Help with crossover selection?

Discussion in 'Home Theater Projects' started by HT-EXT, Jan 8, 2007.

  1. HT-EXT

    HT-EXT Agent

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    I am in the middle of building a two-way speaker using all Dayton components from Parts Express. Two 5" woofers {p#RS125-4}, one 1 1/8" tweeter {p#DC28F-8}, and a two-way crossover {p#XO2W-4.5K}. First question is there a better choice for a crossover for this combo? Should a crossover be around 3K or so for the speakers used? Next question is should I try to keep frequencies below 100Hz from going thru the 5" woofer and if so what is the best means of doing so while still using the Dayton crossover. I will be running a powered sub with the speakers and do not need the 5" to play below 100Hz. Maybe a 10uF to 20uF cap between the crossover and the woofer (on the + side) would solve this problem. Would the cap mess up the crossover I am already using? Any help would be appperciated.

    HT-EXT

    Dayton 5" woofer (Frequency range: 65-4,500 Hz Fs: 65 Hz)
    Dayton 1 1/8" tweeter (Frequency response: 2,000-20,000 Hz Fs: 907 Hz)
     
  2. John Garcia

    John Garcia Executive Producer

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    You don't cross over the bottom end, you let it roll off naturally in a 2 way design - that is what the receiver/processor's crossover is for.

    The problem you are going to run into most likely is actually testing the speaker's response - an out of the box x-over will most likely not be perfectly suited to the exact drivers you chose, and will most likely not give you the best response. Around 3000hz sounds like a good starting point if you were going to design your own x-over.
     
  3. HT-EXT

    HT-EXT Agent

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    Thanks for the reply John. I am planning on testing it both ways just for the heck of it to see the difference. I want to stick with all Dayton parts and speakers so maybe some of the components will match in the long run. Again thanks for the help.

    HT-EXT
     
  4. Cees Alons

    Cees Alons Moderator
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    Joe,

    I move your thread over to the DIY area of the forum.
    You may get some more useful replies over there (... now here [​IMG] ).


    Cees
     
  5. Robert_J

    Robert_J Lead Actor

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    Pairing up the Dayton silk dome tweeter with the RS woofer is not a great idea. The RS series woofers are great drivers and deserve the same quality level on the tweeter.

    Also, using a stock cross-over is never a good idea. Wayne J. wrote a great article about this at his site - link.

    If you are serious about using these drivers, you need to invest in the proper measuring equipment (hardware and software) to build the proper cross-over.

    -Robert
     
  6. Danny Richie

    Danny Richie Stunt Coordinator

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    Actually the tweeter is not too bad especially for the money, but the woofer is a bit of a dud. I found it to not only sound bad but the break-up in the upper ranges make it unusable for anything over 1kHz (unless you like the sound of a ringing metal cone).

    Such drivers are not easy to work with. Only a very step order crossover (maybe an elliptical one) would make it usable in a limited range but you're still left with the poor sound quality.

    I'd re-think the woofer for sure.

    Starting out with a proven kit would be much more of a sure bet.
     
  7. HT-EXT

    HT-EXT Agent

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    Thanks for the help with the thread Cees Alons. I was some what unsure where to post the question. I am by no means an audiophile just a fellow experimenting in the full-range arena. I have been building subs to long and need a new adventure. I have purchase some Dayton and Hi-Vi components and love to tweak, test, change, tweak, test, well you get the idea. I use the PAA2 from Phonic to test the "spectrum of response". I sure it is not the most accurate piece of equipment but it will haft to do. Thanks for all the replies and I will consider all as the build progresses. Please keep the opinions coming and maybe I will end up going in the right direction. Again thanks for the help.

    HT-EXT
     
  8. johnADA

    johnADA Stunt Coordinator

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    I find this funny, but I just finished building something close.
    Same tweeters paired with the RS125S-8.
    I used the Dayton crossover @ 2000hz and series padded the tweeter with a 1 ohm resistor and used a zobel consisting of a 47uF ( PE# 021-02-427) and a 8 ohm resistor (PE # 021-01-309).
    This takes care of the tweeters being a little too loud against the midbass driver and smooth ens out the impedance hump , which causes this peakyness of the midbass.
    These are my rears, sounds fantastic for what they costs and blow away the Polk Rt25i's they replaced.

    I also built a set of TMM's using 2-DAYTON DC160S-4 mid woofers and 1 VIFA D27TG-35 silk dome.
    This was suppose to be a wild mismatch of "JUNK" according to the likes of Audiophiles.
    The crossovers are use the same Zobel, thats where the idea came in for the others, 7.5 uF with a 1.0 mH, used on the tweeter. 5.6 uF and 1.5 mH on the woofers, giving me a 1800 hz crossover point. The tweeter was again padded, this time with a 2.2 ohm resistor in series. Everything but the padding was done
    using online calculators and the padding was a ear thing using a EQ borrowed to determine this amount.

    This was after using a LEAP designed crossover someone on a DIY site had given me I thought didnt sound close enough to right to me.
    There's a funny thing called the Fletcher-Munson curve, it shows how humans hear at different SPLs and I guess the LEAP design doesnt recognize this fact and rely's on a perfect science curve for perfection.

    I tried a L-pad which again was heavily recommended, but it appeared to my ear it took more than sound level away, it took some sound quality with it and I had read quite a few places a series resistor does a easier and better job so I went with it.

    Who's right and who's wrong in how crossovers should be built, tuned etc???? My ear is the determining factor in a game this HIGHLY SUBJECTIVE game of speaker sound!!!
    I love mine and the new ones again blow away what they replaced by 4 fold. Sweeter airy highs, decent midbass and lows that now have me turning the sub off listening to music!!! I always no matter what I did really could pinpoint a sub in some matter of time with speakers set to small, now set on large the sub blends perfectly if I choose it to be on.
     
