Purifi PTT6.5W04-01A 6.5" midwoofer

[Audiocrusader]

There's no standard for woofer distortion measurements as far as I know, so I wouldn't make this comparison. Suffice to say they're both good.

Well the distortion at 1khz is lower at all SPL's. And the ellipticor is probably measured at the best measuring SPL level. If we were to compare the 2nd harmonic THD @ 1khz and 80-90 SPL for the Purifi, the Purifi has 25x less distortion!

 

[617]

VDP for this driver is 133 cubic cm.

Other 6.5"
sb17CAC = 64.9
ScanSpeak Illuminator 18WU = 138 cubic cm
Anarchy 708 = 157 cubic cm
Dayton RS180p = 75.6 cubic cm

8"
Dayton rs225 = 150 cubic cm
Seas Excel 8" = 220 cubic cm
SB23NBAC = 280 cubic cm

So as you can see, this and a few other 6 1/2" class midwoofers are capable of output exceeding some 8" drivers.

 

[Audiocrusader]

VDP for this driver is 133 cubic cm.

Other 6.5"
sb17CAC = 64.9
ScanSpeak Illuminator 18WU = 138 cubic cm
Anarchy 708 = 157 cubic cm
Dayton RS180p = 75.6 cubic cm

8"
Dayton rs225 = 150 cubic cm
Seas Excel 8" = 220 cubic cm
SB23NBAC = 280 cubic cm

So as you can see, this and a few other 6 1/2" class midwoofers are capable of output exceeding some 8" drivers.

Yes but what kind of midband distortion do they produce when driven to 90% excursion? This is the data that sets the Purifi in it's own league. And much of this data isn't even in the Purifi datasheet. Such as IM distortion.

 

[Killingbeans]

Will the PTT6.5W04-01A driver be available for the DIY market?

In the article I linked to in the original post Lars Risbo and Bruno Putzeys are asked:

Who are the customers Purifi aims for:

And they answer:

Audio companies searching licensing deals and the DIY audio segment.

There are other mentionings of DIY in the article. All in all they seem to point at a 'YES', but it's not definitive.

 

[briskly]

@617 I believe you have confused one-way peak and p-p. The usual geometric Xmax formula is given as |coil height - gap height|/2, and be careful when it is not.
Suspension stiffness of the Purifi has already doubled (or compliance has halved) by +/-8mm. The motor force has barely shifted by this point, but it should be apparent that this is not intended for substantially longer excursions.

A picture of intermodulations can be drawn up from the nonlinear components. Displacement dependence of the suspension produces a different result than motor force or effective inductance, which also depends on the frequency and current.

 

[Audiocrusader]

More talk on the driver at the end of this article:

https://www.audioxpress.com/article/purifi-audio-a-straight-wire-to-the-soul-of-music

 

[617]

@617 I believe you have confused one-way peak and p-p. The usual geometric Xmax formula is given as |coil height - gap height|/2, and be careful when it is not.
Suspension stiffness of the Purifi has already doubled (or compliance has halved) by +/-8mm. The motor force has barely shifted by this point, but it should be apparent that this is not intended for substantially longer excursions.

A picture of intermodulations can be drawn up from the nonlinear components. Displacement dependence of the suspension produces a different result than motor force or effective inductance, which also depends on the frequency and current.

Thanks for your correction. I am aware that xmax is not quoted consistently, I was just showing the basic brute output capabilities of different drivers.

 

[KSTR]

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...

 

[RayDunzl]

Measurements are also provided, on which nobody gives a f...,

https://www.boredpanda.com/pretty-girls-transforming-into-ugly/

 

[Audiocrusader]

Thanks for your correction. I am aware that xmax is not quoted consistently, I was just showing the basic brute output capabilities of different drivers.

