[GarageGuitar]

Hi everyone. I'd like to make a set of PA speakers to use with my band
(acoustic folk music). I've got amp modules to build powered cabinets,
and I'm starting to dig around for the right drivers. The amp modules
are 200 watts RMS. Finding woofers that will work in a 2 or 3-way
cabinet is fairly easy. I'm running into problems on the HF end
though. My first thought was to use a piezo horn, but finding
something rated for at least 200 watts rms is proving difficult (seems
CTS stopped making the Powerline horns!?!). I can find any number of
piezo bullet tweeters rated at 75 watts. My question is: can I wire
three 75-watt piezo tweeters torgether to get 225 watts RMS power
handling total in the HF range?

[Scott Dorsey]

GarageGuitar wrote:
Hi everyone. I'd like to make a set of PA speakers to use with my band
(acoustic folk music). I've got amp modules to build powered cabinets,
and I'm starting to dig around for the right drivers. The amp modules
are 200 watts RMS. Finding woofers that will work in a 2 or 3-way
cabinet is fairly easy. I'm running into problems on the HF end
though. My first thought was to use a piezo horn, but finding
something rated for at least 200 watts rms is proving difficult (seems
CTS stopped making the Powerline horns!?!). I can find any number of
piezo bullet tweeters rated at 75 watts. My question is: can I wire
three 75-watt piezo tweeters torgether to get 225 watts RMS power
handling total in the HF range?

The problem with piezo tweeters is that they are horribly screechy sounding
crap. Oh, also the radiation pattern is irregular, and it doesn't match
that of a conventional cone woofer.

Power ratings on all of these things are basically fake, and can be ignored.

My suggestion is that if you want to build a speaker system for acoustic
music, and you don't have a lot of speaker design experience, take a good
12" coaxial driver and use whatever volume and alignment the driver
manufacturer suggests. The 12" Radian drivers would be a good first cut,
but there are worse drivers and better drivers for more and less money.
Use the manufacturer's recommended crossover, or build an exact copy of it
yourself.

The coaxials are pretty wide, but they are going to give you a much better
chance of getting a realistic vocal sound than a conventional 2-way system.
And certainly a hell of a lot better than any nasty piezo crap.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[GregS[_3_]]

In article , GarageGuitar wrote:
Hi everyone. I'd like to make a set of PA speakers to use with my band
(acoustic folk music). I've got amp modules to build powered cabinets,
and I'm starting to dig around for the right drivers. The amp modules
are 200 watts RMS. Finding woofers that will work in a 2 or 3-way
cabinet is fairly easy. I'm running into problems on the HF end
though. My first thought was to use a piezo horn, but finding
something rated for at least 200 watts rms is proving difficult (seems
CTS stopped making the Powerline horns!?!). I can find any number of
piezo bullet tweeters rated at 75 watts. My question is: can I wire
three 75-watt piezo tweeters torgether to get 225 watts RMS power
handling total in the HF range?

This was the one to use, if you really wanted a Piezo.
http://www.bluearan.co.uk/index.php?...e=90248 4_CO1

They will normally handle 200 watts, but its best to use a crossover. Typically they handle 36 watts RMS.
Terribly unlinear.

Scott has good advice. Tou can still make something good if you know what your doing.
Take a look at.....
http://www.usspeaker.com/SUPERTWEETERS-1.htm

You can not use the watts rating unless you compute all the spl's and woofer sensitivities, and
attenuation networks and crossover slops, etc., etc.

greg

[GregS[_3_]]

In article , (GregS) wrote:
In article ,
GarageGuitar wrote:
Hi everyone. I'd like to make a set of PA speakers to use with my band
(acoustic folk music). I've got amp modules to build powered cabinets,
and I'm starting to dig around for the right drivers. The amp modules
are 200 watts RMS. Finding woofers that will work in a 2 or 3-way
cabinet is fairly easy. I'm running into problems on the HF end
though. My first thought was to use a piezo horn, but finding
something rated for at least 200 watts rms is proving difficult (seems
CTS stopped making the Powerline horns!?!). I can find any number of
piezo bullet tweeters rated at 75 watts. My question is: can I wire
three 75-watt piezo tweeters torgether to get 225 watts RMS power
handling total in the HF range?

