Dismiss Notice

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

3 speaker box (ohm question)

Discussion in 'Amps and Cabs [BG]' started by WASHBURNGUY, Jul 21, 2003.


  1. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    First my set up is an ampeg b4r. 1 15"cab 300 watts 4ohms,and 1 8ohm 10"..Im running it biamped..I want to make a cab with this 10"(8ohm) and 2 16ohm 12"...will this get me to my desired 4 ohms running them parallel...thanks for the help

    OOPS I WANT to run it biamped as i cant with an 8ohm load and a 4ohm load
     
  2. geshel

    geshel

    Oct 2, 2001
    Seattle
  3. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    I did,dint see anything about this in faq..I realize (IF)I get 4ohms out of these 3 speakers..
    that Ill get more current draw from the 8 ohm speaker than the other 2 16s..So (I belive i read) that causes the 8 ohm speaker to be a bit louder wich would be great As long as the cab is 4 ohm with this configuration
    Im doing all of this because i can bi amp my amp
    HI and low outputs..So all my lows will be threw my 15" and the mids and highs out of my 2-12 1-10 (hopfully)..my 10" is 150 watts and Im looking at some cheep 12s that are 250 ea so the cab would be 650 watts(rms) and the lows would be 350(rms) into a peavey bw
    Iv been wanting to try this but i couldnt with a 4ohm cab and a 8ohm cab
     
  4. geshel

    geshel

    Oct 2, 2001
    Seattle
    If you read this:

    http://www.talkbass.com/ampfaq/

    You'd have found this:

    But you've got it right so far. The 12s will (both, total) get the same power as the 10. How loud they are in comparison also depends on the sensitivity of the drivers - check that out, as if they are wildly different you won't have what you expect.

    You could bi-amp your current setup - your amp has a level adjustment for the two channels, right? Unless you know that the output into 8 ohms on the top end won't be enough.
     
  5. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    You could bi-amp your current setup - your amp has a level adjustment for the two channels, right? Unless you know that the output into 8 ohms on the top end won't be enough.
    QUOTE"


    Yeah! thats exactlly what i want to do..but i could damage my amp doing it with a 4ohm as lows
    and an 8ohm as highs because this is biamping it down below 4ohms ..this is why i have to be certian that i have a 4 ohm load in the cab im thinking of building to match my 4ohm Black widow cab..as long as 2 16 ohm speakers and and 8 ohm make 4 ohm..then ill be making my new cab this comming up week..
     
  6. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    thanks for your help geshel..i really suck at math though ..as for big diffrences in sensitivity and everythig..Im into trial and error:)I have a windi(I think) or some program for speakercab building..IM just makin sure i dont mess up my head in the process..
     
  7. arfur

    arfur

    Nov 26, 2001
    London, UK
    The 10 will be getting more power than the 12's so that that one driver will probably bottom out before you've hit full whack into all three drivers. The power handling of the 12's becomes irrelevent, so the whole cab will take about 300 watts. (although we know that cabs generally take more than their rated power)

    If this cab is only providing the top end of a bi-amp rig then why bother with this complicated configuration. Why not just run the 10 as it doesn't have to deal with the low frequencies?
     
  8. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    becuase alone its 8ohms...and the 15 is 4 ohms. Doing that would bring me down below 4ohm min bi-amp ratting my head has..so right now im running them (ea cab off seperate chanels) NOT biamping them..thanks for your help though..Why make a complicated cab?well i have powertools i rarley use hehe and it could be a fun project:)
     
  9. arfur

    arfur

    Nov 26, 2001
    London, UK
    That I can relate to. I did a similar thing a few years back. It took a lot of effort and looked good with all those drivers but it ultimately sounded bad.

    I've just spotted this. You do know that if you are running off of different channels then the impedances will not combine. You just have one channel of your amp running at 4ohms and one channel running at 8ohms.
     
  10. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    Ouch. yeah that would be disscouraging for sure.
    the one 10 i built, everone that heard it says it rocks.Thats why im wanting to go bigger with it..

    Yeah this is what im doing right now.but i cannot biamp with them running this way
    thanks for your help and comments arfur i really appriciate it
     
  11. geshel

    geshel

    Oct 2, 2001
    Seattle
    Why not?
     
  12. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    Thanks geshel.I found out that i can do it like it is,its 2 ohm stable biamping in stereo..4ohm stable in mono bridged..I suppose i was a bit confussed on how this amp worked.Its my first biampable amp. Well thanks for all the help guys i appricciate it. You guys rock this site is sweet!
     
  13. geshel

    geshel

    Oct 2, 2001
    Seattle
    OK. Yeah, the lowest load on one channel if you biamp it w/ the 10 and the 15 is 4 ohms (the channel w/ the 15) - it's really the same as running stereo, just that you send the low frequencies to one channel and the high frequencies to the other.
     
  14. WASHBURNGUY

    WASHBURNGUY

    Dec 28, 2002
    Yes thats bad ass. i didnt relize this. i thought it was biamping the 2 internal amps into a mono load for some reason.DOHH live and learn..of course ampeg dosnt (recomend) using 2 cabs diff ohms BUT it dosnt void the warrenty so thats cool. Must be because it will sound diffrent than what there amp does running it the Normal way.and they cant be sure if it will sound "good" running it other ways they havnt totally tryed(Good cuz im making homemade cabs) ..thats what my drummer told me and i have to agree..running it like I am it sounds So sweet i cant Wait to use the crossover and frequency controls.I may not need to build a new cab..Im sure i WILL anyhow.I love new gear!