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Thread: Project M2 DIY Thread

  1. #826
    Senior Member srm51555's Avatar
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    This is really good stuff Ian, thank you for sharing all of this.

    Thanks,
    Scott

  2. #827
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    Hi Scott,

    The intent is to provide you guys something diy as an option or until you get closer to a full active dsp solution. It’s not finalised yet. As l said previously this is a starter passive crossover. It’s not about some really serious effort to conquer the digital domain. It’s a fall back to try out and an option to play with, relax and have fun with.

    Once l have more useful measurement data l will provide the next update and progress.

    Sent to G.T for comment. We are not sure if the D2 voice coils were wired in series or parallel in the 4367.

    Edit 02/06/22

    I stacked up two 5 cu ft jbl dimensioned ported enclosures today outside to get the 2216nd measurements at 1.6m off the ground. Ran a series and even distant low frequency noise from traffic effects the low frequency measurements in the first octave. I will have to go through them and pick the best one out. Also ran a gated series on the M2D2 up on top of the stack. A few less bumps and wrinkles here and there.

    I will assemble a M2 spec’d diy enclosure soon to validate the Diy M2 passive crossover. Please do not ask if it will be Charge Coupled.

    My 486 Pentium old school PC running LMS is over 120 in PC years old so l am avoiding turning it on and off. I think the mother board is about to go.

    Ian

  3. #828
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    Quote Originally Posted by Robh3606 View Post
    Clio Pocket works just fine all my "M2" measurements were done using it. They have updated it 3 time since I have owned it. It's self contained, self calibrating and you just need a USB port. It's a really nice portable measurement system. First time you calibrate wait about a 1/2 hour for the control box to reach it's temp equilibrium.

    Yeah I hear you on the computer my Clio 7 and Leap are on an old Pentium running XP so it's only a matter of time! Hope you get it back! I had the same thing happen and switched out the power supply and it came back to life.

    Rob
    Apparently you can run Leap on a Mac Laptop with software called Parallel provided you have a copy of XP or other MS OS that your version of Leap with run on.

  4. #829
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    A few updates on there Beta M2 diy passive crossover network.

    The write up :

    Today I ran the first global optimisation for the M2 diy passive crossover using new measurement data.

    LF summary
    The system LF voltage drive and response was modelled on the JBL 4367 schematics using real data and then characterised for the M2 diy passive 800 hz 6th order low pass response. The LinearX Leap 4 optimisation engine obtained a response within 0.78 db of the optimisation target curves. Elements such as baffle size and baffle step response were part of the raw data in todays series of measurements. I think the -2 to -3db HP shelving from 100 to 800 hertz will work out once in a domestic room with wall boundaries. The dcr in the inductors will extend the LF naturally.

    HP Summary
    I re-worked the HP filter and obtained excellent phase tracking using Pos's dimensional drawings post 769 here. The straight line above 15Khertz was tail correction for the minimal phase transform and can be ignored http://www.audioheritage.org/vbullet...l=1#post374875 ( Hint: Its about time you guys posted an index somewhere. Pos made a good start in organising the threads. Get one of your kids to do it.)

    Results see attached pdf of the voltage drives, response, impedance etc. No schematic yet available. The response is within a 3 db window from 150 hertz out to 18Khertz. This is what you can do with good data, good tools and some insights.

    My view and I stand by this is that a pfd is a far superior way of viewing the details. HTMLs cannot easily be zoomed in to see the details. You can print or zoom in on a pdf. I don't particularly want this picked up by bots and winding up on Pinterest. This is for you guys not anyone else.

    The next steps.
    Obviously the design will be need work within the constrains of the M2 enclosure. The phase transform can be adjusted for some fining tuning of the driver Z axis.
    I am pleased with the basic response controls and feel that there is sufficient adjustment while minimising complexity.

    My next step is to build up the network for testing. No point going any further at this early stage.
    Attached Images Attached Images

  5. #830
    Administrator Robh3606's Avatar
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    Looking good Ian! Wait till you power them up!!

    Rob
    "I could be arguing in my spare time"

  6. #831
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    Quote Originally Posted by Robh3606 View Post
    Looking good Ian! Wait till you power them up!!

    Rob
    That’s always the fun part.

  7. #832
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    Does anyone know if a drawing of the M2 enclosure was drafted up?

  8. #833
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    Some feedback from Greg Timbers

    “Ian, That looks pretty nice, but you should put a downward tilt in above 1.5 kHz - 2 kHz or so. A flat curve with a constant directivity horn will kill you. I would start with 1 dB/ Octave. it is somewhat subjective and room dependent”.

    Greg.

