Does Speaker Impedance Affect Tone?
When using different ohm cabs with a head, does the impedance make a tonal difference?
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.
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, 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 firstname.lastname@example.org