High Pass for Mids?

Discussion in 'Archived Threads 2001-2004' started by GregSanders, Nov 4, 2002.

  1. GregSanders

    GregSanders Extra

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    Here's my first post at HTF...

    I've finished my car audio project and am now moving onto some form of an HT system, though it'll be audio only for now.

    I'm getting into a DIY speaker project, currently using WinISD to help me choose drivers and design the box. It's a hell of a lot of fun.

    My question is this: Do I need a high pass filter on my midrange speakers? If I don't have one, then the lower frequencies will be hitting my driver that may have an Fs of 50Hz, and I'd think this could kill it. However, I may be missing something...
     
  2. Jonathan M

    Jonathan M Second Unit

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    Welcome to the forum, Greg.

    If you plan to run the speakers (I'm assuming you're doing a 2-way) as Small speakers from a home theatre receiver, then they will be crossed (Likely with a 2nd order high pass at around 80-100Hz) at the receiver.

    The main thing I'd look for is study the X-max curve - I'm not sure if WinISD handles this or not - get hold of Unibox (it's free - but requires Excel) - it's the best box modelling program I've used - handles stuffing etc. pretty accurately.

    Just play around with possible drivers and watch that you don't exceed XMax by too much at the power level you want to achieve. Remember that at 80 or 100 Hz the mid will be already 3dB down if you have them set to small, so that may help. You generally have to go for a 6.5" woofer if you plan to cross much below 100Hz.

    Hope this helps. What sort of alignment/size etc. are you planning?
     
  3. GregSanders

    GregSanders Extra

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    Jonathan,

    Thanks for the reply. I just read the manual for the receiver I'm considering (Denon AVR1603) and it has Large/Small speaker settings for each channel. So that answers my question! I wish they explicitly stated where the over point is for each setting though.

    WinISD is also free, and after I figured it out, it was a late night of drooling over what I could do with different drivers! I will download Unibox and play with it Thursday when I have a little time.

    My goal is to just build 2-way speakers with one mid and one dome tweeter because I'm on a *tight* budget. I have up to 3 cubic feet of space for the boxes, but with 6.5" speakers it seemed there was no need to go even over 1cu ft.

    Thanks again,
    Greg
     
  4. Chris Carswell

    Chris Carswell Supporting Actor

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    I like WinISD b/c it loads runs faster. You can see the graphs as you change the info. Unibox (better) is a little different but once you get the hang of it it is a breeze. I like to start in WinISD then finish up with Unibox. What are you going to build?
     
  5. GregSanders

    GregSanders Extra

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    Well, I'm starting off with a pair of speakers, then some day I'll finish the set. It's a wedding gift for my brother, but since I'm in college it's tough to find the time and money for the project.

    What I build depends on what WinISD and Unibox tell me about different drivers in my price range. I've picked out a peerless tweeter (810369) and I'm thinking about either peerless CSC-X drivers (8"), or MCM Aluminum Cone 6.5" drivers to save some cash. Since it's eventually going to be a 5.1 system, the low bass response doesn't matter much, as the sub will handle that, so I'm leaning towards MCM. Also currently researching veneer vs. stains to figure out what I'm capable of, what looks better, and what I can afford!

    Thanks again for the advice, I will definitely have more questions later in the week.
     
  6. Chris Carswell

    Chris Carswell Supporting Actor

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    WinISD & Unibox only tell you about the low end of the drivers. Keep that inmind. What are you going to do about the xover?
    Looks like the 810369 is ~$16 & the 8" CSC-X ~$22. Not bad I guess. I haven't heard anything about those but Peerless does make good stuff. I will say the 850122 & 811815 is a great combo. Email me for more info, pics, suggestions.
     
  7. Jonathan M

    Jonathan M Second Unit

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    I'd suggest playing with Speaker Workshop for the xover. It's free, and is admittedly a little hard to use at first, but the xover modelling and optimisation section is good.
    Check out this site for a good tutorial on how to get manufacturers data into Speaker Workshop.
     

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