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Calling all Zaph ZRT 2-way users

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  • Calling all Zaph ZRT 2-way users

    I am considering a Zaph ZRT 2-way tower kit...I'd like some feedback for those of you who have built a pair or listened to them. I am be interested in the ported version specifically.

    A) Did you have issues tuning the speakers? Did you adjust the BSC?

    B) I hear these are "Laid back", not exactly lively. I prefer lively. Is the ZRT a bad choice?

    C) How's the bass? Need subs or not?

    D) I will powering these with a 25w class a amp. I don't listen loud, maybe 90db max at the listening position. Will I be underpowering the speakers?

    E) And lastly, is asking for a full range sound too much from a 6+1 tower? My current speakers are a smallish 2.5 way, 5" drivers. I am OK with the bass but I wonder if the ZRT will be thinner in sound.

    I will build the cabs, so that's a big variable. Probably 1" or well braced 3/4 mdf. Any tips you have on the cabs are welcome.


  • #2
    Re: Calling all Zaph ZRT 2-way users

    Do a search for ZRT and the username lunchmoney. He built a pair, moved, treated the room, worked with Zaph to design a hoizontal center channel configuration.

    As to your questions... I haven't built them, so these are somewhat generic responses, however pertinent.

    Tweeter level and BSC are discussed under 2-way options. Nice of him to include it; completeness is a Zaph hallmark. That said, if you're concerned about bass extension and sensitivity, I'd consider the 2.5-way version. Any BSC in a passive XO will reduce system sensitivity 1 for 1, and a second woofer is all you need to add full BSC without changing voltage sensitivity. The 2-way with a full 6dB of BSC is an 8-ohm speaker with [email protected], 1m sensitivity. The 2.5-way, also with full BSC, is a 4-ohm speaker with [email protected], 1m sensitivity; +3dB from the second driver area and +3dB from the drop in impedence.

    Put another way, the 2.5-way will be pulling 2W at 2.83v, compared to 1W for the 2-way, but using a 20W amp, it'll have 10dB of headroom above that [email protected] level, compared with 13dB of headroom above an [email protected] level for a full-BSC 2-way. (Also note that the tweeter padding resistor drops from 6 ohm to 2.2 ohm for the 2.5-way, reflecting the greater output of dual woofers.)

    His bass tuning options show an F10 (-10dB from mid-frequency levels) ranging from 20Hz to the high 20's, the latter with a peak in the 50-60Hz range. Add in 6dB for room gain at 20Hz and that's very respectable bass performance. That comes at a price, however, in that the woofer will be nearing X-max with only 30W. Sounds perfrect for your needs. Note that his power handling discussion is based on a sealed box, and assumes you'll use subwoofage to fill in the low end.

    Laid back vs lively isn't a quantitative question, but a common one nonetheless. Speaking generally, the perception of a speaker as lively is sometimes due to harmonic distortion. These speakers have very low harmonic distortion, below 1% above 100Hz, with the 3rd hamonic at-or-below 0.1% above 200Hz. If they seem laid back, it's a reflection of accuracy. Bass response at the recommended 30Hz tune is quite flat, but you can add more "boom" by tuning it higher, if you'd like. I'd tune lower, knowing that room gain is unavoidable, so why not take advantage of it.

    I hope this helps,


    • #3
      Re: Calling all Zaph ZRT 2-way users

      Lunchmoney made the SR71 speakers. I could be wrong, but I don't think he made the ZRT.
      Statements: "They usually kill the desire to build anything else."


      • #4
        Re: Calling all Zaph ZRT 2-way users

        Look for member 'robert', and you will likely find what you are looking for with his ZRT's.

        Lively- nope.
        Speakers fine with 25W, amp likely not okay with the ~250W capability required to keep from clipping on musical transients of 30dB.
        Maybe subs, your call.

        I still say my Nephila would be a good option for you. I commented on your thread at DIYaudio....

        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
        "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
        "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
        "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

        *InDIYana event website*

        Photobucket pages:

        My blog/writeups/thoughts here at PE:


        • #5
          Re: Calling all Zaph ZRT 2-way users

          Yep, I stand corrected! I thought something sounded wrong... Seas reed 7 + 1 is much better.
          sorry, Frank
          Originally posted by john trials View Post
          Lunchmoney made the SR71 speakers. I could be wrong, but I don't think he made the ZRT.