Guitar AMp speaker ?? 16ohm vs 8ohm Celestion

[CoolCat]

Just curious what is the 16ohm versus the 8ohm buying me?

I had a 16ohm 100watt Celestion Gold Back in this amp (40watts).

I installed a Vintage 30-25watt 8ohm and flipped the switch on the back from 16ohm to 8ohm.

What exactly is going on with this switch?

And how come I didn't notice a big difference.

My main concern is this amp by design runs hot, and I prefer to run it as cool as possible...so if the going 8ohm pulls more current from the amp (ohms law ?), if so I'll switch it back as I didn't hear that big fat difference to the Vintage30 Celestion. and if the 16ohm runs cooler then thats alright.



Amp little Marshall tube combo single 12" 40watt with 8ohm and 16ohm switch on the back. Celestion Gold Back 16ohm was stock on this amp.

 

[Oancient1]

Impedance matching

In order to effect maximum power transfer from the output of an amplifier and a connected load, in this case the speaker, the output impedance of the amplifier should be equal, or near equal, to the impedance of the load. Typically, this is done by having multiple taps on the amp's output transformer, and setting the switch (or using the correct jack) selects the correct tap for the desired operating impedance.

Mismatching impedances results in less power being transferred to the load. Power not transferred to the load is dissipated as heat in the amp.

Tom

 

[Lt. Bob]

And if the amp is properly designed, you shouldn't notice much difference between the different taps as they're intended to maximixe the matching for those different loads. The idea is that an 8 ohm or 16 ohm speaker will behave the same as long as they are run from the appropriate tap. So a 16ohm speaker from the 16ohm tap should sound and put out the same as an 8 ohm speaker from the 8 ohm tap.

 

[Oancient1]

This discussion makes me wonder why amp manufacturers choose one or the other -- 8 or 16 -- for single speaker amps. My only experience with 16 ohm speakers is back in the 70s with a Marshall Super Lead -- one cabinet had 4x16, I think wired as two 32 ohm serial strings connected in parallel to get back down to 16 ohm. There was a 4-8-16 impedance selector -- set to 8 for two stacked cabinets in parallel or to 4 for 4 cabinets in parallel. Made perfectly food sense in terms of flexibility.

But if its only one speaker, then why does a manufacturer choose one over the other in a guitar amp, other than to allow the load to drop only to 8 ohms if a second speaker is connected in parallel? Many Ampeg single speaker bass amps I have looked at use a 16 ohn speaker, which might lead one to believe that using a 16 will compensate for the lower frequency of bass notes -- the actual impedance of a speaker at any frequency being a function of frequency as well speaker coil inductance. But if that were the case, then there should be a noticable difference in the frequency content of the sound, no?

Tom

 

[CoolCat]

I have no idea... but as I said I didn't hear a big difference and was wondering if maybe the amp was better left with the Gold Back as it was the "designed" stock speaker and rated at 100Watts instead of the 25W like the V30.
A firend said he had GoldBacks in his Mesa and I don't believe they are really "worse" speakers than the V30.