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New Member - New Project - Seeking Feedback on Crossovers . . .

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  • Chris Roemer
    replied
    Glad everything worked out for you.
    Don't forget a pic of the final project ...

    Leave a comment:


  • Steve Lee
    replied
    Thought I would add some pics of the mods so that others might follow along more clearly:


    I cut the solder trace leading to the tweeter capacitor using a Dremel tool:

    Click image for larger version

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    Then I tested the circuit mods by using alligator clip-leads to attach the components to the board and connect to the speakers:

    Click image for larger version

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    Soldered the components to the board - 1:

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    Another view of both completed board modifications:

    Click image for larger version

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    Cheers!




    Leave a comment:


  • Steve Lee
    replied
    Originally posted by Chris Roemer View Post
    If you'd digested almost ANY "beginner" book (like SpeakerBuilding 201) you'd know that basically ALL drivers that employ a voice coil have an impedance plot that starts down low (typically referred to as the driver's "Re"), then rise to a peak at the driver's resonant freq. (Fs). This is VERY normally between 30-60Hz for a woofer (you've got no need to be concerned about this AT ALL) and maybe around 1k-3kHz for a tweeter.
    After that there's a fairly broad "valley" of low impedance (often near 200Hz for a woofer / 4k? for tweeters) with a consistent "rise" up to 20k. The distance up to 20k isn't that far away on tweeters (and is generally ignored) but it's a long way up there from 200Hz, so it's often beneficial to run a "Zobel" across a woofer's terminals (about $2?) to effectively flatten out the rise. (You can get by w/out this on the GW woofer - IF . . . )
    That woofer/tweeter combo should work well enough.

    Your "generic" 2k XO CAN be used effectively, BUT you need to add 3 components to it (2 resistors and a cap - to each XO).
    As Geoff pointed out, that woofer DOES have a bad peak at 3k (look at the FR plots to see it). You can snub that by paralleling the iron-core coil with a 4n(ohm) resistor in series w/a 2uF cap.
    The other noted problem (of the tweeter being too loud) can be remedied by adding a 4n resistor between the amp's "+" lead and the entrance side of the tweeter's 5uF cap. That should do it. (you do NOT want that resistor feeding the woofers coil - so you might have to do some surgery on the XO board)

    I'd tune the box to the low 40s (yielding an F3 below 40Hz - FINE for music!) by using either a 2" "Precision Port" that's 4" long, or make your own 3"id x 10" long port out of PVC or a cardboard tube.

    Hard to get a "tower" (usually w/the tweeter at LEAST 36" off the floor) from only 0.85 cu.ft. Either stands are in order, or a larger box w/a false bottom half (that's closed off).


    Chris, your advice was spot-on.

    I have modified the XO as you suggested and had to cut the solder trace entering the tweeter cap to isolate it with the 4 Ohm Resistor but it worked perfectly (I placed an 8 ohm L-pad in there [wiper to one-end] and adjusted it while monitoring its resistance and I settled upon your value of 4 ohms) Good call!


    Additionally, I placed the suggested 2uF cap in series with another 4 ohm resistor across the inductor after figuring out which of the two coils were in play and, Man! That took the harshness right out of the hot peak around 3KHz..

    Everything is alligator clip-lead assembled on a roll around bench right now but I will get the new components attached, insulated/glued soon.

    These speakers have never sounded this good and are about 0.5 CuFt with a 2-3/8 X 5" port tube in the back.

    They are very clear and will play louder than I can bear and are still clean/punchy.

    Thanks for taking the time for this.

    Thanks to everyone else who offered assistance as I used all of it.




    Steve.


    Next project . . .

    Leave a comment:


  • Steve Lee
    replied
    Originally posted by Kornbread View Post
    Steve Lee Somewhere through this build or another, their lifelike portrayal of percussion is mentioned. The drivers are very affordable, not to mention this guy's woodwork is top-notch. http://techtalk.parts-express.com/fo...mp-tower-build
    Wow!

    What a fantastic link/thread!

    Thanks, man!

    :D

    Leave a comment:


  • Kornbread
    replied
    Steve Lee Somewhere through this build or another, their lifelike portrayal of percussion is mentioned. The drivers are very affordable, not to mention this guy's woodwork is top-notch. http://techtalk.parts-express.com/fo...mp-tower-build

    Leave a comment:


  • Steve Lee
    replied
    Originally posted by billfitzmaurice View Post
    He's not going to get it with that woofer, unless it's used in a set of mains along with a good sub or two.
    Exactly the arrangement I pointed out earlier - they *should* work well in the right enclosure with the right port and right crossover.

