Sound Advice - Article 2 |
In this article I thought we'd take a look at the different options available for upgrading your head unit. I'm not going to go into detail about unit specifications etc. as it would take way to much explaining. However, for those interested this is covered in detail at mobileaudio.com. Just read the section on components.
The first question you may want to ask yourself is; "Do I need to upgrade my head unit?" If it already has the features you desire, and you are happy with its performance, then there is no need to spend anywhere from $300.00 to $1300.00 to upgrade. Many of today's OEM (Original Equipment Manufacturer) radios have good features. CD is now a common option which can be had in either of two configurations; in dash or remote changer. The premium factory systems often have an in dash AM/FM Cassette radio with a remote CD changer. This can be the start of a very nice system! Often the only upgrades required will be, some signal processing with perhaps an equalizer, an increase in power through the addition of an amplifier or better sound reproduction through upgraded speakers.
Even if you don't have a CD changer you might want to check your head unit to see if some of the buttons have markings for CD functions. Some OEM radios will have the controls built in to run optional CD changers. You can either buy the factory CD changer (usually pretty expensive) or ask at some of the better stereo stores which after market changers will work. Often only an adapter cable is needed. Voila! You've now got a CD changer system! Yet another option to get CD capability is to connect either an FM modulated or direct connect CD changer to your present system. The FM modulated changers supply a small control panel to operate the changer. They basically broadcast a signal to the FM tuner of your radio. I don't particularly like this set up as the sound quality is dictated by your FM tuner. FM tuners don't have a very wide frequency response and the dynamic range is limited. However, it is a quick and dirty method of getting a CD player. A slightly better method would be to add a direct connect CD changer. You connect this system to either the speaker level or low level outputs of your deck. A similar controller to the FM modulated system is supplied to operate disc functions. An option I'd stay away from is the ones that employ a personal cd player and a cassette adapter. These units play through the head of the cassette player and as result are limited to the performance specs of the tape player; usually not good.
The weakest part of any OEM radio has to be the decks amplifier
section. Since they are located in the dash, and packaged in a relatively small unit, the
built in amplifier section is built as small as possible. As a consequence, they are low
powered and unable to drive speakers to a decent level without distorting. The same can be
said of the after market "high power" decks. Even though they may state a rating
of 35 watts per channel you will not get anywhere near that in reality. Take a look
at the size of a good 2 channel 35 watt amplifier and note its size as compared to your
decks amplifier section. That bulk is there for a reason; to dissipate the heat created by
a true power amp.
Some OEM radios will use an external amplifier or individual amplifiers that are mounted
on each speaker (known as active speakers). These are often low quality units and is
another area the factory will cut corners to save money. The only way to get
decent power and low distortion is with the addition of a quality after market power
amplifier. We'll talk about those in a later column .
O.K. You've taken inventory of your factory system. Apart from the
power output of it, you are content. There is no reason then to get rid of it; build
around it! "How do you do this?" you may ask. Well, the first thing
you'll want to do is change the output from a speaker level to a low level signal so
that you can use additional after market components. This can be done with a relatively
inexpensive gadget called, amazingly enough, a high/low converter. It's often a small box
with wires on one side that attach to the speaker wires coming out of the radio. Female
RCA connectors on the other side attach signal processors and amplifiers etc. To match the
output of the radio to the input of the next piece of equipment small level adjusting pots
are often on top of the box . Since this device is in the signal path and will have a
direct impact on the signal quality you should spend a few dollars more here and buy a GOOD
QUALITY product. The better car audio stores will often carry these; Scosche is a
particular brand that comes to mind. Another alternative would be to use an amplifier that
has high level speaker inputs. Now you can hook up the speaker level output of the head
unit to the amplifier directly. The downside is that there are not to many signal
processing devices, to use in between the head unit and amp, that use high level inputs.
You might want to use this method if you want to add an amplifier that will be used to
power a sub woofer or after market speakers and yet maintain a relatively simple
system.
all right, we're now at about the same point as if we had installed an
after market head unit; namely we have a source of music with a low level output. Future
upgrades at this point will be discussed in later articles, so, you'll have to wait!
