$vboptions[bbtitle]   $vboptions[bbtitle]  
  Terms and Conditions     Project Showcase
  Resource Index   Speaker Terms Glossary
  Security/Privacy   Speaker Replacement Help
Results 1 to 20 of 20
  1. #1
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default How do I make a low pass filter?

    It's for a tiny 4 1/2" 8ohm Woofer (299-001) I got on closeout and I want to make a tiny sub with one or two of them using a Dayton TA2024 (300-385). I figured I could make two low pass filters, and hook up two of these little guys and use both channels: one for left and one for right.

    I tried to follow a schematic I got online:



    from http://www.electronics-tutorials.ws/.../filter_2.html

    I used a 20W 8ohm resistor and four 25V capacitors (2 100uF, 2 47uF), working off the formula :

    R * C = 2 * Pie * Fc

    I was trying to get the Fc to be around 375Hz.

    Sounds like it's trying to cut out high frequencies, but it's also WAY quieter. Cranked with the little dayton is just above audible.

    I see the low pass filters for sale here and they are noting like the circuit I made. They have solid core inductors and a capacitor. If that's the way to make one- how do I do it? How to I determine the mH and gauge and capacitor strength ifI have all the amp and driver info?


    The "bible" has two broken links in the four crossover page links so I have been all over the internet. I am overloaded now- and I think if I just knew what the right parts in the right order were... I'm trying here.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	fil5.gif 
Views:	61 
Size:	4.3 KB 
ID:	40364  
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

  2. #2

    Default Re: How do I make a low pass filter?

    Generally, if you are trying to cut out the high frequencies, an inductor and cap will do it, but it may not do it with good results. Is there any FRD available for the driver you are using? You could use it in PCD to cut out anything above 300-400hz by simming a filter.

    Edit: I just simmed two 4.5" drivers I had the FRD, and was able to get a nice clean, step roll off at 400hz using a 4.0mH inductor and a 50uF cap. Iron core coil and NPE cap should work fine for your purposes. It would be best if you could get measurements of your drivers in the enclosures before designing a filter though.

  3. #3
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default Re: How do I make a low pass filter?

    Quote Originally Posted by dustinbagby View Post
    Generally, if you are trying to cut out the high frequencies, an inductor and cap will do it, but it may not do it with good results. Is there any FRD available for the driver you are using? You could use it in PCD to cut out anything above 300-400hz by simming a filter.

    Edit: I just simmed two 4.5" drivers I had the FRD, and was able to get a nice clean, step roll off at 400hz using a 4.0mH inductor and a 50uF cap. Iron core coil and NPE cap should work fine for your purposes. It would be best if you could get measurements of your drivers in the enclosures before designing a filter though.
    Nothing included with driver. The brand is listed as "Factory Buyout" and the only marking on it is "Made in Taiwan." I asked in the Q&A section if there is one available.

    But I'll try your suggestion and see what happens.
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

  4. #4
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default Re: How do I make a low pass filter?

    Hey-

    Do any of you guys wind your own inductors? What about solid core? I tried looking for solid core iron plain cores and it was impossible unless I wanted 5000 from China.

    I don't suppose an air core would work here?
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

  5. #5
    Join Date
    Jun 2011
    Location
    Odenton and Cumberland, Maryland
    Posts
    212

    Default Re: How do I make a low pass filter?

    Air core would work, just more bucks and higher DCR. Iron core 18ga. 4.0mH is $11.23, air core 18 ga. 4.0mH is $18.81.

  6. #6
    Join Date
    Mar 2012
    Location
    Colorado Springs, CO
    Posts
    485

    Default Re: How do I make a low pass filter?

    Spaker,

    I believe that the diagrams and formulas you discovered there are intended for use in circuits with a high impedance load, or "signal level" applications where the attenuation caused by the series resistor is inconsequential, or the series resistor represents the output impedance of the source (not sure on this).
    Pro/Fi Cinema Speaker project: "From the Ashes"

  7. #7

    Default Re: How do I make a low pass filter?

    http://www.diyaudioandvideo.com/Calculator/XOver/

    Use the smallest gauge available.
    Currently resigned to living in balmy Zephyrhills, FL with the snow birds.
    Howard H

  8. #8
    Join Date
    Sep 2005
    Location
    Appleton
    Posts
    7,444

    Default Re: How do I make a low pass filter?

    Can those drivers even make any bass?

  9. #9
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default Re: How do I make a low pass filter?

    Quote Originally Posted by zhillsguy View Post
    http://www.diyaudioandvideo.com/Calculator/XOver/

    Use the smallest gauge available.
    This... is AMAZING. Thanks for that link!

    I ordered some 18 and 20 gauge last night. A few hundred feet of each. Why not be brave and try to wind one (two) myself?

