Leaning Tower of Piezo

[brucegseidner]

I have not owned a piezo driver since the early 80's and my distinguished looking Dahlquist DQ-10's.

I am leaning in the direction of acquiring 5 of them now. I want to be sure to hear the glass breaking and siren screeching of Television shows and movies in a home theater system using somewhat limited "full range" drivers, the Aurasound NS4-255-8A 4", that like my ears, do not appear to do much above 15kHz. My kids however have less withering audio histories and fresher ear drums. I have learned on this forum that even dogs notice this driver's deficit and think that given the price of a piezo and the typical resistor/attenuator implementation, it is a good solution (especially if they are back firing).

These days is there anything that distinguishes any particular piezo, or given the construction and usage they all perform the same?

Recommendations, resistor values, and other sage advice is welcome.

Bruce

[Racket Scientist]

I've been debating adding a piezo as a supertweeter to my fullrange speaker. In my online perusal, the consensus seems to be that the cheap piezos (like Goldwood) have a pretty high failure rate and maybe don't sound so good. If I do go forward I plan to get some from www.piezosource.com - more expensive but probably worth it. There is also a thread (can't remember if its here or on AudioKarma) that discusses using crossover components to improve the sonic results using piezos.

[Godzilla]

The round one, the lemon squeezer one and the 2"x5" one at PE all sound about the same to me. I am crossing them over around 20k so just about any tweeter would probably sound about the same. Perhaps on paper with measured performance extra circuits and wiring may be better but for such a limited bandwidth i believe keeping it simple is better... imho.

The experience i've had i'd recommend trying two different things:

Rear firing - 20ohm resistor across and a 1uf or a 1.5uf cap (the 1.5uf cap will have more treble)

Front firing - 8ohm resistor across and a .33uf or .47uf cap (the .47uf cap will have more treble)

The resistor protects the amp but also changes the overall volume. 20ohm sounds louder than 8ohm.

I played with L-pads but found the above usually works well for me. Some may add a coil for a 12db slope (rather than 6) but for piezos i like them just fine as described above... and in the spirit of CHEAP... using less sometimes amounts to more.

I used piezos with drivers that were around 90 - 93db per watt (pioneer b20, various fostex, the Betsy and various Tangbands (around 86 - 87db). If the Aura is in this range i think you will have a good match that adds some air and even some realism to the overall sound. Now i am curious how the Dalquist was wired... does anyone know?

Zilla

[brucegseidner]

Funny you should ask. I was reminiscing and curious myself. When I bought them in 1981 they were second hand and just shy of ten years old. I set about re-capping and re-wiring the speakers and taking the big metal screen out from under the cloth. But, apropos to this thread the piezo were made by Motorola which I have just learned is making this driver again.

[brucegseidner]

Oh, and I found the "everything you wanted to know" thread on AudioKarma:

Using piezo tweeters wisely: a "how to" - AudioKarma.org Home Audio Stereo Discussion Forums

[planet10]

Another cheap tweeter worth looking at is the little Audax at ApexJr...



Since postage can often be more than the tweeters, i got a bag of these so if people needed them, they could piggy back on the postage of any order.

dave

[planet10]

Originally Posted by brucegseidner

Oh, and I found the "everything you wanted to know" thread on AudioKarma:

This to. Piezo Tweeter Crossovers | J Risch

dave

[Redge]

Hi all,
it's funny to see this thread because I wanted to post one with questions about piezzos !

Here is some questions about piezzo.

I had to say that I'm not good in english, and it is hard for me to understand all the things there's on audiokarma.

I build a 2 way with a piezo KSN1165a Motororla and a spa 25pa from monacor in a 56 L for the cabin and in bass reflex. First, they were mounted in parallel with only a 3,3µf on the piezo. I wanted to try without crossover.

But the high middle range doesn't sounds good. I guess that the piezzo and the monacor frequencies were playing together and makes some bad resonances.

I have to admit that I'm a noob .

The only solution I found to have a good sound is to connect an equaliser and almost cut between 2500 hz and 3500 hz.

I would like to optimize this configuration but I don't know really how.

Is someone can help me and show me what I have to do to cut the piezo or the monacor (maybe 12 db or 18 db crossover) ?

I don't have a lot of money and so, this project is very important to me.

(I think this 2 way speakers can give a very good sounds, I love this piezo motororla, they sounds smouth and never kill my ears, and the monacor is perfect for the price)

Again, sorry for my bad english, I'm just a french frog

[Radugazon]

Hello...

Once, i did this just for testing: see the pics

from the cheapest chinese piezo, I removed all the plastic stuff, just keeping the paper cone and the piezo disc, and put in a piece of wood.

Well, it's pretty horrific, not better that with the plastic make up horn , and phase plug, never seen such high Q dips and peaks.

Anyway, with a DCX, it's possible to keep it flat (the yellow curve is from something else) and the sound was enjoyable, especially considering the price. For sure something nice can be done with some piezo and some special tricks (Phy-HP Km 30).

[chrisb]

Originally Posted by brucegseidner

Funny you should ask. I was reminiscing and curious myself. When I bought them in 1981 they were second hand and just shy of ten years old. I set about re-capping and re-wiring the speakers and taking the big metal screen out from under the cloth. But, apropos to this thread the piezo were made by Motorola which I have just learned is making this driver again.

Bruce , thanks for the trip down memory lane.

In the first couple of years that the DQ10 were one of the hot items on audio scene, a buddy and I each had a pair, and just for fun decided to mirror image them. We did leave the wiring harness and mesh grille intact.

This required complete mechanical disassembling and reversing the four drivers mounted on individual baffles, and rewiring of 5-way XO, which were dipped in paraffin wax and the wiring was solid core. Both of those ideas seemed strange at the time, when big-*** gauge stranded wire was just becoming "the ticket", but in retrospect ....

FWIW, I owned the DQ10 & matching sub (passive XO) shortly after living with Quad 33/303/ ESL57 combo for a couple of years, and for my money Jon's attempt at homage to Peter Walker's design was an unqualified success. I could never get the same degree of involvement with the Quads as with the Dahlquists - but even 35yrs ago, "domestic" factors precluded keeping the "radiators" in the house.