Speaker designs using PURIFI Audio drivers.

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  • Norm
    Member
    • Mar 2011
    • 62

    Speaker designs using PURIFI Audio drivers.

    Starting this thread for discussions and reports on systems using Purifi Audio’s (https://purifi-audio.com/) groundbreaking loudspeaker drivers.

    This blog post is a good introduction to the technology that led me to pursue Purifi’s drivers:


    I presently have a system I call Fi16v1 (Purifi drivers in 16 liter enclosure version 1) using PTT6.5W04 woofers (one per speaker), PTT6.5PR passive radiators (two per speaker), and Fountek CD 2.0 ribbon tweeter. Crossover is external and should not even be considered a preliminary design. It is repurposed from my NT10 design as a stand in while drivers are measured and Fi16 crossovers (both passive and active) are designed. DSP in JRiver music player software was used to correct the 8.5 dB difference in sensitivity between woofer and tweeter.

    First off a recommendation for and thanks to SMJ Audio http://www.smjaudio.com/ without whose help I would be staring at the Purifi drivers in their cardboard boxes rather than enjoying listening to them. I had a 16 liter box that could be repurposed for this project but the pandemic had closed off my access to CNC and choked off time to cut required baffles manually. Steve Manning to the rescue, just look at the fantastic Birch ply baffles with threaded inserts he created off my drawings. The 3D render is Steve’s he created using my 2D drawings to verify we were on the same proverbial page.

    The PTT6.5W04 seen test fitting Steve’s CNC programming skills is there for a SMJ Audio project I await with anticipation.







    Here is the Fi16v1 bass alignment simulation from UniBox. Before snarking it will ‘only’ do 98 dB bass at 30 Hz note this is from a 15” H x 8.5” W x 10.75” D box.



    Next a drawing of the Fi16. The front and side views showing a dome tweeter reveal this box’s origins from my NT10 design shown at Lone Star Audio Fest in 2018 and 2019. I realized by converting the false back to a windowed brace I would get the 16 liter volume this alignment calls for and the PRs just fitting on the rear. The selection of the Fountek CD 2.0 ribbon tweeter is also a pandemic constraint, I have owned this pair for years and they were rescued from gathering dust in the garage to provide a first listen.



    And the as-built. For these prototypes the finishing was shortcut by the arrival of the drivers from Denmark. The stain + single coat of poly finish will be eventually be upgraded to veneer and high gloss epoxy. That may take a while given how much I am enjoying listening to these in their present state.







    The summary of listening reaction is:

    First reaction to hearing the Purifi woofers is to be stunned at the quantity, depth, and quality of the bass they reproduce.

    Second reaction is to become aware that through the midrange and on up to the hand off to your tweeter transparency, clarity, and dynamic ‘jump’ are by a large margin better than anything I have heard from a 6” – 8” driver. The only other times I have experienced this level of hear into the performance with so many musical details and textures and tones revealed is from 7’ tall line arrays or big horns at the level of Volti Audio.

    The following two links are to more detailed listening impressions I posted on diyaudio.com.
    This driver makes a nice midrange but it was designed to be able to move a lot of air in a vented alignment. It would be a waste to use it on an OB. You couild use so many other drivers there as a midrange. Try Faital 6FE100 or 5MR450NDY. They have higher Qts and are also low distortion, and...

    I went to look at the Hypex Fusion Plate Amplifiers - nice system. Do they come with embedded dacs or can you use your own? - I would like to ideally use a single dac of my choice... don't know if that is easy to do or not Well, with a digital crossover you always need multiple DACs. Fusion...
  • dwk
    Senior Member
    • Apr 2005
    • 251

    #2
    Nice initial design. Where did you cross to the ribbon?

    I have to admit I'm finding it increasingly challenging to resist the temptation of these drivers. The main barrier at the moment is that they're ugly, and since my primary design musings are around a system for our living room, cosmetics matter. I'd have to go with a grille of some sort with these. The secondary barrier is that as great as their bass appears to be, in our big space I'd definitely want woofer/sub support, and if using them as essentially a mid I'm not sure the value proposition is quite as clear/compelling - the 'killer app' for these is definitely the high-end 2-way IMHO. Still, it seems that they're state of the art even if only using from say 100-2k.

    Am I right that at the current DKK exchange they run about $330/driver at qty 2 pricing? Plus shipping, of course.

    Comment

    • AJINFLA
      Senior Member
      • Mar 2005
      • 680

      #3
      Originally posted by dwk
      Am I right that at the current DKK exchange they run about $330/driver at qty 2 pricing? Plus shipping, of course.
      You could...but they are available at Madisound now https://www.madisoundspeakerstore.co...1a-6.5-woofer/

      cheers.

      AJ
      Manufacturer

      Comment

      • dwk
        Senior Member
        • Apr 2005
        • 251

        #4
        Well, crap - thanks!. Don't know how I missed that. Now I have a dilema - continue with my current experiments, or just go for it.....

        Comment

        • Evil Twin
          Super Senior Member
          • Nov 2004
          • 1531

          #5
          I agree that there is much potential to be realized with these drivers, which is why they were chosen for my next generation NatalieP design experiment.

          I hope to see for myself the degree to which they reduce IM distortion in the meat of the power band- from 80Hz to 600Hz- if this proves out, they should also be a candidate for a high performance center channel speaker.

