Members eeddings Posted December 24, 2012 Members Share Posted December 24, 2012 I've read contradicting statements online. Thanks in advance. Link to comment Share on other sites More sharing options...
Members theAntihero Posted December 24, 2012 Members Share Posted December 24, 2012 Ive done it with a SS amp before but i really like to make sure the ohm rating is the same with tube heads. Link to comment Share on other sites More sharing options...
Members dparr Posted December 24, 2012 Members Share Posted December 24, 2012 No problem at all. You can always go higher but never lower. Link to comment Share on other sites More sharing options...
Members DARKMETL/ Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by dparr No problem at all.You can always go higher but never lower. I believe this is generally ok. Just makes the amp work a bit harder. I used a 8ohm Mesa .50 Cal head for a long time with a Marshall 16ohm cab with no issues... Link to comment Share on other sites More sharing options...
Members eeddings Posted December 24, 2012 Author Members Share Posted December 24, 2012 Thanks guys! Link to comment Share on other sites More sharing options...
Members GCDEF Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by dparr No problem at all.You can always go higher but never lower. It never fails. Sigh. With tube amps, it really depends on the amp. You can't make general assumptions one way or the other. Check the owner's manual. Solid state amps will have a minimum impedance. Anything equal to, or higher than the minimum is okay. Link to comment Share on other sites More sharing options...
Members KCTigerChief Posted December 24, 2012 Members Share Posted December 24, 2012 I used to use a 1400w 2ohm Class D subwoofer amp in my car wired at 0.5ohms...It was fine for over 6 years and was loud as {censored}. I don't recommend it, but it can be done. It really just depends on the amp. Personally, I wouldn't do it with a tube amp as components are much more sensitive and volatile then solid state components. Link to comment Share on other sites More sharing options...
Members KCTigerChief Posted December 24, 2012 Members Share Posted December 24, 2012 I used to use a 1400w 2ohm Class D subwoofer amp in my car wired at 0.5ohms...It was fine for over 6 years and was loud as {censored}. I don't recommend it, but it can be done. It really just depends on the amp. Personally, I wouldn't do it with a tube amp as components are much more sensitive and volatile then solid state components. Link to comment Share on other sites More sharing options...
Members dparr Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by GCDEF It never fails. Sigh. With tube amps, it really depends on the amp. You can't make general assumptions one way or the other. Check the owner's manual. Solid state amps will have a minimum impedance. Anything equal to, or higher than the minimum is okay. I've never heard of a amp (tube or SS) where you can't use a higher ohm cab.If you know of one please share. Link to comment Share on other sites More sharing options...
Members shane159 Posted December 24, 2012 Members Share Posted December 24, 2012 In some cases that is an OK mismatch,but it does not apply to all amps. I know Mesa usually says it is ok with their amps, but I know some Marshall's and older Fenders can be ruined in offset ohm loads. What amp are you wanting to do this with? Most modern amps can handle the higher mismatch, but I would still make sure. Link to comment Share on other sites More sharing options...
Members Elder Things Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by dparr I've never heard of a amp (tube or SS) where you can't use a higher ohm cab.If you know of one please share. Any tube amp into an infinite load (aka no speakers hooked up) is asking for a new OT, especially with insulated output jacks (Marshall). SS can tolerate this, but will likely damage output transistors running into a very small load. Link to comment Share on other sites More sharing options...
Members Pine Apple Slim Posted December 24, 2012 Members Share Posted December 24, 2012 older Fenders can be ruined in offset ohm loads. I recently learned this. Evidently there's a lot of old 4 ohm Bassmans out there with replaced output transformers. Story goes some OTs were produced that were closer to 2 ohm spec than 4. So if plugged into an 8 ohm cab, the mismatch is even worse. They are tough old amps but they can only take so much. So most experts will tell you its best to run your tube amps to the specified cab load so as to not overwork the OT. It will last a lot longer. Link to comment Share on other sites More sharing options...
Members paul88lx Posted December 24, 2012 Members Share Posted December 24, 2012 I've been told you can go 4ohm into 8ohm or 8ohm into 16ohm. But not 4ohm into 16ohm. And definitely never ever higher amp impedence into lower cabinet impedence. Please, correct me if I am wrong. Link to comment Share on other sites More sharing options...
Members Pine Apple Slim Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by paul88lx I've been told you can go 4ohm into 8ohm or 8ohm into 16ohm. But not 4ohm into 16ohm. And definitely never ever higher amp impedence into lower cabinet impedence.Please, correct me if I am wrong. Just partly, going low into high can be risky for some tube amps, esp older ones. Link to comment Share on other sites More sharing options...
Members tlbonehead Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by Pine Apple Slim Just partly, going low into high can be risky for some tube amps, esp older ones. yes, with tube amps many times you are somewhat safer running a lower impedance load than higher. Link to comment Share on other sites More sharing options...
Members falseknight Posted December 24, 2012 Members Share Posted December 24, 2012 Advice I've always followed is to match impedances with valve amps and always use the same or higher impedance as specified with transformer keys (SS) units. Link to comment Share on other sites More sharing options...
Members Zozobra Posted December 24, 2012 Members Share Posted December 24, 2012 Jesus suffering {censored}. How many times does it need to be explained that mismatching into a higher load can create large flyback voltages that can destroy an output transformer in a tube amp? It will also generate massive screen currents and blow your tubes. Edit - not a dig at the op, just people who churn out the same misinformation Link to comment Share on other sites More sharing options...
Members guitarbilly74 Posted December 24, 2012 Members Share Posted December 24, 2012 A decent amp can handle 1-up and 1-down without any issues... more than that can be iffy.... but 8 ohm cab with 4 ohm head should be a safe mismatch for most amps. Link to comment Share on other sites More sharing options...
Members charveldan Posted December 24, 2012 Members Share Posted December 24, 2012 Ohms don't matter, do what u want........im sure someone will tell you that. Link to comment Share on other sites More sharing options...
Members FearTheVoices Posted December 24, 2012 Members Share Posted December 24, 2012 When i had my Dual Showman it was only able to run at 4ohms, I used a switcher between that and my JMP into a 4x12 at 8ohms and it was fine for years. Link to comment Share on other sites More sharing options...
Members GibsonVMan Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by DARKMETL/ I believe this is generally ok. Just makes the amp work a bit harder. I used a 8ohm Mesa .50 Cal head for a long time with a Marshall 16ohm cab with no issues... Mesa amps generally don't have this issue because the quality of transformers used. Most other amps, I'd reccomend that the ohms match accordingly. Short answer...depends on amp. Link to comment Share on other sites More sharing options...
Members PlayboyChris Posted December 24, 2012 Members Share Posted December 24, 2012 Another short answer: don't do it. Just look at the responses in this and every other thread like it that's ever been posted here. Half the people say one thing, the other half say the opposite. Link to comment Share on other sites More sharing options...
Members Zozobra Posted December 24, 2012 Members Share Posted December 24, 2012 Originally Posted by PlayboyChris Another short answer: don't do it.Just look at the responses in this and every other thread like it that's ever been posted here. Half the people say one thing, the other half say the opposite. I'd believe the people who can produce graphs and don't rely on anecdote Link to comment Share on other sites More sharing options...
Members eeddings Posted December 25, 2012 Author Members Share Posted December 25, 2012 Thanks for the comments, all! Link to comment Share on other sites More sharing options...
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