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    • #12409
      nitrox
      Member

      Hey guys, I’m Sam. I work in the manufacturing industry (specifically, CNC software support) and I am an avid woodworker that’s always trying to learn more and step out of my comfort zone. I recently got my hands on a small CNC router and I love the idea of making a set of custom speakers, as well as a subwoofer if possible. I have a ton of goals, but the first is to make a solid set of good to great speakers! Any help with crossovers would be greatly appreciated, as well as any hardware/driver recommendations – my goal would be to make 10″X6″ set of speakers for my computer setup. Thank you guys for welcoming me here and I look forward to learning from you all!

    • #12410
      cap
      Participant

      Hi Sam. you’ll probably do well by getting some extra equipment for speaker measurement if you’re planning on going for highest fidelity possible but if not you can more or less tune “by ear”, or guys in the forum can do it for you if you have driver data available. 

       

    • #12412
      tvor-ceasar
      Moderator

      Sam,

      Welcome to the Forum! And Happy 2021!

      So you’ve got the woodworking chops, which is a nice chunk of this hobby. Good.

      For the design aspect, you state a 10″ x 6″ desktop (size of my first speaker build!). I’m going to guess that’s the face plate. Drivers, I wouldn’t go any bigger than about a 4″. Really, there are some 3″ drivers that would do well, such as the Dayton Audio ND91 and PC83, and the FaitalPRO 3FE25. What kind of depth are you looking at and what is the thickness of the material you are thinking of using? This’ll help determine some of the final performance parameters.

      What kind of software are you looking at? There’s lots of free stuff out there, mostly for Windows, though any of the Excel based ones should be cross platform.

      Go ahead and pick all of our brains, That’s what this forum is about. Here’s to success!


    • #12413
      nitrox
      Member

      First off, thanks for the warm welcome to the forum! and Happy New Year!

      Awesome! It sounds like I’m on the right track. I plan on using 3/4″ MDF for the majority of the box with an oak or mahogany faceplate (with or without MDF behind it, depending on what you guys recommend!).

      I’ve been watching a lot of KMA videos on Youtube as a guideline, but I’ve still got a couple questions.

      I attached the image of the circuit I made using VituixCAD (V2, I believe), as well as the SPL graph.


       Here are the questions I still have:

      1) What other components do I need to assemble the Crossover itself? (I.e, Speaker wires, connectors, grounds, etc.)

      2) Any Videos you would recommend for assembling the Crossover? 

      3) Any other general info that I’m missing? 

      Thanks in advance for your wisdom!

       

    • #12414
      123toid
      Keymaster

      @nitrox

      Welcome,

      Before you go too far, just a quick concern is that resistor in front of your woofer.  Any reason you put that there?


    • #12415
      nitrox
      Member

      What is the issue with the resistor? Should I just have the tweeter have less resistance? I probably tripped myself up along the way somewhere and thought I had to add it. Electrical is something I am definitely learning from scratch. 

    • #12416
      tvor-ceasar
      Moderator

      Kirby’s been pretty quiet lately. Wonder what’s up.

      Noticed that your cap on the tweeter was very small. a quick consult of a crossover chart shows that a 2.7 uF at 4 ohms crosses at about 14kHz. Should be a lot lower, say around 3kHz. I also wasn’t quite sure what you were doing with the shunts around the drivers. 

      Put your circuit into X-Sim to see if it would do anything different than VituixCAD. Looked similar. The curve looked a bit low in the middle, so I started playing around with some of the values and got it to flatten out, and also pulled the SPL up a bit. I wanted to check on Parts Express for their crossover parts values, just to make sure they were standard values you can get, but I can’t get into their site at the moment. When you look at the schematic, you’ll see that one of the resistors has a line through it denoting a short and one of the coils and caps have their centers missing denoting an open. That effectively removes them from the circuit.

      Now, this is NOT the end all be all, since there are some things that could use further attention. But it does seem to be a bit more even. I welcome others to chime in.



      Looking at the size you are going for and the mid woofer driver you chose, I don’t think you’d need 3/4″. Smaller panels are stiffer due to their reduced area. At that size, you “might” need to maximize interior volume, so thinner may be needed. You might be able to get away with 1/2″ or slightly less. Of course, if the required volume can be met with 3/4, then use it.

