The speaker setup in my car is weird because I don't have a lot of money to
dump into it yet. I have two tweeters with crossovers on the dash operating
off of the deck's amp, and a 12'' subwoofer tube in the trunk with its own
amp and crossover. There are no midrange speakers, but I still have the
rear speaker wires to work with running from the deck.

I tried alpine and polk 3-way 6-1/2'' speakers back there, and they sound
horrible when the deck is cranked because the low-end breaks apart. I want
to block bass to those speakers without having to buy a crossover. Perhaps
there is a way to rig a capacitor to these speakers to block the low end of
the signal?

Can someone tell me a simple way to block bass with radio shack parts? I
want to try two different ranges: blocking everything below 300Hz and below
400Hz. Whichever sounds better I will use. Any help will be appreciated.

My guess is that the problem is not the speakers, but the amp in the
headunit running out of juice and clipping.

However, as far as an x-over goes, you need to know that one capacitor
will only be a 6db/octave crossover, which means that with a 300hz
x-over point, it will only be down 6db, and then 150 will be down 12,
and 75 will be down 18. I'd suggest something like a 2nd order, or
third order crossover.

A second order has a capacitor and inductor and has a 12db/octave
slope, and a third order has a 18db/octave slope (with three x-over
components). Then a 4th order has a 24db/octave slope.

This is all immaterial though. For a 400hz x-over point, you are
looking at 100uF (this is assuming a 4 ohm nominal load, which is
another thing to think about, the impediance of a speaker changes
depending on the frequency). For 300hz it's 133uF. I'd suggest getting
a good audio quality capacitor from www.partsexpress.com . The dayton
5% tolerance x-over caps are pretty good.

If you go with a more than first octave arrangement, you have to start
worrying about alignments, etc. Probably not worth it, but here is a
calculator to do it with http://www.lalena.com/audio/calculator/xover/
.. Note too that a passive crossover introduces a phase shift,
especially with a second order.

Note though, that these may block the speaker, but your headunit will
still be producing the power to go to them, but it will be absorbed by
the capacitor and reproduced as heat (well, in a way, the impediance
will rise, so less current will be produced, but that is another
discussion), so that won't stop your headunit from distorting.

Hope that this helps.
Bill wrote:
The speaker setup in my car is weird because I don't have a lot of
money to
dump into it yet. I have two tweeters with crossovers on the dash
operating
off of the deck's amp, and a 12'' subwoofer tube in the trunk with
its own
amp and crossover. There are no midrange speakers, but I still have
the
rear speaker wires to work with running from the deck.

I tried alpine and polk 3-way 6-1/2'' speakers back there, and they
sound
horrible when the deck is cranked because the low-end breaks apart. I
want
to block bass to those speakers without having to buy a crossover.
Perhaps
there is a way to rig a capacitor to these speakers to block the low
end of
the signal?

Can someone tell me a simple way to block bass with radio shack
parts? I
want to try two different ranges: blocking everything below 300Hz and
below
400Hz. Whichever sounds better I will use. Any help will be
appreciated.

Bill wrote:
The speaker setup in my car is weird because I don't have a lot of
money to dump into it yet. I have two tweeters with crossovers on the
dash operating off of the deck's amp, and a 12'' subwoofer tube in
the trunk with its own amp and crossover. There are no midrange
speakers, but I still have the rear speaker wires to work with
running from the deck.

I tried alpine and polk 3-way 6-1/2'' speakers back there, and they
sound horrible when the deck is cranked because the low-end breaks
apart. I want to block bass to those speakers without having to buy a
crossover. Perhaps there is a way to rig a capacitor to these
speakers to block the low end of the signal?

Can someone tell me a simple way to block bass with radio shack
parts? I want to try two different ranges: blocking everything below
300Hz and below 400Hz. Whichever sounds better I will use. Any help
will be appreciated.

what you need are non-polar capacitors. There is a formula for determining
the capacitance here -- http://www.teamrocs.com/technical/pages/twoway.htm
Now this shows a two-way setup, but the tweeter section applies to you, only
you will be using bigger capacitors to get lower frequencies.

--
Dan Snooks

In article ,
"Daniel Snooks" wrote:

Bill wrote:
The speaker setup in my car is weird because I don't have a lot of
money to dump into it yet. I have two tweeters with crossovers on the
dash operating off of the deck's amp, and a 12'' subwoofer tube in
the trunk with its own amp and crossover. There are no midrange
speakers, but I still have the rear speaker wires to work with
running from the deck.

I tried alpine and polk 3-way 6-1/2'' speakers back there, and they
sound horrible when the deck is cranked because the low-end breaks
apart. I want to block bass to those speakers without having to buy a
crossover. Perhaps there is a way to rig a capacitor to these
speakers to block the low end of the signal?

Can someone tell me a simple way to block bass with radio shack
parts? I want to try two different ranges: blocking everything below
300Hz and below 400Hz. Whichever sounds better I will use. Any help
will be appreciated.

what you need are non-polar capacitors. There is a formula for determining
the capacitance here -- http://www.teamrocs.com/technical/pages/twoway.htm
Now this shows a two-way setup, but the tweeter section applies to you, only
you will be using bigger capacitors to get lower frequencies.

Two polarized capacitors of double the capacitance back to back is
equivalent and much easier to find in large values. The voltage of each
capacitor must be at least as high as the rail voltage of the amp.

Simulating a 110 microfarad, 50V, non-polaraized capacitor:

+ - - +
----|(-------)|-----
220 220
50V 50V

Hi Bill. Unfortunately you won't find the *non-polarized * capacitors
you need at Radio Shack anymore (probably). I think you might be able
to order them from Radio Shack Unlimited, however (special order
service).

I sometimes build my own 2 & 3 way crossovers and always had to special
order them.

Also you can try a surplus store called All Electronics
(www.allelectronics.com) or maybe Crutchfield as well, although the
prices are much higher for those for sale at Crutchfield or a car
stereo shop.

Good luck.


--
MartyMcLeod
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On Fri, 29 Apr 2005 13:10:43 -0400, Bill wrote:

The speaker setup in my car is weird because I don't have a lot of money to
dump into it yet. I have two tweeters with crossovers on the dash operating
off of the deck's amp, and a 12'' subwoofer tube in the trunk with its own
amp and crossover. There are no midrange speakers, but I still have the
rear speaker wires to work with running from the deck.

I tried alpine and polk 3-way 6-1/2'' speakers back there, and they sound
horrible when the deck is cranked because the low-end breaks apart. I want
to block bass to those speakers without having to buy a crossover. Perhaps
there is a way to rig a capacitor to these speakers to block the low end of
the signal?

Can someone tell me a simple way to block bass with radio shack parts? I
want to try two different ranges: blocking everything below 300Hz and below
400Hz. Whichever sounds better I will use. Any help will be appreciated.

I had the exact same problem, went to an electronics store ready to
spend big bucks but they had cheap ($1.5) 68microF/100V NP capacitors
and got 12 cheap ones. I used 3 per speaker (important: wire the
capacitors in PARALLEL to get 3X68). The difficult part was mounting
them so they wouldn't rattle inside the door. Use tape or whatever
else you want but be carefull because their cases are not very tough
and you can dent them easily (wires and pliers are NO).

I am now able to crank up the bass on the HU, the speakers don't sound
horrible (guitars have a plenty of body) and my sub in the trunk plays
all the bass. If you use 2 caps per speaker you will find noticable
bass-reduction at the speaker and I didn't like that. With caps so
cheap experiment.
--
Leon