Announcement

Collapse
No announcement yet.

Kairos 3-way conversion : tweak my bass

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Kairos 3-way conversion : tweak my bass

    I built my Kairos over 2 years ago and have been enjoying them thoroughly ever since (overdue photos to follow) .
    I originally supplemented them with a stereo pair of active subs, which i already had on hand.

    These helped a bit on the super low end, but didn't really address the one real short coming i saw with the 2-way:
    it has a hard time keeping up with the irrational exuberance it inspires.

    The sound is so sweet and clean with a natural soundstage, you just have to turn the level up! Not an issue on anything pure acoustic, but on something more punchy, the woofer will start dancing. On a few select recordings it could bottom out. This was alluded to in Jeff Bagby's writeup, so no surprise there, since I don't limit myself to listening to pure audiophile recordings. Just have to keep a lid on the exuberance.

    Recently, i finally got around to building the 3-way woofer add-on. This inserts a low cut sent on the 2-way section. The 6.5" satori woofer, (now the "mid") calmly goes about doing its job without breaking a sweat or threatening to jump out of the cabinet. So Mission Accomplished! : sounds sweet and i no longer have to feel guilty about pushing it too hard.

    So now to my question...
    I am finding the low end a little too strong. Its got all the thump you could ever hope for, but on many recordings it's a bit much.

    This possibility was also discussed in JB's writeup. There are 2 woofer options presented. i chose the more reasonably priced ( still not cheap) SB Acoustics SB29NRX-75 woofer. Close examination shows that this one is 4-5 db more efficient between 60 - 120 than the more expensive CSS option. I knew that going in, but I've always been a bit of a bass fiend when it comes to lifelike reproduction. But without my active subamps, i've lost the capability to fine tune.

    What would be some sensible things to try to control the woofer level?


    Some more info:

    Kairos are ported, but currently tubes are stuffed , making it sealed.

    Sub cabinet is repurposed , about 2 cuft. and built like a battleship from the Brooklyn Navy Yard (thanks Roman!). So its a bit larger than as prescribed, but scrapping it is not really on my radar. Also ported, but currently have tubes stuffed, making it sealed.

    Room is a bit small, but has been very well treated with bass traps, diffusion etc etc.

    The 3-way conversion XO is published (unlike the 2-way kairos XO) here:
    https://meniscus.lightningbasehosted...ay-Writeup.pdf
    For the low pass its a 2nd order around 200Hz. It has a 3 ohm damping resistor on the Capacitor leg.


    I've started playing around with some parts on hand to see how it helps. For example increasing the L value or adding a 1-2 ohm resistor just to dissipate some power, but these are just low hanging stabs in the dark.
    Utlimately it will have be based on how it sounds in my room, so I'm wondering what a more informed approach should be.

    Thanks!
    Jeff

    BEER: Proof that God loves us and wants us to be happy

    I've measured many things I cannot hear; and heard things I cannot measure...

  • #2
    Don't use a resistor. You are going to start a fire with one inline to that bass section. You would need be dissipating large amounts of power through them if you are using them in series with the bass driver. Not only that but you will be changing the Qts of the woofer so it doesn't act as designed in the enclosure.

    I think you only have two options in my opinion (well, three if you count a redesign with less baffle step on the top section). You can go active on the bottom to adjust the level independently or you can go with the SDX10 which is less sensitive.
    -Kerry

    Comment


    • #3
      Eq ...

      Comment


      • #4
        While the tweeter has plenty of padding, there's really no route to raising the sens. of the mid-section (short of MTM-ing it, AFAIK, w/out seeing the XO topology - but the mid's got no resistors in it at all, does it?).
        It's important that the 150uF cap be inline (series) on the mid (doesn't really do anything to the tweeter section).
        Can't say that I see the 10n(ohm) parallel resistor doing much (for the rolloff) on the 3-way conversion (still, it can't hurt).

        You COULD try adding (upping) the woofer's L to 10mH, if so, I'd also double the resistor (3n to 5n or 6n) and the shunt cap to 400uF (just throw a 200 npe on there for fun).

        Big problem is (running both closed) your mid and woofer sections (now) have pretty similar (bottom end) rolloff curves.
        Looks like you've got quite a "hump" in the 60-80 range?

        (I'd just go active on the bottom - plate amp / leaving the TM as orig. designed.)
        Last edited by Chris Roemer; 02-23-2020, 01:18 PM.

        Comment


        • #5
          In this case I found the bass to have too much emphasis to be pleasing to my ear.
          As Mr Bagby states himself, this setup isn’t really the best. Some 6dB or more above mean level. The only fix I can think of is redesigning the Xover and crossing bass to mid at 400 to 500Hz. The resulting smaller band pass for the Satori possibly helps sorting things out.

          Comment

          Working...
          X