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Hello, and My Second 3-Way

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  • Brian B
    replied
    I recently picked up an iMM-6 microphone and loaded the calibration file into my Nexus 7 tablet. Finally got it all to work and ran some sweeps. I used the warble tones from Stereophile Test CD 2 for the source. Below are the graphs of these 3-Ways (Lumotas).

    Both the sofa position and 1 meter position curves show a significant drop in frequencies below about 400Hz. But the speakers don't sound thin to me. Not sure what is happening with that. The seated (sofa) position is the red curve and the 1 meter position is the dark curve.

    Click image for larger version  Name:	Lumotas Sweeps.jpg Views:	1 Size:	101.8 KB ID:	1376746

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  • wogg
    replied
    Originally posted by xmax View Post
    These can give surprisingly accurate results with a tablet ​https://www.parts-express.com/dayton...droid--390-810
    +1 You can even use them with proper free software like ARTA or REW if you've got a laptop with an integrated headphone/mic jack. Sent from my SM-G960U using Tapatalk

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  • Brian B
    replied
    Thanks for the suggestion. I'll keep an eye out for when they are back in stock.

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  • xmax
    replied
    These can give surprisingly accurate results with a tablet

    https://www.parts-express.com/dayton...droid--390-810

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  • Brian B
    replied
    My measuring equipment is nearly non-existent. I have an old Fluke 77, a Shure Beta 57A, a pro audio pre-amp, and a free signal generator app for my tablet. Certainly not sufficient tools for any useful measurements. I have other priorities that pull me away from doing more than about 1 speaker design per year, and I don't see myself investing in reasonably good test equipment for so little use. I'd rather buy more woodworking equipment or make some improvements around the house.

    I have no doubt that these speakers could be improved by measurements and appropriate crossover changes. But I'm happy with what I'm hearing in my room, so I probably won't do much more with them at this point.

    Most of the other speakers I listen too are rather old designs, so I don't have much in the way of a reference point for more recent designs. I am currently building a set of Overnight Sensations as a quick acoustic data point. I would have finished them by now, but I'm painting the enclosures and the weather hasn't been warm enough for long enough to complete the painting (outside the house).

    But I did do a lot of listening and crossover tweaking during the development of the Lumotas. It was interesting how certain changes made some recordings sound better while making other recordings sound worse. It seemed there was no combination that made all recordings sound their best. So the Lumotas now stand as a compromise that makes most of the recordings I listed to (a wide range of rock, pop, country, jazz, and bluegrass) sound reasonably good (to my ears).

    It would be nice to get another opinion regarding the results, but building another set represents considerable investment and work on someone's part. And they may not consider the final results worth the effort. Especially given the many excellent DIY designs available.

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  • xmax
    replied
    I remember my first and 2nd 3 way, I wish I would have taken pics...

    Simulations can be fun but nothing is better than the real thing.
    Have you taken any measurements?

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  • Brian B
    replied
    Additional details of this design are posted in the Project Gallery. I named them Lumotas.

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  • Brian B
    replied
    Got them finished and back together. I missed listening to them during the finishing process.

    Click image for larger version

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  • chrisn
    replied
    Originally posted by Brian B View Post
    Thanks for the reminders. I used 10W resistors, and at least one was doubled up. I also spaced them up slightly off the board. All felt cool to the touch each time I checked them. Perhaps I didn't have the volume cranked up enough .
    I had the same experience until I cranked up a pair of 3 ways I gifted, because you never know how they will be abused. They got real hot fairly quick, and they were already doubled up. I now go with 30-50w if they are in series with the mid, if it's crossed low. Nice veneer btw.

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  • Brian B
    replied
    Thanks for the reminders. I used 10W resistors, and at least one was doubled up. I also spaced them up slightly off the board. All felt cool to the touch each time I checked them. Perhaps I didn't have the volume cranked up enough .

    Leave a comment:


  • bullittstang
    replied
    Please keep in mind - this adjustment to the mid (if done via resistors) will get very hot due to the current. Make sure the resistors are an adequate rating (25w) and have plenty of space around them to dissipate the heat they will generate. This is especially true with a 300-Hz woofer-mid XO point (or at least per your estimates)

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  • Brian B
    replied
    With a three way crossed at about 300Hz, there is considerable latitude to adjust the relative level of the midrange to the woofer without adding extra parts to the woofer crossover.

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  • Millstonemike
    replied
    Originally posted by Brian B View Post
    Been listening to these for a few weeks and made another minor padding change to both mid and tweeter.
    I bet you're making up for the exclusion of a BSC in the original XO design.

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  • Brian B
    replied
    Been listening to these for a few weeks and made another minor padding change to both mid and tweeter. I'm happy with the sound of these three ways so I've removed the drivers and started the cabinet finish. I decided on a cherry veneer and the cabinets have an initial coat of finish. It will probably be a couple of weeks before the finish work is complete and they are back together making music.

    Click image for larger version

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  • Brian Steele
    replied
    Originally posted by Brian B View Post
    With the extra padding, the modeled response looks like this:

    [ATTACH=CONFIG]n1364643[/ATTACH]
    ​Looks like you've got some BSC built in there

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