#1
I have a JCM 900 that is running with the impedence at 8 Ohm output. It is selectable to run at either 8 or 4(16) as many of you know. No big mystery there.
I noticed, though, that the G12T-75's that I thought were 8 Ohm, are actually 16 Ohm speakers. Can someone please explain the theory of speaker impedence in this situation. I also have a Carvin Legacy cabinet that is rated at 16 Ohm and its loaded with V30's. Before I crack it open, does anyone know what the speakers are rated at individually? I'd like to pop two of them into the JCM combo. I could probably figure this out on my own, but I'd figure I would start a thread with some actual substance
Thanks in advance.
#2
They're wired in parallel rather than series. If two speakers are wired in parallel, the amp will "see" half as many ohms. So if you have 2 16 ohm speakers wired in parallel, the amp will only "see" 8 ohms. However, if speakers are wired in series, the amp sees the total value, so if you had two 16 ohm speakers wired in series, the amp would "see" 32 ohms. If you need me to, I'll draw you a diagram in Paint

Edit: Also, as far as watts goes, there's a difference between parallel and series. If you have a 100 watt amp feeding two speakers wired in parallel, each of those speakers sees 100 watts of power. However, if you have 2 speakers wired in series and a 100 watt amp, each speaker would see 50 watts. That's why you can use 30 watt speakers in a 4x12 cab for a 100 watt amp -- just wire them all in series, and each speaker is only seeing 25 watts of power.
Hi, I'm Peter
Last edited by Dirk Gently at Aug 7, 2006,
#3
Quote by Dirk Gently
They're wired in parallel rather than series. If two speakers are wired in parallel, the amp will "see" half as many ohms. So if you have 2 16 ohm speakers wired in parallel, the amp will only "see" 8 ohms. However, if speakers are wired in series, the amp sees the total value, so if you had two 16 ohm speakers wired in series, the amp would "see" 32 ohms. If you need me to, I'll draw you a diagram in Paint

Edit: Also, as far as watts goes, there's a difference between parallel and series. If you have a 100 watt amp feeding two speakers wired in parallel, each of those speakers sees 100 watts of power. However, if you have 2 speakers wired in series and a 100 watt amp, each speaker would see 50 watts. That's why you can use 30 watt speakers in a 4x12 cab for a 100 watt amp -- just wire them all in series, and each speaker is only seeing 25 watts of power.

Paint would be good. Maybe crayon?
Then I should be good with swapping the V30's out of the Carvin cab, then. Especially since the Marshall is 50 watts. They should break up great.
Just checking the formula.
Thanks.