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Thread: M2 diy passive crossover thread ---- from down under

  1. #31
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    Quote Originally Posted by srm51555 View Post
    Thanks Ian, unfortunately I only have the capability of running frequency sweeps in REW at this time. Luckily we have the impedance from Rob S which would be more reliable anyway. I still havenít had time to figure out impedance measurements in REW.

    Enjoy the water!

    Thanks,
    Scott
    Hi Scott,

    It was my first go at it. I fell off a lot and got lots of inspiration from everyone watching from the shoreline. Eventually l was standing on the board and paddling for about 2 minutes before l fell off in DEEP water. It was a scream 😱. Each entry into the water was a belly whacker. I then got more innovative and started falling off the board backwards.

    This is the Land of beautiful tanned Aussie blondes btw so there is a possibility l was distracted..Bom Bom.

    The river inlet is a bit like the beach side setting of the movie Jaws with a peninsula in the middle of Maroochy river inlet. On the turn of the tide the currents flow and can take you up the river or out to sea. There are apparently bull sharks and stingrays in the shallows. Fortunately there are no crocodiles in the Maroochy river.

  2. #32
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    Given the heads up from Earl l figure it would be a good idea to think about setting the stage for some common ground with our measurements before the project starts to get busy with numerous measurements.

    DIY Measurement Work arounds - sharing and comparing curves with our diy tools ( Surviver Guide.)
    DATS3
    REW

    Hi Scott, Do you have Dayton DATS3 ? I was trying to remember if the impedance file was yours?

    Sharing Measurements
    Anyway, the good news is l can import a DATS 3 impedance file into my DATS3 and export the file as Clio txt file. So this is a growse (Aussie expression meaning very good ) work around for sharing and comparing impedance curves, importing impedance data or exporting impedance data as txt file into a simulator such as Leap 5.

    An impedance data txt file has three data columns and is typically 200 to 400 data points long.

    Frequency Magnitude units (ohms or spl db) Phase

    Similarly an REW FR response files can be shared with another REW user. So l was able to open your REW file you sent me and look the individual measurements you made perfectly. Using the file export menu data files can be exported as a txt file for import into a simulator such as Leap 5. But the data points should be limited to around 400. Make sure the text editor does not word wrap the data.

    See the format above.

    A few tips we can all contribute to as the project progresses.
    The Curve Junkies Survival Guide - so we don’t go crazy.

    When sharing a frequency response measurement :
    Please advise in the email what you are sending?
    Is it raw driver measurement? If any crossover filters are EQ was used in the measurement?

    Test conditions:
    In the email or in the notes section advise the distance of the mic to the DUT (device under test) and the level? In REW this can be expressed in several data measures such as DFS. Or the spl or the voltage. Then the user you are sharing with can interpret your data correctly or if the magnitude of the curve needs shifting.

    The link l posted earlier is great for calculating db from voltage.

    This is just a mention so we don’t go crazy with measurements flying in all directions…Lol

    Once l warm up l will have a look at the files.

    Talk soon.

  3. #33
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    Hi Scott, Rob and Earl,

    This afternoon I put all the available curves together in three graphic files for a baseline view of what we have here.
    There are two FR files. One with the data as is and one I normalised. I am not worrying about the exact levels at the moment. The 2430 with a nominal 32 ohm VC is the least sensitive of the group and its useable. I had to re format the REW exported txt files so Leap 5 would read it and my brain hurts. (beer o'clock here)

    I felt it appropriate to use the file Scott sent me has its has relevant information on the M2 with the 2451 in the pass band for presentation at this time. Once I have Rob S files I will include them moving forward.

    I'm reading between the lines here but I don't see any insurmountable problems setting up a common passive crossover to manage any driver for a "simple DIY M2 passive crossover.
    The 2430 is a departure from the 0476 and the 2451 in its EQ requirements. That can be dealt with using a "Plug in" EQ circuit. The level matching can be dealt with using a table of resister values.

    I'm open to ideas and suggestions on any approach to the crossover as there could be more than one flavour depending on individual circumstances.

