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3-Way Active - High WAF - Hi-Vi-Fas

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  • Sydney
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by devinkato View Post
    As far as drivers - am I correct in understanding that the closer you push a driver towards its frequency limits, that is where you start seeing more unpredictable phase issues? Like the "not exactly in phase, nor exactly out of phase" phenomenon you describe?
    I not sure what you mean either...

    Leave a comment:


  • ReissM
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    The woofer's voice coil inductance will play some role in this too. Exactly what... I'm not sure.

    Anybody else want to add some insight to this discussion of acoustic phase?

    Leave a comment:


  • ReissM
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by devinkato View Post
    Forgive my ignorance...
    Whoa... time out. No need to apologize. We're all just amateurs here on TT forum. If I came across as an expert, then I apologize to YOU. I was just expressing a few of my own personal opinions based on my past experiences. Please continue to ask questions and learn from everyone here on TT.


    Originally posted by devinkato View Post
    ... I do know that drivers' distortion increases as they're pushed towards their frequency limits. Is phase also affected in the same way? Is it harder to integrate drivers' phase summing when they're being pushed towards their frequency limits?

    I know that all normal crossovers also introduce phase issues, I was referring more to the phase issues that the drivers themselves introduce.
    That's a very intelligent question. I don't have all the answers... but let's take a look at the acoustic phase of your woofer. I took the CLIO data that PE posted and plotted the phase. The "180 degree wrapping" typically seen on phase plots can be misleading, so I unwrapped the phase plot and a trend emerges that seems to follow your intuition. Take a look at how little the phase changes until we approach approximately 7,000 Hz. At 7,000 Hz the rate-of-change of the acoustic phase increases dramatically. This appears to corroborate what you suspected.

    Click image for larger version

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  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by ReissM View Post
    Hmmm... I'm not sure I fully understand what you're asking. The phase summing/cancelling issues are a result of several things.
    Forgive my ignorance - I do know that drivers' distortion increases as they're pushed towards their frequency limits. Is phase also affected in the same way? Is it harder to integrate drivers' phase summing when they're being pushed towards their frequency limits?

    I know that all normal crossovers also introduce phase issues, I was referring more to the phase issues that the drivers themselves introduce.

    Leave a comment:


  • ReissM
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by devinkato View Post
    ...am I correct in understanding that the closer you push a driver towards its frequency limits, that is where you start seeing more unpredictable phase issues?
    1. acousticacoustic
    still

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  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    ReissM - that's exactly what I've been doing in the car over the years. Glad to know I'm doing something right!

    Proper phase is really easy for my ear to find - it usually makes a big difference in terms of something "shouting" and blending.

    As far as drivers - am I correct in understanding that the closer you push a driver towards its frequency limits, that is where you start seeing more unpredictable phase issues? Like the "not exactly in phase, nor exactly out of phase" phenomenon you describe?

    Leave a comment:


  • ReissM
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by devinkato View Post
    ...The main challenge that is new to me that I haven't directly addressed in the car environment is phase interaction of drivers.
    1. Measure woofs only, (with filter.)
    2. Measure midrange only, (with filter.)
    3. Now measure woof and mid at same time, (with filters)
    4. Repeat #3 with midrange driver reversed phased.

    Now look at all four plots at the same time. You'll probably see either that either #3 or #4 produces some acoustic cancellation due to the drivers' phase. Typically one of these will be much better than the other. Welcome to the world of "Phase". LOL.

    Ok, what happens if #3 and #4 are both problematic and the woofers are not blending well with the mid? (Adding properly at some frequencies, but cancelling at other freqs.) That's the challenge of crossover design. It means that the combination of drivers and filters is not exactly in phase, nor exactly out of phase. At this point I would try changing one of the two filters to have a slightly different slope, which will affect the phase... and possibly get the woofers and midrange summing properly.

    By overlaying 3 measurements: just woofers, just midrange and the acoustic combination of them, it becomes clear where the drivers are adding and where they are cancelling due to phase. Make some adjustments and repeat... make some more adjustments and repeat.

    Hope this helps.

