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Overnight Sensations MTM Bass Question

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  • JJanzen
    replied
    Originally posted by Chris Roemer View Post
    Your vol. and tuning are VERY close to Paul's - it's your (stepped) baffle and driver placement that could color things.
    Chris, I had no idea that would effect the sound quality. I think I will build a couple of cabinets identical to Paul's original specs and see if I can do an audible comparison.

    Thanks everyone for your thoughts on this....I learned a lot and really appreciate it.

    Joel

    Leave a comment:


  • JJanzen
    replied
    Originally posted by Prana Ferox View Post
    JJanzen, does your cabinet have any kind of stuffing, liner or fill?

    Paul tends to recommend a fistful or two of Polyfill for his builds to add a bit of damping, seemingly to cure exactly what you're complaining about . A big bag is cheap as heck in your local Wal-Mart sewing section.

    From the OSMTM write-up: "The enclosure could be lined with convoluted foam, which is pretty standard for a vented design such as this. In my case, to keep things simple, I did not line the enclosure at all. Instead, I used a few light handfuls of polyfil behind the woofers (the internal braces sort of held it in place). As I told many people who built the original Overnight Sensations, getting the right amount of stuffing takes a bit of experimentation. I find the best results when I over-stuff a bit, then gradually take some out, listening each time. I know when I get the right sound; the speaker suddenly just sounds "huge.""
    Yes, there is poly in the cabinets. The complete kit that Meniscus sell comes with everything.

    Leave a comment:


  • Chris Roemer
    replied
    Your vol. and tuning are VERY close to Paul's - it's your (stepped) baffle and driver placement that could color things.

    Leave a comment:


  • djg
    replied
    You might want to build a "stock" enclosure including interior treatment to see how that sounds. It's possible you just don't like this design.

    Leave a comment:


  • Millstonemike
    replied
    Originally posted by davidroberts View Post
    djg, sorry that was my oversight on the TMM and MTM version. It still doesnt change the fact that the enclosure volume the OP sighted are way too large
    DJG nailed the issue. Dave, I suspect a comparison pic of the excursion graphs at power would show the the OP what he's hearing.

    Leave a comment:


  • Prana Ferox
    replied
    JJanzen, does your cabinet have any kind of stuffing, liner or fill?

    Paul tends to recommend a fistful or two of Polyfill for his builds to add a bit of damping, seemingly to cure exactly what you're complaining about . A big bag is cheap as heck in your local Wal-Mart sewing section.

    From the OSMTM write-up: "The enclosure could be lined with convoluted foam, which is pretty standard for a vented design such as this. In my case, to keep things simple, I did not line the enclosure at all. Instead, I used a few light handfuls of polyfil behind the woofers (the internal braces sort of held it in place). As I told many people who built the original Overnight Sensations, getting the right amount of stuffing takes a bit of experimentation. I find the best results when I over-stuff a bit, then gradually take some out, listening each time. I know when I get the right sound; the speaker suddenly just sounds "huge.""

    Leave a comment:


  • JJanzen
    replied
    Ok, so I my calculations are all screwed up...I deal in square footage all day long in my regular job and divided my cubic inches by the incorrect number. Guys, thanks for bringing that to my attention! I do agree with djg that Paul's design is .32 cu. ft. My cabinets are .35 cu ft. with the corrected calculations. David, would you be kind enough to re-run the frequency response again with the OS MTM shown as well? Just to be clear, my port size is 1 3/8" I.D. x 5 1/2" long. Thanks again!

    Joel

    Leave a comment:


  • djg
    replied
    If I wanted a pair of skinny mini towers with more than adequate bass, and I had $500 sitting around, I think I would go for Paul C.'s Speedster TMM. I need a pair of those like I need another hole in my head.

    https://sites.google.com/site/undefi.../speedster-tmm

    Leave a comment:


  • djg
    commented on 's reply
    Yes, OP misplaced a decimal point at the very least.

  • Kornbread
    commented on 's reply
    I didn't even realize there was an mtm version of the os.

  • davidroberts
    replied
    djg, sorry that was my oversight on the TMM and MTM version. It still doesnt change the fact that the enclosure volume the OP sighted are way too large for this design.

    Here is the frequency response for the MTM (blue), TMM (pink) and OP's posted volume and port size.

    Click image for larger version

Name:	OS TMM Enclosure.gif
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ID:	1458315

    Leave a comment:


  • djg
    commented on 's reply
    Again, the stock OSMTM cab is .32 cu. ft. 9 liters volume. You're looking at the TMM tower. Similar but different. Probably get more bass from the TMM.

  • djg
    commented on 's reply
    Actually, the volume of the stock OSMTM cab is .32 cu. ft. 9 liters.

  • davidroberts
    replied
    Originally posted by JJanzen View Post
    Ok, I have verified/clarified a couple of items. 1) Paul's design for 3/4" MDF cabinets is by my calculations 3.85 cu. ft. My cabinets are 4.17 cu. ft......a bit of a difference (7.5%). The specs for the (2) ports on my drawings are incorrect. The actual port size that comes with the Meniscus kit is 1 3/8" I.D. x 5 1/2" long. l
    I am not sure what design you are looking at but Paul's website shows the cabinets are 21l or 0.75 cu ft. If your cabinets are 4.17 cu ft (it doesn't look like it from the posted drawing) they are about 5.5 times the designed cabinet size.

    https://sites.google.com/site/undefi...htsensationtmm

    Using your volume and port sizes in Unibox your design results into a tuning of ~15hz. The blue line is the enclosure design per Paul's website, the Red is your current cabinet size and ports.

    Click image for larger version  Name:	OS TMM Enclosure.gif Views:	0 Size:	48.7 KB ID:	1458295

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  • Kornbread
    replied
    Going over the crossover and rechecking driver connections would be my first step. You could cut up some cheap $1.50 extension cords, run that from each driver out the port, pull the crossover out and lay it on the floor, and recheck everything. Even if the connections are correct, moving them around would give you an idea of what it sounds like when one or more drivers are out of phase. ~4ft³ is sub woofer territory.

    Leave a comment:

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