Ohms and Tone

[charvel750]

Does running your amp at different ohm settings change it's tone? Is 16 ohms going to sound better/different than 4 ohms?

[JACKSONFREAK]

The lower the impedance number. The less resistance you get. Which gives you more bottom end. So yes impedance doesn effect tone. Also effects wattage of solid state heads.
Gil

[horns666]

I insisted running my 5150s @ 4 ohms. I discovered that quite some time ago (when I owned them) . Glad to know there is an actual reason and not just my imagination.

[DonP]

I thought I read somewhere that 16 ohms is safer. I run my Marshall at 16 but I'll go try 4 right now.

I agree that the two modes will sound different.

[Matt_B]

I thought I read somewhere that 16 ohms is safer.

Safer how? Safe from what?

[warhead]

I run my Framus Cobra at 8 ohms. It sounds the best that way. At least to my ears. On 4 ohms it sounds too loose. Can`t describe the sound on 16 ohms, forgot what was it like...

[Jayster]

Hey guys ,

My understanding is that you want to match the impedence of your speaker cabs ,to your ohm selection ,and that this is done to protect your equiptment.

[toejam]

The cab or speaker can be of higher impedance than the amp, so running your amp at 4 ohms into an 8 or 16-ohm speaker load is fine, at least that's how I remember it. The 4 ohms will indeed give you more low end.

[charvel750]

Right, I understand about matching impedance with the cabinet, my heads can do 4, 8, or 16 ohms. I have cabs to fit any of that. So the lower the ohms the better the bottom end, huh? I never knew that...

[JACKSONFREAK]

Well there is something to matching the impedance. From what i understand. If you have a head set at say 4 ohms. and you have it hookedup to a cab running at 16ohms.
The output tranny is lloking for a 4ohm load but isnt seeing it. So it runs hot and blows the speakers. If you run it the other way with the head at 16 and the cab at 4 or 8 then the hout put tranny will over heat and blow. The impedance should be set equal to the load. I may be a little off on those facts. but why take the chance right?
Gil

[emperor_black]

I second the "lesser ohm = lesser resistance" theory. however, I was under the impression that the lower the resistance, the amp will "open" up more. Like increased headroom and even probably sound louder. If you set your amp at 4 ohms and feed it a 16 ohm speaker, I bet that it would sound less louder than the same 4 ohms setting fed to a 4 ohms cab.

Maybe I should call it a day and go to bed.

[Matt_B]

Well there is something to matching the impedance. From what i understand. If you have a head set at say 4 ohms. and you have it hookedup to a cab running at 16ohms.
The output tranny is lloking for a 4ohm load but isnt seeing it. So it runs hot and blows the speakers. If you run it the other way with the head at 16 and the cab at 4 or 8 then the hout put tranny will over heat and blow. The impedance should be set equal to the load. I may be a little off on those facts. but why take the chance right?
Gil

No, that's incorrect. You can use a cab at a higher impedance, albeit with less output power, but you should never use a cab with lower impedance than the head is rated for. The exception to the rule is of course a head with selectable impedance.

For example, if a head is rated at 8 ohms, you can run a 16 ohm or 8 ohm cab with no issues but using a 4 ohm cab will cause the head to try to produce more wattage than it is capable which will in turn blow the fuse at the very least.

[CharvelRocker]

No, that's incorrect. You can use a cab at a higher impedance, albeit with less output power, but you should never use a cab with lower impedance than the head is rated for. The exception to the rule is of course a head with selectable impedance.

For example, if a head is rated at 8 ohms, you can run a 16 ohm or 8 ohm cab with no issues but using a 4 ohm cab will cause the head to try to produce more wattage than it is capable which will in turn blow the fuse at the very least.

Actually, it will cook your output transformer unless you have a new, high tech head with a lot of failsafes. I also always thought the idea of using a head with a lower resistance was the greater headroom/volume as well. My Valve Junior seems quieter for sure into 16 ohms, but then again, another offset is the fact I was using it with a 4 ohm 412 before hand so it's a bit hard to compare.

[Rupe]

Lots of misinformation in this thread. You should match your amps output impedance to that of your cabinet for ideal operation. Only certain modern amps that are built to take the variation (Fender ToneMaster for example) should be intentionally mismatched.

Lower impedance does equal less resistance...that's what impedance measures. Making this change on your amp (say switching a Marshall from 16 to 4) is only useful if you have a speaker cabinet rated at 4 ohms. In that case, you will notice more volume, headroom, and low end than you would through a 16 ohm cabinet. Conversely, if you like to fire up tube amps so the power tubes are cooking and helping to define your tone, you can do it at slightly lower volumes using a 16 ohm set up (like most classic Marshalls are wired).

[Spivonious]

I learned something on Google today. Resistance is for direct current, impedance is to alternating current. They both are the same concept though, and both use Ohms as their unit.