      For the crossover, you’ll need wire to connect everything. Grounds are an electrical term for a connection to the “0” (zero) voltage point. In the speaker, that would be the negative terminal. You’ll also need something to mount everything to and either hot glue or maybe zip ties to hold things in place. As for videos, check out some of ToidsDIYAudio for some build inspiration.

      What is the design volume and type of box you are going for? Sealed or ported?

       

      BTW, this graph is at the same voltage as yours so you can easily compare.


    • #12417
      nitrox
      Member

      Thank you for the details! 

      So a couple more questions… What do you mean by shunt? What should my crossover point be? Also, I’m not sure if it makes a difference, but you’re using the 4ohm woofer and I am using the 8ohm. I changed it to a 4 woofer to match. 

      So, when I’m using things like Vituix, I’m picking my crossover point (which would be about the halfway point between the low hz of the tweeter and the high hz of the woofer?), then I am to achieve the lowest rate of change with impedance and as close to a straight line with the reference angle as possible? 

      I’ll go buy some 1/2 MDF, that’s no biggie. I was going to give ported a shot, but I haven’t really gone that far. Honestly, the crossover and the electrical scare me the most given my lack of experience with both. I am going to make a finished design once I have the drivers in my hand so I can make a final decision on height and width and then figure out the depth from there. 

      I changed my circuit to match what you had. #1 is the tweeter (in red) and #2 is the woofer (light blue). Isn’t that a large overlap? if not, I apologize! I’m trying to figure this out.


      Thanks for all of your help guys! It’s greatly appreciated

       

    • #12418
      tvor-ceasar
      Moderator

      @nitrox

      You’re welcome. I hope to help anyone who asks. 

      A shunt is an electrical term for basically a “bypass path” for electricity. In our case it is a frequency dependent bypass, sending a range of frequencies above or below the filter, depending on type.

      Crossover point is usually set to around 2x’s the resonant frequency of the next in line driver. Since you re doing a 2-way system, that would be the tweeter. The TD20F lists it at a little above 1600 Hz, so normally you could go with whatever it would be ( 3200-3300 +- ), but you also have to look at your mid-woofer. It drops off at 5000 Hz, so you need to cross over a bit sooner. 3000 Hz is fair game, giving both some room to roll off in their respective directions. Since it’s a little tight between them, you might want to go with a steeper slope. Currently, this design is a 1st order which rolls off at 6dB /octave, so a 3rd order should give a tighter crossover, keeping the less useable areas of the drivers out the graph. This helps to keep distortion and breakup away. For a better explanation of crossover orders, just Google “speaker crossover orders” to see some of the differences and designs available. Also, watch some of the videos I linked above. They should help too.

      As to the TCP115, I chose the 4 ohm version since the tweeter is a 4 ohm. It is a general assumption that isn’t always right. 😀 You can mix and match impedances, but it is easier to design a crossover if you try to keep the drivers the same equivalent impedance. I say equivalent since you may sometime want to use more than one of a driver in a design, say 2 woofers and a tweeter. Depending on the tweeter impedance, you can get woofers that can be wired to be the equivalent of the tweeter impedance. So say you need to match to 8 ohms, you can wire 2 – 4 ohm woofers in series to get 8 ohms or 2 – 16 ohm woofers in parallel to get  8 ohms. ‘Nuff of that for now.

      Back to the crossover, you want to try to get a flat as possible line. Though you’ll find that once you put it in a box, that will affect it. That’s why CAP mentioned some measurement equipment to help out. I suggest you try designing a box and then take another look at the crossover once you’ve added the box into the mix. I think VituixCAD does that, though I can’t say for sure, since I don’t have it. Anyway, it looks like a box of around 0.081 Cu.Ft. will get you tuned down to about 60Hz. Pretty respectable for a 4″. You’ll have to check port size for velocity and then build that into the interior volume. Or, if it’s long enough, you could be a bit Cyberpunk and put it on the outside. Just a thought. If you need some idea how port size and length and tuning are interconnected, checkout the guys listed in the Sound-Advice YouTube podcast. There’s some good tutorials there.

      Oh, I checked a rough box size for the 0.08 Cu.Ft., and you can use your 3/4″ MDF and still keep it around that size.