Simply looking at maximum volume displacement does not tell us how suitable the driver is for a 2 way design. Just like looking at the quarter mile time of a drag car to see how well it would do a lap on the Nurburgring. For a 2 way speaker midrange performance is vital. And the ability to achieve excellent performance through the entire range with full range music playing through it. As that's how they will be used in the real world.

Another critical fact is that very few people want refrigerator sized speakers in their living room these days. So the ability for 1 small driver to offer this level of performance in a small cabinet makes the difference in manufacturers being able to build speakers that will sell, or going out of business.

 

[restorer-john]

Restorer-John thinks any gear that wasn't made in his glory days of the 70's-80's is junk. When in reality, inflation adjusted, the best gear from that era can't even hold a candle to gear costing a fraction of the price today.

The problem as I see it is this, I've seen the mass deterioration of high fidelity equipment first hand over several decades, across my bench, on the sales floor, and in my large collection. I've got hundreds (perhaps thousands) of examples I could trot out that show this. Not afraid to call it for what it is, unlike some other people who think everything new is by definition, better. Spoiler: It isn't.

I wish currently available gear were better, I really do, because it'd be nice to go and buy a new 30kg hang-the-expense statement integrated amplifier finished like a Mercedes Benz, that was actually good value and well engineered to last a few decades without landing on my bench needing unobtainium parts in 5 years. As I see it, the only equipment brand uncorrupted and true to its roots is Accuphase.

HiFi these days is "guru-driven group think". Massdrop-like snowball, mob mentality. ASR is at risk of descending into such a place. So, someone develops a 6.5" woofer, creates a "buzz" in audiophile circles where the salivating masses lap it up like the Koolaid in Jonestown, and before long, anyone who wants to be "respected" will go stick this (deliberately) polarizing woofer into yet another small bookshelf speaker and call it done. Wow, that's really pushing the envelope isn't it? It's just a loudspeaker component. It's just a commodity woofer.

Today, we have off-the-shelf solutions-driven HiFi. Heavily sanitized and devastatingly boring. Purifi just want to be the goto guys for lazy, ill-equipped assemblers to get something, anything, to market quickly. Be that amplifier/psu solutions or now with a magic woofer. Good luck to them. They might become a Seas/Scanspeak/Peerless/Vifa/Dynaudio/Jamo/Dali equivalent one day, but until they do, it'll be the "purifi inside" stickers on everyone else's bashed together boxes, just like all the other bastardized brands stuck all over bluetooth speakers, laptops and wait for it, lightbulbs.

Yes, JBL on a lightbulb. I bought one for fun, to see just how low Harman would stoop, licensing the JBL brand for a bluetooth LED light bulb. Needless to say, it was an utter joke of a product and got returned.

PS. Get off my lawn.

 

[Audiocrusader]

The problem as I see it is this, I've seen the mass deterioration of high fidelity equipment first hand over several decades, across my bench, on the sales floor, and in my large collection. I've got hundreds (perhaps thousands) of examples I could trot out that show this. Not afraid to call it for what it is, unlike some other people who think everything new is by definition, better. Spoiler: It isn't.

I wish currently available gear were better, I really do, because it'd be nice to go and buy a new 30kg hang-the-expense statement integrated amplifier finished like a Mercedes Benz, that was actually good value and well engineered to last a few decades without landing on my bench needing unobtainium parts in 5 years. As I see it, the only equipment brand uncorrupted and true to its roots is Accuphase.

HiFi these days is "guru-driven group think". Massdrop-like snowball, mob mentality. ASR is at risk of descending into such a place. So, someone develops a 6.5" woofer, creates a "buzz" in audiophile circles where the salivating masses lap it up like the Koolaid in Jonestown, and before long, anyone who wants to be "respected" will go stick this (deliberately) polarizing woofer into yet another small bookshelf speaker and call it done. Wow, that's really pushing the envelope isn't it? It's just a loudspeaker component. It's just a commodity woofer.