    Leave a comment:


  • Steve Lee
    replied
    Originally posted by Kornbread View Post

    Why am I thinking drummer who wants realistic, in a sense tactile reproduction of drums, might be interested in something like the Trump Tower build?
    Are the Trump Speaker Towers YUGE or just Big and Beautiful?

    :D


    Love it - get some political humor along with building advice . . .

    In my workshop I have a pair of BIC America https://www.parts-express.com/bic-fo...eaker--303-434
    speakers mounted on their side at ear level on 5" thick open cell foam blocks about a foot from the wall that I added dampening material too
    and also reduced their internal volume slightly with a 5" X 5" X 1.5" closed cell foam.

    Steely Dan-Gold album is so alive on these things and this is the sound I am after - drums sound like I am sitting on the kit playing them.
    They go deep too and I got rid of the sub-woofer in that setup because of them.

    (That ^ is a really well sound engineered recording on CD).




    The links in your sig line are good references and I will look them over in detail later.

    Later, man.

    Steve.



    Leave a comment:


  • Steve Lee
    replied
    Originally posted by djg View Post
    FWIW, I would advise you to take Chris R's advice. He is very familiar with that tweeter, and has gone to some effort to look up your woofer and XO. It is a few dollars worth of parts to greatly improve your results. You can see for yourself by trying your components with and without Chris' suggested mods. Make the cabs and run the wires out the port to the crossovers to access them to experiment. SOP for XO designing. Get some short alligator clipped test leads when you order the XO parts.


    That's what I would do.
    djg!

    Excellent suggestions and I do appreciate Chris's response as I understand that he had to spend a little time to help me.

    Thanks, man!



    Steve.


    Leave a comment:


  • Steve Lee
    replied
    Originally posted by dwigle View Post

    Welcome:

    In most proven designs (meaning successfully completed and enjoyed by many users) a lot of issues have been addressed and corrected by people a lot smarter than me. In my view, crossover design and fly fishing can only be done successfully after retirement. I have constructed a dozen or more proven designs resulting in immense pleasure and I don't feel cheated out of the experience of not personally designing the system. I also don't have a single poor sounding pair.

    As Chris pointed out, you'll find that some "issues" are crucial, audible and require a fix and others meaningless and a waste of time. You're not alone, I think most newer DIY folks for some reason come here for advice after they've already committed to their own concept and purchased the parts, without knowing if it will work.

    There are some really great folks on this site that can help design a system you will enjoy and maybe encourage you to continue with the hobbie. I would encourage you to build a proven design - in the process you'll get great advice from others who have built the system and possibly the designer. Worst case you'll end up with good speakers.

    There is a wealth of knowledge available in the sticky section of this forum. http://techtalk.parts-express.com/fo...building-bible

    This first thing I learned was that I didn't know how much I didn't know. start here:

    https://sites.google.com/site/undefinition/diy-mfaq

    https://sites.google.com/site/undefi...-provendesigns




    Dwigle!

    Thanks for your feedback - I looked through your links and they are eye-openers.

    The 2 kits offerred here at PE that I keep coming back to are:

    Samba (reconfigured with a front port) --> https://www.parts-express.com/samba-...only--300-7119

    Amiga (modified for height requirements of 30" tall, front port as well) --> https://www.parts-express.com/amiga-...inet--300-7124


    I may well just put these generic crossovers-in the existing cabinets and modify them as Chris suggested as a learning experience and then go build a kit later when I have the extra time to spend on it all.
    Again,

    Thanks for the feedback - I am learning . . .



    Steve.

    Leave a comment:


  • Steve Lee
    replied
    Originally posted by Chris Roemer View Post
    If you'd digested almost ANY "beginner" book (like SpeakerBuilding 201) you'd know that basically ALL drivers that employ a voice coil have an impedance plot that starts down low (typically referred to as the driver's "Re"), then rise to a peak at the driver's resonant freq. (Fs). This is VERY normally between 30-60Hz for a woofer (you've got no need to be concerned about this AT ALL) and maybe around 1k-3kHz for a tweeter.
    After that there's a fairly broad "valley" of low impedance (often near 200Hz for a woofer / 4k? for tweeters) with a consistent "rise" up to 20k. The distance up to 20k isn't that far away on tweeters (and is generally ignored) but it's a long way up there from 200Hz, so it's often beneficial to run a "Zobel" across a woofer's terminals (about $2?) to effectively flatten out the rise. (You can get by w/out this on the GW woofer - IF . . . )
    That woofer/tweeter combo should work well enough.

