Purifi PTT6.5W04-01A 6.5" midwoofer

[Frank Dernie]

I'm curious, which of the TADs have you heard?

If I stick with the 2 monitors + 2 subwoofers system topology, I only have a few upgrade paths from my current monitors. Going with the TAD concentric 3-ways is one of the few moves I can make that wouldn't be lateral.

It was a few years ago, Compact reference one. I liked them but didn't think they were worth the money.

 

[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.

Can we start again considering DIY(OP) which @Audiocrusader has contributed nothing toward.

 

[boXem]

By start again, do you mean comments on the ugliness of the surround and the interrest of the door stopper?

 

[Wombat]

By start again, do you mean comments on the ugliness of the surround and the interrest of the door stopper?

No. Modelling a box using the driver. That excludes most contributors.

 

[watchnerd]

It was a few years ago, Compact reference one. I liked them but didn't think they were worth the money.

Oh, I was thinking of the smaller, cheaper next rung down -- the Compact Evolution One and Micro Evolution One ($22k - $14k).

 

[watchnerd]

No. Modelling a box using the driver. That excludes most contributors.

It's been 10 years since I last DIY a speaker from scratch. What's the best online calculator these days?

 

[watchnerd]

well considering what voice coil does is reviews new drivers, and the Purifi woofer is likely the most cutting edge new driver seen for years, I think any dummy could predict a review coming shortly.

It’s a shame the the common “groupthink” mindset of this forum is that anyone who discusses the thread topic, or provides accurate information pertaining to the thread topic is viewed as a threat. Ohhh must be an evil outsider with a agenda!! When the ignorant clowns with absolutely nothing valuable to add, take over the threads. It’s no surprise that when anyone with an ounce of knowledge decides to contribute here, it ends up being extremely short lived.

Keep up the good work soldiers. And remember he who has the highest post count is the hero.

Okay, so it's just a random guess about Voice Coil's publishing schedule.

 

[watchnerd]

Anyway, back to your new-old comparison. I think that's an big exaggeration. Dennis Murphy thought ScanSpeak's expensive 20+ year old paper cone 7" woofer was good enough choose it over newer and often cheaper designs from ScanSpeak, Satori, and others for the low end of his superbly-measuring Philharmonic BMR.
https://www.audioholics.com/bookshelf-speaker-reviews/bmr-philharmonitor-1

That's a very unusual combination of drivers.

I was thinking it might lead to directivity mismatches, but the polar graphs look excellent.

Pretty reasonably priced, too!

 

[Frank Dernie]

That's a very unusual combination of drivers.

I was thinking it might lead to directivity mismatches, but the polar graphs look excellent.

Pretty reasonably priced, too!

The BMR was in development by NXT in Huntingdon in the late 1990s when I was doing some consulting for Lola Cars, also in Huntingdon. One of the guys who did the computer modelling and prototyping stayed in the same place as me and I went and listened to prototypes with him and later got invited to a show where prototype speakers were being demonstrated to potential licensees (NXT, born out of Mission wanted their business to be selling licenses not manufacturing). These prototypes sounded exceptional to me. Naim bought a license, and I think Linn did too, I was there when Ivor Tiefenbrun of Linn came to talk to them. Naim made a range of speakers with them just before being bought out by Focal, which killed them. Linn never did.
As I understand it the BMR was the most practical thing to come out of NXT distributed mode research. I have some NXT speakers which work very well for the price, but need to be big for low enough bass, like any panel. The BMR acts pistonically at first but at high frequency radiates by distributed modes. The biggest production problem was consistency. The bond area and consistency of the rubber surround material end up being much more critical when the driver is going up to such high frequencies, so getting production tolerances from companies used to making conventional drivers good enough is a major limitation. The BMR doesn't need a tweeter at all but I guess getting a cheap enough version in production means top octave consistency is sacrificed in favour of a tweeter.
I would buy these speakers if they were available shipped to the UK, just for nostalgia's sake!

 

[oivavoi]

I also think that these speakers seem like possibly the best box speakers available right now. The dispersion is superbly even and smooth, and it is unusually broad horizontally - something which I think people usually like. The Raal ribbon also seems to well liked by almost everybody who hears them. One of the major downsides is that the efficiency is very low, though. That could probably be helped by running them with an active crossover and connect amps directly to the drivers, but then one would need the exact slopes and settings from Dennis.

 

[Audiocrusader]

The one acting like this here happens to be your mentor...
If your intent is being aggressive with any member posting here, maybe you should go out for a walk, calm down and enjoy life. There are beautiful things outside you know.

That was a perfectly reasonable question. If one shops for drivers based on magnet type, why would't they shop for amplifiers based on the aluminum thickness?

 

[Audiocrusader]

That's a very unusual combination of drivers.

I was thinking it might lead to directivity mismatches, but the polar graphs look excellent.

Pretty reasonably priced, too!

The reason he chose that Scan-Speak woofer was because it's cheap. Not because it's better than newer alternatives. However it's still a pretty decent woofer even though it's a 23 year old design.

 

[Audiocrusader]

I also think that these speakers seem like possibly the best box speakers available right now. The dispersion is superbly even and smooth, and it is unusually broad horizontally - something which I think people usually like. The Raal ribbon also seems to well liked by almost everybody who hears them. One of the major downsides is that the efficiency is very low, though. That could probably be helped by running them with an active crossover and connect amps directly to the drivers, but then one would need the exact slopes and settings from Dennis.

