I installed a while back a set of Memphis tweeters. 15-PRT1 I believe.
Aluminum coated mylar dome is jsut a little bit sharp for my liking. Can
anybody recommend a nice pair of possbily silk dome tweeters? Price around
$100, maybe more, maybe less. I have no idea what to look at.

I installed a while back a set of Memphis tweeters. 15-PRT1 I believe.
Aluminum coated mylar dome is jsut a little bit sharp for my liking. Can
anybody recommend a nice pair of possbily silk dome tweeters? Price around
$100, maybe more, maybe less. I have no idea what to look at.

Hey Kirby, it's going to depend a bit on what you're doing for crossovers.
If you're running an active xover, I say try a hit and miss with some cheap
8 ohm tweets from like Parts Express or Madisound or something. I wouldn't
necessarily limit yourself to just silk. You can sometimes find some
"smooth" metal dome tweeters. If you're going with an existing passive
crossover (or plan on just using a capacitor), then you may have to be a bit
more specific in your search. In that case, you'll want it to present the
right impedance at the right frequencies.

As bad as it may sound, I never did figure out the difference between an
active or a passive crossover, I have an idea that the passive is simply a
"bass blocker" type thing, and the active is a woofer/tweet adjustable
frequency type unit. I think I'm totally wrong.. am I? And as for the
material, I havn't really heard many metal tweeters that had a more smooth
sound. I know that I am fond of the Kenwood Excelon series of gear. The
crossover that came with the Memphis' isn't bad though. Oddly shaped (its
basicly in a 3" cardboard tube) but it does have the woofer/tweeter outputs.
If it'll save me money, I'd prefer to get just the tweeters without the
X-over.



"MZ" wrote in message
...
I installed a while back a set of Memphis tweeters. 15-PRT1 I believe.
Aluminum coated mylar dome is jsut a little bit sharp for my liking. Can
anybody recommend a nice pair of possbily silk dome tweeters? Price
around
$100, maybe more, maybe less. I have no idea what to look at.

Hey Kirby, it's going to depend a bit on what you're doing for crossovers.
If you're running an active xover, I say try a hit and miss with some
cheap
8 ohm tweets from like Parts Express or Madisound or something. I
wouldn't
necessarily limit yourself to just silk. You can sometimes find some
"smooth" metal dome tweeters. If you're going with an existing passive
crossover (or plan on just using a capacitor), then you may have to be a
bit
more specific in your search. In that case, you'll want it to present the
right impedance at the right frequencies.

As bad as it may sound, I never did figure out the difference between an
active or a passive crossover, I have an idea that the passive is simply a
"bass blocker" type thing, and the active is a woofer/tweet adjustable
frequency type unit. I think I'm totally wrong.. am I?

No, that's close enough. The most simple (and probably most accurate)
definition is this: an active crossover requires power whereas a passive
doesn't. So the crossover inside many amps is an active crossover because
it gets its power from the amplifier's power supply. You can also buy
external active crossovers made by companies like Audiocontrol that requires
12v to operate. Passive crossovers are the little boxes that come with
component sets that have tweeter and woofer outputs. They don't require
external power. They simply "split" (for lack of a better term) the audio
signal into high and low. And yes, a bass blocker is a simple passive
crossover. Also, those little modules that crutchfield used to sell that
went between your RCA wires and amplifier input were passive crossovers,
even though they filtered before amplification took place.

Anyway, the importance of this is that the cutoff frequency of passive
crossovers that come with most component sets (and bass blockers too) is
very dependent on the impedance of the speaker. So, if you're using a
passive crossover that came with another pair of speakers, you want to
somewhat match the impedance of the new speaker with the old one. In other
words, if you had a 4 ohm tweeter hooked up before, you probably want to
stick with 4 ohms.

On Tue, 28 Jun 2005 05:25:18 GMT, "Kirby"
wrote:

As bad as it may sound, I never did figure out the difference between an
active or a passive crossover


The differences between active and passive crossovers are in the
components used, and where in the signal path they're inserted.

Active crossovers require power and ground wires to operate because
they use electronics (microchips) to alter the signal. They're also
designed to operate on the low-voltage preamp signal, so they go
*before* the amplifiers. The crossovers that AudioControl makes (4XS,
2XS, etcetera) are perfect examples. They connect between the head
unit and the amp(s) using RCA cables, and send the crossed-over
signals to the amplifiers.

Passive crossovers use only passive circuit elements (resistors,
capacitors, and inductors), so they don't require a power or ground
source. They're meant to work on the speaker-level signal, so they go
between the amplifier and the speaker. You'll often find them on the
speakers themselves (like the capacitor you see connected in parallel
with the tweeter on a two-way speaker.)

Which type is better depends on your application, but here's a
breakdown of some of the considerations:

1) Flexibility-- The crossover frequencies on active crossovers can be
easily adjusted, since it's all microchips and circuitry.

The frequencies for passive crossovers are fixed and depend on the
values of the capacitors, inductors, and resistors used. There ARE
variable inductors, capacitors and resistors on the market, but they
tend to be bulkier and more expensive than the fixed-value ones.

2) Power handling-- Active crossovers can be used with any amount of
amplification, since they alter the signal while it's still at the
low-voltage preamp level, before it gets to the amp.

Passive crossovers are limited in the amount of power they can handle,
since the resistors, capacitors and inductors can only handle so much
power and current.

3) Cost-- If all you need is a moderate-power fixed-frequency
crossover, passive components are a lot cheaper. You can go to Radio
Shack and pick up the components needed for a simple crossover for
less than a buck.

4) Efficiency-- There's virtually no signal loss through an active
crossover, and it wouldn't matter anyway since you could compensate
for the reduced signal by increasing the gain on the amp.

Passive crossovers, on the other hand, waste a portion of the power
passing through them as heat. The signal loss through a passive
crossover can easily be 3 dB or more.

5) Crossover slope-- The slope for an active crossover is usually
pretty steep, like 12, 18, or 24 dB per octave. This keeps the
speaker from reproducing sounds outside of its intended range. For
example, if you have a low-pass 24 dB/octave filter set at 80 Hz going
into your subwoofer amplifier, a signal of 160 Hz will be almost
completely blocked by the crossover. If you only have a 6 dB/octave
slope and an 80 Hz crossover point, the 160 Hz note will still get
through the crossover and to the speaker with almost 25% of its
strength left.

The crossover slope for a passive crossover is usually only 6 or 12
dB/octave. It's possible to make a 24 dB/octave passive crossover,
but both the number of components needed to build it and the signal
loss rise pretty dramatically.


**There are some other factors, like how the crossover affects the
phase of the signal passing through it, but the five factors I've
already listed are the big ones.


Hope this helps,

--
Scott Gardner

"There is a wicked pretense that one has been informed. But no such thing has truly occurred! A mere slogan, an empty litany. No arguments are heard, no evidence is weighed. It isn't news at all, only a source of amusement for idlers." (Gibson-Sterling, The Difference Engine)

Scott Gardner wrote
Kirby wrote:

As bad as it may sound, I never did figure out the difference between an
active or a passive crossover


The differences between active and passive crossovers are in the
components used, and where in the signal path they're inserted.



Thanks both to MZ and Scott for their refreshing insight
regarding crossovers.