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I've recently bought an old vintage Sovtek MIG 60 - it's beautiful and I'm really excited to play it more frequently. However, as much as I try with Google, I can't seem to get a straight answer anywhere about how best to pair it with a guitar cabinet, and the positives/negatives of these pairings.

It has three outputs - One 8ohm and two 4ohms.

Obviously an 8ohm cab is ideal, but can I play this safely through a 16ohm cab? Are there any downsides to this (loss of volume? weird tone?) It's often that I'm reliant on a house cabinet in a venue when playing a gig, and these are often 16ohm by default.

If this is always a no-go, is there an easy way for me to connect this head to a 16ohm when in these situations?

Thanks!

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Basic safety rule is use a speaker/cab that has more ohms impedance than the output supplying it. There will be a little loss in volume, but nothing to worry about. If the house cab was 4ohms, and you used the 8ohms out from the amp, that wouldn't be a good scenario. Always worth checking what the actual impedance of someone else's cab is, before plugging in. If it's not on a label, a multimeter will give a good guide - although the figure it shows will only be approximate.

  • Ah perfect - so running the 8ohm output into a 16ohm cab for a few hours would be fine? – David Dec 12 '19 at 14:11
  • If you're worried, get a high-power 16-ohm resistor and attach it across the speaker inputs. That's not perfect, as the input and output impedance is frequency-sensitive, but it'll be close enough to 8-ohm effective that your amp will be happy. – Carl Witthoft Dec 12 '19 at 15:40
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Tube amps like the Sovtek differ from solid state amps in the use of an output transformer (and quite a few other details of course). While the worst case for a solid state amp is operating on a short circuit, tube amps easily get damaged by using them open, without a load. That gives the output an almost exclusively inductive load to work with causing high voltage peaks in the output stage that can damage some parts not specified for them. Using 16 Ohms of cabinet is likely ok with an 8 Ohms amp, but if you can get 8 Ohms, it's not just better for the amp but also for the resulting volume.

Don't use your amp without an actual load.

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Welcome to the site. The thing to understand when hooking up a speaker cabinet to an amp is that if you attach a speaker with a lower impedance than the rated impedance output, you will effectively be running your amp into a partial "short circuit" which may possibly cause the amp to overheat the output stage of the amp and burn up the transformer and output tubes (valves). That danger does not exist if the impedance of the speaker cabinet is higher than the rated output impedance of the amplifier, but you can expect to have a lower power output from the amp itself resulting in lower volume. Depending on what kind of music you play, this may or may not be a problem for you, but it won't cause damage to the amplifier itself. It's always a good idea to double check the impedance of any unfamiliar speaker cabinet before hooking it up to your amp. Often enough, speakers are changed out in cabinets and replaced with a speaker with a different impedance and it's better to be safe than sorry.

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