Audio processing techniques for Amateur Radio
Don Snodgrass
Hello to the group...
I've been a licensed Amateur Radio operator since 1972. Recently, I and
other Amateurs have been experimenting with the use of external audio
processing equipment to enhance our transmitted audio quality. You can
learn more about this by visiting my Amateur Radio site at
http://webpages.charter.net/donsno/wb4kr.htm . This site is fairly complete
including a description of equipment, hookup scheme, settings, etc. I even
have a link to a sound bite.
Relatively narrow radio transmission bandwidth severely challenges my
ability to replicate the kind of results most of you are accustomed to.
That's because Amateur Radio transmitters are typically restricted to a
narrow bandwidth of 100 Hz to 3000 Hz when transmitting single sideband
(SSB) information.
What I try to do is to make the most effective use of studio mics, preamps,
EQs and other processing equipment. However, not being a professional
audio engineer, I often feel frustrated with my efforts to find the right
equipment settings. I end up resorting to a trial and error approach
testing the results of settings with other Amateur Radio operators over the
air. I've also have tried to use audio analysis software such as
SpectraPLUS with equally frustrating outcomes.
Any comments/advice/recommendations would be appreciated. Please visit
the above link and let me know what you think of my equipment settings.
Perhaps you have some other settings that you feel might yield better
results. Input from those using the Behringer DEQ2496 for processing male
vocals would be especially welcome.
Best wishes,
Don
Amateur Radio Station K4QKY
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>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Don Snodgrass
1624 Tabard Drive
Murray, KY 42071
270-767-9944
http://webpages.charter.net/donsno
k4...@charter.net
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Adair Winter
Do you ever hang out on 14.178? if you don't you should get involved with
the audio nuts on there.. I'm think I may have heard you on there but I
can't remember.. I listen to those guys faily often..
Sorry I can't offer any more info.
Adair - KD5DYP
Mike Dobony
"Don Snodgrass" <don...@charter.net> wrote in message
news:109kusq...@corp.supernews.com...
If you have the best speakers and mics available you will still be limited
greatly by the quality of gear that is being transmitted to you. The best
sound gear available will not make me sound very good (distortion box might
be an exception if I want to do hard rock). Likewise, if you are trying to
improve on the sound originating from poor gear you can only do so much to
improve it. The computer proverb applies to sound also, Garbage In Garbage
Out. You might be able to minimize some of the noise and improve the vocals
a notch or two, but even the very best gear out there will not likely do
very much with a poor quality sound source. The best advice I can give is
to just get decent speakers and use some noise filtering HW. A good quality
EQ can help adjust things a little, but I would not recommend spending lots
of money on it.
--
Mike D.
Remove .spamnot to respond by email
0jun...@bellsouth.net
there.
fOr DOn, see my reply in rec.audio.pro where I've already seen at
least one other relevant reply to your query.
Anybody wants to check out my on-air audio which is an Icom rig
barefoot through a Heil mic on a desk stand can meet me on 14.300 most
afternoons. I'm NEt control at noon eastern time on that net. I
usually monitor there however and will be glad to qsy off with you to
help with critique and such.
73 de nf5b
Richard Webb
Electric Spider Productions
REplace anything before the @ symbol with elspider for real email
--
Adair Winter
Anybody wants to check out my on-air audio which is an Icom rig
> barefoot through a Heil mic on a desk stand can meet me on 14.300 most
> afternoons. I'm NEt control at noon eastern time on that net. I
> usually monitor there however and will be glad to qsy off with you to
> help with critique and such.
>
> 73 de nf5b
HF mobile.
Adair
0jun...@bellsouth.net
On 2004-05-07 drumme...@mail.com said:
>Anybody wants to check out my on-air audio which is an Icom rig
>> barefoot through a Heil mic on a desk stand can meet me on 14.300
>>most afternoons. I'm NEt control at noon eastern time on that
>>net. I usually monitor there however and will be glad to qsy off
>>with you to help with critique and such.
mornings at 9 eastern. I'm around quite a bit though and do some fill
in work.
>I'm making a trip to dallas this weekend i'll listen for you.. I
>love having HF mobile.
HOpe the band's short enough we've got a path from NEw Orleans to
DAllas then.
