Mark_ii Posted July 20 Posted July 20 I was considering purchasing a MESA TT800 amp, there is a 3 way switch on the back to select either 8 ohms, 4 ohms or 2 ohms. My question: I have a 4 ohm cab and an 8 ohm cab. If I set the MESA to 2 ohms would I damage the amp at all by running both cabs, I realise that my 2 cabs combined would offer a resistance of 2.67 ohms and yet the amp would be expecting a full 2 ohm load. So would the discrepancy be harder or easier on the amp itself, or is it asking for trouble to have a mismatch in the first place ? Hoping you can help guys. 👍 Quote
JGSpector Posted July 20 Posted July 20 you will be fine. If you set the amp to the 2ohm setting, it means that the amp can take a speaker load down to 2ohms, so your 2.67ohm load is fine because the number is higher than 2. As long as the total load doesn't go under 2ohms the amp will be just fine. 2 Quote
Mark_ii Posted July 20 Author Posted July 20 Wow, that's a speedy response. Much appreciated, fair play 👍 1 Quote
Bill Fitzmaurice Posted July 20 Posted July 20 Note that SS and valve amps aren't the same. SS impedance load ratings are minimum, but valve load ratings are maximum. For instance if you have a valve amp with 4 ohm and 2 ohm output taps you'd use 4 ohm with a 2.67 ohm load. 1 Quote
BassmanPaul Posted July 20 Posted July 20 (edited) Another point is that the 4Ω cabinet will draw twice the power of the 8Ω box. That could be more than the speakers can safely handle.. Edited July 28 by BassmanPaul Quote
agedhorse Posted July 20 Posted July 20 5 hours ago, BassmanPaul said: Another point is that the 4Ω cabinet will draw twice the power of the 8Ω box. That Ould be more than the speakers can safely handle.. Not necessarily. Using the Subway 115 and 215 as examples, the 8 ohm 115 is rated at 400 watts RMS, the 4 ohm 215 is rated at 800 warts RMS, when driven from the 2 ohm tap (switch position) each DRIVER receives 1/3 of the ~800 watt rated power or about 260 watts which is well below the rated power handling of the driver in those cabinets. Perfectly safe, perfectly good power match as well. Here's the handy table from the owner's manual, and why I strongly recommend reading the owner's manuals for our products: 1 Quote
Mark_ii Posted July 22 Author Posted July 22 Wow, that is useful indeed. Much appreciated guys. 1 Quote
BassmanPaul Posted July 28 Posted July 28 (edited) Y'know Andy I DID say could be!! LOL Edited July 28 by BassmanPaul Quote
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