thanks for the feedback!
if the coil with the small cap across is not last then the driver does not see the high load impedance caused by the LC tank. However, you would also normally like to have a cap to ground after the L to get a 2nd order electrical filter. This is why Kim (app not author) made the separate notch coming after the first usual series L with a C to ground. Then you both get the roll off and a load impedance peak at the notch frequency.
Its a nice trick to add the amp in series with the driver to check the sensitivity to the motor distortion (which can be modelled as a voltage source in series with the driver)
yes and Vance from VC mag. But please note that we deliberately make Kms progressive to help keep the coil in the linear Bl range, Bl linear stroke is wider than Kms linear stroke. We do this to reduce IMD under real life conditions where the driver also reproduces midrange. We wrote a blog post about it
we have a shallow 10" in the pipe and it will hopefully pick up some execution speed soon. One of the headaches is to figure out how to assemble it the best way. comsbing a purifi driver with acceleration servoing could be an ulitmate way to reproduce sub 100Hz. The servo wos down where Kms dominates and the constant Sd surround makes sure that line motion turns into linear sound pressure
Lars & Purifi team congratulations on getting to the preview stage for PTT8.0X04-NAB-01. With the present state of the supply chain accomplishing any research or production development activity is a herculean activity.
Given this is the first 8”/200mm class driver from Purifi I am wondering will it come with a warning label:
WARNING within a radius to 30 meters this device is able to stun birds, puppies, kittens and other small animals with deep concussive sound pressure waves. Use with care under adult supervision.
I am joking of course, maybe. Recently I have been exploring what my PTT6.5s can accomplish using bi-amping and DSP based crossovers. After two years and several different enclosures I thought I had heard what the PTT6.5 was capable of (overachieving) in the bass as I wrote here:
PTT6.5W04 and the evil twins PTT6.5PR want to explode your speaker box https://www.diyaudio.com/forums/mul...ifi-woofer-speaker-builds-48.html#post6383932
With the high level inductors and other filter parts out of the amp to speaker signal path replaced by amp direct connect to PTT6.5 in a bi-amp rig with upstream DSP EQ applied for baffle step correction and to extend deep bass expectations have been completely reset. Here is a plot at the listening position with just one of the stereo pair active.
This has been great fun to listen to although I suspected I have a bit much bass dialed in. Chasing that while setup for near field measurements I took the above readings at the sofa where one sits for serious stereo in my room. The sweeps are with the microphone at ear level left then center then right seating locations. We find the lovely flat nearfield responses now include a -5 dB drop at 150 Hz then a 6 to 7 dB boost at 35 Hz, yes the bass has been banging! I am rather proud that if we call the overall mean of these curves 75 dB the -3 dB bass point is 22 Hz. No wonder the very low frequency content of music and video has become so apparent since this DSP’ed iteration of my rig has been placed in service. Yes, next time I have the programmer out I will take a few dB out of the 30-70 Hz range but too much bass when it is so deep, clean and clear is BIG FUN.
Experiences like I am presently enjoying is why when Lars joins us to announce the PTT8.0 is nearly ready and the responses are “how about a 10” then “I want a 12” I just shake my head. On Purifi woofers the Sd and Xmax are just part of the story. When I read ‘Purifi 8’ I make the comparisons to anybody else’s 10, or 12, or 15. The Purifi voodoo in the magnet system and soft parts of the suspension and surround makes all the difference. And then as I am asking 'who needs more than an 8” Purifi' the joke is on me as Lars starts speculating about a servo controlled 10”. This journey is big fun, I am so glad to be a Purifi early adopter enjoying such great HiFi the last two years.
Given this is the first 8”/200mm class driver from Purifi I am wondering will it come with a warning label:
WARNING within a radius to 30 meters this device is able to stun birds, puppies, kittens and other small animals with deep concussive sound pressure waves. Use with care under adult supervision.
I am joking of course, maybe. Recently I have been exploring what my PTT6.5s can accomplish using bi-amping and DSP based crossovers. After two years and several different enclosures I thought I had heard what the PTT6.5 was capable of (overachieving) in the bass as I wrote here:
PTT6.5W04 and the evil twins PTT6.5PR want to explode your speaker box https://www.diyaudio.com/forums/mul...ifi-woofer-speaker-builds-48.html#post6383932
With the high level inductors and other filter parts out of the amp to speaker signal path replaced by amp direct connect to PTT6.5 in a bi-amp rig with upstream DSP EQ applied for baffle step correction and to extend deep bass expectations have been completely reset. Here is a plot at the listening position with just one of the stereo pair active.
This has been great fun to listen to although I suspected I have a bit much bass dialed in. Chasing that while setup for near field measurements I took the above readings at the sofa where one sits for serious stereo in my room. The sweeps are with the microphone at ear level left then center then right seating locations. We find the lovely flat nearfield responses now include a -5 dB drop at 150 Hz then a 6 to 7 dB boost at 35 Hz, yes the bass has been banging! I am rather proud that if we call the overall mean of these curves 75 dB the -3 dB bass point is 22 Hz. No wonder the very low frequency content of music and video has become so apparent since this DSP’ed iteration of my rig has been placed in service. Yes, next time I have the programmer out I will take a few dB out of the 30-70 Hz range but too much bass when it is so deep, clean and clear is BIG FUN.
Experiences like I am presently enjoying is why when Lars joins us to announce the PTT8.0 is nearly ready and the responses are “how about a 10” then “I want a 12” I just shake my head. On Purifi woofers the Sd and Xmax are just part of the story. When I read ‘Purifi 8’ I make the comparisons to anybody else’s 10, or 12, or 15. The Purifi voodoo in the magnet system and soft parts of the suspension and surround makes all the difference. And then as I am asking 'who needs more than an 8” Purifi' the joke is on me as Lars starts speculating about a servo controlled 10”. This journey is big fun, I am so glad to be a Purifi early adopter enjoying such great HiFi the last two years.
NICE. Well done team, a worthy addtion to your line up. I look forward to placing my order for a pair.thank you also, was just about to post
That's a really good paper, for everyone not just users of purifi products! Also how good is VituixCAD.
Yep, as Lars said above, I have this one and another of their speakers. It's been in queue for about 3 months now and I am FINALLY getting close to being able to review it. I took on way too many speakers at one time and have spent the last few months not getting much sleep. 25 reviews since January. I look forward to having some downtime.
We all wait patiently for other variants too eg. polypropylene cones.
Smooth as a baby's bum from 100Hz to 10,000 Hz, I'm sure, at typical listening distances eg. 2+ m, distortion below the room's noise floor, and super wide dispersion...
Hificompass has published the 6.5NAA review a couple of days ago
https://hificompass.com/en/news/mea...-long-stroke-midwoofer-purifi-ptt65x04-naa-08
Lars, I would like to know if a 8 Ohms version of the PT8.0x is on its way too ?
Erin, fullyderstood. Its far better to actively choose some down time than one's body deciding that - been there , done that. Also too much to do here at purifi