HF mobile can be a real good time. I'm sending off an Icom 730 to
burkburnett (spelling) to have a guy look at the alc circuit so as it
will behave properly then we'll probably put it in the mobile when
making road trips using a ham stick.
USed to do some hf mobiling back in the '70's, lots of fun when on the
road. I highly reccomend ham radio to the touring professional.
HElps kill those late night hours when traveling and can even help
save the old phone bill.
Richard Webb
Electric Spider Productions
REplace anything before the @ symbol with elspider for real email
--
"So she said it was either her or ham radio....OVER"
Tim Perry
preamps,
EQs and other processing equipment. However, not being a professional
audio engineer, I often feel frustrated with my efforts to find the right
equipment settings. I end up resorting to a trial and error approach
testing the results of settings with other Amateur Radio operators over the
air. I've also have tried to use audio analysis software such as
SpectraPLUS with equally frustrating outcomes.
>Any comments/advice/recommendations would be appreciated. Please visit
the above link and let me know what you think of my equipment settings.
Perhaps you have some other settings that you feel might yield better
results. Input from those using the Behringer DEQ2496 for processing male
vocals would be especially welcome.
Don, you have obviously given this matter a lot of thought and what you have
achieved is close to the audio processing chain found in broadcast stations.
the objectives are about the same: to achieve maximum spectral energy in
information carrying sidebands in an effort to overcome ambient noise and
sound louder and better then the competition without sacrificing fidelity.
a typical US monophonic AM station today uses an air chain consisting of
AGC > multiband compression> limiting> 75uS preemphasis > NRSC filter.
some incorporate a "bass tilt" feature for tube type transmitters. often AM
stations use no additional processing on the mics as the normal air
processing squishes it enough already.
as multiple people use the same equipment a happy average must be found. a
good starting point on mic processors is: set the compression ratio at 2:1 -
adjust drive level to obtain about 3 dB of gain reduction when speaking at
normal level at a normal (3 inch) distance from the mic- set the expander
threshold to just mute at ambient room noise. if the processor has an
adjustable desser start with the freq at about 4K and bring up the threshold
while talking.
the EV RE-20 or RE-27N/D is the mic of choice. its "variable-D" design
minimizes proximity effect some male announcers prefer the shure SM-7
because when they "eat" the mic the emphsizes the low end "gives their
voices balls" ... or so they say. it has a conceiled upper mid boost switch
and bass rolloff switch.
others like the senheiser MD421/u. maybe its 5 position rolloff filter makes
them feel like they are more in charge or something.
when a studio condenser is used in this manner mic technique becomes
critical. a pop filter makes a noticeable difference (and hopefully an
improvement). i have been using the dual filter versions on studio
condensers with adequate success.
in the heyday of AM radio it was noticed that some announcers voices "cut
through" better and sounded louder then others. it was discovered that these
voices had an asymmetrical modulation to them. the positive peak was much
greater then the negative peak of their voice waveform. when this occurred
the transmitter would modulate further in the positive direction and thus
when demodulated in the receivers would sound louder to the listener. some
bright boy (i think it was Lenard Khn) acted on this an invented something
called the symmetrapeak. it rotates the phase until the largest peaks point
up. (not much call for this in live PA work)
the biggest enemy you have to face is the narrow bandpass filter in the
other guys receiver. trying to push broadcast quality audio through that is
like trying to push a wet string up a sand dune. give any thought to
compandered audio? there's been some experimenting with it for NBFM.
good luck! Tim - KA8DSO
Neal Newman
Besides doing Live sound.. I happen be be the Chief Engineer for a few
local AM and FM stations
I operate on 75 and 160 Meters AM FONE..
I use Modified Broadcast transmitters for my Amateur station. Running an EV
re-20 Mic and an Optimod 9100B. for my audio processing. a friend of Mine
is running a Bheringer mic and Processor on his Gates transmitter...
BTW the AM station I Run is running Harris C-QUAM..
AM STEREO.. and sounds better than Most FM's in my Market...
It was a Long day yesterday.. we had the Disco Biscuits
at the Club... it was hippy Night.. Im going back to Bed.
Neal-KA2CAF
http://www.angelfire.com/nj4/wttm
H.A.N.D. Audio Systems inc.