Let's talk a little about some of the different formats that are available for head units. Am/Fm and cassette, as a package, is the most popular combination followed by Am/Fm and CD. CD is the format I prefer most for the following reasons: Any song title you can think of is likely available on CD. The same cannot be said for some of the other formats we'll get to later. CD is durable, has the best sound quality of any format and the technology is well proven. I've had CD's for 14 years now and they still play as well as the day they were bought. The players are available from many manufacturers and in recent years have dropped in price considerably. I remember paying over $600.00 for my first good player, nowadays you could purchase a similar or even better product for around $350.00. Complete AM/FM- Cassette with CD changer systems can be had on sale for as little as $400.00. That's quite a bargain!
A few years ago Mini-disc made an appearance. What's Mini-disc?
Well, it's similar to CD but differs in a few respects. Mini-disc cartridges are about the
same size as a computer 3 1/2" floppy diskette but a little thicker. The big feature
of Mini-disc is it's recording ability. You could have a Mini-disc player at home and
record on blanks, then play them in your vehicles player. Of course, with the availability
of CD Rom writers today you could do the same thing to blank CD's. All you would need is a
multimedia package on a PC. Pre- recorded song titles on mini-disc are also limited, so
finding some of the more obscure titles may be a challenge. The sound quality on Mini-disc
is not quite up to par with that of CD. In order to get the small size the engineers need
to compress the sound. This compression affects the dynamic range of the music. As a
result, the music may sound a little flatter or not as full as
compared to the same song on a CD. Whether or not you'll actually listen to the music
under conditions that would allow you to hear these differences is up to your
listening habits. In a moving car you would likely not hear a difference but sitting with
the engine off would be another matter. In competition the judges would likely be able to
tell the difference and they usually only have the test software on CD or Cassette.
To get the best of both worlds (mini-disc and CD) you could buy an in dash AM/FM mini-disc
player with external CD changer.
Prior to Mini-disc another format known as DAT was introduced. Digital
Audio Tape (DAT) was another means of using a player at home to record on a digital tape
and play it back in the car. The sound quality was better than Mini-disc but had a number
of drawbacks. Since it was a tape then you had to have physical contact with it to read
the information. This causes both the head and tape to wear with time and use. There is
also no direct access ability. You would have to search for a track like a you do on a
cassette. DAT players were also expensive, relatively rare and with the arrival of
Mini-disc became an obsolete format.
What if you have one of the really crummy factory head units?
Well, there's not much hope in keeping it if you want decent performance. I'll leave it up
to you to decide if it's worth keeping or not. Here's some things though to think about
before picking up that "SALE" item at the local retail store.
As I mentioned earlier; to upgrade your factory head unit you can spend
anywhere from $300.00, for a half decent in dash AM/FM CD player, to over $1200.00 for a
top grade AM/FM cassette deck with external CD changer. This is a sizable investment, so
knowing your needs and a budget beforehand will make your choice a little easier. I
listen to the radio only for short periods (mainly one station), don't have any cassettes
and don't mind manually changing CD's, so having a cassette player or CD changer is not
important to me. What was important was the sound quality of the unit and it's ease of
use.
But what about you? Do you have any cassettes? What about CD's?
Lots? or just a few? At home do you find yourself constantly changing Cd's or are you
content to listen to just one? Do you have any Eight Tracks? Just kidding! If you
do, you're in the WRONG place! And the wrong DECADE!.Back to the topic at hand, do you
listen to the radio much? Am or FM mainly? You get the idea? Think about what you'll be
listening to mostly and what format the majority of your software is on
(cassette/cd/DAT/mini disc).
There's not much reason to have a cassette player in the
car if you have a grand total of three cassettes! You might want to consider instead an in
dash AM/FM CD player AND a CD changer. Now you can have a supply of CD's in the changer
and the ability to play, with the in dash player, that brand new CD you just bought.
