This time we explore another
"common denominator" we all share in our ham stations ... audio!
For years we probably haven't paid too much attention to the microphones
and speakers we use with our rigs, or the impedances when using devices
other than the normal options for a given rig. But with the
plethora of fancy accessories we can get these days, it behooves us to
better understand some of the basics so we are not losing half the levels
or half the frequency range of the devices and/or radio.
So here we have a collection
of "audio basics" and a review of some of the nifty devices for the
shack that we could either buy or make to enable our audio to sound
better over the air and in our ears.
73, George N2APB & Joe N2CX
Podcast -- Listen
by double-clicking the link, or right-click and save to local hard drive for
later listening pleasure.
Online text discussion during the show ...
<20:27:20> "Joe N2CX": George's earrs were damaged by too
many heavy metal bands which he liked as much as he now likes heavy metal
boatanchor rigs...
<20:29:38> "Joe N2CX": Guys can get more bass from their voice by wearing
jockey shorts instead of boxer shorts!
<20:33:27> "Charles WC5MC": Good thing we aren't trying to sing to each
other.
<20:33:33> "George - N2APB": Opposite of that, right Joe? Tighter is higher?
<20:34:44> "George - N2APB": And thanks for pointing out the date error on
the home page Clint. Was able to correct it while Joe was last talking, and
all ittakes then in a refresh ... but we're all here anyway, so it doesn't
matter for us!
<20:38:31> "Charles WC5MC": The voiced speech of a typical adult male will
have a fundamental frequency from 85 to 180 Hz, and that of a typical adult
female from 165 to 255 Hz. http://en.wikipedia.org/wiki/Voice_frequency
<20:40:27> "Todd K7TFC": I'm ugly-building the NEscaf circuit. Will you be
talking about that or other scafs in the DDS section?
<20:40:50> "Todd K7TFC": DSP I mean.
<20:42:02> "Joe N2CX": KD1JV did a resonant speaker piece!
<20:43:18> "Charles WC5MC": afk a few mins
<20:43:52> "Joe N2CX": KD1JV resonant speaaker (sic)
http://kd1jv.qrpradio.com/resonatespkr/CWSPKR.HTM
<20:45:54> "Todd K7TFC": I want some pi.
<20:51:56> "Joe N2CX": EBay linux distro on SD card"
http://www.ebay.com/itm/8GB-SD-SDHC-Card-Raspbian-Linux-for-Raspberry-Pi-Preinstalled-/330766113061?pt=UK_Computing_Other_Computing_Networking&hash=item4d03325925"
<21:01:59> "Ray K2ULR": How about the one JJ brought to NJQRP on Saturday??
<21:04:42> "Joe N2CX":
http://newenglandqrp.org/nescaf
<21:04:56> "Todd K7TFC": NEscaf link:
http://newenglandqrp.org/nescaf.
<21:07:05> "Todd K7TFC": YouTube demos of the NEscaf:
http://www.youtube.com/playlist?list=PLIe6EGOjQefdfc3thLQhSoRRO16Pa-AqP
<21:14:42> "George - N2APB": Ha! That's the one. (No wonder why I was coming
up with the Nescafe coffee websites in my quick search.)
<21:24:14> "Alan W2AEW": I've started to play with these little RFM12B
modules. nice wirelss modules for about $7
<21:25:01> "Joe N2CX": Alan what protocol/freq range?
<21:25:04> "Alan W2AEW": Also, a real nice Arduino clone with the RFM12B
included www;moteino.com , less than $20, all inclusive
<21:25:27> "Alan W2AEW": 433 MHz, low data rates
<21:25:35> "Joe N2CX": Thanks!
<21:25:39> "Alan W2AEW": www.moteino.com
<21:25:52> "Alan W2AEW": breadboard friendly
In phone operation, it all starts with the microphone.
(And when using digital modes it really starts as
electronically-generated audio tones, but we'll get to that in a minute!)
Condenser microphones
are the most common types of microphones you'll find
in studios. They have a much greater frequency
response and transient response - which is the
ability to reproduce the "speed" of an instrument or
voice. They also generally have a louder output, but
are much more sensitive to loud sounds.
Condenser microphones are generally much more
expensive than dynamic microphones, but keep in
mind, many cheap condensers exist. The problem is
that most of these mics are coming from a couple
factories in China, and all sound the same -- very
brittle and with little low end.
They require the use of a power supply, generally 48
volt "phantom power", and that's supplied very
easily by most mixing boards or external power
supplies (look for a switch that says "P 48" or
"48V" on the channel strip or on the back of the
mixer.)
