Re: Small Speakers

[Mike Curtis <wd6ehr@xxxxxxxxxx>]

> 
> The following was asked of me and I don't know answer. I do know about the
> harmonics but not the effect on small speakers. Anyone know?
> 
> >I hear that a harmonica releases a wide variety of harmonics and can be very
> >>brutal on small speakers at high volumes.

That depends on what you're running into the speakers.  If you use a Green
Bullet, they tend to suppress high order harmonics.  Also, if you use the tone
control (or treble cut) to minimize higher harmonics, there will be little
present.

But smaller speakers will tend to emphasize higher harmonics more than larger
ones.  Their smaller mass favors higher frequencies.  you'll also get a better
damping factor from a smaller speaker, all other factors being equal. 
"Damping" is a technical index of how well the speaker stops vibrating after
the signal has stopped.  whether a good damping factor is good for amplified
harmonica or not is  subjective call - if you like it, then it's good, etc.

As far as higher harmonics impact on smaller speakers, it will make little
difference, assuming the voice coil is capable of handling the power you're
putting into it.

If you're using small speakers for amplified harmonica, I assume you'll be
using multiple speakers.  This raises a different spectre - impedance peaks
and series speakers.  common amplifiers are 8 ohms, as are common speakers. 
To get 8 ohms from 4 8 ohm speakers, you must put them as 2 sets of series
speakers, with both sets in parallel, e.g.

-----o-----o
     |     |
     O<    O<
     |     |
     O<    O<
     |     |
-----o-----o

When you place 2 speakers in series, the resonant peaks and dips combine, and
multiply (more or less.)  This produces a more ragged frequency response than
would be the case if you used just one speaker.  It is quite feasible that
this effect could cause some pretty nasty stuff when amplifying harp and
you're already close to feedback level.

With a tube amp, you can tap a proper impedance, i.e. 2 ohms (4 eight ohm
speakers in parallel), which eliminates this problem.

Hope this is the information you wanted.

 --  mike curtis
wd6ehr@xxxxxxxxxx