    Your "generic" 2k XO CAN be used effectively, BUT you need to add 3 components to it (2 resistors and a cap - to each XO).
    As Geoff pointed out, that woofer DOES have a bad peak at 3k (look at the FR plots to see it). You can snub that by paralleling the iron-core coil with a 4n(ohm) resistor in series w/a 2uF cap.
    The other noted problem (of the tweeter being too loud) can be remedied by adding a 4n resistor between the amp's "+" lead and the entrance side of the tweeter's 5uF cap. That should do it. (you do NOT want that resistor feeding the woofers coil - so you might have to do some surgery on the XO board)

    I'd tune the box to the low 40s (yielding an F3 below 40Hz - FINE for music!) by using either a 2" "Precision Port" that's 4" long, or make your own 3"id x 10" long port out of PVC or a cardboard tube.

    Hard to get a "tower" (usually w/the tweeter at LEAST 36" off the floor) from only 0.85 cu.ft. Either stands are in order, or a larger box w/a false bottom half (that's closed off).
    Chris!

    Man, thanks for your excellent direction and assistance - I didn't really expect to get this level of technical help at all so I am quite impressed. Thanks - seriously.

    I will take heed of your advice and put those components in my next order here from PE.

    Wow. What a community you guys have here . . .

    Thanks again Mr. Wizard!




    Steve.

    Leave a comment:


  • billfitzmaurice
    replied
    He's not going to get it with that woofer, unless it's used in a set of mains along with a good sub or two.

    Leave a comment:


  • Kornbread
    replied
    Originally posted by Steve Lee View Post

    To answer your questions in order"

    1. Yes, I have the drivers and the crossovers are showing up later today. These are all inside a JBL TLX-121 speaker cabinet but they lack the fullness I am seeking as mains. (tom-toms on drums have punch but no resonance like they should have (I'm a hobby drummer).
    Steve.

    Why am I thinking drummer who wants realistic, in a sense tactile reproduction of drums, might be interested in something like the Trump Tower build?

    Leave a comment:


  • Geoff Millar
    replied
    Originally posted by djg View Post
    FWIW, I would advise you to take Chris R's advice. He is very familiar with that tweeter, and has gone to some effort to look up your woofer and XO. It is a few dollars worth of parts to greatly improve your results. You can see for yourself by trying your components with and without Chris' suggested mods. Make the cabs and run the wires out the port to the crossovers to access them to experiment. SOP for XO designing. Get some short alligator clipped test leads when you order the XO parts.


    That's what I would do.
    +1

    Geoff

    Leave a comment:


  • djg
    replied
    FWIW, I would advise you to take Chris R's advice. He is very familiar with that tweeter, and has gone to some effort to look up your woofer and XO. It is a few dollars worth of parts to greatly improve your results. You can see for yourself by trying your components with and without Chris' suggested mods. Make the cabs and run the wires out the port to the crossovers to access them to experiment. SOP for XO designing. Get some short alligator clipped test leads when you order the XO parts.


    That's what I would do.

    Leave a comment:


  • dwigle
    replied
    Originally posted by Steve Lee View Post
    Hi Geoff!



    Concerning your thoughts on purchasing an already available design, I have spent many hours going over all the kits and their specs and keep finding issues with them when combined with my existing center channel, and surrounds and their impedance and efficiencies.

    If I were to know now what I wish I had known in the past, I would have just bought all the BIC America matching speakers and been down the road already.


    Welcome:

    In most proven designs (meaning successfully completed and enjoyed by many users) a lot of issues have been addressed and corrected by people a lot smarter than me. In my view, crossover design and fly fishing can only be done successfully after retirement. I have constructed a dozen or more proven designs resulting in immense pleasure and I don't feel cheated out of the experience of not personally designing the system. I also don't have a single poor sounding pair.

    As Chris pointed out, you'll find that some "issues" are crucial, audible and require a fix and others meaningless and a waste of time. You're not alone, I think most newer DIY folks for some reason come here for advice after they've already committed to their own concept and purchased the parts, without knowing if it will work.

    There are some really great folks on this site that can help design a system you will enjoy and maybe encourage you to continue with the hobbie. I would encourage you to build a proven design - in the process you'll get great advice from others who have built the system and possibly the designer. Worst case you'll end up with good speakers.

    There is a wealth of knowledge available in the sticky section of this forum. http://techtalk.parts-express.com/fo...building-bible

    This first thing I learned was that I didn't know how much I didn't know. start here:

    https://sites.google.com/site/undefinition/diy-mfaq

    https://sites.google.com/site/undefi...-provendesigns





    Leave a comment:

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