Help an old school guy out with a sub

[[email protected]]

I've got an aftermarket head unit with 20 clean watts per channel and
four quality full range speakers in my convertible. It sounds
mediocre, but I need some bass.

I don't want to pay more than $150 for upgrades and only have one set
of pre-amp outputs.

Wally World has a 10" sub cabinet for $20 and a pioneer subwoofer for
about $50. I could mate this with a low end amp or wait for a better
used one on craigslist.

I don't understand how to the fading will work on my stereo and how I
can best keep the full range speakers from trying to reproduce bass
that they can't handle.

Do I need bassblockers or is there a particular set of features I need
in an amp?

MD

[MOSFET]

Well, the very easiest way would to do what you suggest and connect the RCA
outputs of your HU to your amp that will drive the subwoofer.

There is a very cheap and easy way to block the bass from your four existing
speakers (something you will most DEFINTAELY want to do as it will add
substantially more volume to your system, bass consumes the most power and
taxes small woofers the most). Check out this site for a diagram and
explanation of how a passive
crossover would work.
http://www.the12volt.com/caraudio/cross.asp

In a nutshell, you will connect a capacitor in line to the positive
connection of each of your four speakers. Capacitors are cheap and you can
pick four up at Radio Shack for about a buck a piece. This will give you a
6 dB per octive crossover. This is not a terribly sharp crossover so I
would suggest a capacitor value of 200uF (200 micro-farads) to 100uF. The
200uF will start the attenuation (crossover) at about 200 Hz (easy to
remember). The 100uF will begin the attenuation at about 400 Hz (much
higher and will cut more low bass out and will allow you to play your
speakers louder). Capacitors are so cheap you may even want to experiment
with a couple different values. I have used this type of crossover many,
MANY times in the past for myself and other installations and they work
GREAT. They are easy to install (only one wire has to be cut for each
speaker) and they just twist right onto the copper wire, then just cover the
whole thing with electrical tape and you're done.

Now, as far as a subwoofer volume control, there are many options for this.
PERHAPS (and this is a big perhaps) the RCA output level can be controlled
indepentally from the other four speakers. My strong guess, however, is
probablly not. The easist is to buy an amplifier that has an outboard level
control. They are usually connected via phone cords and consist of a simple
volume knob you will have to mount somewhere near the dash. This would be
your best bet. Trust me, you ARE going to want to be able to control your
subwoofer output on the fly, perhaps from song to song as bass varies
dramtically in music. If your amp DOES NOT have a remote volume knob you
can actually make one using a simple potentiometer (pot) connected between
the RCA outputs on your HU to the subwoofer amp. The pot again will have to
be mounted somewhere you have access to you and it is just a volume knob
with three connections on it (I will not go into what all three do).

If you want to amp your four other speakers as well, I would STRONLY
encourage you to use two amps or a four channel amp (two channels bridged to
one channel for the sub, two channels for the four speakers, you can bridge
two speakers to one connection). But this way you will lose fader controls
(you would connect right front and rear to one channel, and left front and
rear to the other). If fader is important, you will probably need yet
another amp. But there's a way around this issue. Keep in mind that your
front speakers are the MOST important. Like at a concert, music should come
from the front. Your rear speakers should only give you some "rear-fill" or
some ambience as a natural room would when sound bounces off the back wall.
Therefore, 20 watts IMHO is plenty for your "rear-fill". If you intend to
amplify the four cabin speakers, start first with the two fronts only and
see how you like that letting the HU power the rears (you will have fader as
you will be able to raise or lower the rear-speaker volume). Again, once
the passive crossovers are installed and your front four speakers no longer
have to play low bass, your front four speakers will be dramtically louder.

Hope all this helps, good luck.

