NEW PURIFI 8'' MWoofer [PTT8.0X04]

[Rick Sykora]

These Danes at Purifi are arguably the leaders in driving the state of the art, and its pretty nice that they are sharing bread board mockups with visitors and maybe they do put out a rug for the shop dog? Those floors do look cold.

Maybe the little boxes in the back right are some music sources in digital storage? Purifi and Hypex are the top dogs of digital after all. No vinyl or CD's are lying around and they have a fancy Mola Mola dac in the center.

This thread is about the PTT8. Do you think the Mundorf AMT25CS is the best possible companion for the PTT8 mid-woofer? Would you go 2 way or do you think you could get more performance from a 3 way? These are expensive drivers, but if you dream about having SOTA drivers it seems like you should just make an all out assault on performance and get the best drivers you can, with the only constraint being reasonable size like 50 liter boxes and being easy to build? I have a big room and occasionally listen at rock concert levels in the mid-field so I am looking for something with some oomph.

As Purifi used a Mundorf AMT for the SPK5, I am pleased with the overall performance. Amir’s main complaint was over the bass balance and that is remedied with different port tuning. Directivity was pretty good and so is a decent design once you fit the crossover inside! As the Crowe design shows, you can make a 2-way work nicely with a properly designed waveguide. Multiple PRs across the back is an accident waiting to happen imo though. In the end, as a 3-way can get good directivity and hopefully forgo the waveguide, seems the better compromise. A Purifi tweeter might change my mind if it can reach low cleanly.

Below is another take on a PTT8 speaker. May have already been posted. It's interesting that it is horn loaded. I would be really interested to know what Lars Risbo thinks is the best set up is for this new driver, I assume it is the Mudorf AMT tweeter.

Speaker Design Study Using New Purifi 8" Woofer

DIY Plans No.1736 Purifi is a high end driver manufacture located in Denmark. Purifi is in the process of releasing their new 8" woofer, model PTT8.0X04-NAB-02. Purifi reached out to me and asked me if I would be interested in developing new DIY speaker plans for this new driver. This plan would...

josephcrowe.com

The tweeter of choice is a TBD compression driver. Hard to comment much more without knowing specifics. Should help with low-end power handling though. Also not clear what he is charging for the plans but his other prices seem reasonable. Last I checked, he is a forum member, so would leave specific questions to him. Is the guitar included?

 

[fineMen]

I tried…but sorry, nope, still looks like sh*t

Try this for starters, from HiFi Compass quoting (obviously) Purify.

https://hificompass.com/sites/default/files/review/PTT8.0X04-NAB-02/NeutralHal221202R04.gif

You may wont, or not, to measure the intermodulation of your currently beloved midwoofer at its surround's resonance (~500..700Hz). Still ugly the Purify, or the other?

 

[thulle]

Should be ten pcs. to match surface area of two 18"

But surface area doesn't generate sound pressure, moving that surface does.

 

[voodooless]

You may wont, or not, to measure the intermodulation of your currently beloved midwoofer at its surround's resonance (~500..700Hz). Still ugly the Purify, or the other?

Yes, my subjective view of what it looks like has no bearing on the measurements whatsoever.

 

[Deleted member 48726]

But surface area doesn't generate sound pressure, moving that surface does.

I responded to the old comment that stated 20 x 8 " was equal surface area to that of 2 x 18 ". It's ten.

 

[thulle]

I responded to the old comment that stated 20 x 8 " was equal surface area to that of 2 x 18 ". It's ten.

Now you're making stuff up, the comment said nothing about surface area, I was talking about SPL.

 

[Deleted member 48726]

Now you're making stuff up, the comment said nothing about surface area, I was talking about SPL.

Oh, I didn't though. But your follow up comment below escaped me. -Sorry for the misunderstanding.

 

[thulle]

Oh, I didn't though. But your follow up comment below escaped me. -Sorry for the misunderstanding.

View attachment 273082

I didn't even remember making the follow up comment, it just seems pointless enough to talk about surface area without taking Xmax into account when talking about subwoofers - where it's the capacity to move large amounts of air we're looking for - that it felt obvious what I was calculating. Which I tried to hint to you with my reply about the need to move that surface area, and then you said that I was actually talking about surface area when I had mentioned nothing of the sort, which is why I said you were making stuff up
But yeah, first post didn't explicitly mention SPL either. Could've been clearer.