    P.S. - use the exact same methodology for midrange to tweeter crossover design, except that you'll be keeping the midrange polarity that you determined already, and you'll be changing the tweeter's polarity until you get the drivers to sum properly.
    Last edited by ReissM; 12-05-2012, 09:25 PM.

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  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by phidauex View Post
    Looks great! I'm glad I made the transition to spraying automotive urethanes, and I suspect you are, too. The quality of finish is just a lot nicer than what you can get through normal DIY means.
    Thanks! Yes, moving away from spray paint was the best thing I ever did. I'm only upset that I didn't move to HVLP'ing earlier. I wasted a lot of time trying to get spray paint even a fraction as good as what I get now much easier. Just bought a new house, and unfortunately the builder chose an ugly kitchen cabinet color. Just spent 2 days masking off the kitchen from the rest of the house, and sprayed this same white onto the cabinets. Looks great.


    Originally posted by phidauex View Post
    I may have missed it, but what are you using for amps?
    Not sure yet, I have a nice a/d/s 6 channel car amp that I've used before with a 55 amp power supply. Sounds really good. I suspect adding a small 12v atv or motorcycle battery to the chain could be even better.
    I also have 3 AMP One's that I could use (they're a bit underpowered IMHO).
    Last option is a pair of crowne CTS 4200 4 channel amps. That could be a bit overkill.

    Originally posted by phidauex View Post
    I'm very interested to hear about how the XO development goes, I was seriously tempted to build my last pair of floorstanders (Zaph ZDT3.5 variant) as an active set, but chose not to for the time being - the next set, however, will be worth the time to experiment with.
    Yah, XO development will probably take up a lot of time. I'm trying to teach myself to use ACD, but I keep getting frustrated and dead ending. I need to upgrade my brain. That said, I have a lot of experience tuning by ear and using RTA in the car audio environment with active crossovers, so I've gotten ~ 80% there with just generic-ish settings. The main challenge that is new to me that I haven't directly addressed in the car environment is phase interaction of drivers.

    Leave a comment:


  • phidauex
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Looks great! I'm glad I made the transition to spraying automotive urethanes, and I suspect you are, too. The quality of finish is just a lot nicer than what you can get through normal DIY means.

    I may have missed it, but what are you using for amps?

    I'm very interested to hear about how the XO development goes, I was seriously tempted to build my last pair of floorstanders (Zaph ZDT3.5 variant) as an active set, but chose not to for the time being - the next set, however, will be worth the time to experiment with.

    -Sam

    Leave a comment:


  • superspeeder
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    These are looking really nice! I really like the idea of a thin tall tower, especially when the WAF is tossed into the mix. I may actually show this project to her to demonstrate how nice a small tower can look (she tends to think all speakers are ugly...). Throw in some paint that matches our trim and she might not be able to resist... yeah right!

    I have a question that's only kind-of related to your build, so instead of hijacking your thread I decided to start a new one. The question is in regards to directivity, and I would appreciate everyone's thoughts:

    http://techtalk.parts-express.com/sh...78#post1872578

    Thanks in advance, and good luck with your bases! The concrete idea could be cool, or it could be a mess... I'll be interested to see how it turns out either way!

    Leave a comment:


  • greywarden
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    My dad did the countertops for his outdoor kitchen in concrete and stained/sealed them. He actually sanded them down with his palm sander, which nearly destroyed it, but they're pretty legit.

    Leave a comment:


  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Decided to try my hand at working with a new material - concrete!

    Going to make short "sleeves" that the speaker will slide into. Should be fun. Anyone have any experience with decorative concrete?

    Leave a comment:


  • bolland83
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    How about a truncated circle with a 1/4" chamfer around the top edge, in gloss black?

    Leave a comment:


  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    They're surprisingly stable, the bottom 7.5 inches are solid MDF. But yes, I will be making some bases. I really don't have any idea what to do though. Reached a bit of a dead end. Only ones I've seen that I kinda like (maybe I like the speaker more than the base) are these.



    Anyone else got any ideas? I did buy the isolation spikes thus far

    Leave a comment:


  • ReissM
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Great looking design! Any thoughts on a base to help stabilize them? You wouldn't want these to accidentally tip over.

    Leave a comment:

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