Today, we have off-the-shelf solutions-driven HiFi. Heavily sanitized and devastatingly boring. Purifi just want to be the goto guys for lazy, ill-equipped assemblers to get something, anything, to market quickly. Be that amplifier/psu solutions or now with a magic woofer. Good luck to them. They might become a Seas/Scanspeak/Peerless/Vifa/Dynaudio/Jamo/Dali equivalent one day, but until they do, it'll be the "purifi inside" stickers on everyone else's bashed together boxes, just like all the other bastardized brands stuck all over bluetooth speakers, laptops and wait for it, lightbulbs.

View attachment 37888

Yes, JBL on a lightbulb. I bought one for fun, to see just how low Harman would stoop, licensing the JBL brand for a bluetooth LED light bulb. Needless to say, it was an utter joke of a product and got returned.

PS. Get off my lawn.

Yes it’s true that if you shop poorly, it’s possible to buy junk. This is why being knowledgeable is an asset. Knowledgeable people frown upon blanket statements, and look at each product individually to decide if the design has merit. If we use IcePower as a case example, their historical module failure rate since 2001 is 0.2%. Is that poor reliability in your books? And if a module does fail it costs less to replace than repairing a small part on one of your prized antiques. And the performance is light years ahead of anything from the 70’s-80’s.

Regarding this driver, if the Purifi team decided to licence the driver to Scan-Speak or SEAS, would it be a better driver? Most people don’t seem to realize that 90% of the cutting edge drivers out there are just designs licensed from a handful of driver engineers. Engineers like the guys who developed this Purifi driver. So if you just shop by brand like yourself, rather than the technical merits of the actual product, yes you’re bound to get duped.

 

[617]

The problem as I see it is this, I've seen the mass deterioration of high fidelity equipment first hand over several decades, across my bench, on the sales floor, and in my large collection. I've got hundreds (perhaps thousands) of examples I could trot out that show this. Not afraid to call it for what it is, unlike some other people who think everything new is by definition, better. Spoiler: It isn't.

I wish currently available gear were better, I really do, because it'd be nice to go and buy a new 30kg hang-the-expense statement integrated amplifier finished like a Mercedes Benz, that was actually good value and well engineered to last a few decades without landing on my bench needing unobtainium parts in 5 years. As I see it, the only equipment brand uncorrupted and true to its roots is Accuphase.

HiFi these days is "guru-driven group think". Massdrop-like snowball, mob mentality. ASR is at risk of descending into such a place. So, someone develops a 6.5" woofer, creates a "buzz" in audiophile circles where the salivating masses lap it up like the Koolaid in Jonestown, and before long, anyone who wants to be "respected" will go stick this (deliberately) polarizing woofer into yet another small bookshelf speaker and call it done. Wow, that's really pushing the envelope isn't it? It's just a loudspeaker component. It's just a commodity woofer.

Today, we have off-the-shelf solutions-driven HiFi. Heavily sanitized and devastatingly boring. Purifi just want to be the goto guys for lazy, ill-equipped assemblers to get something, anything, to market quickly. Be that amplifier/psu solutions or now with a magic woofer. Good luck to them. They might become a Seas/Scanspeak/Peerless/Vifa/Dynaudio/Jamo/Dali equivalent one day, but until they do, it'll be the "purifi inside" stickers on everyone else's bashed together boxes, just like all the other bastardized brands stuck all over bluetooth speakers, laptops and wait for it, lightbulbs.

View attachment 37888

Yes, JBL on a lightbulb. I bought one for fun, to see just how low Harman would stoop, licensing the JBL brand for a bluetooth LED light bulb. Needless to say, it was an utter joke of a product and got returned.

PS. Get off my lawn.

I see where you're coming from but loudspeaker transducers have gotten way way better in recent years. Drivers from even the early 90s can't hold a candle to modern offerings, certainly if price is taken into account. I mean I've taken apart some nicer older speakers and the drivers are just shit compared to cheap stuff today.

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

 

[Audiocrusader]

Restorer John doesn’t like class D amps because none over them ever make it to his bench for repair. They’re too reliable.

