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

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

    A stunning looking speaker, good job! Nice set of drivers too, should be quite impressive in the end.

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

    Drivers installed. Yay. Need to figure out bases.



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

    Sometimes simplicity is best, these are looking quite nice. Good job!

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

    Got the terminal plates done. It is a 3-way active so needed 6 posts.

    I went with gloss black acrylic, as it is the exact opposite of the matte white color of the cabinets. I also made the plate intentionally taller vertically just like the cabinets themselves.

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

    Holy wow, that paint looks freaking awesome!

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  • bkeane1259
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Love the paint choice. Looks really sharp.....very nice.

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

    Paint dried. Looks great - really even and flat, just the way I expected it. The "flatness" really makes it pick up the characteristics of whatever light it's in. I took pics of it under 2 different temperature lights to show.





    Next up is fabricating the stands/feet and the terminal plate.

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

    Looking good.

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

    Painting these with automotive paint.

    I decided to go with a "frozen" color instead of gloss as usual. These paint jobs are getting pretty popular on high end sports cars, and I've always liked the look as they sit between gloss and total matte.

    My girlfriend wants to repaint the kitchen cabinets white, so I figured this would be a good experiment before doing all of the kitchen work.

    Used this paint.
    http://www.tcpglobal.com/kustomshop/HRF202.aspx

    Here they are right after being sprayed. I believe they'll dry to be more flat.


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

    Originally posted by devinkato View Post
    As always, I had (on the sides) the bit cut end right on the edge of the joint, so if it starts telegraphing the joint in the future, its not noticeable to the eye, as you already expect a line there.
    I saw somebody here on TT do this trick a while back. I love this idea and think I might borrow it on some future builds. (I'm always learning something on this forum!)

    The fact that your eyes already "expect" to see a line/ edge at that exact location is brilliant for hiding seams, and doesn't look fudged in any way. Nice job.

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

    Sanded and filled in all the cracks and hit it with some high build primer. If anyone has any favorite high build primers that I should try, let me know. This is just the first one I saw and bought.

    http://www.tcpglobal.com/restoration...+KIT-KFP305-GL

    Leave a comment:


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

    Originally posted by devinkato View Post
    My question regarding crossing over in the audible range was more intended to discuss phase issues that occur around crossover slopes (not phase perfect crossovers). Are these phase issues also mitigated by C2C spacing, or are they simply due to the laws of physics in the crossover math? I know that many 2-ways crossover using crazy order slopes sometimes without issue smack dab in the middle of the range, yet I keep on reading (mainly from full range nut heads) how important it is to keep any sort of phase issues out of the mid range.
    You touched on several things here... let me make a few statements and then try to answer your questions.

    At this point I'd like to say that I'm not an expert and you can choose to dismiss any of my ramblings as nonsense.


    With no XO network:
    The raw driver will have an acoustic frequency response and acoustic phase response. In addition, there will be an electrical impedance curve plus an electrical phase curve.


    The Crossover filter:
    The choice of crossover filter type (Butterworth, Linkwitz-Riley, Bessel, Chevychev, etc..) and choice of slope (6, 12, 18, 24 dB/octave) will introduce a particular electrical response.


    The trick is to be able to combine all of the acoustic stuff above (response and phase) with all of the electrical stuff above (response and phase) and wind up with something that works well. The biggest reason I use Jeff Bagby's Passive Crossover Designer (PCD) is that it shows you all of the above items and the results that you should expect when they are ALL combined. This is no small task, and I can testify that it is amazingly accurate. The fact that he gives PCD away for free is quite shocking. I feel like I'm stealing a $500 software package every time I use it.

    So back to Phase. How does that relate to frequency response?

    People are always talking about phase... both acoustic phase and electrical phase but it's one of those techie terms that many don't fully understand. Not too long ago (prior to my PCD days) I assumed that all 2nd order networks had to be reverse-phased on the tweeter. As I saw it, the two-pole filter introduces 180 degrees of phase rotation so I figured you always had to flip the tweeter's polarity. I oversimplified things and completely ignored the acoustic phase of the driver and the interaction it has with the filter. Sometimes the combination of driver phase and filter phase requires a reversal of the polarity, sometimes it doesn't. Curt was kind enough to explain it to me.

    My point is, without looking at all of the phases and amplitudes, you don't have the full picture of what's going on. For example, if the phase is not tracking between a mid and a tweeter, then the frequency response can get a little mixed up. The mid and tweeter's responses won't add together smoothly and you might hear something that sounds a little "off". You might find that the two drivers are adding nicely below the XO freq but canceling above the XO freq. What the heck? I used to think that they would either add perfectly or cancel to produce a deep null. But there are dozens of variations on the XO filter designs that can produce a whole mess of in-betweens if you don't take everything into consideration.

    It's possible that a 2nd order lowpass on the woofer will add nicely with a 3rd order highpass on the tweeter. Or maybe the the other way around... it all depends on the phase of the driver/filter combination. Those textbook formulae are only the tip of the iceberg... a starting point that needs to be tweaked for every driver that you use, in order to get the phase and frequency response correct.

    So back to your comment about keeping any sort of phase issues out of the midrange... My opinion is that if a multi-way speaker is designed and optimized correctly, (utilizing all acoustic and electrical phase data) then it shouldn't matter what frequency you're mid-to-tweeter crossover is designed around. Just my opinion.

