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SCM 50ASLT with subs -- stuff the ports?

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  • SCM 50ASLT with subs -- stuff the ports?

    I'm now four weeks into a pair of 50ASLT's, replacing 40A's and 19A's before that. I was using JL Audio e-110 subs with the 40A's, which they complemented nicely, and have continued over with the 50's, although I've held off fine tuning the set to give time for burn in. Since the 50's are ported, are there some different considerations that apply in integrating with subs? JL Audio's tech suggests that plugging the ports make for a better integrated response and ATC midrange. I'll set things up without first, of course, but I'm wondering, has anyone tried that or had problems integrating subs with the 50's? Thanks,
    Last edited by highstream; 06-07-2022, 12:39 AM.

  • #2
    I have no experience to offer - sorry - but perhaps some thoughts.

    I think the port tuning frequency on the SCM50 is very low (23 Hz or so - from interpreting the impedance curve in the HiFi Critic passive SCM50 test). So the port probably does not have much output until the SCM50 input is down at a very low frequency. AIUI ATC tunes loudspeaker ports for power handling primarily rather than low frequency extension.

    Do you use a high-pass filter to feed the SCM50s? I think the e-110 has this. I suspect stuffing ports probably has more impact if you don't. But if you are, and are crossing over well above the port tuning frequency I am not sure stuffing the port is going to change anything significant.

    However it's an easy matter to try and see if it does work in spite of my thoughts. And I am sure there are people who use JL subs with SCM50s so I am sure they can offer better comments than mine.


    • #3
      Thanks. I got the following response from ATC: “The ports are tuned to fs which is around 28Hz on our SCM50. Sealing the ports will make a difference to the shape of the rollout and therefore will affect the response well above fs.”

      I am still interested in hearing others’ experience with integrating subs with the active 50’s.


      • #4
        I tried a REL t-7 series sub without much success. I just couldn't tune it right in the room and sub didn't have much punch and I didn't like the cheesy gloss finish and cheap controls. I then tried a B&K Monolith Plus. Great sub, but the same story with integration. I couldn't get the cross over right. The 50asl's just sounded better without a sub.


        • #5
          I think the in room bass response is the difference to consider (from 40 to 50) and that is in part due to the ports but it is also a different cabinet and driver set up, as you know.

          But the idea of plugging the 50s port seems odd. I think the JLs you have are a sealed design? As a comparison the ATC subs are all sealed but I don’t think I’ve seen advice to plug the ports of ATCs when integrating their own subs.

          Personally I think it is hard to answer your question given the multitude of variables at stake. The main one being, what sound are you looking for?

          If it were me I would be taking some basic room measurements and looking to get a smooth (not flat) bass response in room. Something I’ve not achieved, for many reasons!

          At the end of the day it’s only got to sound right to you but we all worry about what others might think, right?!


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