Condenser microphones are generally used only in
studios because of their sensitivity to loud sounds
and the fact that they're quite a bit more fragile
than their dynamic counterparts. That being said,
you'll find them onstage at live music venues for
use as drum overheads or for use in orchestral or
choral sound reinforcement
An electret microphone is a type
of
condenser microphone, which eliminates the need for
a polarizing power supply by using a permanently charged
material.
Compared to condenser
microphones, dynamic microphones are much more
rugged. They're also especially resistant to
moisture and other forms of abuse, which makes them
the perfect choice onstage. Dynamic microphones like
the Shure SM57 and Shure SM58 are legendary for not
only their good sound quality, but the amount of
abuse they can withstand. Any good rock club
probably has at least 5 of each of these microphones
in various states of aesthetic ruin; however, they
still turn on and more than likely sound just as
they did the day they came out of the package.
Dynamic microphones don't require their own power
supply like condenser microphones. Their sound
quality is generally not as accurate, however. Most
dynamic microphones have a limited frequency
response, which makes them well-suited, along with
their ability to withstand high sound pressure
levels, for loud guitar amps, live vocals, and
drums.
That being said, there's a few companies right now
producing "boutique" dynamic microphones -- some
with characteristics similar to that of a condenser
with the sustainability of a dynamic. Good dynamic
microphones include the Shure SM57 ($99), Sennheiser
E602 ($100), and the Shure SM58 ($109).
In 1930, two amateur radio operators,
Creed M. Chorpening, W8WR (later W8MJM) and F.H. Woodworth,
W8AHW began experimenting with different types of
microphones for their "ham' stations. Their mutual
friend, Charles Semple, worked for Brush Development Company
where he had been experimenting with
Rochelle salt
crystals. Semple demonstrated some crystal pick-ups that
Brush was working with, leading Chorpening and Woodworth to
found The Astatic Microphone Laboratory, Inc. in Youngstown,
Ohio in 1933. Semple was brought into the company as general
manager to manufacture and market the company's model D-104
Crystal Microphone as well as other crystal microphones,
crystal phonograph pickups and recording heads. In 1944,
Astatic moved operations to Conneaut, Ohio and supplied
microphones, pickups and crystal cartridges as well as
hydrophone and Sonar devices to the military during World
War II.
After World War II, Astatic Microphone
Laboratory became The Astatic Corporation. Currently, the
company is located in Solon, Ohio and offers microphones and
audio accessories to various audio industries. The Amateur &
CB product division of Astatic was sold to Barjan, LLC, a
major mobile communications product distributor. Barjan has
since expanded the Astatic name to include many accessories
including coaxial cables, meters and antennas. Astatic also
currently manufactures bullet style microphones, which are
extremely popular among harmonica players. The Astatic model
JT30 is the most popular of these, which is also sold as the
Hohner BluesBlaster.
The new
HM-12 microphone is designed specifically for amateur radio
communications.
The high output full range ‘Genesis’ dynamic element is designed to
work with just about every amateur radio low impedance transmitter.
The element is mounted in a unique internal shock mount and exhibits
nearly –35 dB of rear rejection,
which reduces background and ambient noise from the transmitted
signal.
The Heil
HM–12 exhibits a very natural audio response from 80Hz – 14 kHz. The
traditional Heil +4 dB peak centered at 2 kHz
gives the new HM-12 excellent voice articulation balanced with
clean, clear low-end response producing a high quality AM, FM or SSB
signal.
The ‘soft
touch’ PTT switch is wired to pins 3 and 4 for transmitter control
with the microphone signal fed to pins 1 and 2 of the four-pin XLR.
The Heil HM -12 uses the HEIL CC-1 Connecting Cables.
The HM-12
microphone has an internal foam windscreen and includes a 5/8”-27
microphone clip that is designed for our booms and desk stands.
Heil
Pro Micro Single
The Pro Micro
Single Side is a very unique high performance single sided headset.
The headset is
outfitted with the HC-6 element. Designed for commercial broadcast
applications, the -3dB points are fixed at 100 Hz and 12 kHz with
sensitivity of -57 dB at 600 ohms output impedance (centered at 1 kHz.)
The microphone
audio for the Pro Micro series terminates into a 1/8” male plug while
the head phone terminates into a 1/8” stereo with adaptor.
To adjust the
headset simply bend the stainless steel piece that is inside the black
padded headband.
Mic Gain
Adjust the mic gain while watching the ALC meter. Adjust so
that the audio peaks just fill out the ALC scale and do not go
beyond the ALC scale.
Speaker
The 706 speaker works all the time. To turn that off simply
plug an empty 1/8” plug into the front headphone jack.
Vox
Set the Vox gain controls for proper activation.
Carrier Balance
If your rig has carrier balance it acts as a type of mic tone
control. It is best to listen to yourself in another receiver as you
transmit into a dummy load. You are actually moving the carrier + or
- 200 Hz above or below the center of the filter network, which
causes your microphone audio to change its tonal quality.