      For the overlap, I was just messing with your values until I liked, more or less, what I saw. Give it a try with this new information and a fresh design and see what you come up with. It’s all worth the learning experience.

      ** As a reference, here’s a Capacitor X-over chart to give you an idea of what you should be seeing at first.


    • #12419
      nitrox
      Member

      So a shunt is equivalent to a Highpass/lowpass? and when you refer to “next-in-line” you’re referring to the first driver coming from the power source? 

      The general idea of increasing order makes sense – you get more “control” of the sound the higher order you go.

      I’m going to take a step away from the crossover for a little bit, because I’ve spent 2 days sitting behind my computer at this point. Here is where I’m at:


      I hope this looks better. 

      I’ll take a step back and look at making an enclosure. 

      I’ll also look at some of the sources you guys have posted and if there are any other sources you suggest I look at, let me know! 

      Again, thanks for all of the help. 

    • #12421
      tvor-ceasar
      Moderator

      A shunt is more of a “bleed” in our case. For example, if you have a spike at a certain frequency, you can design a filter that can “shunt” or bleed” some of that energy to ground in order to smooth things out. Hope that better explains it.

      That graph looks much better than the first. Let us know what you come up with for a box and port, then we can go from there.

      Gotta get some stuff done around he house. Catch you later.


    • #12428
      123toid
      Keymaster

      @nitrox

      the issue with the resistor in front of the woofer, is the woofer sees the majority of the power.  So by adding that there, it will heat up fast and stop doing it’s job.  Really you typically only want to add a resistor in front of a tweeter for this reason.  There is a power dissipation, that goes on in loudspeakers. The basic premise is the lower you go in frequency the more power it will receive.  The higher, the less power.  As an example, if you gave that speaker 50w, your tweeter would probably see less than 5 watts of it. 


    • #12549
      nitrox
      Member

      Alright… SO I have made my speakers! (I’ll gladly post the end results once I’m completely done and content) I just have one problem… the speakers cut in and out above half power using my stereo amplifier (Lepai LP-2020TI). I ran out of time last night to start troubleshooting, so I am at square one. What are possible issues and where do I start? Thank you in advance for your time guys! Thanks for helping me get this far already! 

    • #12556
      123toid
      Keymaster

      @nitrox

      Show us your impedance plot. If it is the one pictured above it is probably due to you impedance dropping to 2 ohm at 2.5khz. I missed where you posted the last picture, otherwise I would have said soemthing.  This is common though with your first build, to focus only on frequency response. 


    • #12575
      nitrox
      Member

      @123Toid

      The last picture is the most recent. Would a better amp fix this or am I screwed with the current crossover? 

    • #12577
      nitrox
      Member

      @123toid

      Also, can you post a picture of a proper/realistic impedance graph for reference? Thanks for your time Toid. I’ve watched a lot of your videos and they’ve been extremely helpful. 

    • #12579
      123toid
      Keymaster

      @nitrox

      First of all, don’t worry about it.  This is a very common mistake when people first create crossovers.  You get so caught up in the frequency response you forget about the impedance.  Every speaker builder has been where you are right now.  And it is completely fixable. You may need to work with a few values or even see if adding something like a 4ohm resistor in front of the tweeter, then adjusting your l-pad. 

      I don’t have a picture, because an impedance graph can vary wildly. However, the basic rule is you do not want your impedance to drop 20% your nominal ohm rating of your amplifier.  So in this case, if it is a 4ohm rated amplifier, you want to keep your impedance above 3.6 anywhere on the graph.  It looks like your graph dips at around 2.5Khz to almost 1 ohm. Which would be my guess that this is your crossover region.  You will want to pull this up to closer to 3.6 or above.  You may have just a tad too much overlap.  So you could try adjusting the values some to get your impedance in line or try the resistor trick I mentioned above. 

       

      *P.S. There are exceptions to this basic rule, but for simplicity sake you will want to always keep this in mind.


    • #12582
      nitrox
      Member

      @123Toid

      It’s quite the frustrating spot to be in 🤣 What is the purpose of the l-pad? I don’t have one in this current setup. 

