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Mid Size Tower Rebuild Options

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  • Mid Size Tower Rebuild Options

    I have a pair of old NHT 2.1 mid-size tower speakers that have a customer built in into existing window seating that becomes a built-in TV center. There are cutouts for these mid size tower speakers and no one makes mid-size tower speakers.

    I'm interested in all options for reusing the enclosure and if need be abandoning speakers (to fill in the enclosure). All the woofers are intact but the MF has completely degraded . I'd like to explore options of replacing speakers and/or using a new crossover or recap the cross over. Based upon these speakers being from the early 90s, the woofers could probably be replaced as well. The specifics of the speakers and what they look like are located at this webpost:

    I reached out to the manufacturer and they don't have any information on it but would recone. The crossover is probably a butterworth type with 3 capacitors, 2 inductors, 4 resistors. The inductors don't have any values on them, nor are there impedance values on the speakers.

    You'll observe that there is additional information, that is because I took apart the whole speaker.

    Design: 3-way, 4 driver, acoustic suspension
    HF : 1" soft-dome, fluid-cooled tweeter, 3.75" with filler plate
    MF : 6.5" high compliance, mid-woofer
    LF : 2 x 6.5" long-throw, polypropylene woofers (in parallel)
    Crossover: 3,2 kHz, 6 dB/oct; 80 Hz, 6-12 dB/octave (3 capacitors, 2 inductors, 4 resistors, prolly butterworth type)
    Response: 40 Hz - 25,000 Hz ±3 dB
    Sensitivity: 87 dB (2,83 V/m)
    Impedance: 8 Ω nominal, (3,2 Ω minimum)
    Power Handling: 200 W/ch max. (35 W/ch minimum)
    Dimensions (W x H x D): 7" x 34" x 12"
    I appreciate your help

  • #2
    Not an expert on this particular speaker, But would help immensely to see a real life picture of the mid driver damage they have incurred.

    If it is just the foam surround, there would almost for sure be a repair "kit" to replace the surround by itself, assuming the driver is not damaged.

    Crossover caps might be old, but they are easily replaced.

    Could you measure the exact width of the drivers? ( To the outside edge of the metal frame) They say 6.5", but often with woofers, they may vary between 6.5"-7.0 inches.


    • #3
      Is just the foam surround degraded? If that is the case, it can be replaced. I have done a few and it is pretty easy. There are videos online with good tutorials. Also, I am not sure where you are at, but Midwest speaker in St. Paul MN does these type of repairs.


      • #4
        Yea maybe I should or reclarified. I'd like to reuse the box and don't want to refoam things. The one speaker that hasn't degraded( cause of pair), sounds sub-par. I believe speaker advancements have been made since the early 90s. Should I just go buy some pioneers and just drop them in place and see how things sound? Like dual cones for the woofers and a 3 or 4 way for the mid?


        • #5
          How thick are the cabinet walls ( OR/ give us the INside dimensions - guessing there're TWO compartments: the lower (sealed) woofer pair, and the top (tweeter & mid)?

          Do you want to keep the tweeters?
          There are (nearly) an "infinite" number of driver diameters. You've been asked for the exact frame dimensions for your drivers?
          Odds are that using "modern" drivers, you'll no longer get satisfying bass without adding a port to the bottom (woofer) cab.
          You'll need an entirely new crossover design.


          • #6
            Replace drivers = new crossover, possible box modifications. You should really consider then what it is you are salvaging? A box? The simplest and easiest to construct part of a speaker??

            My recommendation would be to either repair the existing drivers and carry on or ditch/sell them and move on to completely new speakers. The latter would seem to be more logical given you're unhappy with the sound in the first place

            A speaker is a complete system - box, drivers, crossover....replacing two of these and salvaging one, in my opinion and experience, is close to pointless in terms of the economics and final result.
            Constructions: Dayton+SB 2-Way v1 | Dayton+SB 2-Way v2 | Fabios (SB Monitors)
            Refurbs: KLH 2 | Rega Ela Mk1


            • #7
              Do the woofers still produce satisfying bass? Are the enclosures still in pretty good shape? Do you already have or would you be willing to invest in a cheap measurenent microphone, cable, and some other bits and pieces?

              I drive way too fast to worry about cholesterol.


              • #8
                Also what area of the country do you live? There might be one of us close by that would be will to help out with the driver measurements and crossover design.

                I drive way too fast to worry about cholesterol.


                • #9
                  The Amiga tower speaker kit is 34" high, 8" wide, and 11" deep. The NHT is 34" high, 7" wide, and 12" deep. Would the Amiga fit? It may look plain, but it is an excellent speaker.




                  • #10
                    The same designer used the same cab for this design.