Going to be using a combo with a 16ohm speaker with an 8ohm cab.
Naturally there is no 5.3 ohm setting.
I remember seeing some tube amp experts saying that you actually are safer setting it for 8 ohm since tube amps don't like to have higher impedance load than the setting... Opposite of solid state amps...
Looking for advice from people who actually are tube amp techs.
5.3 load, choice of 4 or 8 setting.
Thanks
Not a tube amp technician here either, but a long time electronics tech.
In general, with tubes, the idea is to match as close as possible the load (speaker) to the source (amp).
When impedances are matched you get the maximum transfer of energy.
As you move away, either side of that perfect match, you get a less efficient transfer of energy.
By the numbers, 5.3 is closer to 4 than it is to 8.
But consider that the speaker impedance (ohms) rating is only nominal. (Nominal... by name only.)
4 ohms, or 8 ohms, only happens at one specific frequency.
At other frequencies, the impedances will be all over the place, higher or lower than nominal.
It may be that one cab is going up in impedance while the other is going the opposite direction and they would tend to help maintain a normal impedance range. Then again, they may both change impedance in the same direction, up or down, and you start to have extreme mismatching with the two cabs, while all is well with either one alone. It all very much depends on the individual characteristics of the two cabs.
I would suggest you approach this with caution.
Contact the amp manufacturer, if they are still in business, tell them what cab you intend to add and see what they recommend. Failing help from the manufacturer, seek someone who does have a lot of experience with tube amps.
