1. Welcome to Tacoma World!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tacoma discussion topics
    • Communicate privately with other Tacoma owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Running this amp at 8ohms?

Discussion in 'Audio & Video' started by oofy15354, Apr 4, 2011.

  1. Apr 4, 2011 at 6:52 PM
    #1
    oofy15354

    oofy15354 [OP] Proud Tundra *****

    Joined:
    Nov 2, 2009
    Member:
    #25311
    Messages:
    513
    Gender:
    Male
    First Name:
    Dave
    Massachusetts
    Herculiner, Access Tonneau, Uniden cb, firestik antennae, Bosch Wipers, JVC Ipod headunit, Boston Acoustic Speakers
    http://www.pioneerelectronics.com/PUSA/Car/Amplifiers/GM+Digital+Series/GM-D8500M

    I apologize, I'm a little new at this whole subwoofer deal. The subs I'm looking at are rated for 1000w peak and 200w nominal at 4ohms. Is nominal the same as RMS in that i want an amp that puts out 200w rms?

    I found a great deal on that amp and would like to use it if possible. It is rated for 600w at 2 ohms and 300w at 4 ohms. Running in parallel, does this mean the subs are getting 300w RMS which is too much? If I run in a series, that would mean the amp makes 150w at 8ohms but is it safe to run the amp like this?

    Sorry for the noob questions and lack of searching (ive done it elsewhere) but im not sure how to approach this. Thanks for all the help!
     
  2. Apr 4, 2011 at 7:07 PM
    #2
    lbridges

    lbridges Well-Known Member

    Joined:
    Mar 6, 2011
    Member:
    #52434
    Messages:
    403
    Gender:
    Male
    First Name:
    Lee
    Indialantic, FL
    Vehicle:
    '11 PreRunner SR5
    It is safe to run the amp like that, but results in each sub "seeing" only 75 Ohms. It would be better (IMO) to run them in parallel (2-Ohm load) and control the power output by using the gain knob on the amp. BTW, you don't specify the subwoofer(s) so its hard to say how much is too much/enough/too little.
     
  3. Apr 4, 2011 at 7:14 PM
    #3
    oofy15354

    oofy15354 [OP] Proud Tundra *****

    Joined:
    Nov 2, 2009
    Member:
    #25311
    Messages:
    513
    Gender:
    Male
    First Name:
    Dave
    Massachusetts
    Herculiner, Access Tonneau, Uniden cb, firestik antennae, Bosch Wipers, JVC Ipod headunit, Boston Acoustic Speakers
    http://www.pioneerelectronics.com/PUSA/Car/Subwoofers/Champion+Series/TS-W253R

    theres the subs i plan on using. im aware they are on the cheap side but my budget isnt great. I can get 2 subs, that amp and a wiring kit with cap for $300 and make my own box.


    so running at 2ohms at 600w nominal is safe as long as i keep the gain low? any way to tell how much is too much or just keep it low?

    also, can you explain how each sub sees 75 ohms? if its too complicated and math-y forget it. ill just take your advice and take comfort in that someone else know what theyre talking about :D

    im using this diagram that shows two 4 ohm speakers in series drawing an 8 ohm load
    http://www.caraudiohelp.com/ohms_law/ohms_law.htm
     
  4. Apr 4, 2011 at 8:18 PM
    #4
    ItalynStylion

    ItalynStylion Sounds Gooooood

    Joined:
    Jun 15, 2009
    Member:
    #18467
    Messages:
    4,866
    Gender:
    Male
    First Name:
    Steven
    DFW, Tx.
    Vehicle:
    09 Double Cab TRD Sport 4x4
    When the sub starts sounding crappy like it's popping it's too much.

    Every time you double the impedance (ohms) you cut the power in half. 300@4ohms will turn into 150@8ohms. So 150watts divided by 2subs will yield 75watts each.
     
  5. Apr 4, 2011 at 10:26 PM
    #5
    pinktaco808

    pinktaco808 Hot Steppa

    Joined:
    Jul 23, 2010
    Member:
    #40651
    Messages:
    2,785
    Gender:
    Male
    so can you runs a amp at a higher ohm if it rated at a lower ohm??? like it says it make 500 watt at 2 ohm but you have 8 ohm subs??? will it work???
     
  6. Apr 5, 2011 at 4:31 AM
    #6
    oofy15354

    oofy15354 [OP] Proud Tundra *****

    Joined:
    Nov 2, 2009
    Member:
    #25311
    Messages:
    513
    Gender:
    Male
    First Name:
    Dave
    Massachusetts
    Herculiner, Access Tonneau, Uniden cb, firestik antennae, Bosch Wipers, JVC Ipod headunit, Boston Acoustic Speakers
    yes it will work (to the best of my understanding) but you will be running at 125w output from that 1000w amp and if you have multiple subs, that wattage will be divided again
     
  7. Apr 5, 2011 at 6:14 AM
    #7
    ItalynStylion

    ItalynStylion Sounds Gooooood

    Joined:
    Jun 15, 2009
    Member:
    #18467
    Messages:
    4,866
    Gender:
    Male
    First Name:
    Steven
    DFW, Tx.
    Vehicle:
    09 Double Cab TRD Sport 4x4
    If your truck can drive 50mph can you drive it 30mph? A higher impedance (ohms) means the amp will make less power and therefore do less work.
     
  8. Apr 5, 2011 at 10:49 AM
    #8
    lbridges

    lbridges Well-Known Member

    Joined:
    Mar 6, 2011
    Member:
    #52434
    Messages:
    403
    Gender:
    Male
    First Name:
    Lee
    Indialantic, FL
    Vehicle:
    '11 PreRunner SR5
    I meant 75 Watts, my fingers don't always type what my brain thinks they were told to do. The answers from others clarified I think, just wanted to make sure.
     
  9. Apr 5, 2011 at 5:17 PM
    #9
    oofy15354

    oofy15354 [OP] Proud Tundra *****

    Joined:
    Nov 2, 2009
    Member:
    #25311
    Messages:
    513
    Gender:
    Male
    First Name:
    Dave
    Massachusetts
    Herculiner, Access Tonneau, Uniden cb, firestik antennae, Bosch Wipers, JVC Ipod headunit, Boston Acoustic Speakers
    yup figured that out, makes sense to me. thanks for the input.

    i guess my mind equated "resistance" with making the amp work harder and producing more heat but that seems to be the opposite. will do that
     
  10. Apr 5, 2011 at 9:14 PM
    #10
    pinktaco808

    pinktaco808 Hot Steppa

    Joined:
    Jul 23, 2010
    Member:
    #40651
    Messages:
    2,785
    Gender:
    Male
    even though it bridged
     
To Top