Speaker loading

[Wakefield Turntables]

Quick question.

I have a speaker which can be run at 4 or 8 Ohm. Which is better? I presume the lower load puts the amplifier under a little extra stress when trying to drive the speakers a bit like the american 1 Ohm monsters we sometimes hear about. My amp has 4 and 8 Ohm taps, I've been running 8 ohm. I also presume your all going to say, "Whatever sounds best".

Ta.

A

[Barry]

Either the 4/4 or 8/8 Ohm setting ought to sound identical. But audiophile subjectivists would say "choose whichever sounds the better". Sorry! :eyebrows:

[Wakefield Turntables]

Thanks, I thought their might be an optimal best.

[Lawrence001]

Just out of interest what are they? Quite old I take it?

[Wakefield Turntables]

Just some old Celestions.

[AJSki2fly]

Quick question.

I have a speaker which can be run at 4 or 8 Ohm. Which is better? I presume the lower load puts the amplifier under a little extra stress when trying to drive the speakers a bit like the american 1 Ohm monsters we sometimes hear about. My amp has 4 and 8 Ohm taps, I've been running 8 ohm. I also presume your all going to say, "Whatever sounds best".

Ta.

A

My understanding is that its may be as simple as you would hope. If I recall correctly a key issue in how best to match amps to speakers is what the damoing factor is, with tube amps this can be very low, 10 or below, whereas a SS amp can easily be well over 50.

I never really understood how the damping factor is worked out but the higher it is then the easier it is for the amplifier to minimise the effect of the back-EMF)electro-magnetic-force) as generated when the drivers are returning to their neutral position. I believe lower frequency range 300hz and below is where this is most important as driver movement is at its greatest at low frequencies. If I remember correctly inefficient loud speakers can drop as low a 1ohm,or below, at low frequencies, which puts a high load on the amp and if it is not able to handle it will resort in distortion at higher volumes.

Trying to remember this I found https://www.thehifiguide.com/4-ohms-vs-8-ohms/, the rest of the article talks about impedance matching amps to speakers.

"Impedance Effect on Speakers
The ohm rating of a speaker tells you nothing about how difficult it is to power. You can easily get a 4 ohm 96dB speaker loud, but if you want to drive an 8 ohm 84 dB speaker, it will be hard for it to get loud enough without a bigger amp.

It’s important to ensure that the amp you are using is rated for the same impedance as your speakers, otherwise, it can cause some damage.

A 4-ohm speaker is more difficult for an amp to drive, requiring more current for higher volumes. This is where you want to be careful with what amp you get. A cheap amp might fry itself at high volumes, and possibly your speaker too.

This can happen if your amp has a cheap power supply and cannot supply the required current which can cause a fuse to blow. So do your research!

The 4-ohm speaker has less resistance than the 8-ohm speaker, thus, requiring more watts at the same voltage than if you were to use an 8-ohm speaker."

[Barry]

The damping factor is the speaker impedance divided by the output impedance of the amplifier. Clearly the speaker impedance will vary with frequency, as will to some extent that of the amplifier's output impedance, but a damping factor of 30, or more, is quite sufficient.

Ideally the amplifier will have a vanishingly small output impedance so it will short out the back emf generated by the speaker, i.e. to stop the 'tail wagging the dog'.

With some solid state amplifiers offering output impedances of the order of 0.01 Ohm, the above criterion is effectively achieved.

With valve amplifiers using an output transformer, the idea is to match the amplifier output to that of the speaker for maximum power transfer. Since the source impedance will be higher (~ 1 Ohm), the damping factor will be lower.