So here's the hard part; now we know what's important for
intelligibility, it is
time to implement this in our station.
Lots of modern transceivers offer enough control over the frequency
response and over the compression ratio (often called processing) to
optimize your audio.
In these cases, you don't have to add additional devices to get things
However, proper adjustment is easier said than done, allthough often
a necessity, since a factory default is not likely to bring the desired
I've heard plenty of brand new, high tech transceivers that sound
absolutely crappy right out of the box.
They really need some attention and tweaking to get them right.
The audio report of the other stations is important, but generally too poor to really refine your
A good way to go is: Monitor yourself using good headphones on
a second receiver.
Do not only use your transceivers monitor function for your
your audio does not pass all stages in a normal radio chain, and therefore
it will yield different results.
No, take a second radio and good headphones, listen for a while to
stations with the best audio you can find, and then listen to your
own transmitters signal.
If you repeat this a few times, you will get a good impression what
your audio is like, and what is needed for further improvement.
Take plenty of time for this, and divide your judgement into two
parts, the dynamic behaviour, and the frequency response, as
Lots of transmitters can be overloaded quite easily, with loud but
unreadable audio as a result.
This is absolutely to be avoided! Check if you can find a setting of
audio gain and compressor level to avoid overload, but at the same
time the less loud parts of speech must be boosted a bit to keep
them audible. Take care to use the microphone in the right way; do
not hold a handmike right in front of your mouth at only a few centimeters
distance as you see in movies; you will surely "pop" the
mike with every letter P or F you say. Here's a bad example: sound/popping.mp3
It's better to hold a handmike in a
90 degree angle beside your mouth, so the top or side of the mike is towards
you, in this way you're less likely to blow into the membrane. Be sure to
keep a constant distance, and train yourself to use a steady volume
Note that a battery fed mobile transmitter may initially sound great
with a full battery, but may overdrive easily when the battery
voltage slowly drops after some time of operation!
This is a commonly heard problem, since the mobile operator has no
or little means to properly monitor his signal.
If your radio appears to be easily overloaded, you could decide to
add a limiter-compressor to your audio chain, but take time for
proper adjustment of this device as well.
Read the page on tayloring your audio in the audio menu.
Avoid unnecessary high settings of audio gain even if your set
shows excellent dynamic behaviour; it will emphasize room
reverberation and the noise of fans, and
even your breathing noise will become audible.
Also, your microphone input will be more likely to pick up RF radiation.
So, just don't overdo it.
Here's an example of way to much compression, the S-meter showed S9
throughout the recording, during speech as well as in speech
And here is an example of far to much audio gain.
The frequency response is highly depending on your specific
microphone. Some handmikes really sound poor, but if your handmike
uses a electret element, it should be quite useful. The electret has
a nice flat frequency response, and is quite immune to RF radiation.
If you are thinking of a different mike, read the page on
microphones in the audio menu.
Listen carefully to your
audio, and compare it to other stations with clear audio. You will
almost certainly have to take out some bass, and turn up some treble in most
(often called Microphone EQ or Transmit EQ in the rigs menu)
Just experiment and see how much low end you can take off before you
start to sound "thinny". The low end is just moving
S-meters on the other side, activating theirs AGC as well, causing your audio
to sound less powerful.
Taking off the excess low will make your signal sound considerably
louder on the other side, because all of your power is used for the
functional part of the audio passband.
If your set has no proper tone control, but plenty of excess audio
gain, you may put a small series capacitor in your mike to get rid
of the excess low. The roll-off should begin to set in below about 500Hz,
depending on the roll off already present in your set.
At 250Hz your audio should have lost a few dB already.
You may also improve the high end:
Most radio-microphones use capacitors running from the element to shield to
take away RF. They may be chozen quite big, and a reduction of that
capacitance may get you more brilliance and still provide good RF filtering.
In my Icom handmike I reduced the capacitor to 1/5th of its original
value. And this was a big improvement.
The last step is to get some external tone-control.
Read the page on tayloring your audio in the audio menu.
Some examples of good audio and some retransmissions:
Note that considerable changes in frequency respose will have effect
on dynamic behaviour as well, and vice versa.
So if you change one, check
After your tests and tweaking, ask a few stations with good audio themselves
about their opinion, you may get something like this:
(I was testing a new mike with the settings of the old mike, which
resulted in a little too much high frequencies...)
A small real-time adjustment resulted in this:
And no, I am not using external audio processing, just a carefully
adjusted, fine transceiver:
Note that any comments on your audio, good or bad, are rather useless
unless the other side explains why he has this opinion!
Another on air check:
sound/nice ssb audio.mp3
And a spontaneous comment on my audio in another QSO:
Here's some examples of very good and loud audio from II5GAL:
My QSO with Gordon, MA0GPZ/p who was operating on 40m from the beach
of EU010, so no fancy audio equipment there, but nevertheless very
And again positive feedback on my audio from Gordon as well.
In QSO with David, G8KAP: Listen hoe well he can be copied in
spite of all the QRM. His signal was hardly moving the S-meter over the
Now that' s functional audio!
Here's a sample where I am not very strong near Quebec, but my audio
pulls me through:
And a similar case:
sound/but very nice audio.mp3
And here's how my (modified handmike) audio is recorded and re-transmitted by Tony,
Note that my audio here has too
much compression, since my signal has been processed twice, once
during the original transmission, and then again during the IK1JUO
transmission. This will also affect the frequency response. Still nothing to be ashamed of. Thanks Tony!
And another re-transmission, this time by Fred, PA0PAF, who has a
nice, relaxed sounding audio thanks to his software defined radio:
The first 10 seconds is my voice re-transmitted, the rest is
Fred. Did you notice I've got the bigger mouth? Also my thanks to Fred.
If you want your small station to sound big, don't waste your
transmitters energy on low audio frequencies.
Reduce the low end and emphasize the high end to put most energy in
But don't overdo it though, try to stay reasonably close to the natural sound
of your voice.
The emphasized high end will make your voice less difficult to copy
in noisy conditions,
With the reduced low end your transmitter will have 6 to 10dB (!)
more power available for the important part of the spectrum!
Once I experienced a
A station with an awful lot of low end in his audio, running
100w and a lot of additional audio devices and a super microphone,
responded to my CQ calls on 40m.
I heard him call amongst other responding stations after at least 4
of my CQ-calls, but every time other guys with "economic"
audio beat him in the small pile-up, even one station running 10
So at last, I
called for this specific station only, just to give him a chance,
and had a QSO with him.
I told him how
he was surpassed in the pile up again and again because of his audio
which sounds great by the way, only as long as no other signal was
spoiling the fun...
increased his power up to 400w and only then he was a match for the
This guy would have got through much, much better if he would have
cut off everything below 250Hz...
However, there's nothing wrong in restoring a little low end when
having a QSO in perfect conditions.
When you're constantly 59+20dB, there's plenty of energy available
to "dress" your voice with a warm sounding low end.
And you may take back some of the compression as well since there's
plenty of headroom to keep everything audible.
Pre-emphasis / De-emphasis:
Wouldn' t it be nice if all hams using SSB would:
Emphasize the high end up to 10dB on transmission, using a standard
and reduce the high end 10dB on reception, using the same standard
Because then, our signal / noise ratio could improve up to 10dB with
almost no costs...
Revolutionary? Not at all.
The same trick is done in FM technology, to improve the already very
good signal / noise ratio there.
And in much more (ancient) audio applications, where the audio has to
pass some kind of noisy process.
As far as I know, this technique is not used in SSB, where 6 to 10dB
improvement really would make a big difference.
How about some experiments?