    This is a goofy project made mostly out of spare parts. The woofer is just part of it and it stumped me. Because I am dumb and new at this, no matter how much I read... I just have to "do it" or see something done to know it. Thanks for all the assistance. Even though this project is meaningless, I have learned a lot stumbling through it: info I will use when it matters.
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

  10. #10
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default Re: How do I make a low pass filter?

    OK. So I am back on this... in a way. I have been messing with that link zhillsguy posted trying to figure out a crossover for a different project. Then I wondered... can this thing (the link) calculate a low pass filter if I tell it 8ohm tweet (imaginary), 8ohm woof (real) and lets say a crossover at 400Hz, and it gives me a simple design with a cap and inductor wired to a tweet and woof.... what would happen if I made it and didn't include the tweeter? Would it act as a low pass? Obviously, to complete a circuit, omitting the tweet means a straight connection between where the tweeter + is in the diagram to where the - is. So just a wire and not a tweeter.

    I have a feeling this is no good... I have a feeling it needs the impedance of the tweet to make the crossover work. But It was just a thought... because I am still trying to figure this out and learn more about XO in general.
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

  11. #11
    Join Date
    Jun 2008
    Location
    Laporte, IN
    Posts
    3,133

    Default Re: How do I make a low pass filter?

    I am going to suggest that you read the stickies at the top and get a better understanding of what a crossover does and how it does it. There is more to this than assuming a driver has a nominal load so requires x crossover for y crossover point. The crossover freq is a function of the impedance profile, the transfer function, etc, etc, etc.....

  12. #12

    Default Re: How do I make a low pass filter?

    Quote Originally Posted by Spaker View Post
    OK. So I am back on this... in a way. I have been messing with that link zhillsguy posted trying to figure out a crossover for a different project. Then I wondered... can this thing (the link) calculate a low pass filter if I tell it 8ohm tweet (imaginary), 8ohm woof (real) and lets say a crossover at 400Hz, and it gives me a simple design with a cap and inductor wired to a tweet and woof.... what would happen if I made it and didn't include the tweeter? Would it act as a low pass? Obviously, to complete a circuit, omitting the tweet means a straight connection between where the tweeter + is in the diagram to where the - is. So just a wire and not a tweeter.

    I have a feeling this is no good... I have a feeling it needs the impedance of the tweet to make the crossover work. But It was just a thought... because I am still trying to figure this out and learn more about XO in general.
    You cannot replace a tweeter with a straight piece of wire. What you are suggesting is a direct short for high frequencies.

    Learn to use WinISD alpha. It is free and simple to use once you get to know it. Lots of people here use it for uncomplicated sub builds. It has simple x-over calculators also. JohnnyRichards has a tutorial on it.

    Also, as suggested, start educating yourself following the stickies at the top.
    When the only tool you have is a hammer, all problems start to look like nails.

    If we all did the things we are capable of doing, we would literally ASTOUND ourselves - Thomas A. Edison

    Some people collect stamps, Imelda Marcos collected shoes. I collect speakers.

  13. #13
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default Re: How do I make a low pass filter?

    Oh I have. Several of the crossover links in the stickies are broken links. Aaaand I hate to pull this card out, but I am severe ADHD / learning disabled. I can read pages and pages and pages and retain nothing. I have to "do it" to get it. It's not like I am trying to shortcut the due diligence. I am trying best I can... and have been day in and day out and sometimes all night long for almost a year. It takes me much longer than most. However, once I do something right, it's in there and in there forever. I know, it's hard for people to understand this and most probably think- what the hell are you doing this for, then? Because I love it. And because, like I said, once I do something, I can do it forever.

    I'll look into the WinISD (software?) And I love JohnnyRichards stuff; I'll look for the tutorial. I wish his DIY designs still had available drivers! Love the inexpensive way!
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

  14. #14
    Join Date
    Jun 2008
    Location
    Laporte, IN
    Posts
    3,133

    Default Re: How do I make a low pass filter?

    I would also say to download Jeff Bagby's software. In particular PCD. Playing around in there will show you how "textbook" values do not work. A driver whether it is a woofer, mid, or tweet has an impedance that changes with frequency. The nominal values give us an indication of the driver but are basically useless when finding out how the driver will behave with different slopes and crossover points.

    I really do understand about ADHD. I was not diagnosed with it as a kid as I probably should have been and I now have 3 kids that do have various degrees of it.


    Oh and JRs stuff is great. I have built a couple of his designs and heard others. Building one if his designs (say cabrinis) will give you some experience in how crossovers work and part of the design progress. Simple build with a minimal crossover.

  15. #15
    Join Date
    Sep 2005
    Location
    Appleton
    Posts
    7,444

    Default Re: How do I make a low pass filter?

    What range of "bass" are you expecting (hoping?) to get out of these drivers (in Hz)?

  16. #16

    Default Re: How do I make a low pass filter?

