out there and some will inevitably end up here, however there are a lot of very well informed posters here that tend to tackle and correct the BS.

 

[Wombat]

It’s amazing how when a DAC comes out around here with 2dB better SINAD 20dB below the threshold of audibility we see a massive circle jerk. But when a driver is released that will have a massive impact on possible system sound quality for the money, in a much smaller form factor, nobody understands what the big deal is.

Telling, isn't it? Some are not as impressed as you are. That's life.

 

[Killingbeans]

What is the great leap forward with the OP driver?

Well, that's what I'm trying to find out.

I'm not best best qualified person to judge the date, but so far it points at unprecedented low amounts of distortion (?).

 

[restorer-john]

So, who actually makes it for them? That's the real question. Seas?

 

[Audiocrusader]

Telling, isn't it? Some are not as impressed as you are. That's life.

Or some just don't have the knowledge to know what matters.

 

[Audiocrusader]

So, who actually makes it for them? That's the real question. Seas?

Why would one of the highest ranking teams of engineers in the Danish driver industry, outsource their work to a Norwegian company? My guess is they have the parts manufactured by Tymphany to their specs, then do the finally assembly in house in their Danish factory.

 

[DDF]

I'd say if most of the claims should hold as expected, given the reputation of the designers and the comprehensive datasheet, this is a milestone driver design. Period. Also I'd expect it is extremely well suited to exploit advanced driving schemes with mixed feedback / motional feedback. Well, if it only had bifilar-wound dual coils...

Reading the white paper, it brings two real innovations to the table with very positive benefits over previous state of the art.
1. In the past it was "common knowledge" (see numerous AES papers and Martin Columns loudspeaker book) that magnetic non linearity and suspension non linearity can be designed to have a point of "cancellation" in the stroke, and that this was desirable. Purify show this is not true as IMD jumps even if low frequency THD drops
2. "Traditionally", the spider was the dominant suspension and the cone surround mainly sealed air and stayed out of the way (while trying to minimize rocking and terminating/damping cone resonances). This is the first instance I've ever seen (after many years) of a claimed surround that provides linear displacement with stroke, reducing distortion.

Some of the TS params seem odd for ported https://www.diyaudio.com/forums/mul...dio-bruno-putzeys-friends-11.html#post5921366 but can't wait to see how this driver pans out in a well thought out design

 

[Audiocrusader]

Funny that the head of the Purifi Transducer division other company has several pictures of Scan-Speak drivers on his website:

http://en.pointsource.dk

It's also pretty cool that Pointsource shares the same address as the Purifi transducer division. He better call up SEAS for some tips on driver design.

 

[Wombat]

Or some just don't have the knowledge to know what matters.

So you have access to members professional and private knowledge and experience or is that a rash generalisation you make?

Fill us in on yours if you will.

 

[Audiocrusader]

So you have access to members professional and private knowledge and experience or is that a rash generalisation you make?

Fill us in on yours if you will.

All just based on the posts around here. Or are you insinuating they keep the intelligent posts to themselves, and only share BS with the public?

 

[restorer-john]

Reading the white paper, it brings two real innovations to the table with very positive benefits over previous state of the art.
1. In the past it was "common knowledge" (see numerous AES papers and Martin Columns loudspeaker book) that magnetic non linearity and suspension non linearity can be designed to have a point of "cancellation" in the stroke, and that this was desirable. Purify show this is not true as IMD jumps even if low frequency THD drops
2. "Traditionally", the spider was the dominant suspension and the cone surround mainly sealed air and stayed out of the way (while trying to minimize rocking). This is the first instance I've ever seen (after many years) of a claimed surround that provides linear displacement with stroke, reducing distortion.

Point 1 is interesting.

Point 2 however I don't agree with. "traditionally" the spider was less suspension and more voice coil centering. The surround offered considerable additional suspension. Take a traditional speaker with no surround and drive it. See what happens. The spider was traditionally also placed much closer to the pole piece. This driver is like the Seas driver Wombat linked with the spider halfway along the basket arms, almost 50% along the cone.

I can also recall numerous drivers using helix-like surrounds, no surrounds at all, pleated, angled, channeled and shaped, all in the interests of linear excursion over the entire stroke and cone to surround interfacing to reduce distortion. It's hardly new.

 

[DDF]

Point 2 however I don't agree with. "traditionally" the spider was less suspension and more voice coil centering. The surround offered considerable additional suspension. Take a traditional speaker with no surround and drive it. See what happens. The spider was traditionally also placed much closer to the pole piece. This driver is like the Seas driver Wombat linked with the spider halfway along the basket arms, almost 50% along the cone.

Perhaps its not intuitive because you physically see the surround and not the spider, but the spider dominates Cms for most all modern mids or woofers. For example:
https://www.klippel.de/fileadmin/_migrated/content_uploads/Loudspeaker_Nonlinearities–Causes_Parameters_Symptoms_01.pdf

Here the surround stiffness becomes significant only when it starts to "get in the way" of the stroke.

Measuring Cms with the eye isn't a very effective way to quantify a physical parameter.

PS edit: I think you (and Wombat) missed my point about the surround innovation. Its not that Purify made the surround cms more "linear" in the sense of the graph above (though they may have accomplished that as well), its that they made the volume displacement of the surround linear with stroke. I've never heard of anyone even caring about this before (and I follow this stuff fairly closely).

 

[Wombat]

All just based on the posts around here. Or are you insinuating they keep the intelligent posts to themselves, and only share BS with the public?

On face value you should take a look in the mirror. Your posts have not been addressing your concerns with factual responses but rather with put-downs.

 

[Killingbeans]

All just based on the posts around here. Or are you insinuating they keep the intelligent posts to themselves, and only share BS with the public?

Please don't turn this thread into a shitfest. I get that you for some reason you feel protective toward Purifi products, and you do have some good points. But your hostility is not helping neither the thread nor yourself.

Of course it's hard to keep your cool when someone throws you a 'this can't possibly be anything but a toy!", but try anyway

 

[Audiocrusader]

On face value you should take a look in the mirror. Your posts have not been addressing your concerns with factual responses but rather with put-downs.

It's called sharing valid information pertaining to the thread topic. Rather than posting here for the sole purpose of discrediting the product without an ounce of data to back it up. If the latter is what you prefer to read, I suggest making use of the ignore feature.