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  • DeZZar
    replied
    Originally posted by davidroberts View Post
    Long story short, sometimes you have to throw the measurements out the window and trust your ears.
    Your ears are definitely the final judge but sometimes when trying to triage issues in the middle of design you need the measurements to tell you what you are hearing (this is a perfect example of that).

    Shallow/Steep slopes etc....my view is there are no rules here - everything has to be application specific. Shallow slopes wont work here - but might with other drivers and baffles, and so on. To follow a rule might result in sometimes awesome, but sometimes disaster. Its why my advice is always build a kit if you're thinking you can use some calculators and general rules of thumb to design from scratch!

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  • davidroberts
    replied
    Several years ago I convinced Dennis Murphy to help me with a set of speakers. At the time there was a lot of buzz going around about the high order filters so we decided it would be fun to publish the measurements and allow others a shot at the xovers. Many known designers chipped in and posted their results. Funny thing is that although Dennis' design had the most shallow slopes it was also the most preferred when compared. Long story short, sometimes you have to throw the measurements out the window and trust your ears.

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  • DeZZar
    commented on 's reply
    It appears in the off-axis modelling. I hadn't done any actual off-axis measurements on the early prototype crossovers so I hadn't confirmed it was the case, but certainly sounds like it was there. Once I can try a higher crossover point per below I'll run the full off-axis measurements and confirm.

  • Steve Lee
    replied
    DeZZar, not sure where that 2.4 KHz peak came from but it wasn't in your prior postings.

    Yes - that specific frequency is a really nasty peak to have - Cybill-Aunt as hell, too!

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  • Wolf
    replied
    Uh- that will definitely get fatiguing! I'm sure that was the cause.
    Wolf

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  • rpb
    commented on 's reply
    Can they supply absorption data? Nothing beats fiberglass that I'm aware of.

  • DeZZar
    replied
    Thank you to everyone for the suggestions. I've worked up a few more models and I think I'm going to try the one below. Thanks to rpb and Wolf for getting me to re-consider where the crossover point could be. I really didn't believe a higher point was going to be possible but working up a little higher has actually provided the best modelled result so far. As soon as I can I'll throw this one together and see how well it translates into reality.

    This is around 2.6K actual crossover point. It looks as though its crossing at 3K due to the diffraction null that's occurring at 3K.

    Click image for larger version

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    I didn't confirm this with measurements but I think this was probably a contributing factor in the brightness on one of the earlier attempts. Thoughts?
    (in terms of how smooth this response looks I note that the modelling tends to be a little more extreme looking than what it actually measures like)

    Click image for larger version

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  • DeZZar
    commented on 's reply
    I've never really used EQ - I mean I use it sometimes to help in development - add some filters etc to test speakers out but not for my main listening system. I've just concluded over the years that some songs just wont suit some speakers particularly when you're talking high resolution systems. The old 'bad recording made worse' is definitely true. In this case I just want to make sure there are no technical mistakes in the implementation! Few more iterations to go I think! :D

  • DeZZar
    commented on 's reply
    Its from a local electronics supplier - described as "650gsm Acrylic Speaker Dampening Material"

  • rpb
    commented on 's reply
    Leave a 1" to 2" airspace behind the foam on one, or both sides. That will increase effectiveness.

  • Steve Lee
    replied
    We will never get away from the need to EQ.

    There are no perfect speakers/rooms for all audio . . .

    Good luck, DeZZar - I gave up trying to mix for everyone else . . .

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  • DeZZar
    commented on 's reply
    I'll give that a go!!

  • rpb
    replied
    Originally posted by DeZZar View Post

    Not absolutely certain no. However, in a lot of testing I would listen to either just the woofer or tweeter. The woofer got a little 'honky' with a sort of ring to it in some cases which resulted in trying to further smooth out its knee and bring down the lumps around 1k. Female vocals, tenors etc just sounded a little harsh at the top end of their scales. Once that was taken care of the same content sounded spot on - even smile inducing for my neighbor (who these are for) and a very nice warm yet detailed sound. The tweeter mostly added only ambience to a lot of this music. However, switching it up to some metal tracks is where things were getting a bit bright/hot and I again though maybe the woofer. But in this case when playing the tweeter on its own it definitely seemed to be the contributor - where before when addressing the woofer - the tweeter barely added anything (with different musical content).

    Based on the models for these current crossovers there does appear to be an off-axis increase in output between 2-3K. I'm not sure at this point what I might be able to do about that - however - for the meantime I've just going to get both boxes caught up to the same point and then resume modelling and testing.

    I'll try the resonance trap (notch?) and see how that goes as well.
    This sounds like insufficient damping to me. See added comment in above post.

    A thin layer of felt probably does very little below 2k.

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  • rpb
    commented on 's reply
    Is it just felt on the side walls? If so, I'd add a lot of the acoustic foam there.

    What exactly is that acoustic foam?

  • DeZZar
    replied
    Originally posted by augerpro View Post
    Are you sure it's the tweeter misbehaving? Try a resonance trap, some tweeters just really don't tolerate the Fs getting tickled. Try 2.0 mH, 22 uF, 2.0 ohm trap on one speaker and see if that makes a difference. Model it first, that is for a ScanSpeak 9130 but the Fs is similar to the SB29 you're using and should get you close.

    Off axis modeling is essential, off axis flares in the 2khz area can really make for a hard/harsh sounding speaker.
    Not absolutely certain no. However, in a lot of testing I would listen to either just the woofer or tweeter. The woofer got a little 'honky' with a sort of ring to it in some cases which resulted in trying to further smooth out its knee and bring down the lumps around 1k. Female vocals, tenors etc just sounded a little harsh at the top end of their scales. Once that was taken care of the same content sounded spot on - even smile inducing for my neighbor (who these are for) and a very nice warm yet detailed sound. The tweeter mostly added only ambience to a lot of this music. However, switching it up to some metal tracks is where things were getting a bit bright/hot and I again though maybe the woofer. But in this case when playing the tweeter on its own it definitely seemed to be the contributor - where before when addressing the woofer - the tweeter barely added anything (with different musical content).

    Based on the models for these current crossovers there does appear to be an off-axis increase in output between 2-3K. I'm not sure at this point what I might be able to do about that - however - for the meantime I've just going to get both boxes caught up to the same point and then resume modelling and testing.

    I'll try the resonance trap (notch?) and see how that goes as well.

    Leave a comment:

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