Speaker change ?

[SpareRibs]

Hello,
      I know I ask a lot of dumb questions, but if everyone will just bear with me this time I would like to know what dictates speaker ohms. I have a (Crate GX-40C+), there are two speakers that are 4ohm-6". I want to change the speakers. I have two 8ohm-12" speakers that I would like to use, however it is my understanding that this will cut power by half. While I never dime the controls, how much would it effect the sound at lower levels ? Would there be any chance of damage to the amp ?
      I understand the obvious solution would be to buy two 4ohm-12" speakers, but that could easily cost two
to three hundred dollars. At this point that is not an option for me. Thank you in advance for any information.

[Enzo]

People often assume that power is loudness, and it isn't.

Moving from 4 ohm to 8 ohms will indeed mean the speakers will draw only half the power at the same output voltage.   And if it were as simple as that, you would hear only a 3 decibel reduction in volume.  And that is not much.   In fact, you know on a lot of amps, especially fenders, with two input jacks, and one is louder than the other?   Those are usually 6 decibels different.  SO you would not notice the loss of power.

Having said that, speakers have efficiency ratings, also in decibels.  The higher the number of dbs, the louder the speaker.   And if you replace a 100db rated speaker with a 97db rated one, there would be the exact same 3db difference in volume.  It works the other way too.  If you replace a 96db speaker with a 99db speaker, it would be the same as doubling the power into that 96db one.


More than that, just having 12" instead of 6" speakers has a major effect on the amount of sound.

[SpareRibs]

Hello,
      Thank you Enzo for your reply. It was very informative and straight to the point. I kept looking to
find an answer before just posting the question. Every post I found just kept going off into the weeds
about transformers, preamps, and different values of all kinds of stuff. It's not hard for me to get lost.
      At this point I think I am just going to cut the amp into two pieces, using the top part as a head and modify the bottom part as a 2X12 speaker cabinet. That is one option to think about. I am sure there are a few other things to consider before I make a final decision. Thanks again.