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Theorized and proven: "Zingers", an InDIYana 2019 8" 2-way design...

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  • Wolf
    replied
    Phil, yes, I got lucky on the plywood veneer again. This board had scuffs and marks on it. A little sanding is all it took to make it pretty again.
    Eric, yes MWAF they will go. Under 200, I suspect.
    Djg, I hope it is a hit! They really do sound much better than I anticipated.
    Wogg, it is possible the other tracks would have bettered their standing. They do dig quite well.
    Nick, we seem to agree more often than not.
    Dcibel, yes, you hit the nail on the head as to what I did and why. This is my 3rd 8" 2-way, so I made some clever assumptions. The plots are however, gated responses without any blending. I use the time of flight phase from OM, and don't like the Blender program. Plots are on-tweeter-axis, 20deg H off-axis, and HD. The NF was only to get an idea of the bottom roll-off. Both channels have some dips in the right places, and off axis does not suffer one bit. Mind you, I do prefer the 6 part network, and I'm fine with your playing around. I would have given you the data files had you asked.

    Thanks for looking!
    Wolf

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  • dcibel
    replied
    Nice project Wolf, and a good result for an 8" 2-way with 5 components!

    I hope you don't mind me adding this in here. I was looking at all the squiggly lines trying to figure out which was which, and getting confused that your far field right response looks too similar to the near field left plot. Anyway, I found the file names that you posted which cleared a few things up for me. This isn't really a criticism of your project, just something I decided to play around with because I can, and you had provided a lot of squiggly lines to play with.

    It strikes me as odd that you took a nearfield measurement, but then didn't use it in your simulation, it appears that a far field "blended" plot was used in simulation, IMO this makes it hard to judge how much BSD you are adding in, but I'm sure you have your reasons and methods that work for you. I had a half hour to kill, so I traced your data with this neat online tool and loaded it into SoundEasy. I merged your nearfield data with a BSC sim with the far field data at 600Hz, so you can see the low end response a lot better. To be clear, I checked that the transfer function and impedance is a match, the only real difference here is the woofer frequency response data (I used the left speaker data).

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    I think what you have here is very good, especially the fact that there is a bit of a dip in the 3kHz region, this will help compensate for the "directivity bloom" from crossing a 8" woofer to a 1" tweeter. There is a bit of a lump in the response at 1kHz that doesn't show up really in your response simulation above, but it is evident in the filter transfer function. I think you made good compromises here, as you'd have to go over the 5 component rule to improve this further IMO.

    For reference, this is the raw woofer "merged" response:
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  • 6thplanet
    replied
    Nice to see some wood, Benny! Will these show up at MWAF this year?

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  • philthien
    replied
    I'll also add that, you've been lucking-out on the veneer front, that is a lovely baffle.

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  • Thezeek
    replied
    Cool build Wolf.

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  • djg
    replied
    CL = craigslist. As in $20 vintage rotted foam driver cabs. Most I've seen are taller and shallower than the design calls for. I think this could be a very popular design.

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  • ugly woofer
    replied
    I really liked these, I voted for them.

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  • wogg
    replied
    I liked these, very easy to listen to. Not sure why they didn't stand out of the tough crowd in your group, but I'm sure the more challenging tracks with the deep bass would have put them in a better spot. I can't speak for anyone else in the room, but when I hear 40Hzish notes filling the room my attention is piqued. I'm a little bass biased

    djg CL?... my guess is constrained layer, is that right?

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  • Wolf
    replied
    Very cool! Keep us posted.
    Wolf

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  • djg
    replied
    I'm going to look for some CL cabs to make these.

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  • philthien
    replied
    I sure would enjoy hearing these.

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  • Wolf
    replied
    I was able to get the network on a 4" x 7" board relatively easily. Yes- you do see 2 other twisted taps on the xover's LP coils. I wound those in my jig so I had 2 other options to play with. I had 1.8mH, 2.0mH and 2.2mH (simmed), and wound up (HA! LOL!) at the 2.2mH level. I tried 7.6, 8.2, and 9.1 ohms for the 1st resistor on the tweeter. 7.6 was not enough, 9.1 was dull, and 8.2 might be just a touch over. Then I added the 33 ohm across the tweeter, and it came into the right spot as well as reducing the grit/glare/nasality.

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    Total cost as built came out to about $240 with the parts I used. $111 or so in drivers, and guesstimating on the xover parts I used since some are NLA. Using 250V CSA caps drops the cost to about $230 total.

    FWIW, I really like these! Bass for days that extends really low, sensitivity that is in the upper 80s, and a size factor that won't make most builders cringe. Top it off with an affordable cost, and these are a very easy project to stomach that would gut punch you with bass if you said otherwise.

    I look to get actual measurements of the final responses and post them in the near future, as I've not verified them as yet.

    Thanks for looking, and hope you find these interesting.
    Later,
    Wolf

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  • Wolf
    replied
    You can see the breakup for the woofer was in different places for the left channel (above, 2.5K) and the right channel (below, 1.9k).

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    Since the right channel FR measured closer to the spec sheet, I used it as info in the initial sim, and made sure off-axis FRs, and the left channel FRs did not produce any peaking with the simulated schematic.
    This is what I came up with for the on tweeter axis right channel FR:

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    The impedance and phase angle make for a relatively benign load, albeit a 4 ohm nominal load. The breakup is reduced enough that I did not find it (them) audible. The acoustic phase (not shown) was about 90 degrees out, so this is likely closer to a Butterworth alignment than an LR, but I do get a very narrow reverse null that dips to -20dB from reference. I'm assuming more parts can make it better aligned, but since the off-axis is not causing issues, I'm leaving it alone! Xover point came out about 1850Hz. Second order electrical on the woofer rolls it off fairly well. The tweeter is second order as well with a series resistor for level, and an added parallel resistor for Fs compensation. Trust me- it needed it!

    Network is as follows:

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    Just a bit more...
    Wolf

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  • Wolf
    replied
    Click image for larger version

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    You can see here that the HD of the woofer and tweeter really are not awful being -35dB from reference for the woofers, and even lower for the tweeters. They might not be world-class SOTA low HD, but it's still quite decent. The added benefit of the HD inherently reducing itself above about 1.2kHz is a welcomed bonus on the woofers.

    And to also show the right channel...

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    Woofer nearfield:

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    More to come...
    Wolf

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  • Wolf
    replied
    Left speaker measurements; on-axis/20*H/HD:

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    Woofer at same mic position:

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    To be continued...
    Wolf

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