Speaker Question: 16 Ohm Speaker with an 8 Ohm Output Transformer

[Andy40]

Hey Guys,

I thought that I had an interchangeable output transformer but I don't, its only an 8 Ohm....... and I have a 16 Ohm speaker.

From my little internet research, it looks like it's not going to be a problem but I always like to hear other's opinion on this stuff in case I need to get a different output transformer or speaker.

Thoughts?

[Simon Barden]

It depends on the quality of the design and the output transformer. If it's near the edge, you probably shouldn't do it. But most valve amps will cope with a step up or down in speaker impedance, but they won't be at their best and shouldn't be run near full output if you want the amp to last. It's the sort of thing you'd do to get you through a gig if your own speaker started playing up and borrowed someone else's cab, but it's not really something you want for a permanent solution.

If it were me, I'd get a new 8 ohm speaker for the amp and use the 16 ohm one for another project.

You'll have put a lot of time and effort into the build, so you might as well get it right from the start. Then you can relax and not have to worry about it, ever.

[McCreed]

Simon for the win!

Good advice...

[Marcel]

Both your safe options involve getting another speaker.

Get a 8 ohm speaker of wattage greater than your amp and run it solo in a 1 x ?? cab.... or
get a 16 ohm speaker of wattage greater than your amp and parallel it with your existing speaker in the same cab and run it as a 2 x ?? cab....

My 2 x 12 cab is two 16 ohm speakers in parallel to give me a 8 ohm load.... A V30 and a G12H Creamback... handles any amp I can hook it up to and sounds nice to boot....

Running mismatched load on a tube amp can be done for low volumes and workshop testing. Problems will arise as the listening volume attempted increases, though there are some amps that will not care. Most often the problem will be unwanted distortion or self squealing or unwanted self oscillation of some type, all being horrible loud sounds to the ear and indicating that the amp is not happy with the current setup. Bad mismatches can damage the amp and output tubes if left in place and not corrected, and the high chance of resulting in expensive repairs being required to the amp.

[jugglindan]

I think that Simon's advice of a new speaker is the best. Marcel's advice is also good, but I am pretty sure this is for your 5e3 which is a 1 speaker combo.

One more temporary, but safer, alternative to let you test with the 16 ohm speaker is to wire a 16 ohm resistor in parallel to the speaker so your output transformer sees an 8 ohm load. The downside is that half your output power is wasted on the resistor, so volume will suffer. But it will let you test more safely until you get a replacement speaker.

[fender3x]

You should be able to use a 16 ohm speaker with output designed for 8 ohms. Everything else being equal an 8 ohm speaker will just not be quite as loud as an 8 ohm. But it will work just fine. The output rating generally shows you the lowest ohm load you can put on the amp. So this should not be a danger to the amp or the speaker.

If you own this speaker, I don't think you lose much by trying it.

If you want it to be louder you either add another 16 ohm speaker or swap for an 8 ohm with otherwise similar specs. If you amp has two speaker outputs and you hook up one to each of the amp's outputs the amp will see 8 ohms. Still fine.

What you don't want to do is go BELOW what your output was designed for.

I don't think the ohms are the issue with mismatching speakers and cabs, but Marcel is certainly right that it can produce some nasty results.

Of course this is very general... Is this for a guitar? Are you building or replacing? What lead to this predicament?

[Andy40]

Hey guys that's brilliant advice. Now I have the tech talk to baffle the wife into another speaker purchase.

I knew you'd all come through for me

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[jugglindan]

Of course this is very general... Is this for a guitar? Are you building or replacing? What lead to this predicament?

I think this is for the 5e3 that Andy is building.

[fender3x]

Ahhh. Better speaker needed definitely ;-)

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[Andy40]

Ordered a WGS greenback. Excited

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