Bass Of Spades Posted March 28 Posted March 28 So, I have managed to get myself in an Ohm quandary - I have a 2x10 cab rated 8 ohms, and a 2x15 cab rated 4 ohms... I have been running the amp through each cab individually, but fancy seeing what I get if I were to run through both. Knowing very little about Ohms, I thought I better ask the question. Can I run both cabs from the amp, and if so, what output do I run the amp at (would this be 2 Ohms?) Also, do I run an output to each cab individually (using both outputs from the amp) or do I link the cabs together using one output from the amp - just want to ask you good folk before I blow up my amp, speakers, or indeed both... Quote
fretmeister Posted March 28 Posted March 28 Why do people post this sort of question without saying what the amp is? Quote
Bass Of Spades Posted March 28 Author Posted March 28 People? This person simply didn’t realise it was important... Mesa TT 800, it has a switchable output 8, 4, or 2 ohms... 1 Quote
JJMotown Posted March 28 Posted March 28 Why don't people post this sort of question in the Amps & Cabs section, where they talk ohms? Quote
fretmeister Posted March 28 Posted March 28 1 hour ago, Bass Of Spades said: People? This person simply didn’t realise it was important... Mesa TT 800, it has a switchable output 8, 4, or 2 ohms... That would give you 2.67ohms so set the amp to 2 ohms. 2 cables from the amp or daisy chaining will be fine. Quote
neepheid Posted March 28 Posted March 28 Going forward, so you can work it out for yourself in future without the danger of subjecting yourself to snippy comments - adding impedances together in parallel works like this: So in your case: 1/R = 1/8 + 1/4 1/R = 3/8 R = 8/3 = 2.67 ohms 1 Quote
Bass Of Spades Posted March 28 Author Posted March 28 @fretmeister and @neepheid really appreciate your help - I know its probably a basic question but when you dont know you dont know. Appreciate your time in helping out. cheers 5 Quote
bremen Posted March 30 Posted March 30 On 28/03/2025 at 19:04, neepheid said: Going forward, so you can work it out for yourself in future without the danger of subjecting yourself to snippy comments - adding impedances together in parallel works like this: So in your case: 1/R = 1/8 + 1/4 1/R = 3/8 R = 8/3 = 2.67 ohms Or if you're as lazy a sod as I am: https://www.allaboutcircuits.com/tools/parallel-resistance-calculator/ 1 Quote
Suburban Man Posted March 30 Posted March 30 You may have already discovered that you will get twice the power going into the 4 ohm cab as you get going into the 8 ohm cab. Sonically quite interesting since it’s the 15” speakers that will be working hardest. Quote
bremen Posted March 30 Posted March 30 True, but the 8 ohm cab only needs to be 3dB more efficient than the 4 and they'll both be equally loud. And they'll have response variations that might result in better, maybe worse sound. Quote
Suburban Man Posted March 31 Posted March 31 5 hours ago, bremen said: True, but the 8 ohm cab only needs to be 3dB more efficient than the 4 and they'll both be equally loud. And they'll have response variations that might result in better, maybe worse sound. Agreed. I was probably being a little too oblique when I said “sonically interesting“ 🤔 Quote
prowla Posted March 31 Posted March 31 On 28/03/2025 at 17:37, JJMotown said: Why don't people post this sort of question in the Amps & Cabs section, where they talk ohms? Why don't people write Ohms correctly? 🙂 1 Quote
prowla Posted March 31 Posted March 31 1 hour ago, Bass Of Spades said: At least the sun us out... ...doo do doo-do. Quote
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