4 ohm output to 8 ohm speaker?

Discussion in 'Amps and Cabs [BG]' started by billengelman, Dec 6, 2001.

  1. I have a '67 Bandmaster amp head with 4 ohm output. I believe the original Bandmaster cabinet had (2) 8 ohm speakers, making it 4 ohm. I am now outputting to a single 8 ohm speaker. Is this going to do any damage to the amp head? Does it have any serious affect on the sound? I just spent $150.00 getting the amp fixed and I don't want to do anything to screw it up.
  2. ThunderStik

    ThunderStik Guest

    Jun 25, 2001
    Claremore OK.
    No, there is never anything bad about going higher in ohms, its when you go below your minimum ohm rating that creates problems. It will likely cut your power in half though, 300wt @4ohm usually equals about 150wt@ 8ohm. Those are just made up numbers but you see where im goin.
  3. The bandmaster would be a tube amp, right? If it is the same rules don't quite apply. Tube amps have output transformers that have secondary taps to deal with specific impedences (ohms). Ideally you should match the impedences, but a mismatch like that probably won't do any damage to the amp or speaker, but the amp will perform better when the impedences are matched.

    So, in the realm of tube amps there is the possibility that running at higher than rated impedences is a bad thing. If you ran a 16 or higher Ohm speaker off that output I'd be concerned about damaging the amp. Whatever you do, don't turn the amp on and play it with no speaker attached. This will definately destroy your output transformer. If it's not a tube amp, disregard this post...:D
  4. The Bandmaster may have some sort of impedence selector on the back (either a switch, or a soldered/solderless jumper).

    It is best to match the impedence of the cabinet to that of the amp, but in my experience there isn't much in it.

    I've got a copy of a Bassman (similar deal) that has a soldered jumper on the back - i've got it set to 4Ohms, but use it almost exclusively with 8Ohm cabinets. I just have it set this way so that I can connect a 4Ohm or another 8Ohm cabinet without worrying about the head.

    Like Spacegoat sez, don't play the beast with no speaker attached (well, you can leave the amp ON, but with the standby OFF)...
  5. Are you using this head for bass?The first amp I used for bass was my brothers Bandmaster and 212 cabinet in 1968.It was ok for getting started but I soon realized that it wasn't a bass amp,it was a guitar amp.They only put out about 35 watts and sound ok at real low volume for bass.Sell it to a guitar player(they sound real good for guitar)and buy yourself a BASS AMP.
  6. Thanks again for everybodies input, and yes, Blues Bass 2, I am using it for a bass. And yes, it sounds real good at low volume. I'm just starting out and have not had a chance to play with others so volume is not an issue yet.