Please review the site Rules, Terms of Service, and Privacy Policy at your convenience. Rules, TOS, Privacy
Get familiar with the reaction system: Introducing the Reaction System

The Zonkers - An isobarik 8" two-way

124»

Comments

  • The same 60L cabinet and driver and 100W power, simply ported vs sealed.

    4thtry
    I'm not deaf, I'm just not listening.
  • You'd think the pressure below the tuned frequency would drop off as there's no loading below it in the ported box.

  • That would be my thought as well. Who knows what math determines that chart in SoundEasy, it could be wrong for all I know. It's the only software I know of that will plot the cabinet pressure though. One of these days I might connect a pressure sensor to a cabinet and see for myself just to confirm the above graph, I should be able to whip that up with some spare parts from work.

    I'm not deaf, I'm just not listening.
  • Had to google kPA to get an idea of the pressure. 1 kPa is approximately the pressure exerted by a 10-g mass resting on a 1-cm2 area. Or 1 kPA = 0.145038 PSI.

  • I believe that SoundEasy plot to be correct. I think there would still be high pressure in the box, but it is increasingly out of phase with the driver cone motion at decreasing frequency.

  • It is out of phase, the port becomes a hole offering no resistance to the speaker, hence no way for the speaker to create pressure. Like a cylinder with no spark plug in it.

  • @4thtry said:

    @ugly_woofer said:
    I like the steep crossover slopes Bill, nicely done.

    Thanks, Nick. I kept the cost down by using Daytons I-core's and NPE's on the woofer branch. It is sounding pretty good so far and the tweeters seems to be able to handle the power when I crank them up into the 90dB+ range. I'll run some 95dB distortion plots and post them later.

    Sorry for the delay in collecting and posting this data. I decided to take the Zonkers to SDC and see how they do in the Dayton category. Since I am crossing at 910Hz to a one inch dome tweeter, the judges will most certainly ask me if I have any HD measurements. I was always meaning to run up some HD plots, but then covid hit and I forgot all about it. So here they are. Taken this morning with OmniMic at a distance of 1 meter on tweeter axis at a 95dB playback level.

    95dB is a fairly high level for just one speaker at a distance of 1 meter. So, analyzing the crossover regions 2nd and 3rd harmonics, I think I am in good shape. Group delay doubles for an 8th order xover, but I don't think most people can hear group delay.

    500Hz 2nd: -47dB or 0.4% 3rd: -47dB or 0.4%
    600Hz 2nd: -55dB or 0.15% 3rd: -43dB or 0.7%
    700Hz 2nd: -55dB or 0.15% 3rd: -44dB or 0.6%
    800Hz 2nd: -62dB or <.1% 3rd: -48dB or 0.4%
    900Hz 2nd: -51dB or 0.3% 3rd: -51dB or 0.3%
    1kHz 2nd: -50dB or 0.3% 3rd: -60dB or 0.1%

Sign In or Register to comment.