The use of
the AD-1 series mic adapters allow simple interface with popular
transceiver inputs. The adapter is 6” long and has a 1/8” female
input jack for the boomset microphone and a 1/4” female that is for
the PTT (push to talk) line for the Heil foot switch or hand switch.
The 1/4” stereo plug goes into the headphone jack on the transceiver
front panel.
A typical stock mic and many
manufacturers desk mics have a narrow frequency response to go along
with their own radios. They usually boast a 300Hz to 3,000Hz
frequency range. And that is including the roll-off areas on each
end of their range. These mics do not even cover the full frequency
range of the radio. Notice in Figure (B) below,
that the roll-off of these mics (in red) begin at around 500Hz and
2,000Hz. So the frequency range that these mics actually cover at
normal volume levels is 500Hz to 2,000Hz. Your radio can do so much
better than that.
Notice in Figure (C)
below, how the studio mic goes far beyond the range that your radio
can use. And it does this with full volume of each single little
Hertz. ALSO, the studio mic more than covers the roll-off range of
your radio's audio amplifiers of both transmit and receive. So when
you transmit and speak, the full frequency range that your radio can
possibly produce, is getting your audio at 100% dB across the
spectrum. And the receivers of those hearing you are also producing
every possible Hertz that their radio can produce. This effectively
doubles the frequency response over a typical stock or manufacturers
desk mic. The result is better lower frequencies, better midrange
frequencies, and better high frequencies. This means cleaner and
more natural sounding audio. This means more UMPFFF to your SSB
power without distortion........Need I go on?
The world of input and output processing of the ham radio
operator's signal is a fascinating carry-over of the traditional audiophile
(hi-fi sound system aficianados).
Ham Radio Audio Equipment
The YouTube video below is about the audio equipment in the ham radio shack
of Tyler, N7TFP.
This audio equipment is all connected and interfaced to the ham radios ...
http://www.youtube.com/watch?v=dER-WJPWXI8
W2IHY Products
These are the deluxe products for the ham radio audiophile ...
http://www.w2ihy.com/
W2IHY 8-Band Audio Equalizer
"EQplus" by W2IHY
Audio sample of
EQplus processing In this example, WV4R turns off the W2IHY audio
processing stages and turns them back on. Listen to the fascinating procedure and the
stunning results ...
Listen
AE6LX demonstrates how to connect the 8 Band
EQ to the EQPlus. He also demonstrates adjusting the units where you can see and hear the
difference.
Alan W2AEW ... Equalization Amplifier for the Astatic D-104 Microphone
This video describes the microphone preamp and equalizer that
I designed in 1999 to use with my Astatic D-104 microphone with my ham
radio.
The D-104 suffers from two issues when used with modern ham radios -
impedance mismatch and non-ideal frequency response.
The circuit addresses both of these issues.
The video briefly describes the circuit, it's frequency response, and
demonstrates the bass and treble adjustments using an oscilloscope and
signal generator.
More information can be found on this webpage:
http://www.qsl.net/w2aew/myd104amp.html
Note that it is quite likely that you will have to employ strategically
placed bypass capacitors, ferrite beads, etc. to keep RF from coupling into
this circuit. Every application and installation is different, so you may
have to "play" with these components to eliminate RF from your circuit. You
can see some of the ferrite beads I used when the video shows the circuit
board in the base of the microphone
The response of this circuit can be adjusted basically
between the limits shown in the plot above.
Preamp and tone control built Manhattan Style" in base of the mic.
AUDIO OUTPUT
Everyone listens to audio coming from the rig, right?
Well, as you'll see here, there are some ways to enhance the sound to make
it easier to hear the voices, Morse code or digital tones.
There is no better
product than the Heil Pro Set 3 stereo headphones, to illustrate the
fact that Bob Heil’s ability to listen leads to his company (Heil
Sound Ltd.), to build high quality professional sound products.
Anyone who has ever professionally recorded or monitored audio will
tell you that the last thing they worry about is whether headphones
look good…The fact that the Heil Pro Sound 3 looks so good is a
bonus.
What is needed;
however, is a professional lightweight head-set that can be
comfortably worn for hours on end, without producing “headphone
fatigue”, in addition to providing accurate sound recreation. It
helps to know when you’re “tracking”, that what you hear in the cans
is not colored such that it will be a disappointment later. The Pro
Set 3 headphones will work for all types of music recording, as well
as be great for internet and commercial broadcasting, in addition to
amateur radio.
With the Pro Set 3
headphones you get three detachable cables. A 1.8 M flexible
straight cable; and a 1.8 M straight cord with mating iPhone/iPod
compatible 3.5mm plug; and also, a 3 M coil cord - all twist lock
terminating in a 1/8" (3.5 mm) professional gold plated screw-on
1/4" (6.3mm) adapter.