 

[JRS]

Ah, missed that one. So best stary below 2 Khz, which is to be expected from an 8" woofer. Several waveguided tweeters will match this just fine.

One I can think of is the Satori Beryllium with WG = 500/side (relatively inexpensive ). That can be XO'ed over at 1300Hz with 12dB/octave complimented with the drivers 12dB/octave to form a 4th order. Going active I'm sure you can dip even further with 8th order or more. Not sure how much you would gain--appears to be about 5dB down at 60 degrees @ 1.25 KHz. So doable.

 

[fineMen]

One I can think of is the Satori Beryllium ...

This German site has a tweeter plus w/g that will do 'it' for just 50 bucks:
https://heissmann-acoustics.de/en/hochtoener-mit-waveguide/ (English translation isn't correct throughout , but you'll surely get the point)
... only without the cargo cult.

Regarding the woofer itself, it is said that the inevitable Doppler frequency modulation doesn't hurt too much. The reasoning is surely beyond recognition. Anyway, in the presence of countless reflections in-room, leading to nasty peaks 'n dips in frequency response mostly smoothed flat in measurements the frequency modulation is transformed into amplitude modulation. You may want to invest a thought or two on this. If not, what shall I say

 

[Scott Lanterman]

A member from S.Korea made a visit and posted too.

He owns t25b-6 and m74b-6, after the tour he is worried BlieSMa won't be end game after listening to purifi speakers!

And Purifi launching tweeter is not just a rummor but it is delayed and delayed we don't know if it will be done in a year...

Can you point me to the member who visited from South Korea and where he posted? I am fairly intrigued by the engineering folks behind these speakers as well as looking for a potential DIY project.

 

[Scott Lanterman]

As Purifi used a Mundorf AMT for the SPK5, I am pleased with the overall performance. Amir’s main complaint was over the bass balance and that is remedied with different port tuning. Directivity was pretty good and so is a decent design once you fit the crossover inside! As the Crowe design shows, you can make a 2-way work nicely with a properly designed waveguide. Multiple PRs across the back is an accident waiting to happen imo though. In the end, as a 3-way can get good directivity and hopefully forgo the waveguide, seems the better compromise. A Purifi tweeter might change my mind if it can reach low cleanly.



The tweeter of choice is a TBD compression driver. Hard to comment much more without knowing specifics. Should help with low-end power handling though. Also not clear what he is charging for the plans but his other prices seem reasonable. Last I checked, he is a forum member, so would leave specific questions to him. Is the guitar included?

Hey Rick here is a little more from the link Rasmus Larsen:

"Of course we also got to listen to some of their products. I was particularly impressed by the 2-way speaker incorporating their new 8" aluminum driver and a Mundorf AMT tweeter in a custom waveguide designed by Lars. The passive crossover was designed by Kim Nordtorp Madsen, and the enclosure featured ports with 1/4 wave stubs for cancelling the port resonance (something I've been curious to play with)."

Do you know what 1/4 wave stubs are? It seems like they have some low frequency resonance cancelling ideas in this speaker.

 

[JRS]

Yes to OB, the only other comparable experience I have had was using 18" (x2) infinitely baffled (IB) woofers. The back wave went into my crawl space no box vibration or back pressure the woofer is fighting. Just articulate, plentiful and palpable bass to fill the room (large open floor plan--no nodes of note). The other + to IB is the lack of cancellation, and yes I understand that the dipole radiation is a feature, not a bug. But the drawback is gobs and gobs of Vd to make it work--which is labor intensive, visually daunting, requires huge excursions and subject to tunnel resonances. The two long stroke Avalanche woofers in my IB able to do 105+ into the low teens, the Qts was about 0.6 so taut/articulate.

 

[Rick Sykora]

Hey Rick here is a little more from the link Rasmus Larsen:

"Of course we also got to listen to some of their products. I was particularly impressed by the 2-way speaker incorporating their new 8" aluminum driver and a Mundorf AMT tweeter in a custom waveguide designed by Lars. The passive crossover was designed by Kim Nordtorp Madsen, and the enclosure featured ports with 1/4 wave stubs for cancelling the port resonance (something I've been curious to play with)."

Do you know what 1/4 wave stubs are? It seems like they have some low frequency resonance cancelling ideas in this speaker.

Yes, think of a small tube trap (cylinder with a closed end) tuned to the frequency or (some close multiple of the one) you are trying to cancel.

Have seen some buried in the port itself (a tube within a tube). Could also be inside the cabinet but can be big enough to alter the volume so you have to compensate.

