The AlTi, a DIY 2-way bookshelf speaker design.

Discussion in 'DIY Speakers and Subwoofers' started by Matt Grant, Aug 15, 2017.

  1. I had purchased the newer black coned Hi-Vi M5N-B a little while back, finally swapped one into on of my AlTi speakers and tested it against the original M5N. The frequency response overlaid nearly perfect, so those are a drop in swap for this design if you like the look of the black woofer cone over the original M5N's light copper/gold color.

    Added some new photos of that woofer on the few posts.
     
  2. Hi Matt,

    Thank you for this design, I am currently looking for my first DIY speaker project and this one looks very promising. I was originally considering the C-Note kit but the AlTi looks like should sound better.

    I'm slightly worried about this part of your description :
    I going to be using them in my living room, where I'll frequently be more than 20 degrees off axis. Should I except an audible degradation in higher frequencies in this case ?

    My current amp is a small class D so I'll add the resistor to the crossover. I read that C-Notes don't play well with class D amps (notable rise in HF). Should I expect similar issues with the AlTi or is the resistor going to help with this issue ?

    Thank you for your patience !
     
  3. #28 Matt Grant, Apr 18, 2025
    Last edited: Apr 18, 2025
    The extra rolloff in that range doesn't result in any kind of drastic change in the balance or timbre, it's just a subtle decrease in some of the sparkle or air in the treble. It won't be too different then many regular dome tweeters off axis.

    The resistor prevents a capacitive load in the ultrasonic range which many class-D amps don't play nice with causing audible distortion, noises or shutdown issues. This is separate from the frequency response variability issues certain class-D amps have with differing load impedance.

    I did test the AlTI among several other speakers in some measurements looking for the frequency response issues of class-D amps, and it shows basically any speaker design that does not have a flat impedance and phase over the top two octaves will result in some form of response irregularity on any class D amps that are susceptible to that issue. Unfortunately that does include the AlTi.

    Here is a link to that testing I did:
    https://www.mtg-designs.com/tips-tr.../amp-frequency-response-variability-with-load
     
  4. Hey Matt,

    I'm in the process of modeling the cabinets to prepare for the cnc machining and I noticed a difference between the flange thickness in post #2 (5/32") and the 3D render in post #25 (5/16"). I checked the woofer and tweeter, the thickness is indeed 5/32". It would be great if you could edit the render to correct this.
     
  5. Thanks for pointing that typo out, crazy enough the 3d render has the correct dimensions it's just that I manually changed the text from the decimal 0.15625" to fractional to make it easier to read and made a typo putting 5/16" instead of 5/32".
     

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