  9. HT-EXT

    HT-EXT Agent

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    Thanks John for the very helpful info. I also believe it is up to the listener's ear to determine quality of sound. The environment the speaker will be used in will also have alot to do with the quality of sound. To say something will not work or is not compatable is the reason for trying the impossible and to over come certain obstacles in the way.

    I am curious if a Zobel Network would help with some of the woofer issues. Does anyone think the tweeter might also benefit from the Zobel Network. The Re on both woofers and the tweeter are close to the same( two 5" in series Re=5.8 ohms Le=.68mH) (one 1 1/8" Re=5.2 ohms). The spl ratings also are a close match with the woofers around 91db +/- 2db and the tweeter around 88db +/- 2db. The calculations for the Zobel is 12uF cap and 8 ohm 10w resistor for the 5" woofers. Does this sound close to right? Any opinions or info would be greatly appreciated.

    HT-EXT
     
  10. johnADA

    johnADA Stunt Coordinator

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    I got 7.25 ohms and a 12.94 cap for the woofer scenario, close enough for 10%.
    I dont see any value for using a Zobel on the tweeter at all. Its impedance curve, while not perfectly flat, isnt bad within "EAR" range.
    But after playing with such, I have a feeling it'll be about 6 db louder than the mids.
    Oh by the way, do you know how small the 5 inch really is. 3 1/2 inches max across the driver surface , including the rubber surround. Quite amazing sound from such a little driver with the ability to make very clean presence, with authority down to its FS rating.
     
  11. HT-EXT

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    Thanks John. The numbers you come up with are the exact figures. I tend to use the 10% rule because there are so many variables. Any suggestions for the tweeter that would help the Dayton crossover work correctly. Maybe a series resistor to raise the Re value. Let me know if there is anything I should do to help the tweeter perform up to par. Thanks again.

    HT-EXT
     
  12. johnADA

    johnADA Stunt Coordinator

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    All I can say is this is up to you how you choose to go with it.

    The tweeter is more than well going to be up to par. Its problem as I found and a few other similar type projects found at parts express, DIY speaker builder etc is that the tweeter will play louder, just louder, no other problems against the mids.

    Thats all that needs to be dealt with. You can pad it with a L-pad or series add just a resistor.

    I found the L-pad pulled a little life outta the sound, but "science", perfect world says it wont. I padded with a series resistor without changing the rest of the crossover. This was suggested by a Wayne J in this project-http://www.partsexpress.com/projectshowcase/so1.html

    So in my case on my new mains I put them together as I calculated the crossover and built them as is. Listened closely, near the speaker using my ear covering from top to bottom and found the tweeter was definitely noticeable louder. I used the receiver's treble adjustment to level the drivers. I found - 6DB setting to equal it out and someone had told me every ohm added in series is roughly 2 DB. I had boughten some extra resistors anticipating this problem and had 1 ohm, 2.2 and 3 and 3.7, they were cheap. I added with wire nuts a 1 ohm, not enough, jumped to a 3 ohm, too much and then added the 2.2, perfect for my ear.

    When I did the rears I had the leftovers, the dayton crossover and had picked up some more 2 ohm ones. I chose to pad the rears bright as I thought it gave some color and padded them with a 1 ohm, leaving the rears playing about 2-3 DB higher on the tweeters than the mids.

    Overall I am deeply happy and impressed from the sound I now have against any boughten units I had, I had tested and went 3-4 times or more overall in cost. I have MY SOUND, the way I like it. From all the toying around I did, just adding one new mid, 2 new mids, a tweeter, stock crossovers, custom my builds, I learned alot.
    Crossover if there totally off sound crappy.
    Crossovers using the calculators come very close and need a tweak or 2 ro get the driver balanced and then sound great.
    Perfect science built ones, where the curves are dead flat, well, I'm glad the measuring equipment can pick it up, but I find it really hard pressed that a ear could unless the ear and brain got together along with the eyes would know.

    I left the zobels in for peace of mind only, since I tried with and without one and really, honestly, "BARELY" and it could be a mind trick, heard a faint whisper of difference.
     
  13. HT-EXT

    HT-EXT Agent

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    Everything has come together nicely and the set up as a whole is more than adequate. It is amazing how much bass comes out of two little 5" woofers (actually 3 1/2). The tweeter itself sounds very good and might need to be attenuated but I going to let it ride for now. The Zobel help out also and I only lost about 1db to 1/2db of the top but it smooth out the entire signal for better clarity. The sub that goes with this combo is two Dayton RF 8"s in a single fold TL. I used two 10mH coils in series to roll the 8"s off about 100Hz. I highly recommend the Dayton Reference Series to anyone wanting good quality sound at an affordable price. Thanks for all the replies and I appreciate the extra info John. It inspired me to go through with the experiment even though I had my doubts. Thanks Again.

    HT-EXT
     
  14. Cees Alons

    Cees Alons Moderator
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    Great to hear that, Joe!


    Cees
     
  15. johnADA

    johnADA Stunt Coordinator

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    Congrats!!!

    Feels good doesnt it knowing you built your own and it isnt as difficult as all the crap you read about it makes it out to be.

    And it is really amazing how such small surface area drivers outdo the alot of the big boys. with clarity and enough bass you'd be thinking its at least a 6 1/2 or 7 inch driver.

    But be careful of the bug!!!!!!

    It has a wild tendency to take over and go onward and upward again.
    I have a bug biting me now that says to get the reference 6 1/2's and lose the classics. But I hope I beat it down finalizing the sub I built that was lacking a good plate amp which comes next week!!

    ENJOY!!
     

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