Resistors in Parallel

Michael8it
Michael8it Posts: 192
edited August 2011 in Vintage Speakers
Ok, it's been just a few......... years since I was an Electronics Technician, and my memory of how resistors acted in parallel has left me.

I am working on a pair of original RTA 12 crossovers and identifying all the parts. It has two sets of resistors in parallel:

R3 is a pair of 4.5ohm, 10% 5W resistors
R2 is a pair of 6/2ohm 10% 5W resistors.

When I replace them, can I simply use one resistor (instead of two in parallel) and if so, what is the resistance value?

Thanks,
Mike
Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
Post edited by Michael8it on
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Comments

  • Outfitter03
    Outfitter03 Posts: 563
    edited August 2011
    R3 = 2.25 ohm A 2.2 ohm resistor will be within tolerance.

    R2 = 1.5 ohm

    Link to calculator

    http://www.sengpielaudio.com/calculator-paralresist.htm

    You can use a single resistor. I would recommend going to a MRA-12 from Sonicraft. The power handling will be same or greater than the parallel resistors.

    Sonicraft still has 20% sale. http://www.soniccraft.com/mills_resistors.htm
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  • BlueFox
    BlueFox Posts: 15,251
    edited August 2011
    Like capacitors in series. :wink:
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  • Michael8it
    Michael8it Posts: 192
    edited August 2011
    Now I am more confused - OUtfitter03 - I used the calculator your referenced, and R2 (2 6.2 ohm's) came out to 3.1, which is what the schematic says it should be.

    R3 comes out to 2.25 using this calculator, but the schematic says it should be 1.69. The schematic is handwritten (downloaded here). Do I go with the schematic or with the value listed?

    I am not sure how you came out to 1.5 on R2.
    Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
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  • Outfitter03
    Outfitter03 Posts: 563
    edited August 2011
    Michael8it wrote: »

    R3 is a pair of 4.5ohm, 10% 5W resistors
    R2 is a pair of 6/2ohm 10% 5W resistors.

    I read that you had two resistors. One that is 6 ohm and one that is 2ohm in parallel. Not a pair of 6.2 ohm. So your calculated value is right.

    I would always go with what you find in the speaker unless there is some indication that these are not the original factory crossover component and modded by someone else. Particularly if they sound good as it is.
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  • Michael8it
    Michael8it Posts: 192
    edited August 2011
    Ok. thanks. I will stick with what is on it!
    Carver C-1, M-500 MKII, Yamaha HTR-5835, Polk RTA 12BM's (M-for mod'd).
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  • MNmike
    MNmike Posts: 41
    edited August 2011
    You may want to up the wattage going to one resister as they split the current in the parallel origionally
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