Speaker Impedance Article.

[DrNomis_44]

While posting a comment in a thread in this forum section, I found this article on Speaker Impedance, anyway, as I thought it would be a useful article to read for those wanting to build guitar amps, I thought it would be a good idea to post it in it's own thread, hope this article does prove useful:

http://education.lenardaudio.com/en/05_speakers_3.html

[Andy40]

I was actually pondering whether it would be possible to connect a 8 ohm output transformer to a 16 ohm speaker with another 16 ohm resistor instead of a second speaker.

[Bakersdozen]

I was actually pondering whether it would be possible to connect a 8 ohm output transformer to a 16 ohm speaker with another 16 ohm resistor instead of a second speaker.

Man, I never thought of that. Haha I just looked up a 50w 8ohm resistor and they are massive. So is it a thing or not advised?

[Simon Barden]

You can, but that 16 ohm resistor needs to be rated at a similar wattage/heat dissipation capacity to your speaker (or at least a bit more than 1/2 the amps maximum power output (which could be 50% more than the nominal value, which is its clean rating with a maximum 3%THD). So you'd probably need a 16 ohm resistor with say a 20W heat dissipation capacity for safety. 5W ceramic is a pretty normal maximum size for a resistor, so you'd need to make a series + parallel arrangement of 4 x 5W 16 ohm resistors (just like a 4 x 12" cab arrangement) with suitable heat sinks to dissipate that power. It's not a simple task. If you can only get 2W resistors, than you'd need more of them until you got 16 ohms and 20W capacity (though you can use different value resistors to cut down the number needed, but still a minimum of 10).

[Andy40]

I can get 10W ceramics but not 20W that easily as supplies from mouser are about as fast as pitbull kits internationally. Just have to give some thought about heat dissipation too. I was just thinking about it as a testing mechanism.

[DrNomis_44]

I can get 10W ceramics but not 20W that easily as supplies from mouser are about as fast as pitbull kits internationally. Just have to give some thought about heat dissipation too. I was just thinking about it as a testing mechanism.

You could try ordering them from Evatco, they happen to have guitar amp speakers in stock:

https://www.evatco.com.au/speakers/