MOSFET


> wrote in message
...
> I've got an aftermarket head unit with 20 clean watts per channel and
> four quality full range speakers in my convertible. It sounds
> mediocre, but I need some bass.
>
> I don't want to pay more than $150 for upgrades and only have one set
> of pre-amp outputs.
>
> Wally World has a 10" sub cabinet for $20 and a pioneer subwoofer for
> about $50. I could mate this with a low end amp or wait for a better
> used one on craigslist.
>
> I don't understand how to the fading will work on my stereo and how I
> can best keep the full range speakers from trying to reproduce bass
> that they can't handle.
>
> Do I need bassblockers or is there a particular set of features I need
> in an amp?
>
> MD

[[email protected]]

On Feb 23, 2:46*am, "MOSFET" > wrote:
> Well, the very easiest way would to do what you suggest and connect the RCA
> outputs of your HU to your amp that will drive the subwoofer.
>
> There is a very cheap and easy way to block the bass from your four existing
> speakers (something you will most DEFINTAELY want to do as it will add
> substantially more volume to your system, bass consumes the most power and
> taxes small woofers the most). *Check out this site for a diagram and
> explanation of how a passive
> crossover would work.http://www.the12volt.com/caraudio/cross.asp
>
> In a nutshell, you will connect a capacitor in line to the positive
> connection of each of your four speakers. *Capacitors are cheap and you can
> pick four up at Radio Shack for about a buck a piece. *This will give you a
> 6 dB per octive crossover. *This is not a terribly sharp crossover so I
> would suggest a capacitor value of 200uF (200 micro-farads) to 100uF. *The
> 200uF will start the attenuation (crossover) at about 200 Hz (easy to
> remember). *The 100uF will begin the attenuation at about 400 Hz (much
> higher and will cut more low bass out and will allow you to play your
> speakers louder). *Capacitors are so cheap you may even want to experiment
> with a couple different values. *I have used this type of crossover many,
> MANY times in the past for myself and other installations and they work
> GREAT. *They are easy to install (only one wire has to be cut for each
> speaker) and they just twist right onto the copper wire, then just cover the
> whole thing with electrical tape and you're done.
>
> Now, as far as a subwoofer volume control, there are many options for this.
> PERHAPS (and this is a big perhaps) the RCA output level can be controlled
> indepentally from the other four speakers. *My strong guess, however, is
> probablly not. *The easist is to buy an amplifier that has an outboard level
> control. *They are usually connected via phone cords and consist of a simple
> volume knob you will have to mount somewhere near the dash. *This would be
> your best bet. *Trust me, you ARE going to want to be able to control your
> subwoofer output on the fly, perhaps from song to song as bass varies
> dramtically in music. *If your amp DOES NOT have a remote volume knob you
> can actually make one using a simple potentiometer (pot) connected between
> the RCA outputs on your HU to the subwoofer amp. *The pot again will have to
> be mounted somewhere you have access to you and it is just a volume knob
> with three connections on it (I will not go into what all three do).
>
> If you want to amp your four other speakers as well, I would STRONLY
> encourage you to use two amps or a four channel amp (two channels bridged to
> one channel for the sub, two channels for the four speakers, you can bridge
> two speakers to one connection). *But this way you will lose fader controls
> (you would connect right front and rear to one channel, and left front and
> rear to the other). *If fader is important, you will probably need yet
> another amp. *But there's a way around this issue. *Keep in mind that your
> front speakers are the MOST important. *Like at a concert, music should come
> from the front. *Your rear speakers should only give you some "rear-fill" or
> some ambience as a natural room would when sound bounces off the back wall.
> Therefore, 20 watts IMHO is plenty for your "rear-fill". *If you intend to
> amplify the four cabin speakers, start first with the two fronts only and
> see how you like that letting the HU power the rears (you will have fader as
> you will be able to raise or lower the rear-speaker volume). *Again, once
> the passive crossovers are installed and your front four speakers no longer
> have to play low bass, your front four speakers will be dramtically louder.

[MOSFET]

Don't know if you are still looking for a subwoofer volume control, but
Scosche makes one without the need to make your own. It's basically a
potentiometer with stereo inputs and outputs (like I suggested in my last
post) but it surely looks more classy than one if you are I built one.
Again, this would only be necessary if your sub amp had no remote gain
control OR there was no subwoofer output on your head-unit that would allow
subwoofer volume control (this would only be likely if your HU had three
sets of outputs: fronts, rears, and subwoofer).

Anyway, there's a used one on Ebay right now (that's where I stumbled onto
it, just browsing Ebay) and I recalled you mentioned a need for just such a
device. It's going for dirt cheap and would certainly be easier and perhaps
even cheaper (you'd have to buy the pot., the knob, the connectors, etc.)
than building your own. The Ebay link to this device is:
http://cgi.ebay.com/SCOSCHE-EFX-CAR-AMP-REMOTE-LEVEL-CONTROL-BASS-KNOB-RLC_W0QQitemZ270365101275QQcmdZViewItemQQptZLH_Def aultDomain_0?hash=item270365101275&_trksid=p3286.c0.m14&_trkparms=72%3A1462|66%3A2|65%3A12|39%3A1|240%3A13 18|301%3A1|293%3A1|294%3A50

Hope this info is useful, perhaps it will give you other ideas.