 

[fineMen]

Hi guys,

I've found the example of FM (Doppler, pysically unavoidable with high cone excursion) versus AM (motor non-linearities) again, on Purify's website:

Doppler distortion vs IMD? - PURIFI

Let’s get this out of the way first: Doppler distortion is a form of IMD. This is interesting because IMD in general tends to get little interest on loudspeaker forums, whereas Doppler distortion is often made a big deal of. Any distortion process will cause both harmonic and intermodulation...

purifi-audio.com

Thing is: over headphones there is a vast difference between the two, FM is not objectional while AM is; with speakers* there is no difference, both AM and FM are objectionable.

*Speaker used mono: BMS state of the art 1" compression driver on 90x60 waveguide with proper CD equalizer. Had the same result with more common hifi-speakers likewise

What do you get?

 

[fineMen]

Yes, think of a small tube trap (cylinder with a closed end) tuned to the frequency or (some close multiple of the one) you are trying to cancel.

Have seen some buried in the port itself (a tube within a tube). Could also be inside the cabinet but can be big enough to alter the volume so you have to compensate.

Bose (!) holds a patent on it. That's why all other have to circumvent the most simple solution. They've hidden it as an addendum to some esoteric 'chimney' patent. From what I know? I re-invented it.

 

[JRS]

This German site has a tweeter plus w/g that will do 'it' for just 50 bucks:
https://heissmann-acoustics.de/en/hochtoener-mit-waveguide/ (English translation isn't correct throughout , but you'll surely get the point)
... only without the cargo cult.

Regarding the woofer itself, it is said that the inevitable Doppler frequency modulation doesn't hurt too much. The reasoning is surely beyond recognition. Anyway, in the presence of countless reflections in-room, leading to nasty peaks 'n dips in frequency response mostly smoothed flat in measurements the frequency modulation is transformed into amplitude modulation. You may want to invest a thought or two on this. If not, what shall I say

??? Why on Earth would we want to use $50. tweeter with $700. woofer? The Satori is a worthy stablemate to the Purifi with very little distortion and able to absorb large amounts of peak power. The scan speak tweeters mentioned (an Illuminator and Revelator series) are very nice, but now we are getting back to 400 per side. I prefer SBA because they are underdogs with much engineering savvy and trying to keep if affordable. The Satori 6.5" woofer is superb midbass for less than $200. Not up to the Purifi, but at this point Purifi seem to be w/o peer. I working on project using Satori Be tweeter with Satori 9" woofer. Naturally one would wonder how this Purifi 8" would do--I'm sure fabulous, but the 500.00 difference in price buys nice 10 or 12 long stroke sub driver with plate amp. The P8 may be a wonder, but when talking about sub duty only, there are plenty of drivers that have lots of grunt but little extension that would be fine.

Which is what people have been saying. It's an engineering knockout but one is paying for a lot of bandwidth and it's silly overkill for 3 way. In other words, too expensive for all but niche 2 way SOTA application or a pair per side perhaps in a tower or large monitor TMM. Nice line array might be endgame as well.

 

[SDC]

Can you point me to the member who visited from South Korea and where he posted? I am fairly intrigued by the engineering folks behind these speakers as well as looking for a potential DIY project.

Sorry he don't post in english, but if you want to find him in dcinside nickname is 나무늘보5

one of the image he posted it will be easier to find the original post with this...( direct link not possible by ad-ful site)

 

[SDC]

Hey Rick here is a little more from the link Rasmus Larsen:

"Of course we also got to listen to some of their products. I was particularly impressed by the 2-way speaker incorporating their new 8" aluminum driver and a Mundorf AMT tweeter in a custom waveguide designed by Lars. The passive crossover was designed by Kim Nordtorp Madsen, and the enclosure featured ports with 1/4 wave stubs for cancelling the port resonance (something I've been curious to play with)."

Do you know what 1/4 wave stubs are? It seems like they have some low frequency resonance cancelling ideas in this speaker.

something like this? not sure though

 

[sloth_kwj]

Can you point me to the member who visited from South Korea and where he posted? I am fairly intrigued by the engineering folks behind these speakers as well as looking for a potential DIY project.

I was the one who visited Purifi. I considered posting here, but they are already very busy. I didn't want them to get a bunch of mails because of my post, so I decided not to post it. Instead, you can ask me and I'll explain it to the best of my knowledge.