This was the one to use, if you really wanted a Piezo.
http://www.bluearan.co.uk/index.php?...ame=90248 4_C
O1

They will normally handle 200 watts, but its best to use a crossover. Typically
they handle 36 watts RMS.
Terribly unlinear.


I MEANT 36 VOLTS RMS
..

Scott has good advice. Tou can still make something good if you know what your
doing.
Take a look at.....
http://www.usspeaker.com/SUPERTWEETERS-1.htm

You can not use the watts rating unless you compute all the spl's and woofer
sensitivities, and
attenuation networks and crossover slops, etc., etc.

greg

[jakdedert]

GregS wrote:
snip
My question is: can I wire
three 75-watt piezo tweeters torgether to get 225 watts RMS power
handling total in the HF range?
snip

You can not use the watts rating unless you compute all the spl's and woofer sensitivities, and
attenuation networks and crossover slops, etc., etc.


The last statement above really gets to the meat of the matter. The
tweeters in a properly crossed-over system, powered by a 225 watt
amplifier, will never see 225 watts. That would imply that ALL of the
power was going to the high-frequency drivers, which will just never be
the case.

If the OP wants to get into designing/building his own speakers, getting
enough education to at least understand that much, will result in a much
more viable system, at best. At worst, it will prevent a large waste of
money.

jak
greg

[Mike Rivers]

GregS wrote:

This was the one to use, if you really wanted a Piezo.
http://www.bluearan.co.uk/index.php?...e=90248 4_CO1

My, how times have changed. I remember when people used to steal
Motorola piezo drivers out of ultrasonic detectors for traffic light
controllers and use them in speaker cabinets. I think I had some of
those to work with at a festival once. The guy from the audio contractor
asked why I had the highs rolled off and I told him it sounded better.
He said "You just must not be used to hearing real high end."


--
If you e-mail me and it bounces, use your secret decoder ring and reach
me he
double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers
)

[Scott Dorsey]

jakdedert wrote:

You can not use the watts rating unless you compute all the spl's and woofer sensitivities, and
attenuation networks and crossover slops, etc., etc.


The last statement above really gets to the meat of the matter. The
tweeters in a properly crossed-over system, powered by a 225 watt
amplifier, will never see 225 watts. That would imply that ALL of the
power was going to the high-frequency drivers, which will just never be
the case.

The piezo tweeters are very efficient and very high impedance, so when
bridged across a woofer with a series resistor (and you will still need
a low-pass on that woofer to keep it from breaking up), hardly any power
actually flows into the tweeter.

If the OP wants to get into designing/building his own speakers, getting
enough education to at least understand that much, will result in a much
more viable system, at best. At worst, it will prevent a large waste of
money.

One of the most important things to learn at first is that the power ratings
of drivers are ballpark numbers at best and aren't really useful for anything
much. The efficiency numbers will tell you something useful, but still
not enough to match drivers.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Mike Rivers wrote:
GregS wrote:

This was the one to use, if you really wanted a Piezo.
http://www.bluearan.co.uk/index.php?...e=90248 4_CO1

My, how times have changed. I remember when people used to steal
Motorola piezo drivers out of ultrasonic detectors for traffic light
controllers and use them in speaker cabinets. I think I had some of
those to work with at a festival once. The guy from the audio contractor
asked why I had the highs rolled off and I told him it sounded better.
He said "You just must not be used to hearing real high end."

The first time I encountered those awful Motorola things was in a set of
speakers that some student had built as a class project, which were set up
on the stage at the EE department auditorium at Georgia Tech. He did at
least realize that the things were supertweeters and couldn't go down very
far, so the systems were three-way with the tweeter crossed over around
4KC or so. Even so, they took your head off, and you could walk back and
forth in front of them and hear the driver cancellation going on.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."