Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Ok... Now I am just confused...

Discussion in 'Amps and Cabs [BG]' started by Tecx, Feb 23, 2004.


  1. Tecx

    Tecx Radio Rock Leads To Sterility

    Jun 9, 2002
    Halifax, NS, Canada
    I decided to keep my curent setup, but I just downsized it (a bit)... But I just got off the phone with SoundTech service - and he told me my amp is only 100w @ 8ohms and 200w @ 4... Even though it is labled on the back... I have only ever used 1 cab with this setup, and I have never tryed using 2 or a 4 ohm... my curent cab is rated for 200w rms @ 8 ohms...

    So how can I test it?.. I have a digital voltmeter, would that work?..

    Also if it is 200w @ 8ohms, would it be 400w at 4ohms...

    Sorry guys... my brain is fried...

    Alex
     
  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Which SoundTech amp do you have? Your profile indicates a PL200, which is rated 65 watts/channel into 8 ohms, 100 watts/channel into 4 ohms and 200 watts bridged into 8 ohms.

    Ohm's and Watt's Laws might suggest that an amp's output power could double as the load impedance is cut in half. However in reality it doesn't. It often becomes a power supply capacity issue.

    http://proaudiomusic.com/sound_systems/soundtech/PL200_amplifier.htm
     
  3. Tecx

    Tecx Radio Rock Leads To Sterility

    Jun 9, 2002
    Halifax, NS, Canada
    Thanks man... Ya its the PL200, and the guy I talked too was a total dick today... He basicaly told me I was an idiot for thinking it was 200w @ 8 ohms.... So thats for re-asuring myslef that I am not a tool, on the other hand do you think it would be worth it to try running it at 400 @ 4?..

    Alex

     
  4. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    I'm not quite sure what you're asking... If you try to run it bridged at 4 ohms when the minimum rated impedance is 8 ohms, one of two things will happen over the long run...

    1. The amp will operate intermittantly because the protection circuit will shut it off when it overheats...

    2. The amp will blow up.

    You can't really force an amp to put out power levels that it wasn't intended to produce. It's more like you connect a load of known impedance to the amp, then feed the amp a signal voltage from your preamp, which it amplifies the signal and drives the speaker. If you try to force the amp to produce more output power than it was designed for, you have to "overdrive" the amp. Doing this can cause clipping in the input stages, clipping in the output stages (because the amplifier wants more power than the internal power supply can provide) and/or thermal problems as the output transistors overheat.