          Congratulations on finishing your build and enjoying the fruits of your labor.
          DFAL
          Dark Force Acoustic Labs

          A wholly owned subsidiary of Palpatine Heavy Industries

          Comment

          • Dave Bullet
            Senior Member
            • Jul 2007
            • 474

            #6
            Your unibox model seems wrong to me as well as interpretation. 15mm xmax? where did you get that from. Isn't the woofer xmax 10mm? (ok you can usually add 15% "safe" overexcursion if you want). Your graph has 10Hz at the origin, so you are hitting ~93dB @ 30Hz (not 98dB as claimed).

            Comment

            • Norm
              Member
              • Mar 2011
              • 62

              #7
              Dave Bullet commented and asked: “Your unibox model seems wrong to me as well as interpretation. 15mm xmax? where did you get that from. Isn't the woofer xmax 10mm? (ok you can usually add 15% "safe" overexcursion if you want). Your graph has 10Hz at the origin, so you are hitting ~93dB @ 30Hz (not 98dB as claimed).

              The PTT6.5W04-01A data sheet lists Linear Xmax +-10mm and Mechanical Xmax +-14.5mm, the passive radiators are listed as having Mechanical Xmax +-15mm. One aspect of using UniBox I have always found a little fuzzy is the driver parameters have the entry for Xmax listed as “Xmax peak”. If one wants to use the Linear Xmax does one enter in the PTT6.5W case as 10 mm or the plus and minus unsigned sum of 20mm? For the graph above the Unibox Xmax peak is set at 14.5mm and PTT6.5PR Xmax peak is set at 15mm. That and using the manufacturer’s data sheet IEC power handling = 350 watts I readily admit states system redlined case.

              In more typical drivers that lack this Xmax capability one exercise I find useful is to reduce the Unibox ‘Nominal power’ input until the SPLtot line (blue line in graph above) lies below the red excursion limited SPL line. And that is what I take as your objection “~93dB @ 30Hz (not 98dB as claimed)”. I agree 93 dB is the more conservative number. Would you agree 93dB @ 30Hz bass out of a box with the height and width of a Yamaha NS10 (15 x 8.5 x 10.75 d in inches) is a technical accomplishment of note?

              I posted the downhill with a tail wind result for two reasons. First in comments to journalists and directly to me Purifi brag the PTT6.5W is extremely rugged telling one reviewer to go ahead and bang it against the mechanical stops you will not hurt it. Second I posted after living with my Fi16v1 for a couple of weeks and unless your living room hosts a JBL 4331 or 4333 or 4345 you will find a PTT6.5W04-01A based speaker will rock your world.

              Comment

              • Bear
                Super Senior Member
                • Dec 2008
                • 1038

                #8
                Originally posted by Norm
                Dave Bullet commented and asked: “Your unibox model seems wrong to me as well as interpretation. 15mm xmax? where did you get that from. Isn't the woofer xmax 10mm? (ok you can usually add 15% "safe" overexcursion if you want). Your graph has 10Hz at the origin, so you are hitting ~93dB @ 30Hz (not 98dB as claimed).

                The PTT6.5W04-01A data sheet lists Linear Xmax +-10mm and Mechanical Xmax +-14.5mm, the passive radiators are listed as having Mechanical Xmax +-15mm. One aspect of using UniBox I have always found a little fuzzy is the driver parameters have the entry for Xmax listed as “Xmax peak”. If one wants to use the Linear Xmax does one enter in the PTT6.5W case as 10 mm or the plus and minus unsigned sum of 20mm? For the graph above the Unibox Xmax peak is set at 14.5mm and PTT6.5PR Xmax peak is set at 15mm. That and using the manufacturer’s data sheet IEC power handling = 350 watts I readily admit states system redlined case.
                Use 1-way Xmax or Xmech, depending upon what flavor of modeling you are doing (e.g., "Will it sound good?" vs "Will I damage it?").

                In more typical drivers that lack this Xmax capability one exercise I find useful is to reduce the Unibox ‘Nominal power’ input until the SPLtot line (blue line in graph above) lies below the red excursion limited SPL line. And that is what I take as your objection “~93dB @ 30Hz (not 98dB as claimed)”. I agree 93 dB is the more conservative number. Would you agree 93dB @ 30Hz bass out of a box with the height and width of a Yamaha NS10 (15 x 8.5 x 10.75 d in inches) is a technical accomplishment of note?

                I posted the downhill with a tail wind result for two reasons. First in comments to journalists and directly to me Purifi brag the PTT6.5W is extremely rugged telling one reviewer to go ahead and bang it against the mechanical stops you will not hurt it. Second I posted after living with my Fi16v1 for a couple of weeks and unless your living room hosts a JBL 4331 or 4333 or 4345 you will find a PTT6.5W04-01A based speaker will rock your world.
                If you look at each of the detailed worksheets, you will see dedicated Peak Excursion charts. For PR modeling, this helps you see how the acoustic load is transferred between the PR(s) and the driver(s) with changes in tuning (mass, box volume). For the Purifi, a single Wavecor PR223 looks like a decent fit, but a Dayton RSS265-PR does not.
                Welcome to Rivendell, Mr. Anderson.

                Comment

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