I recently posted a thread under "speakers" about replacing the cheap, piezo super tweeters in my Dahlquist DQ-10's. The new drivers, considerably better made and costlier than the piezos they replaced made a difference, but not that great a difference, and one many may feel not worth the effort.

Still, there is a veritable army out there of folks who decried Jon Dahlquist's use of the piezo in the first place, believing that such a cheap, crummy driver had no place at all in a "high-end" loudspeaker. What's important here is that it wasn't that people heard horrible stuff coming out of the piezos, but they believed that they did. Jon explained numerous times that nothing below 12,000HZ comes out of the piezos, and that most people either wouldn't hear the difference, or wouldn't hear anything at all. Stll, the perception that the use of such cheap drivers damaged the overall performance of the DQ-10 held strong.

I know of two other incidents in which perception played a damaging roll. The first occurred when ADC introduced its first compact disc player. The player was a small, single-play unit (manufactured by Kyocera of Japan no less!) designed for retailers to "promote" at a price of $199.95 around 1985. Such a low price was unheard of for a CD player, as most retailed at the time for $350 or higher. Dealers snapped up this ADC player in droves.

Then the unthinkable happened: almost none of them sold.

Why? The answer, while not initially evident, became quite clear after a while, and that was that the perceived value of such a low priced CD player was such that it "just can't be any good at such a low price." As it was, the little player was quite good, and incredibly reliable too, but it just didn't look particularly fancy, and was so cheap, that most people just thought it was junk.

Ultimately, ADC sold its inventory of well over 14,000 units, but it took a long, long time, and most those sold were sold at a loss.

The other was a review on the dbx Soundfied 1a speaker system in The Absolute Sound magazine. Personally, even though I was working for BSR at the time (who owned both ADC and dbx branded products), I never much cared for the 1a's sound, though I admired its imaging capabilities. The 1a used an outboard, electronic equalizer, much as the Bose 901 series of speakers did.

In reviewing the 1a in the magazine, The Absolute Sound's reviewer stated that, though he couldn't hear any distortion coming specifically from the equalizer, he believed such distortion to be there anyway, and downgraded the speaker as a result of this perception.

So, there are clearly intangibles involved in the opinions of those in this industry/hobby, that are pretty difficult to deal with. Perhaps charging $100 for a piezo tweeter, or $1,000 for the ADC CD player might have done the trick, no? One never knows...

I agree with you a bazillion percent. If you don't mind a story:

Shortly after I opened my retail store in 1981, I went to an auction and bought several hundred 25' 14ga. CAROL extension cords (good quality) that had a realistic retail value of between $8-10 dollars. They cost me just over a buck each, so I put them in my store for $4 ea. Nothing. In the first couple months, I bet I didn't sell a half a dozen.

I got irritated one day, opened all of the cases, and dumped them on the floor in a big pile. I then took an old stick, stapled a piece of cardboard to it and wrote "SPECIAL: $6.00 ea.

They were gone in three days. The word "SPECIAL" triggered the sale.

it can be a tough nut to crack, once a perception sets in it becomes extremely difficult to change.

I recall the heyday of piezo tweets - they were cheap to make, but yet promised excellent technical performance. However, because of the very fact that they were ($) cheap, they always seemed to end up in cheap speakers with inadequate crossovers, mated to big floppy woofers, and the whole thing was billed as "digital ready." What a joke. I was once shown a diagram of a proper crossover for a piezo tweet, and it was fairly complex. I can only guess that few people considered the piezo tweet to be worthy.

I have often thought that some of the bad reputation piezo drivers have is due to the "you can use them without a crossover" fallacy and also, the use of this driver mainly in cheap loudspeakers.
But, it doesn’t mean the DQ-10 KSN-1005 piezo (not the cheap knock offs) with some modifications can’t be a pleasant, non-fatiguing driver adding some air and presence to the high frequency output of a speaker with relatively little in the way of circuitry.

Here’s some interesting ideas from Jon Risch about the piezo:

How to crossover a piezo:
Add a resistor in parallel, and the driver can be made to look like a current driven device to any outside components, such as a crossover cap. However, to keep costs and power dissipation down, 8 ohms is way too small of a value. The impedance of most piezo's is still quite high at 20KHz, so use a 22 ohm resistor, this makes any series crossover cap smaller and less expensive, and the resistor dissipates less energy. Use of an 8 ohm parallel resistor will also tend to lose you a little bit of output level.

For most piezos, use of a 22 ohm resistor, and a 4-4.7 uF cap will allow the response to be identical to what it was in stock form, but rolls off the lows at 6 dB/oct below 1 kHz or so. This actually increases the power handling of the piezo, as it is voltage limited. Exceed the voltage
used to pole (polarize the piezo element during manufacture) the unit, and it will loose sensitivity, and eventually burn out. Most pro grade piezos will handle 35 volt transients, and 28 volts continuous, which are 150 watts and 100 watts into 8 ohms respectively.

Add in a capacitor and 22 ohm resistor, and the power handling could effectively be quadrupled, as the LF voltages are not imposed upon the unit, just the HF voltages.

Piezo's crossed over in this manner don't sound as harsh and spity, and tend to be quite a bit more reliable. Many of the piezo units have a mild peak just before they roll off in the LF, so making the series cap a little smaller can actualy flatten response, and provide even more
protection and smoother sound. For the smaller piezo units that cut off at 4-5 kHz, a series cap of 1.5 uF will do the trick, larger units that go down to 3 kHz can use a 2.2 uF, and the large compression driver units meant to be mounted on a horn need about 5 uF, as they do not peak, and any higher would lose the sloping output even more.

Attenuation, HF roll-off AND the crossing over can all be done at the same time. To attenuate, place a cap in between the piezo and the 22 ohm resistor that is shunting across the unit, then if HF roll-off is desired, use a series resistor in this location too. Then the series crossover cap should be in front of the 22 ohm shunt.

Looking from the amp, first the series crossover cap, say 4 uF, then the 22 ohm shunt from hot to ground, then a series cap of about 0.15uF for 6 dB attenuation, and then a series resistor of about 30-50 ohms to tame the very top end, then the piezo itself.

Yes gents, proper attenuation it's where it's at. The DQ-10 piezo is crossed over with a classic 18bd/oct slope, preceded by a paralleled 30 ohm resistor and a series 35 ohm resistor off of the main network. The 18db values are C7=.1uf, C8=.18uf and the parallel choke is .5mh, at least on my units. Incidentally, the piezo is connected reverse polarity. I disconnected this entire network when I removed the piezo and tweeter for a Morel MDT-10, wherby I get the high end extension with less network. I smoothed out the Morel top end with a Zobel, and they're sounding very nice indeed.

Cosmetics mogul Helene Rubenstein marketing principle was; cheap connotes cheap, if you price it expensive then everyone will want it.

And that's the truth. I have some background in sales and I've seen it over and over again.

More recently I tried to sell a spare subwoofer I had on the local CL. It was an M&K 12", a brand I'm partial to, worked and sounded great but wasn't in the best of cosmetic shape... I priced it what I thought was very reasonable and got a few "tire kicker" emails but *no one* ever made an offer or even came to see/hear it! The next week I put up exactly the same ad but jacked the price up another $200. By the end of the second day I had had over half a dozen emails and finally someone gave me my *asking price* without any squabble, over TWICE what I had originally asked!