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  • #16
    Originally posted by Colonel7 View Post
    To connect back to the thread, these statements don't apply to the Purifi driver as measured.
    ​​​
    In what way? It's not a 6.5" driver? The cone and surround don't resonate? It has a bit more clean deflection compared to a standard range driver but to quote from Erin:

    - Max SPL for 80Hz to 5kHz is approximately 105dB @ 1 meter. The compression threshold was exceeded above this SPL.

    So with subwoofers to cover < 80 Hz it is sufficient for a desktop speaker at standard levels. At 2m you would need to drop a bit below standard levels to maintain clean transients. This seems to be in line with the contents of the post you seem to be disputing to quote:

    - Clean SPL to resolve transients at standard levels should be OK for a 6.5" driver above 80-100 Hz at 1m.

    unless I am misunderstanding something?

    Comment


    • #17
      Originally posted by andy19191 View Post

      In what way? It's not a 6.5" driver? The cone and surround don't resonate? It has a bit more clean deflection compared to a standard range driver but to quote from Erin:

      - Max SPL for 80Hz to 5kHz is approximately 105dB @ 1 meter. The compression threshold was exceeded above this SPL.

      So with subwoofers to cover &lt; 80 Hz it is sufficient for a desktop speaker at standard levels. At 2m you would need to drop a bit below standard levels to maintain clean transients. This seems to be in line with the contents of the post you seem to be disputing to quote:

      - Clean SPL to resolve transients at standard levels should be OK for a 6.5" driver above 80-100 Hz at 1m.

      unless I am misunderstanding something?
      Here's the link to the actual review so folks can reference. I'm really not sure if you're pulling my leg but I'll respond. BTW, what is a "standard" level to you for "transients", THX home theater? I'll note that Erin listened to the Purezza at a distance of 11 feet at 95-100 dB, so I'd think your version of a desktop speaker is an auditory weapon. The Purezza box-tuning was also 35Hz I believe. The Purifi's Fs as measured is 30.3 Hz so it's not exactly an RS180P and it's 1% distortion extension is not exactly Dayton 6.5 classic woofer either (two good drivers for what they aim to do).

      For his compression test the result was actually 100.6 dB from 40 Hz - 3200 Hz. Not sure where you got your quote from but here it is.
      • Max SPL for Test 2 is 100.6dB. The compression threshold was exceeded above this SPL.
      Does this mean the speaker will not play above this level? No. It simply means, within a set of limits, the above values are the maximum the speaker output is. Above that SPL, the limits are further and further exceeded.
      ----
      Here are some nice cut-and-pastes from his review. I'll skip the section where he notes that the only driver he's measured in its category that has more xmax is the 18wu Illuminator (tested in 2011). I'll bold some parts for emphasis.

      Frequency Response:
      • The average sensitivity is measured at about 88.1dB from 300Hz to 1000Hz.
      • On-axis response linearity is ±1.5dB within 100-2kHz with some mild bumps here and there.
      • On-axis response linearity is ±3.0dB within 66-2.5kHz.
      • Breakup is kept to a very respectable +4dB above the mean SPL at 3kHz. This is quite good.
      • Off-axis response shows nice linearity until about 4kHz (evidenced by the 60° measurement showing a +4dB resonance at ~3.9kHz).


      Distortion and Compression:
      • This is the best speaker I have tested (I don’t have the same distortion data for the Scan 18wu I mentioned above). An incredibly low 1% THD above 70Hz at 100dB output!
      • The dominant mode of distortion is 2nd-order. But, really, it is so low… who cares what order is the contributor. 3rd-order distortion is 10-20dB lower than 2nd-order.
      • The maximum SPL tests are limited by the -2dB compression threshold; namely by the 500Hz region. Looking back at the HD and IMD measurements, there appears to be something in this region causing higher 3rd-order distortion HD. I’m not seeing traces of it in the impedance, though, which is the first place I normally look for problems “in band” (as opposed to out of the typical bandpass region).
      This speaker has the best distortion values I’ve seen with even higher SPL output capability than larger drivers. The 6.5-inch nominal speaker size combined with its excellent distortion and notable frequency response linearity make this a great option for those who want a smaller, compact 2-way bookshelf speaker.

      --------

      Oh, I forgot about the resonance issue. You said there would be resonances at higher frequencies in your earlier post. Where are they? If it's within the 1.5 dB to 3dB well, alrighty then!

      Comment


      • #18
        Originally posted by Colonel7 View Post
        I'm really not sure if you're pulling my leg but I'll respond. BTW, what is a "standard" level to you for "transients", THX home theater?
        Standard levels are the ones that are typically used when people concentrate on listening to music as the sole foreground activity. It is the level in the cinema, the level typically used (by the more sensible) in studios and to a fair extent defines the minimum level required for high fidelity reproduction in the home. Due to indifference to sound quality by the music industry there are no standards for recorded music requiring competent sound engineers to create their own in order to perceive the same sound from day to day and location to location. Typically it is 80-85 dB average with a 20 dB headroom for peaks. There are a few larger peaks but most settle on 20 dB as a practical figure.

        Originally posted by Colonel7 View Post
        I'll note that Erin listened to the Purezza at a distance of 11 feet at 95-100 dB, so I'd think your version of a desktop speaker is an auditory weapon.
        Is this for high fidelity music? Does it line up with the measured values presented? What might be the explanation? (I tried to get an earlier poster to respond along these lines).

        Originally posted by Colonel7 View Post
        For his compression test the result was actually 100.6 dB from 40 Hz - 3200 Hz. Not sure where you got your quote from but here it is.[LIST][*]Max SPL for Test 2 is 100.6dB. The compression threshold was exceeded above this SPL.
        I got it from my first hit on google. I have minimal interest in extremely expensive 6.5" drivers however well engineered (but I did look at the data when it first appeared) and so skipped to the summary at the end and picked what looked like the most representative value.

        Originally posted by Colonel7 View Post
        Oh, I forgot about the resonance issue. You said there would be resonances at higher frequencies in your earlier post. Where are they?
        The main cone resonances begin in earnest around 1 kHz and below the floppy surround may be contributing but one would need to be more on top of the measurement technique to be confident is separating measurement artefact from physical artefact.

        Originally posted by Colonel7 View Post
        If it's within the 1.5 dB to 3dB well, alrighty then!
        Eyeballing the rolling off rigid cone level with the measured rigid cone + resonances level, at 3 kHz the resonances would seem to be adding more than 5 dB and perhaps pushing 10 dB. Despite the ear/brain being pretty sensitive to hearing resonances and the resonances lying in a sensitive frequency range you would not expect this to be audible?

        I am not pulling your leg. I am genuinely interested in what you and others are extracting from the information published about the driver.

        Comment


        • #19
          Andy,

          can I suggest you read the entire review from Erin.

          then Read the review of the 7 SS Illuminator

          https://www.erinsaudiocorner.com/dri...ak18wu4741t00/

          then the SB17CAC
          https://www.erinsaudiocorner.com/dri...ak18wu4741t00/

          Compare and contrast.

          you may be surprised…

          Comment

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