Speaker impedance choice

[Bluefinger]

Hi,

Does it make a difference If I choose to run an amp on 2, 4 or 8 ohms? What I mean is that I have a tranny that has a 2, a 4 and an 8 ohms tap and I can have that same speaker built with either 2, 4 or 8 Ohms. Of course there are strategic decisions like with which cabs will I probably combine that one in the future with and do I want to use the speaker in a different amp as well. Leaving all this aside and looking at it from a strictly technical point of view, will the 2 ohms speaker on the 2 ohms tap sound the same, be as efficient and reliable as the same speaker as an 8 ohms version on the 8 ohms tap? Does what I am saying make sense at all?

thanks!

[Austin]

If the speaker is the same brand and type but different ohm load, it should sound the same. They make a celestion blue in 8 ohm as well as a 16 ohm for instance, but other than that different seakers sound so much different that it is hard to really compare.. The imedance selection on the back of the opt is more of a convienence, say you stick 6v6 tubes in there instead of 6L6 to get a different tone, the 6v6 has a higher plate resistance and might sound better with a 8 ohm seaker on the four ohm setting. Or if it is a four twelve cab, then you could run 16 ohm speakers in parallel on the four ohm setting or connect 8 ohm speakers series/parallel for an 8 ohm load. You might just like the tone better of a 4 ohm speaker on the 8 ohm setting, it gives a more compressed feel but be careful about going the other way, don't try a 16 ohm speaker on the 2 ohm setting, it can make you draw too much screen current and could damage your output tubes. The impedance of a speaker is not the same over the frequency range, it increases with the frequency so there are no real hard and fast rules and in the end you will have to do some experimenting to see what sounds best to you. But that is the fun part right?

[Bluefinger]

thanks!
I am building me a top. The tranny I am going to use is a bassman/Super Reverb type with a 2, a 4 and an 8 ohms tap. I am building me a 1x12 cab as well and the Weber speaker I am going to use is available in either 2, 4, 8 or other impedance options. I think I will have it with 4 ohms so I can run it in parallell with my 4ohms 3x10 cab at the 2 ohms amp setting.

[J M Fahey]

I think your actual 3x10" cabinet is 2.7ohms , used into the 2 ohms tap because it's quite close and safe.
I suggest you use an 8 ohm extension speaker, so total impedance becomes 2 ohms and everybody's happy.

[Chuck H]

Just don't expect the 8R cab to carry a lot of the power. That is, it may seem quieter than the lower ohm cabinet. But no problems running this way.

[Bluefinger]

No, it's 4 ohms actually. There will be 3 12 ohms speakers in the cab. The idea was to make them both the same impedance so they both get half of the signal.

[JoeM]

Where did you find 12ohm speakers?

[Bluefinger]

Weber offers them in all kinds of odd impedances. I have three 12 ohms, 10A125s (my all time favorite speakers) on the way.

[Chuck H]

I was actually remarking about what to expect if you used an 8R cab/speaker as per JM's suggestion.