    For example someone might want just the passive EQ or a straight 24 DB LR network with passive EQ. Or basic but diy friendly variable tonal level shifting like I posted in the simple diy passive crossover aka 3134 - 4430 approach. The thing is its already been called out that some diy tweaking in the tonal balance could be required. I'm mindful of that while ensuring the basic crossover transfer function is as good as it can be made.

    Edit: I have upscaled the Jpeg images, transferred and processed these measurements so they can be viewed and used in LinearX Leap. These raw driver response measurements have the response magnitude normalised for comparison of the JBL 2430, 2451 and 476 compression drivers. All measurement are of the drivers mounted on the M2 horn. Note. the 2451 measurement has a Crown DSP crossover filter in use.
    Attached Images Attached Images   
    Last edited by Ian Mackenzie; 06-19-2022 at 08:26 PM. Reason: Re Scaled JPeg images

  4. #34
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    Hi Scott,

    Please find below a result I obtained tonight with the Ultra Simplistic M2 Passive High Pass Network.

    Attached are the FR, voltage drive and impedance. Once I obtain the full 2451 response from Rob S I will then complete the HP filter. The HF tail is a measurement problem I think. It can be resolved if not.

    I am confident I can set you up for success with a network for your 2451 driver including a range adjustment for you to consider in your subjective appraisal. The attached FR curve is within 1.5db from 1296 hertz up to 6.696khertz and then a planned reduction of 2 db on the HF response per hints from GT. There is latitude for adjustment to suit the individual.

    Edit: I have re scaled the Jpeg images and updated the files notes for clarity. Note this images are for illustration only of the passive EQ functionality of the M2 Diy Ultrasimplistic passive network.

    Network Modifications:
    The network can be modified for virtually any scenario and / or adjusted out in the field by using REW to make measurements with detailed instructions provided by myself. I can also modify the network using measurements from the user on site and provide technical support. This will a game changer for those interested in diy updating or amending passive crossovers for any JBL loudspeaker system

    https://tapeop.com/interviews/btg/10...-manley-bonus/
    Attached Images Attached Images    

  5. #35
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    Quote Originally Posted by Mr. Widget View Post
    I have nothing to add, but it is nice to see all of this DIY action in the forum!


    Widget
    H Widget,

    Yes its really cool.

    I've also been looking the measurements "Space " and how this information can be shared. I have posted how this can be done.

    With portability of the data at a diy cost via DATS3 and REW this type of activity can be embraced by anyone here. Whether you are a bystander, an on looker, thinking about or considering taking the next steps. Just hanging out. There is little bit of a learning curve but its not hard work. Its fun.

    My focus here is on the JBL stuff we love so much. Its about being enabled & engaged in something you enjoy.

    Those tapped transformers are fairly straight forward to model btw.

    Ian
    Last edited by Ian Mackenzie; 06-19-2022 at 02:26 AM. Reason: typos

  6. #36
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    Hi Robert,

    Please find attached the result of using the 476 files you sent with the Ultra Simplistic 36db LR passive high pass crossover.

    The principle is the same as Scott's 2451 file application. In addition I have added a tuned VHF LP filter to trim the top end. Not that you would hear it. More for the cats and bats in the neighbourhood. This is more just to illustrate to the guys what can be done.

    No low impedance problems and smooth voltage drives as can seen from the attachments. I think its pretty smooth and subject to the original measurement.
    A subtle EQ slope shelving at 2db was applied above 5 hertz to illustrate what can be done for a particular circumstance.

    Edit : To everyone
    These images for for illustration only to show the functionality of the M2 Diy Ultra-simplistic passive network. The network can be modified out in the in the field by using REW to make measurements and with detailed instructions provided by myself. I can also make modifications remotely with the measurements made on site by the user. This might also include validating your stock or diy network or the system response for particular circumstances. This is a game changer for anyone considering or thinking about updating or wishing to modify their JBL system network. The REW measurement software is free and I found it relatively easy to use. The results are far better then I expected. REW is fully supported with a Q & A and help on the REW www website. All you need is the Minidsp microphone which can be ordered online if you are a Mac User. Details for Windows ussr are provided on the REW www site. All you need to do is send your GF or spouse out shopping with your credit card for the arvo..LOL. Have a Saturday arvo audio met with friends while your communicating with Down Under.

