Speaker for 1958 Gibsonette

[schteim]

Hi there, I'm not a technician, but would like to change the speaker in the 1958 Gibsonette I own (1x 12AX7,2x 6V6GT,1x 5Y3GT) and it's not easy to find something about the impedance of the speaker needed. Can someone help me with an information ? Got a 3.2 Ohm Weber speaker. What would happen, if it's not the right impedance and I would place it nevertheless?

[K Teacher]

If you use a 3.2 ohm speaker (instead an original 8 ohm), the reflected impedance on the secondary will be too low and this will result in a higher current flowing through the output tubes when driven hard. So, NOT recommended.
Which speaker you ended-up using?

[mozz]

Are you sure the original was 8 ohm? Gibson very often changed the schematics and parts while keeping the same model number. You can't say any 2 1958 Gibsonettes are the same. With tube amps, it's often better to go lower impedance than go higher. With solid state, it's better to go higher than lower. Best is to measure the output transformer impedance and calculate it out based on output tubes and running voltages. The original could have been 4, 8 or 16. Some of these also had the 6V6 in parallel single ended.

[g1]

The OP made one post 10 years ago and this is it. I have doubts they will respond.

[Helmholtz]

This thread is 10 years old.

Generally, higher than optimum load is likely to cause excessive screen dissipation.
Lower than optimum load is likely to cause excessive plate dissipation.

Either effect can reduce tube life depending on circuit/voltages.

[schteim]

Totally forgot about that. A reminder email came in today. Nice. Since the Amp is stored in Dortmund Germany and I'm here in Switzerland it will take a while to look what I've done then 10 years ago...can't remember that. I end up to be curious myself.

[The Dude]

FWIW: I suspect the original 3.2 ohm reading is DCR and not impedance. It's more likely a 4 ohm speaker.