Guitar Amp-Cabinet Impedance MISMATCH - How does it sound? Damaging? And HOW TO SOLVE IT!

If the amp and cabinet doesn't have the same Impedance, you know 4,8,16 Ohms, a Mismatch: How does that sound? Can it damage my amp? And a way to completely solve this problem: Weber Z-Matcher!!

[USDAselect]

Thank you for this Johann. I actually wanted to see impedance tests for a long time.

[antoniomonteiro]

A technical comment on impedance matching:
- You only can get the full power safely from the amp with the matched situation;
- If the load is lower you kind of short-circuit the output of the amp which drains more current and may not be healthy for the amp if the levels are high for a long period; moreover, if the amp is powerful enough to supply the current, it may burn out the speaker.
- If the load is higher it will do no harm but you don't get the full power.
Note: higher but not MUCH higher or infinity, like no speaker connected. This case may lead to internal oscillation on the amp and damage to the output tubes.

[danielakerman]

To my ear, on earbud headphones, it sounds like having the amp at higher ohms than the cab made the sound more compressed, with less transient response, and also less full — as if you were running a frequency specific compressor that was attenuating transients and the low end. Not a huge volume difference per se, just a less dynamic and full sound.

[frantisca]

It's OK to play a 4 Ohm or 8 Ohm amp on a 16 ohm cab. You will get a slightly more compressed, trebly tone. But NEVER play a mismatch with a cab that has a lower impedence than the amp: you will eventually damage your amp/fry your transformer !!

[justinshaffer]

Thanks for doing this Johan!

In my humble opinion... 3x10 Bandmaster and JTM45 are great examples of slight mismatches on either end of the spectrum (JTM45 into proper load is the equivalent of a 1:2 mismatch because of the extremely high 8k OPT primary). Both sound great... equal and opposite if you will.

It’s speculated that one reason for the unique tone on the Beano album is because EC’s bluesbreaker was running out of the 16ohm out but into 8ohm load... effectively making the OPT function like a normal 6L6 (KT66) 4k opt instead of the extremely high 8k Radiospares Deluxe or Drake 784-103. Who knows

[billyray]

Thanks Johan, I wouldn't be game to do what you did, but it sure was good to hear the difference. You got balls dude!

[AdamRainStopper]

The cabinet providing a HIGHER impedance than what the amp requires is not going to harm the amp. This is why most amps say "(X)ohms minimum" on the output. It does, theoretically, cut the output as much as half, to double the impedance, but in practice it doesn't shave off much actual volume and probably only cuts the actual output by a few watts. Having too LITTLE of a load on the output transformer is dangerous, because the OPT is designed to push a certain amount of power through a specific impedance, and not having it there is almost like having an insufficient amount of support under a heavy weight, as the OPT will be freed to push far more current to a lower impedance speaker than it was designed to push, thus overheating the OPT. That is the simplest way I can think of to explain it, and the weight analogy isn't great. Basically, don't put any less than X-ohms on an amp that requires X-ohms, or your wonderful and expensive vintage amp will blow up and burn down your house and kill or maim everyone you love and you'll go to prison for 80 years for arson and everyone will know you as the bastard who burned down the neighborhood.

[cookq]

quick lesson learned here is match your amp and your cabinet impedance OR for something that sounds like it has some more overtones, have the cabinet set to double the impedance output of your amp. Those two settings sound best IMO. Thanks Johan

[KB_Joys]

Thats so weird, because just today i was wondering about this. Then you made a video about it for us. Thank you so much Johan 😁

[samueljett]

Dude I could listen to your voice all day... it's so amazing...

Cheers from West Virginia!

[Beizeiten]

I had a Z-Matcher for a while. Worked great and sounded totally neutral. Weber also makes killer speakers!

[BillHesse]

As I understand it from Mesa Boogie, you can run a cab that has a higher Ohm rating than your amp setting, but you should not do the opposite. I often set my heads to 8 ohms and run it the same into my studio 8 or 16 ohm cabs. No problems as of yet and I run at or above 5/10 master volume typically.

[jcoulter]

Great video as usual! I tended to like the sound of the match better than any of the mismatched sounds. I'm sure in a mix, my mileage may vary. God bless and rock on brother.

[tapilaha]

any out of the norm guitar situation i can think off, wonder how it sounds, i open youtube, johan to the rescue! thanks again!

[nickbenjamin]

There's a great blog post called 'Ohm Cooking' on the Hughes and Kettner website that covers this topic. My Mark Stephenson amp has an impedance selector labeled '1-2-3' because you can use it in any setting you like for tonal manipulation: the OT is massively over speced!

[revelry]

Jimmy Page created one of the greatest albums ever with a mismatched impedence on his amp/speaker. LZ 1 tone is largely driven by output tranny having a much lower impedence than the speaker. Great video Johan. I was taught never hook a load up lower than the amp. Only have higher or equal on cabinet or speaker. Higher impedence on speaker compared to output of amp will reduce current to the speaker (ok). Vice versa more current and makes the amp work harder

[innocentoctave]

Some interesting differences in tone here, but the main takeaway for me is that the Z-Matcher really does what it claims, and you can hear that in the sound.

[ajaykumargoel]

My favorite was when the cabinet was way higher impedence than the amp. Just more clear and powerful distortion!

[kospandx]

WARNING: This works well for tube amps. If you use a solid state amp, however, you will most likely damage something if the speakers have a lower ohm rating than the amp can handle. Most higher-end solid state amps can handle down to 4 ohm, so you should be safe, but be cautious.

[vincenzoerriquenz]

As long the impedance mismatch is above the minimum load of the amp head ( usually 4 ohms) there' s no harm to the amp and speakers, so 8/16 ohms mismatch is way safe. It does slightly changes the tonal response, for example Eric Johnson prefers to run his Marshall cabinets at 16 ohms. I' m curious to listen the sonic results!