      I just got done messing around with this for a while after taking your advice and I came up with two resolutions:

      #1

      #2

      Is there a decisive “better” or are they just different? Thank you again. I hope I’m understanding this better… lol

    • #12583
      123toid
      Keymaster

      @nitrox

      As far as impedance goes both of those look fine for a 4 ohm amplifier. An l pad is typically used when you need to match the sensitivity of a tweeter to a woofer. Typically a tweeter is more sensitive and needs to be padded down. If not done the Tweeter will play significantly louder.

      Which program is this? Virtuix cad? I’m assuming those are your simulated off axis responses? What you’ll notice is that you seem to be a little out of phase at the crossover point. That’s being shown by as you go off access you’re getting a dip in your response at the crossover point. 


    • #12585
      nitrox
      Member

      But both graphs are acceptable? It’s just the dipping that I should be concerned about going forward? 

      Yes – it’s VituixCAD. Alright, I’ll look more into fixing that when I get home and I’ll learn more about the phase. I want these to sound great. Thank you!

    • #12587
      nitrox
      Member

      @123Toid

      I went back and watched your video on Xsim and I used that software. I read more on being out of phase and I looked at a bunch of different examples of schematics for 2-way and 3-way crossovers. I also referenced a couple of the examples that came with Xsim. This is what I came up with using Xsim:

      Crossover: 

      Frequency Response: (6.02 dB difference from reference line to crossover point)

      Impedance:

      I appreciate all of your patience and advice (@CAP and @TVOR-ceasar included). I know I’ve got a long way to go to get a truly full understanding of this art, but I understand a lot more thanks to you guys. 

    • #12588
      123toid
      Keymaster

      @nitrox

      Looks better.  Did you account for the offset?  You might want to consider putting a tank cap on the woofer inductor.  If you notice around 10Khz the red and blue deviate.  That is due to the woofer interfering.  Putting a small cap on the in parallel with the woofer inductor should bring that down and give you a much cleaner sound. 


    • #12594
      nitrox
      Member

      @123Toid

      I did not account for offset, but I am going to look into it for the next build. I watched your video on it and I plan on purchasing an Omni mic in the near future. I got away with doing this build without one because all of Dayton Audio’s products have downloadable .fra and .zma files, but I know I won’t be able to tune the sound without one. Okay! I’ll add a little one in there. What would that interference sound like?

    • #12596
      123toid
      Keymaster

      @nitrox

      What the graph is showing you is that the woofer breakup is creating deconstructive waves in that region.  It will add distortion. By adding a cheap cap, which will cost less that $1 probably, it’ll eliminate that. I would go ahead and guesstimate z-offset.  It looks like that tweeter is relatively small at on 0.5″ deep and the the woofer is about 2.3.” SO you could guesstimate anywhere from 1″ to 2″.  It is really just a guess without the measurement.  I do think an omnimic is one of the best purchases I have ever made I this hobby. If you need help when you get it, let me know. 


    • #12646
      nitrox
      Member

      @123Toid

      I gotcha! I had to buy 2 (.63uF is what I was looking for, but they only had .1 & .47 so I wired them in parallel), but that’s no big deal. 

      Your “5 tools every speaker builder should have” video shed a lot of light on why you’d need one, so I’m sold on buying it. I deconstructed a broken Bose Acoustimass subwoofer and plucked the two 6.5″ woofers from that and I plan on using the mic to help develop the sound.

      ANYWAYS – the speaker sounds great and I have learned SO MUCH from all of you guys; Thank you I may not be an expert, but I definitely know what I’m looking for moving forward. I hope I’m able to help people with their own builds moving forward. 

      I’ve got to go back and finish the outside of the one speaker and build the other and I’ll post a pic of the finished product on this thread when I’m done! 

      Thanks again, Toid 😀 

       

    • #12782
      nitrox
      Member

      Final Product!


       

    • #12783
      nitrox
      Member

      One last question for y’all… 

      as far as a basic step by step process goes, is this correct?

      1) Using a software (WinISD), make a box with driver info (using Dats to get measurements)

      2) Test box with drivers inside and take a reading using a calibrated mic

      3) Create .frd and import into crossover sim (Xsim) to create an accurate crossover

      is this, in general, correct? I just want to do this 100% correct next time. 

      Thanks for all of the help guys.

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