MOSFET

"MOSFET" > wrote in message
m...
> Well, the very easiest way would to do what you suggest and connect the
> RCA outputs of your HU to your amp that will drive the subwoofer.
>
> There is a very cheap and easy way to block the bass from your four
> existing speakers (something you will most DEFINTAELY want to do as it
> will add substantially more volume to your system, bass consumes the most
> power and taxes small woofers the most). Check out this site for a
> diagram and explanation of how a passive
> crossover would work.
> http://www.the12volt.com/caraudio/cross.asp
>
> In a nutshell, you will connect a capacitor in line to the positive
> connection of each of your four speakers. Capacitors are cheap and you
> can pick four up at Radio Shack for about a buck a piece. This will give
> you a 6 dB per octive crossover. This is not a terribly sharp crossover
> so I would suggest a capacitor value of 200uF (200 micro-farads) to 100uF.
> The 200uF will start the attenuation (crossover) at about 200 Hz (easy to
> remember). The 100uF will begin the attenuation at about 400 Hz (much
> higher and will cut more low bass out and will allow you to play your
> speakers louder). Capacitors are so cheap you may even want to experiment
> with a couple different values. I have used this type of crossover many,
> MANY times in the past for myself and other installations and they work
> GREAT. They are easy to install (only one wire has to be cut for each
> speaker) and they just twist right onto the copper wire, then just cover
> the whole thing with electrical tape and you're done.
>
> Now, as far as a subwoofer volume control, there are many options for
> this. PERHAPS (and this is a big perhaps) the RCA output level can be
> controlled indepentally from the other four speakers. My strong guess,
> however, is probablly not. The easist is to buy an amplifier that has an
> outboard level control. They are usually connected via phone cords and
> consist of a simple volume knob you will have to mount somewhere near the
> dash. This would be your best bet. Trust me, you ARE going to want to be
> able to control your subwoofer output on the fly, perhaps from song to
> song as bass varies dramtically in music. If your amp DOES NOT have a
> remote volume knob you can actually make one using a simple potentiometer
> (pot) connected between the RCA outputs on your HU to the subwoofer amp.
> The pot again will have to be mounted somewhere you have access to you and
> it is just a volume knob with three connections on it (I will not go into
> what all three do).
>
> If you want to amp your four other speakers as well, I would STRONLY
> encourage you to use two amps or a four channel amp (two channels bridged
> to one channel for the sub, two channels for the four speakers, you can
> bridge two speakers to one connection). But this way you will lose fader
> controls (you would connect right front and rear to one channel, and left
> front and rear to the other). If fader is important, you will probably
> need yet another amp. But there's a way around this issue. Keep in mind
> that your front speakers are the MOST important. Like at a concert, music
> should come from the front. Your rear speakers should only give you some
> "rear-fill" or some ambience as a natural room would when sound bounces
> off the back wall. Therefore, 20 watts IMHO is plenty for your
> "rear-fill". If you intend to amplify the four cabin speakers, start
> first with the two fronts only and see how you like that letting the HU
> power the rears (you will have fader as you will be able to raise or lower
> the rear-speaker volume). Again, once the passive crossovers are
> installed and your front four speakers no longer have to play low bass,
> your front four speakers will be dramtically louder.
>
> Hope all this helps, good luck.
>
> MOSFET
>
>
> > wrote in message
> ...
>> I've got an aftermarket head unit with 20 clean watts per channel and
>> four quality full range speakers in my convertible. It sounds
>> mediocre, but I need some bass.
>>
>> I don't want to pay more than $150 for upgrades and only have one set
>> of pre-amp outputs.
>>
>> Wally World has a 10" sub cabinet for $20 and a pioneer subwoofer for
>> about $50. I could mate this with a low end amp or wait for a better
>> used one on craigslist.
>>
>> I don't understand how to the fading will work on my stereo and how I
>> can best keep the full range speakers from trying to reproduce bass
>> that they can't handle.
>>
>> Do I need bassblockers or is there a particular set of features I need
>> in an amp?
>>
>> MD
>
>