piezo tweeters

[Mainlander]

The gear you get to work with sometime... I have a couple of Ashton PB15
two way PA speakers that have Motorola / CTS KSN1142 piezo tweeters
(probably mounted on separate horns) and 15" woofers.

The high frequency end of the audio spectrum reproduction is very bright
and sharp. Without knowing very much about the speaker design, I know
that piezotweeters are often used without a crossover and it seems likely
to me that not enough attention has been paid to matching the speakers in
the bin so the tweeter probably has higher sensitivity than the woofer
resulting in the sharp HF tones.

I'm just looking at output EQ and whether the highs can be brought down a
little in a 1/3 octave graphic equaliser or whether the effort would be
better expended on new speakers because cheap tweeters will never sound
as good as the more expensive ones.

 

[Phil Allison]

The gear you get to work with sometime... I have a couple of Ashton PB15
two way PA speakers that have Motorola / CTS KSN1142 piezo tweeters
(probably mounted on separate horns) and 15" woofers.

The high frequency end of the audio spectrum reproduction is very bright
and sharp. Without knowing very much about the speaker design, I know
that piezotweeters are often used without a crossover and it seems likely
to me that not enough attention has been paid to matching the speakers in
the bin so the tweeter probably has higher sensitivity than the woofer
resulting in the sharp HF tones.

** That piezo tweeter is rated at 92 dB @ 1 w, 1m - what kind of 15
inch drivers are LESS efficient than that ???


see:
http://www.delsound.com.au/audio speakers horn tweeters 1 01.htm



................ Phil

 

[Gidney and Cloyd]

...two way PA speakers that have Motorola / CTS KSN1142 piezo tweeters
... piezotweeters are often used without a crossover and it seems likely
to me that not enough attention has been paid to matching the speakers in
the bin so the tweeter probably has higher sensitivity than the woofer
resulting in the sharp HF tones.

The Motorola division that makes the piezo's had an app note
about crossovers to tame the tweet; I'll see if I can dig it up.

 

[Rob Judd]

The gear you get to work with sometime... I have a couple of Ashton PB15
two way PA speakers that have Motorola / CTS KSN1142 piezo tweeters
(probably mounted on separate horns) and 15" woofers.

The high frequency end of the audio spectrum reproduction is very bright
and sharp. Without knowing very much about the speaker design, I know
that piezotweeters are often used without a crossover and it seems likely
to me that not enough attention has been paid to matching the speakers in
the bin so the tweeter probably has higher sensitivity than the woofer
resulting in the sharp HF tones.

I'm just looking at output EQ and whether the highs can be brought down a
little in a 1/3 octave graphic equaliser or whether the effort would be
better expended on new speakers because cheap tweeters will never sound
as good as the more expensive ones.

Those Motorola piezo's are horrible, but you have worse problems. If
you're going straight from a 15" woofer to a tweeter, you're missing the
all-important midrange. The highest your woofer should be doing is about
200Hz. From there to about 2.5kHz isn't being handled by anything.

Rob

 

[Phil Allison]

Those Motorola piezo's are horrible, but you have worse problems. If
you're going straight from a 15" woofer to a tweeter, you're missing the
all-important midrange. The highest your woofer should be doing is about
200Hz. From there to about 2.5kHz isn't being handled by anything.

** Get real dickhead - 15 inch PA / guitar speakers are good to 3 or 4
kHz at least on axis.

Go look at the curves for a JBL 2226 or EVM 15 L for a fright.


BTW Did you ever figure out the dynamic range of a decent hi-fi VCR
????????




............ Phil

 

[Steve]

** Get real dickhead - 15 inch PA / guitar speakers are good to 3 or 4
kHz at least on axis.

Go look at the curves for a JBL 2226 or EVM 15 L for a fright.


BTW Did you ever figure out the dynamic range of a decent hi-fi VCR
????????




........... Phil

Most 15 inch speakers that I know sound bad past 1k or so.
In fact most sound bad full stop.
Any way there is no need to be rude. Save that for the alt.politics groups.

Steve Lane

 

[Scott Dorsey]

The gear you get to work with sometime... I have a couple of Ashton PB15
two way PA speakers that have Motorola / CTS KSN1142 piezo tweeters
(probably mounted on separate horns) and 15" woofers.

I am terribly sorry.

The high frequency end of the audio spectrum reproduction is very bright
and sharp. Without knowing very much about the speaker design, I know
that piezotweeters are often used without a crossover and it seems likely
to me that not enough attention has been paid to matching the speakers in
the bin so the tweeter probably has higher sensitivity than the woofer
resulting in the sharp HF tones.

Piezo tweeters are high-Z devices that are very capacitive. So, to make
a high pass filter with one, you can use a series resistor and let the
device capacitance be the rest of the filter. So that series resistor
you see in front of it _is_ a first-order crossover. It's about as
effective as any other first-order crossover (like the capacitor in
series with the horn on an Altec A-7).