 

[Killingbeans]

It's just a loudspeaker component.

But why would a loudspeaker component be unable to evolve into something better? And why are you so convinced that this one hasn't?

What would it have to do well in order to actually impress you in a good way?

 

[restorer-john]

Regarding this driver, if the Purifi team decided to licence the driver to Scan-Speak or SEAS, would it be a better driver?

Most likely yes. 50+ years in the driver manufacturing industry- they've seen it all.

Most people don’t seem to realize that 90% of the cutting edge drivers out there are just designs licensed from a handful of driver engineers.

OK, let's see some evidence for that bold statement. Firstly, how about defining a "cutting edge driver" for me? And then, the handful of engineers please.

And if it's true, it merely illustrates my point that 'designs' are sanitized and boring versions of each other doesn't it? Who is going out on a limb with full range speakers and real midrange drivers as opposed to a 6.5" mid/woofer struggling to cover half the spectrum in its de-riguer '2 way bookshelf' footprint?

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.

So if you just shop by brand like yourself, rather than the technical merits of the actual product, yes you’re bound to get duped.

Oh dear.

 

[Audiocrusader]

I see where you're coming from but loudspeaker transducers have gotten way way better in recent years. Drivers from even the early 90s can't hold a candle to modern offerings, certainly if price is taken into account. I mean I've taken apart some nicer older speakers and the drivers are just shit compared to cheap stuff today.

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

Reminds me of a friend of mine who flew 3000 miles to pickup a 69 firebird to restore because “they don’t make em like they used to” He decided to drive it back. By the time he got home he hated the thing and put it up for sale because “ they don’t make em like they used to.”

 

[Audiocrusader]

Most likely yes. 50+ years in the driver manufacturing industry- they've seen it all.



OK, let's see some evidence for that bold statement. Firstly, how about defining a "cutting edge driver" for me? And then, the handful of engineers please.

And if it's true, it merely illustrates my point that 'designs' are sanitized and boring versions of each other doesn't it? Who is going out on a limb with full range speakers and real midrange drivers as opposed to a 6.5" mid/woofer struggling to cover half the spectrum in its de-riguer '2 way bookshelf' footprint?

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.



Oh dear.

Well manufacturers don’t publicly disclose licensing deals protected by NDA’s. So you’ll just have to fall back on testing each individual product for technical merit before judging.

And yes when you build a product that’s superior to what’s available elsewhere for the cost, that means you built a product that’s superior to what’s available elsewhere for the cost. And such a thing has value to those in the market.

 

[March Audio]

My initial post in this thread was in response to the fact that 70-80% of the posts in this forum are nothing but hot air. Restorer-John thinks any gear that wasn't made in his glory days of the 70's-80's is junk. When in reality, inflation adjusted, the best gear from that era can't even hold a candle to gear costing a fraction of the price today. Watchnerd is suggesting an 18 yr old SEAS driver with a graphene powder coating must be superior, without an ounce of data to back it up. And the reasoning is because the Purifi team are only electronic's manufacturers. Which is also false information.

The Purifi amp thread (outside of the couple posts made by Bruno) is an absolute disaster riddled with copious amounts of misinformation and hot air. So when I seen this thread off to the same start I decided to respond. The problem is likely around 70-80% of the folks who read these threads don't have the technical knowledge to decipher the facts from the BS. So what happens much of the time is they think the BS is indeed factual. Then they start spreading it themselves across other forums. And then after a while total BS becomes the truth in the minds of the masses.

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.

 

[restorer-john]

Well manufacturers don’t publicly disclose licensing deals protected by NDA’s. So you’ll just have to fall back on testing each individual product for technical merit before judging.

So let me get this straight, you made a bold, unsubstantiated claim and have zero facts to back it up?

In that case, retract your statement: "that 90% of the cutting edge drivers out there are just designs licensed from a handful of driver engineers."