Radio 8-10 ohm speaker required before powering?

[kna4977]

Original radios say to have the radio attached to an 8-10 ohm speaker before powering up. I see that also indicated in several threads, but why what's the reason what will happen if you don't?

[1970cstblazer]

Originally Posted by kna4977

Original radios say to have the radio attached to an 8-10 ohm speaker before powering up. I see that also indicated in several threads, but why what's the reason what will happen if you don't?

If you use a 4 ohm speaker for a long period, it will overheat the output transistors. 8 will work, but 10 is preferred with the vintage Delco OEM radios.

[kna4977]

Originally Posted by 1970cstblazer

If you use a 4 ohm speaker for a long period, it will overheat the output transistors. 8 will work, but 10 is preferred with the vintage Delco OEM radios.

Right, but what if you just power it up with no speaker just to see if it lights up?

[1970cstblazer]

Originally Posted by kna4977

Right, but what if you just power it up with no speaker just to see if it lights up?

That will damage the aforementioned output transistors. Make sure that any old Delco radio has the speaker hooked up before powering it up.