What nobody ever talks about with this speaker is it can't play loud at all. That mid has no balls. Take some distortion measurements with them playing at over 100db. A 2 way with this Purifi woofer and a good tweeter can play up to 110dB, and still have less distortion than most drivers at any SPL level. While moving much more air in the low end than the Scan-Speak 8545.

 

[617]

Glad I was too busy cheering on my wife at her second NY marathon to see the developing multi-car pileup here... "Crusader," like "terrorist," is not an identity to aspire to in polite company.

Anyway, back to your new-old comparison. I think that's an big exaggeration. Dennis Murphy thought ScanSpeak's expensive 20+ year old paper cone 7" woofer was good enough choose it over newer and often cheaper designs from ScanSpeak, Satori, and others for the low end of his superbly-measuring Philharmonic BMR.
https://www.audioholics.com/bookshelf-speaker-reviews/bmr-philharmonitor-1

Overall the Purifi driver looks neat, though at the claimed price I would like a lighter driver driven by a neo magnet, not a big heavy magnetized clay ring between the polepieces. The most interesting part of the Purifi driver to me is how the surround repeats. I can't find it now, but one of the KEF/Celestion engineers did a video about Celestions's new 3D-stamped titanium compression driver that is supposed to play higher than anything else its size. He kept mentioning "periodicity" (a small feature that repeats) as the key to new diaphragm design work. It looks like something similar may be going on with this woofer's surround.

LOL. As I typed my comment about old drivers in the back of my head I was thinking "well, those scanspeak carbon pulp drivers are pretty good.." Those drivers are really good, but they were very high end in their day. Even Dunlavy was using Vifa PL series in his speakers. The 8535 unit in particular I have a fondness for, works well in sealed boxes. Still, having taken apart some pretty nice ADS/Infinity/EPI speakers my comment stands.

The BMR Philharmonitor is such a wonderful idea for a speaker.

 

[617]

The reason he chose that Scan-Speak woofer was because it's cheap. Not because it's better than newer alternatives. However it's still a pretty decent woofer even though it's a 23 year old design.

Nobody chooses a Scanspeak 85*5 because it's cheap. It retails for $174 dollars, only 30 dollars less than a revelator. You can get two sb17 aluminum cones for that.

 

[Audiocrusader]

Nobody chooses a Scanspeak 85*5 because it's cheap. It retails for $174 dollars, only 30 dollars less than a revelator. You can get two sb17 aluminum cones for that.

So did he pay retail? How do you know he didn't get a killer deal on a lot of 100+ drivers?

 

[oivavoi]

What nobody ever talks about with this speaker is it can't play loud at all. That mid has no balls. Take some distortion measurements with them playing at over 100db. A 2 way with this Purifi woofer and a good tweeter can play up to 110dB, and still have less distortion than most drivers at any SPL level. While moving much more air in the low end than the Scan-Speak 8545.

1: Have you seen any max spl measurements for this amp? I haven't. If it's capable of doing 105-110 db instantenous peaks in-room with a powerful amplifier (and there is no reason to use anything but powerful amplifiers these days), with the help of room gain, it's perfectly fine for all domestic applications.

2: Human listeners don't actually seem to pay much attention to distortion in loudspeakers, particularly during powerful peaks and in the bass, according to the studies I have seen (Geddes and others). If you get significant distortion in the tweeter range - nah, that's not good. But if THD rises below 1000 hz during powerful peaks, in a loudspeaker which is otherwise impeccably designed, I honestly couldn't care less.

 

[Audiocrusader]

1: Have you seen any max spl measurements for this amp? I haven't. If it's capable of doing 105-110 db instantenous peaks in-room with a powerful amplifier (and there is no reason to use anything but powerful amplifiers these days), with the help of room gain, it's perfectly fine for all domestic applications.

2: Human listeners don't actually seem to pay much attention to distortion in loudspeakers, particularly during powerful peaks and in the bass, according to the studies I have seen (Geddes and others). If you get significant distortion in the tweeter range - nah, that's not good. But if THD rises below 1000 hz during powerful peaks, in a loudspeaker which is otherwise impeccably designed, I honestly couldn't care less.

They can't play much more than 95dB without crapping out. If that's loud enough for you then that's great. But not for me. I'd rather have a 2 way that can play 15dB louder, with less distortion than that speaker has playing at 90dB. I've read a few comments of people saying they sound like crap when pushed at all.

 

[oivavoi]

They can't play much more than 95dB without crapping out. If that's loud enough for you then that's great. But not for me. I'd rather have a 2 way that can play 15dB louder, with less distortion than that speaker has playing at 90dB. I've read a few comments of people saying they sound like crap when pushed at all.

Source for the 95 db claim?

 

[Audiocrusader]

Source for the 95 db claim?

I read it somewhere. They actually start straining when pushed over 90dB. Do some modelling on the midrange and see what you can come up with. It's a $3 mid at wholesale pricing. What do you expect? 10W power handling with 82dB-78dB efficiency above 1000hz.

https://www.parts-express.com/tecto...MIq5Hj7ITW5QIVQiCtBh2bIAUwEAQYAiABEgKx7PD_BwE