Question about impedance.

[gush]

I have a Mesa head with two 8 ohm outputs and two 4 ohm outputs.

Am I hurting anything putting a 16ohm 4x12 on it?

I understand how it works with most sound gear but I'm just assuming it works the same with tube heads.

Thought I'd ask.

Thanks

 

[toothace]

Oh...you are asking about impedance...

 

[11top]

Oh...you are asking about impedance...

You thought this was another wood topic?

 

[Deleted member 5962]

Am I hurting anything putting a 16ohm 4x12 on it?

No, won't hurt anything. While it may not sound optimal (and it might sound better...) using speakers with higher ohm ratings will never hurt a tube amp, it's only using ones with lower ohm ratings that can hurt. But most Mesa's advertise that they are safe for mis-matching that way as well.

Edit: higher ohm ratings "THAN THE Output spec," to be clear. If using the 8 ohm jack, 8 or 16 is safe, and with most amps, 4 is not. But Mesa specs their OTs to be safe with mismatches even downward, which most don't. Still, I wouldn't use a 4 ohm cab with a 16 ohm output. But you can always go the other way, it just reduces OT efficiency and will not sound the same.

 

[Boogie]

I’ve used a 16ohm cab/speaker into my MkIII’s 8ohm input for years without issue. The reduced efficiency translates into a slightly reduced loudness that is very nice with that amp.

 

[gush]

Thanks guys. I was pretty sure it was safe to do but with my luck I needed to ask.

Just wanted to avoid the dreaded " oh crap, you're not running that mesa head with a 16 ohm load are you??"!

Lol

 

[Deleted member 5962]

p.s. Santana is known for using the "intentional mismatched impedance" with his Mesa amps.

 

[gush]

p.s. Santana is known for using the "intentional mismatched impedance" with his Mesa amps.

Why does he do that?

 

[dkilpatrick]

Oh...you are asking about impedance...

I think there’s a pill for that.

 

[Deleted member 5962]

Why does he do that?

He said he prefers the tone, but even more, the feel of it with the mismatch. As some Mesa smps (Marks in particular) are known for being "stiff," he uses this to soften the feel of the amp some.

 

[gush]

He said he prefers the tone, but even more, the feel of it with the mismatch. As some Mesa smps (Marks in particular) are known for being "stiff," he uses this to soften the feel of the amp some.

I see. My Stiletto has a switch on the front just for that. I always run it in the softer setting.

I threw in the towel last night and set it up using my 4x12 cab. Sounds so much better than my 2x12 or the 1x12 I used to have.

 

[Rider1260]

More info than you will ever need

https://mesa-boogie.imgix.net/media/Amplitudes/2013/June/Speaker Impedance Matching and Hookup.pdf

 

[László]

As some Mesa smps (Marks in particular) are known for being "stiff," he uses this to soften the feel of the amp some.

If the amp is stiff, no pill is necessary for a woody tone.

 

[gush]

If the amp is stiff, no pill is necessary for a woody tone.

If your gig lasts more than four hours call your physician.

 

[Alnus Rubra]

Side effects may include, vomiting, nausea, dizziness etc....

 

[Deleted member 5962]

Side effects may include, vomiting, nausea, dizziness etc....

hopefully not til AFTER the 4 hours of fun. I mean gigging fun.

 

[elvis]

No, won't hurt anything. While it may not sound optimal (and it might sound better...) using speakers with higher ohm ratings will never hurt a tube amp, it's only using ones with lower ohm ratings that can hurt. But most Mesa's advertise that they are safe for mis-matching that way as well.

Edit: higher ohm ratings "THAN THE Output spec," to be clear. If using the 8 ohm jack, 8 or 16 is safe, and with most amps, 4 is not. But Mesa specs their OTs to be safe with mismatches even downward, which most don't. Still, I wouldn't use a 4 ohm cab with a 16 ohm output. But you can always go the other way, it just reduces OT efficiency and will not sound the same.

Be careful with this statement. Never say never. It used to be common to hear that solid state amps would be damaged by too heavy a load (very low impedance) and tube amps by too light a load (high impedance). These were true at the time, though while SS amps were happy with as high an impedance as you wanted to throw at them, tube amps have a limit for low impedance.

These days SS amps are generally protected from any load or fault condition.

Tube amps have a relatively narrow "safe" range. Too low an impedance will run too much current in the output tubes and output transformer, eventually the tubes or the transformer will burn up.

Too high an impedance will make the output transformer take more voltage from the output tube stage and will melt the transformer. A quality design should allow for about 4x mismatch in either direction. Good practice would recommend no more than a 2x mismatch.

 

[Deleted member 5962]

Be careful with this statement. Never say never. It used to be common to hear that solid state amps would be damaged by too heavy a load (very low impedance) and tube amps by too light a load (high impedance). These were true at the time, though while SS amps were happy with as high an impedance as you wanted to throw at them, tube amps have a limit for low impedance.

These days SS amps are generally protected from any load or fault condition.

Tube amps have a relatively narrow "safe" range. Too low an impedance will run too much current in the output tubes and output transformer, eventually the tubes or the transformer will burn up.

Too high an impedance will make the output transformer take more voltage from the output tube stage and will melt the transformer. A quality design should allow for about 4x mismatch in either direction. Good practice would recommend no more than a 2x mismatch.

The specific question was 16 ohm cab, 8 ohm output, and Mesa. I get that making “general” replies can be dangerous, which is why I edited to say that Mesa usually spec’d mismatches to be OK the other way too. But the general rule is very simple. Use what it says. Plug your 8 ohm cab into the 8 ohm input. Other than that, “it depends” and I do not make a general recommendation on mismatches other than one up. I wouldn’t go more than one either way, and have never seen a reason to do so.

 

[elvis]

Nothing against you, brother. I just see some terrible generalizations frequently, plus I'm super bored this weekend.

Rock on!

 

[Deleted member 5962]

Nothing against you, brother. I just see some terrible generalizations frequently, plus I'm super bored this weekend.

Rock on!

No sir, I get it. Have to be very careful making "general" recommendations. I even edited it once, to add more specifics after thinking the first part was too generic. You always have to remember that many don't know even the basics of this stuff and sometimes can get in trouble by assuming "well surely they know this much so I'll skip that and address the next level."

Two things I need to remember when posting about this type stuff. 1) I may know more than many. 2) I don't know nearly as much as some. Sometimes I feel goofy, like I'm overexplaining something, and then every time I DON'T, you wonder if the other readers all understand fully because you left out basics.

I had a guy PM me at TGP a couple weeks ago, and asked me a question. I just scratched my head... this guy has been gigging for years, has lots of gear, and hangs out at TGP a lot. The question he asked me is something you'd think ANYONE would know who had been playing for a couple years. I almost thought he was pulling my leg, but he really didn't know, and he really had done it wrong often. I ASSumed, and you know what that makes me.