    Ian
    Attached Images Attached Images    
    Last edited by Ian Mackenzie; 06-19-2022 at 09:06 PM. Reason: Updated images and text

  7. #37
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    Just a heads up I will edit and make these images larger later today. I have to update some settings in the software. If you would like pdf attachments for hi resolution download images I can also do this if required.

  8. #38
    Senior Member srm51555's Avatar
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    Hi Ian,

    Everything is looking real good. Thanks for posting the progress. For future learning I will still be trying to replicate what you receive from Rob S in REW.

    The best part of being on the other side of the globe are the fresh measurements to look at here when I get up. Better than coffee.

    Thanks,
    Scott

  9. #39
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    Hi Scott,


    I hear you. It can be addictive. Sometimes l just keep going and the time just flys. Itís fun connecting with people who are interested in this type of thing.

    Once l have my new laptop l will be able to do this thing more in the moment rather than late in the day. I may post the odd image of Noosa Heads beach and other interesting places like Fraser Island which is a really cool place to camp, take a beach drive and off road 4wd tracks to various lakes. One of the lakes is really nice. Audio measurements in the Outback.

    https://www.visitfrasercoast.com/product/lake-mckenzie/

    Up north we have the barrier reef and other cool stuff like the Outback Savannah which l visit. Beautiful gorgeís with water to cool off and relax.

    PS. I still need my large cappuccino.
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  10. #40
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    Quote Originally Posted by srm51555 View Post
    Interesting about the possible distortion. I left the slope filters on in the crown on accident and wonder if this is the issue. Here is a real quick measurement with the filters off compared to the original one I sent Ian. I started the sweep at 450Hz

    Attachment 90736

    Thanks,
    Scott
    Hi Scott,

    Thank you for posting this measurement.

    If you have time email me this REW file. I will have a squiz at the file once I have eaten my prawns. Then add the passive high pass filter in Leap 5 for you.

    Ian

  11. #41
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    Block diagram of network attached.
    Attached Images Attached Images

  12. #42
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    My 2451 drivers arrived today.

    I will check them out over the next couple of days and see how they go on my M2 horns.
    Attached Images Attached Images   

  13. #43
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    Those look real nice!

  14. #44
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    Getting the 2451 compression driver ready for testing tomorrow. Robert S kindly provided these flanges.

    Unfortunately the studs on this particular driver where slightly bent because the idiot who used it last forced the horn off instead of lifting the horn flange carefully of the studs. He was not the sharpest tool in the shed obviously. This meant l had to carefully straighten the studs before l could fit the flange.

    Just for grins l have started a passive of the JBL DSP EQ settings of the 2430 fitted to the M2 horn.

    I have not finished yet. I am up to about 7000 hertz. The response is starting to look as smooth as a polished mirror. The downside itís requires a number individual of passive EQ filters.
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  15. #45
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    Quote Originally Posted by Ian Mackenzie View Post
    My 2451 drivers arrived today.

    I will check them out over the next couple of days and see how they go on my M2 horns.

    Really cool work you're doing here Ian - thank you! I'm following with great interest, as I'm considering a 2216nd + 2451 build, so lots of useful info here even for fence-sitters like myself who aren't 100% committed (yet!?) to building an M2 clone.

    Part of the reason I'm interested in going 2216nd + large format jbl (I'm leaning toward crossing slightly lower than the M2 using a Yuichi or Tad derived horn), is because I haven't seen any hi-fi specific projects documented using 2216nd in place of the 15" Altecs I'm accustomed to working with, and very little info comparing their preformance, even if only subjectively. There are the M2 clones of course and some documented home theatre projects, but I'm aimimg for strictly passive and will be using 6 cu/ft Altec 612 Iconic cabs + horn on top.

    All to say, thanks for your efforts and looking forward to seeing more!

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