If you listen to the radio a lot then you might want to consider
looking for a unit that has good tuner specifications (see mobileaudio.com.), AM stereo or even a
"diversity tuner". A diversity tuner uses two antennae and will switch between
the two looking for the stronger signal. Of course this means you will require an extra
antenna to be installed. To get the best utilization one antenna is usually at the front
of the vehicle and the other at the rear. On a DSM this might look a little strange.
Digital radio is just starting to make an appearance and promises to provide
"near CD sound". I don't know of many stations that broadcast in digital yet and
the tuners are considerably more expensive than regular ones. However, in future years
this will be best way to get decent radio performance.
Cassette listeners will want a unit that offers Dolby B and C noise
reduction, music search and auto reverse. Check mobileaudio.com. for specifications. As a
reference, Nakamichi was always a brand long associated with top quality tape decks. They
were out of the car audio scene for a few years but I think they are making a come back;
they are not cheap though.
We've already discussed CD but to summarize, you might want to look for
units with shuffle(random play) and music programming. Nearly all Cd players will sound
good and only the most discriminating listeners will likely be able to tell
differences in sound between players. Therefore it will be the features that will be the
difference. For changer systems consider the size of the unit. There are many brands
available with tiny changers that can fit in center consoles or glove boxes. If you have
little free space you might want to look for a small changer. Ask also the following
questions. Does the changer take a cartridge or is it loaded disc by disc? Cartridges can
be filled up in the house and you can buy extras. How many discs will it hold? 6? 10? or
more? What is the disc change time? Some units take an eternity to change from one disc to
another. Get this demonstrated in the store and compare. If you constantly jump from disc
to disc or use random play a lot then you'll want a unit with quick access time. What kind
of D/A (Digital/Analog) conversion is used? i.e. over sampling or the better M.A.S.H (not
MASH the show but rather single bit conversion) technology? Can the unit be mounted at any
angle? Good changers should be able to be mounted at any angle between 0 and 90 degrees.
In all cases consider the following:
Does the unit have a detachable face plate? and does it come with a case for it? Does it
have a remote control? Do you prefer buttons or knobs? A few years ago nearly all
the manufacturers switched to buttons to control functions and in the process pi$$ed off a
lot of people! To me knobs are more user friendly. It's much easier to twist a volume knob
than punch away on buttons, especially when you are driving. Some of those buttons are
even harder to operate because they are so damn small! To make it even WORSE they do
multiple functions, so half the time you think you are adjusting bass only to find the
volume increasing. Very annoying! As a compromise, manufacturers have brought out
some units that have rotary switches that operate like the traditional knobs. So, make the
choice; buttons, knobs or a combination of both.
Find out how many RCA outputs the unit has. If you add amplifiers at a
latter time and want to be able to fade from front to rear you'll need both front
and rear RCA outputs. Most will have only two that are designated as rear. You can get by
on two, mine only has two. Once you get the system designed and set up properly you should
not need to keep using the fade control.
If you ever consider competing in events then find a unit that is very
easy to use. Judges like an 7ergonomic (easy to use) system. Some competitors have fitted
the remote control from a head unit in to the steering wheel so that you don't have to
remove your hands, in the process points are gathered for ergonomics and safety. Also
consider looking for a unit that has high voltage RCA outputs. Most decks RCA
outputs are between 1 and 2 Volts but there are units are out there with 7 Volt outputs.
This makes a big difference when it comes to noise rejection. There will be less chance
that noise will be introduced into the system if the signal coming out of the deck is
bigger and more immune to such anomalies. Another minor thing to consider is the
backlighting of a unit. Some are switch able from amber,green, red or blue. You might want
to make sure the back lighting matches your present dash lighting or can be switched to
match. It's also desirable if the lighting is dimmable. Once again this is more for those
that want to compete or are just fussy (like me). I had to change the lighting on my
Alpine from lime green to amber because it bothered me so much, and I was losing points in
competition.
Whew! I think we're done! Lots to think about I know, but there is so much choice when it comes to head units. Future topics should be a little more focused. Stay tuned! Next we'll look at actually installing a head unit and wiring it up.