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May 2014
more... GearAmpsAsk Amp ManGear BlogJune 2010

Does Speaker Impedance Affect Tone?

Hello, Jeff.

I read your stuff with Premier Guitar and decided to write with a question about ohms. I was trying to decide on a Mesa/Boogie 2x12 (8 ohm) or an Orange 2x12 (16 ohm) when I came up with a question. Tone—do the ohms change anything if all other things are equal? Say, an 8-ohm head in an 8-ohm cab, or a 16-ohm head in a 16-ohm cab? My head will do 4, 8, or 16 ohms. I’m not sure if the Orange is two 8-ohm speakers in series or two 16-ohm speakers in parallel, I just know I cannot get the impedance lower. I love the Celestion Vintage 30s. I love the closed-back design and construction of both cabs. I really LOVE the look of the Orange cab. I have always heard the lower the ohms, the better the speaker response. Does any of this really matter as far as tone goes? As I get older, I am thinking a load is just a load. If it is a match, you are not overheating your amp and everyone is happy. So I guess the question is: Does the same speaker have a different sound depending on the ohm rating?

Forgive me if this is just a really silly question.
Sean


Hi, Sean.

Thanks for reading and thanks for writing. We all appreciate it. Let me see if I can reciprocate by answering your question. Your primary question is: Can the same model of speaker in different impedances sound different? In a word, yes. Substantially different? Probably not. But there is the possibility of a subtle difference. I have experienced this phenomenon myself in the past, so I do know that the situation can exist, but I was not sure enough of all the facts to be able to explain the cause. Thankfully, my friend Anthony Lucas at Eminence Speaker was able to shed some light on this for me. Here’s my interpretation for you based on his explanation.

The physical differences between an 8-ohm and a 16-ohm speaker of the same type generally come down to voice-coil wire size and the number of voice-coil wire turns in the magnetic gap. When a speaker is manufactured, different wire is used for winding the voice coil based on the desired speaker impedance. The wire used to wind an 8-ohm voice coil will be of a particular size and will be applied with a particular number of turns. The coil, once wound with this wire, will have a certain diameter and weight. This wound coil will then not only determine the impedance of the speaker, but will also be somewhat of a determining factor in the SPL (sensitivity) and frequency response of the speaker. If the same voice coil was wound to be 16 ohms, a smaller, lighter wire would be used and the number of turns would be increased to achieve the desired impedance. This will change the physical characteristics of the wound coil, which may slightly affect the sensitivity and frequency response of the speaker. A higher number of turns in the 16-ohm coil may slightly increase the response of the speaker at higher frequencies due to an increase in inductance. This potential change, however, may be offset to some degree by the possible increased weight of the 16-ohm coil due to the increased number of windings. We’re talking total weights in grams here, but every little difference has the ability to affect some type of change. This may be a lot of information to process, but the bottom line is that two of the same speakers have the potential to be slightly different in tone and response, but probably not to any substantial degree. Generally, any perceived difference might be that the 16-ohm speaker could be a bit brighter.

Also, just to clarify the speaker installations in the cabinets in question, the Mesa, having a total impedance of 8 ohms, more than likely uses two 16-ohm speakers wired in parallel. The Orange, having a total impedance of 16 ohms, would use two 8-ohm speakers wired in series. Knowing that, along with the knowledge that the 16-ohm speakers could potentially be a bit brighter, one might assume that the Mesa cabinet has the potential to be the brighter of the two. But there is a bigger issue here that may not be obvious—the cabinet itself. You are attempting to make your choice based on two different cabinets from two different manufacturers. Each manufacturer produces its cabinets to different specs, using different woods and different construction techniques. This will make a far greater difference than the subtle differences between 8- and 16-ohm speakers. I have experimented with many woods over the years, and I can tell you from personal experience that each one has its own characteristics. This can have a huge effect on the tone and response of the cabinet. How bright it is, how much bass it has, and how immediate it feels are all very dependent on wood. The bottom line: Play them both with your amp and pick the one that you think sounds best.

If this hasn’t completely confused you, I hope it helps you with your cabinet selection.


Jeff Bober
Jeff Bober, one of the godfathers of the low-wattage amp revolution, co-founded and was the principal designer for Budda Amplification. Jeff has just launched EAST Amplification. He can be reached at pgampman@gmail.com

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