    I have incorporated a tilt control in the network with some switchable adjustments to fine tune the subjective assessment.
    Attached Images Attached Images

  9. #834
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    Quote Originally Posted by Ian Mackenzie View Post
    Does anyone know if a drawing of the M2 enclosure was drafted up?
    This is as close as I could find to one when I was building mine.

    http://www.audioheritage.org/vbullet...l=1#post374875

  10. #835
    Administrator Robh3606's Avatar
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    Some feedback from Greg Timbers
    “Ian, That looks pretty nice, but you should put a downward tilt in above 1.5 kHz - 2 kHz or so. A flat curve with a constant directivity horn will kill you. I would start with 1 dB/ Octave. it is somewhat subjective and room dependent”.

    Greg.
    Hello Ian

    That's interesting. When I was doing the compensation on the M2 waveguide I went maximally flat like the M2 with a 1dB step down about 1K. Fixed no tapper per octave. That said I did design in additional attenuation just in case they were too bright for my room. They are as Greg predicted and I run them with an additional 1dB fixed pad.

    I have not heard of any complaints from anyone who has heard the M2 or hear any complaints from all who cloned them about them bring overly bright.

    Question I have is if any of the clones on the forum run the stock curve or use a house curve as Greg suggests??

    Rob
    "I could be arguing in my spare time"

  11. #836
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    Quote Originally Posted by Robh3606 View Post
    Hello Ian

    That's interesting. When I was doing the compensation on the M2 waveguide I went maximally flat like the M2 with a 1dB step down about 1K. Fixed no tapper per octave. That said I did design in additional attenuation just in case they were too bright for my room. They are as Greg predicted and I run them with an additional 1dB fixed pad.

    I have not heard of any complaints from anyone who has heard the M2 or hear any complaints from all who cloned them about them bring overly bright.

    Question I have is if any of the clones on the forum run the stock curve or use a house curve as Greg suggests??

    Rob
    It was a heads up only. I sent Greg the a flat curve for feedback with all the adjustments up full and he made the comment. Another set of eyes helps.

    Its stating the obvious. A refresh. But of course if any M2 cloners are wondering why its killing them its a helpful insight if you are not familiar with the impact of a full cd horn like the M2 in a standard home living room with 6 flat hard surfaces. The simple message is the Horn is working okay, but wind back the highs till your ears stop bleeding.

    Non CD JBL systems are far more forgiving and the go to is flat HF extension.

  12. #837
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    Quote Originally Posted by Robh3606 View Post
    Hello Ian

    That's interesting. When I was doing the compensation on the M2 waveguide I went maximally flat like the M2 with a 1dB step down about 1K. Fixed no tapper per octave. That said I did design in additional attenuation just in case they were too bright for my room. They are as Greg predicted and I run them with an additional 1dB fixed pad.

    I have not heard of any complaints from anyone who has heard the M2 or hear any complaints from all who cloned them about them bring overly bright.

    Question I have is if any of the clones on the forum run the stock curve or use a house curve as Greg suggests??

    Rob
    On your question if the read your post perhaps they will response. It depends on the prevailing acoustics. Technically if you room has reflective surfaces and a longer than desirable reverberation time your going to notice it. That's why I plan to damp my room once the renovation is done.

    The tweak is fairly straight forward in Leap with a change in the C and the R in the RCL filter

    BTW the hint on Parallels for Leap on a Mac was from Greg. He said it works great.

  13. #838
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    The house is bomb site after the measurement mayhem..Lol. Bau.

    I was busy this afternoon doing an inventory of the mdf panels in Excel. I think I will get it flat pack delivered cut to size. There is actually some well document diy of the M2 cabinet construction on various forums. I'm going to build the enclosure stock or close to it. Only seven years late to the party...Lol.

    Someone needs to make one out of Corian or concrete and prove it sounds better then see it fall through the floor. Or maybe one inch aluminium.

  14. #839
    Senior Member srm51555's Avatar
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    Quote Originally Posted by Ian Mackenzie View Post
    ....“Ian, That looks pretty nice, but you should put a downward tilt in above 1.5 kHz - 2 kHz or so. A flat curve with a constant directivity horn will kill you. I would start with 1 dB/ Octave. it is somewhat subjective and room dependent”......
    Thanks for the confirmation, This echo's what I read here on AudioScienceReview. I still need to try this on my active setup. Can I assume I will be able to achieve this same tilt with the 2451 passive you posted?

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    Quote Originally Posted by Ian Mackenzie View Post
    ...... ( Hint: Its about time you guys posted an index somewhere. Pos made a good start in organizing the threads. Get one of your kids to do it.)
    I had the same intention on page 1 of this thread. I did happen to take paper notes on certain posts in the original M2 thread that may be helpful. Once I find them, I'll post what I have.

    Also the PDF's are much appreciated for viewing.

    Thanks,
    Scott

  15. #840
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    Hello Scott

    Thanks for posting! I hope other users chime in to see what they are actually using with the speakers dialed in. I wanted to like them "flat" but no they needed something off the top end. Might take out my 1db out and update the network to follow the curve or combine. Must admit I am very happy with them now. See what happens.

    Rob
    "I could be arguing in my spare time"

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