I'm just looking at output EQ and whether the highs can be brought down a
little in a 1/3 octave graphic equaliser or whether the effort would be
better expended on new speakers because cheap tweeters will never sound
as good as the more expensive ones.

The real problem with the piezo tweeters is that they have a lot of narrowband
resonances, and you can't easily EQ those out. Get an oscillator and sweep
back and forth in the high end and listen; the response plot looks like a
porcupine, so it'll sound nice and clean until you raise the frequency a
little and it starts to squeal when it hits a resonance. You could try
using a parametric EQ set up as a bunch of notch filters although I don't
know how much good you can really do.

I have never heard any piezo system that I liked, but Marshall Leach has
and he tells me I shouldn't just discard the whole piezo thing out of hand.
I'd suggest replacing your horn assembly with something that will cross over
at about the same place.
--scott

 

[AccuLab]

Is this the way you normally speak to people?

** Get real dickhead - 15 inch PA / guitar speakers are good to 3 or 4
kHz at least on axis.

Go look at the curves for a JBL 2226 or EVM 15 L for a fright.


BTW Did you ever figure out the dynamic range of a decent hi-fi VCR
????????




........... Phil

 

[Scott Dorsey]

Scott, you seem to be succumbing to the getting-things-backward syndrome that's
been affecting me and a lot of other people the last week or so.

Sticking a resistor in series with a capacitor produces (with respect to the
voltage across the capacitor) a low-pass filter.

Sorry, too little sleep. I meant shunt and not series. If you check the
back, you will find a shunt resistor. There is a really nifty Motorola
app note about these things which is probably on their web site.
--scott

 

[Phil Allison]

Is this the way you normally speak to people?

** Mr Judd has a previous record of posting absolute bullshit.

BTW Do you normally to post smart asre remarks - if so get stuffed.


............ Phil

 

[Phil Allison]

Regrettably it is.

** Have you ever heard me speak to anyone Budgie ??

She thinks she's the Roddles of aus.electronics. The key difference
is that Roddles knows what he's on about most of the time.

** Budgie thinks John Laws is an intellectual and Allan Jones is a genius.

The name "budgie" indicates the size of his brain.



............. Phil

 

[Gidney and Cloyd]

The Motorola division that makes the piezo's had an app note
about crossovers to tame the tweet; I'll see if I can dig it up.

The appnote I was thinking of was written by Jon Bost, but
I can't find a copy of it ... maybe on a cold disk somewhere.

The Moto ceramics division was sold to http://www.ctscorp.com/.

Did find bookmark for http://members.misty.com/don/pzfix.html.

 

[Rob Judd]

** Mr Judd has a previous record of posting absolute bullshit.

BTW Do you normally to post smart asre remarks - if so get stuffed.

Right, this is getting a bit personal.

Shut the **** up. Now.

Rob

 

[Phil Allison]

Mr Allison.

As they say in footy circles, "play the ball and not the man".

** Then take your own advice - smartarse.

You have no proof of that statement, and the concensus around here seems
to be that you were incorrect on both VCR and 15" speaker issues.

** What consensus ??

You were completely wrong on both matters.

I'd suggest you pull your head in, read for a while and try to learn

something.


** I see you are playing the ball - right ?

That ball must be called Phil Allison.

And in case you wonder if _I_ know what I'm talking about,

** I have absolutely no doubt, whatsoever, that you are a prize
bullshit artist.

I worked for a world-class hi-fi designer in the late '70's and still manage to amaze
him with some of my more innovative designs.

** My certainty is increasing.

I've also consulted to an electrostatic loudspeaker manufacturer on solving some difficult issues
that they hadn't been able to fix after 20 years of R&D (and solved them.

** It can get no higher.

I am also Australia's only HDCD licensee, and have engineered two
CD albums. I am also a musician, an electronics engineer and am
currently working on audio DSP systems.

** You are a fraud - pure and simple.

You're outgunned. Quit while you're ahead.

** You lack even a pop gun.

Have you any idea how **pathetic** you sound big noting yourself
like this ???

What I said is fact - and I quoted references for you to check.

Where are yours ??

I do not see any.



......................... Phil

 

[Steve]

Is this the way you normally speak to people?

** Mr Judd has a previous record of posting absolute bullshit.

BTW Do you normally to post smart asre remarks - if so get stuffed.

........... Phil

Please ignore the pretentious hypocrite.

 

[Phil Allison]

Please ignore the pretentious hypocrite.

** Hotmailer !


............ Phil

 

[Rob Judd]

Phil,

I'll be ignoring any further tirades from you. There's no point arguing
with an idiot, since the casual observer is unlikely to be able to tell
the difference.

Have a nice life.

Rob

 

[Steve]

** Hotmailer !

so what? what is that supposed to suggest about me?

 

[Phil Allison]

so what? what is that supposed to suggest about me?

** The addy says it all.

What a moron.



........... Phil

 

[Oldus Fartus]

so what? what is that supposed to suggest about me?

Ignore Aunty Phyllis, she is obviously having her period again.