    Quote Originally Posted by Spaker View Post
    OK. So I am back on this... in a way. I have been messing with that link zhillsguy posted trying to figure out a crossover for a different project. Then I wondered... can this thing (the link) calculate a low pass filter if I tell it 8ohm tweet (imaginary), 8ohm woof (real) and lets say a crossover at 400Hz, and it gives me a simple design with a cap and inductor wired to a tweet and woof.... what would happen if I made it and didn't include the tweeter? Would it act as a low pass? Obviously, to complete a circuit, omitting the tweet means a straight connection between where the tweeter + is in the diagram to where the - is. So just a wire and not a tweeter.
    just delete the entire part that goes to the tweeter.

    The (high pass + tweeter) circuit and the (low pass + woofer) circuits are both complete circuits, operating in parallel. lose the tweeter and associated components, and the woofer / low pass is still functional. This is basically what was suggested before with the 4.0 mH laminate core inductor and the 50uF cap, except that version is what you'd get as a "2nd order" crossover, which rolls off the high frequencies at a steeper rate, which is better for your application than just the inductor. playing around with that crossover calculator and choosing different 2nd order types instead of the 1st order type might be useful.

  17. #17
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default Re: How do I make a low pass filter?

    OK. So I forgot to mention that visual aides help me a lot. Schematics and such. Like this:



    So you're saying on this one, just totally ignore the tweet and it's inductor and capacitor? If thats the case, I have everything right here and I can do this in minutes. The Inductor it wants is 4mH and capacitor is 31.25uF. I can come damn close to those values with what I have here... not so sure about the .25 in the cap. All my caps on hand are whole numbers and the inductor I have is 3.9, not 4mH but that should only effect the XO frequency a little, I hope. This isn't a high end project. It's quite goofy actually.... but helping me learn and that's all I care about.

    I tried so hard today to read more about crossovers. I read and read and read until my eyes went crossed. If you asked me one thing about all that stuff right now, I couldn't tell you anything. I felt so stupid after I posted last. I am trying so hard and feel so dumb. Then I see a schematic and say, I can do that. Easy. Thank you.
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

  18. #18
    Join Date
    Sep 2010
    Location
    Laurel Hill, FL
    Posts
    4,063

    Default Re: How do I make a low pass filter?

    If you're just working with a woofer, then yes, just an inductor in series and a cap in parallel on the woofer.
    रेतुर्न तो थे स्रोत

    return to the source



  19. #19

    Default Re: How do I make a low pass filter?

    Quote Originally Posted by Spaker View Post
    OK. So I forgot to mention that visual aides help me a lot. Schematics and such. Like this:



    So you're saying on this one, just totally ignore the tweet and it's inductor and capacitor?
    heh, those are hard to add on a phone... . but yes, drop the tweeter, C1, and L1 from that diagram. Only wire up C2, L2, and the woofer. If you have close values, you'll be in the ballpark. just give it a try.

    also, since the driver will play a lot of content above that crossover frequency, wire up your 2nd driver as the tweeter so you can hear what the crossover is doing if you listen to each of them.

  20. #20
    Join Date
    Jan 2013
    Location
    Irondequoit, NY
    Posts
    65

    Default Re: How do I make a low pass filter?

    I got it!

    Teenie weenie sub. Low pass with a capacitor and an inductor. Works like a charm. Figured out how to make two with components I had lying around. Put them in their own chambers in an old, weird factory produced center channel, stuffed with some amp boards, full range drivers on the sides, inputs and an AC Jack. Pretty neat little portable. Sound comes from three sides and bass radiates in all directions. Sounds cool out in the yard with the kids. Best part is, it's all made from junk / spares / less than $5 drivers / freebies... So I can back over it tomorrow and no big deal.

    But I learned a helluvalot about crossovers
    a lot about high / low pass filters
    Got some new tools for computing
    Introduced to people who still want to help a new guy who loves this doing this stuff but has trouble learning about it without seeing and doing. Thanks to them. Sorry if this was annoying.
    A/V Obesessed Amateur and really, really green.
    I bet you never heard the my favorite on band. Push this (1, 2, 3) through your new project. Radio DJs can't help telling you what to listen to. Please don't mistake it for rudeness or that we think we're superior to you. We are not. At all.
    about.me/spaker
    Facebook

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  




Your #1 Source for Audio, Video & Speaker Building Components


Clearance Center
Deal of the Day
New Products




View Our latest
Sales Flyer

Prices Effective
Through 8/31/14


Order our FREE 336 Page Full Color Catalog


Speaker Component Categories

Home Audio Speakers

Professional Audio & Guitar Speakers

Car Audio Speakers

Speaker Buyouts

Measurement & Design Tools

Subwoofer Plate Amplifiers

Full-Range Plate Amplifiers

Crossover Components

Cabinet Hardware & Speaker
Grill Cloth

Speaker Cabinets

Subwoofer System Kits

Speaker Kits

Speaker Repair Parts

Speaker Wire