From 10 Hz all the
way to 22k Hz, the Heil Pro Set 3 headphones have got you covered.
Common Speakers from today and from days of y'ore ... Can you identify
the manufacturers?
Some popular USB speakers available with modest proces
Finding resonant frequency
on a "tube" makes a great speaker for CW reception
For those that would like to "get a jump" on ordering the parts for this
project. the details can be found on Allen's web site.
http://www.kg4jjh.com/dspspeaker.html
Frank N3PUU has upgraded his Arduino+XBee experiments to now use the Series
2 XBee modules. This is a necessary step for "going multi-node" with a
mesh network.
So
if you are interested in continuing along toward the Mesh Network goal, you also
should get some Series 2 modules for using in our experiments from now on.
Franks notes and photos here show the easy way you can substitute the Series 2
XBee modules for the Series 1 modules we've been using thus far.
XBee Series 2
Series 2 modules run the Zigbee stack.
Every Zigbee network must have one (and only one) "Coordinator" to
manage the network.
"Router" nodes are end devices on the network that will also relay
traffic from other nodes. Because they are relaying, their power usage
is higher. Because of this, "router" duties are generally reserved for
devices with 24x7 line power.
The third type of Zigbee node is an "End Device." These will not relay
traffic from other nodes, and are generally used when the node is
battery powered.
Coordinator:
Connect Module to PC
Start X-CTU
In X-CTU, under Modem Configuration Tab, Download New Versions (of
firmware)
Flash with "ZIGBEE COORDINATOR AT" Firmware (Version 20A7)
Write firmware to XBee
Configure:
PAN ID (ID) - 0C2D (For "Chat 2 Designers")
Destination Address High (DH) - 0013A200
Destination Address Low (DL) - (8 char hex address of router)
40814000 (in my case)
Write configuration
Router:
Connect Module to PC
Start X-CTU
In X-CTU, under Modem Configuration Tab, Download New Versions (of
firmware)
Flash with "ZIGBEE ROUTER AT" Firmware (Version 22A7)
Write firmware to XBee
Configure:
PAN ID (ID) - 0C2D (For "Chat 2 Designers")
Destination Address High (DH) - 0013A200
Destination Address Low (DL) - (8 char hex address of router)
40813F6C (in my case)
Write configuration
Testing:
Attach XBees to PC(s)
Fire up terminal programs pointed to serial ports where XBees are
attached (9600 baud)
Chat!
***************************************************************************************************
Experiment 2 - Standalone Temperature-Sensing Remote Radio Link
Addresses (For Reference):
Coordinator (To Arduino): 40814000
End Device (Temp Sensor): 40813F6C
Module Configuration (Series 2 Modules):
Coordinator:
Connect Module to PC
Start X-CTU
In X-CTU, under Modem Configuration Tab, Download New Versions (of
firmware)
Flash with "ZIGBEE COORDINATOR API" Firmware (Version 21A7)
Write firmware to XBee
Configure:
PAN ID (ID) - 0C2D (For "Chat 2 Designers")
Write configuration
End Device:
Connect Module to PC
Start X-CTU
In X-CTU, under Modem Configuration Tab, Download New Versions (of
firmware)
Flash with "ZIGBEE END DEVICE API" Firmware (Version 29A7)
Write firmware to XBee
Configure:
PAN ID (ID) - 0C2D (For "Chat 2 Designers")
Destination Address High (DH) - 0013A200
Destination Address Low (DL) - (8 char hex address of coordinator)
40814000 (in my case)
Sleep Mode (SM) - 4 "Cyclic Sleep" (likely default)
Time Before Sleep (ST) - 3
Cyclic Sleep Period (SP) - C8 (2000 (200x10) milliseconds)
D1 AD1/DIO1 Configuration - 2 - ADC
IO Sampling Rate (IR) - 32
Write configuration
Photos of the
N3PUU Series 2 XBee Setup
Picture of the front of a series 2 module
Picture of the rear of a pair of modules to show where the addresses
are printed
Picture of module on desk while it was being
programmed
Picture of 2 modules on the desk during the chat test
Screenshot of the 2 terminal windows talking
Screenshot of the Arduino serial output showing received temperature
Picture of the remote temp node with Arduino base
station
Sketches ...
Series2_IoSamples_CWTD_RemoteTemp.ino - Sketch
for receiving the remote temp data, adapted from the "Series2_IOSamples"
example sketch that comes with the xbee library
emonlib_test.pde
- This is the code that I use on the whole house power monitor which sends
the data off over xbee. The XBee portion is adapted from the "Series2_Tx"
example sketch that comes with the xbee library.