    And yes, keeping the center-to-center distances as small as possible certainly helps matters. But as always, it depends on the wavelengths involved.

    Example 1: Two woofers are separated c-t-c by 9". That 9" corresponds to a wavelength of about 1500 Hz. But if the woofers have a Low Pass roll off at 80 Hz, then the shortest wavelength they will reproduce is up around 170 inches, so the c-t-c distance of 9 inches doesn't really matter all that much in this case.

    Example 2: Mid to tweeter c-t-c distance is 9" and XO freq is 3000 Hz. At 3000 Hz the wavelengths are about 4.5". So you've got 2 point sources separated by 9" trying to both reproduce a 4.5" wavelength. That's going to be a nightmare, creating massive constructive and destructive interference patterns. In this case the 9" separation REALLY matters!


    Sorry that I wrote a novel in response to a simple question. Have fun!

    Leave a comment:


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

    Edges done.

    Went with a 3/4" roundover on the sides, and a 3/4" chamfer on top. I didn't engage the chamfer all the way to the full 3/4" - woulda looked too deep. As always, I had (on the sides) the bit cut end right on the edge of the joint, so if it starts telegraphing the joint in the future, its not noticeable to the eye, as you already expect a line there.

    Leave a comment:


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

    Thanks again ReissM - I'm glad my little project has gotten some gears turning.

    I do realize the importance of C2C in terms of point sourcing multi way speakers - Although I do believe it becomes less important the further away the listening position is. I used speed of sound / C2C spacing = MAX crossover point. This is MUCH easier in a 3-way than in a 2-way with a large woofer. This is the exact reason I am a HUGE proponent of 3-way front stages in car audio. There is no way that a 2-way setup with a woofer in the door, and a tweeter on the dash will EVER be okay acoustically.

    As far as home audio - I tend to stay away from any personal 2-way builds, as there are a lot out there that have been proven to work really well and I'm perfectly content standing on the shoulders of giants for those projects. That said I tend to do more "random" projects such as this thin 3 way for my own use. I definitely tried to keep the drivers as close as cosmetically possible.

    My question regarding crossing over in the audible range was more intended to discuss phase issues that occur around crossover slopes (not phase perfect crossovers). Are these phase issues also mitigated by C2C spacing, or are they simply due to the laws of physics in the crossover math? I know that many 2-ways crossover using crazy order slopes sometimes without issue smack dab in the middle of the range, yet I keep on reading (mainly from full range nut heads) how important it is to keep any sort of phase issues out of the mid range.

    Leave a comment:


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

    Originally posted by devinkato View Post
    Last question/comment - I know a lot of people try to avoid having a crossover point in the middle of the audible midrange - you seen to not agree with this, as you mention crossing over right at ~ 2000hz. Is this something you've wrestled with, or think its a non factor in your experience? In car audio (worst environment) at least, having a point source driver handle as much midrange as possible has proven to improve imaging. Of course, this is dealing with driver placement, time alignment, etc, which can be controlled much better at home.
    In my experience, if properly implemented, it's fine. So what does "properly implemented" mean?

    Well, let's take a step back for a second. In a perfect world we would have one transducer reproducing the entire audible range from 20 Hz to 20 kHz. A point-source. As you probably know, it's nearly impossible for a single driver to do that. The high cone excursions required for deep bass will mess up the delicate midrange. Also, in order to produce deep bass we typically need a larger diameter woofer... which will have beaming issues at higher frequencies. (We don't normally see a 12" woofer playing up to 20kHz right? Even if it could, the beaming would be terrible, like a flashlight shinning out light in a very narrow cone.)

    So we typically split up the range into 2 or 3 pieces. Hence "2-way" and "3-way" designs. There are even 4 and 5-way designs but let's not get carried away.

    So in order for 2 drivers to appear as though they are acoustically one, we try to locate them as close to each other as physically possible. Remember that at the crossover frequency both drivers are producing sound. Depending on the slope of the filters, the overlap can be 1 to 2 octaves above and below XO freq. Any time there are multiple sources producing the same sound there will be interference issues. This issue can be minimized by placing the acoustic centers as close together as possible.

    Combining the knowledge of beaming that I discussed earlier with the physical proximity of the 2 drivers to each other is key.

    2-way example:
    We could push a 12 woofer up to 1800 Hz then have a tweeter take over from there up to 20 kHz. The problem is that the dispersion of the 12" woofer will be pretty bad at 1800Hz while the 3/4" tweeter will have a nice, wide dispersion at the same frequency. That wouldn't be a well designed system as far as driver integration goes.

    A 6" woofer would be a better choice in the above design. It's dispersion would be much better at 1800 Hz and the two drivers would integrate better.

    So to answer your question, I personally don't think it's a problem to crossover drivers at 2 kHz (or any other freq.) Just keep the two drivers located as close as you physically can, and cross them as low as you can safely do it without risking driver failure or high distortion. The lower the frequency, the longer the wavelength... and thus, the less chance that the physical offsets can create problems.

    These are just my personal opinions and I'm sure there are many out there that will disagree. I'm open to hearing other people's opinions on this subject.

    Leave a comment:

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