Spelling Death for WLE Piezos... A Tweeter Comparison

[Strapping Young Stu]

Ok, so not being one to do things by halves last night I got out one of each the piezos I own to see how they perform



As you can see I own the 1005 tweeters, the 1177 dual elements and two slightly different models of what I have always considered to be a great sounding tweeter - the discontinued CTS Powerline



Ok so after David Perrys thorough piezo testing of the CPC vs. WLE piezos not being one to believe anything unless I have done it for myself I opened up mine to see what was the deal inside




Ok so on the left (upper pic) is the powerline driver, in addition to the piezo element and paper cone, there is also damping material behind the piezo and some sort of supension system at the rear, and of course the bulb which gives it protection to 400W.




As you can see the piezo element in both is the same, the difference is that the WLE driver (right) moves freely, it has no suspension system, whereas the powerline driver is held much more rigidly in place by the damping material and suspension system.

First I plugged in the 1005 to have a listen, ok not bad, then I plugged the 1167 element in in parallel and now I couldnt actually hear the 1005 at all, the powerline was THAT MUCH louder. Worrying since as I remember for that sort of effect to happen the powerline must have been at least 6dB louder across its entire frequency range. The powerline also sounded less choked and had a more open natural sound.

Ok so initial testing revealed that the 1005 is trash compared to the 1167. Right now on with the 1177 dual element, again plugged in in parallel with the 1167, um hello? the response was marginally better but the single 1167 easily drowned out the 1177 dual element.

Just for kicks I tried the screw on powerline element on the 10x4 horn against the 1167 and there was no audible difference in response but I preferred the sound of the 1167 smaller horn.

I would hazard a guess that this is pretty much the same conclusion David came to with the CPC elements vs the WLE, I will definitely be purchasing some CPC elements to see how they stack up to the Powerline drivers.

My recommendation is this:

The WLE tweeters are ok, but I would limit their use to backline only, for this application 3-4 were enough to match the output of an Omni 10.5

This is where I shall be using my tweeters, and also perhaps in a TLAH where sensitivity is not so much of an issue.

They are not total crap but I would not recommend them for high power PA use.

Stu

[Bill Fitzmaurice]

For US and Canadian builders the piezos sold by Parts Express appear to be the same as those sold by CPC in the UK, and are what I use.

[fender3x]

Here they are at $3 for two.

http://search.store.yahoo.com/cgi-bin/n ... y%20Brands

[DAVID_L_PERRY]

........not being one to believe anything unless I have done it for myself ............Stu

Exactly the same mindset I have.

Great bit of subjective info stu...

One thing I would say is that, as even the CPC piezo's are still stupidly cheap , it isnt even worth using the WLE ones that you now know are not as good.

I sold all my unused WLE piezo's (as I had bought 30 of them from WLE and only used 12 to try out in my DR280) on ebay made a wee bit of profit.....so it payed for the 12 I already used.

Dave

[Strapping Young Stu]

@Dave, im not into selling stuff that works, so I shall put the 1005s to use in a TLAH or some line array box for HT and use the 1177s for a pair of Omni 10.5s I am going to make for a quick and easy multipurpose rig for reinforcement in "church hall type" theatre shows and and for my keyboard backline in my band.

Stu

[rafaro]

Can you show more details of the suspension and damping system on the powerline piezo and measure thermistor (heat sensitive resistor) Ohm values, and give wattage and details on the bulb. Apparently as power goes up the thermistor opens up and allows excess power to light up bulb acting as power limiter to the piezo. It would be nice to mod all piezos or at least ech bank with above setup. Your help appreciated.

[MYork]

For US and Canadian builders the piezos sold by Parts Express appear to be the same as those sold by CPC in the UK, and are what I use.

I see the Goldwood GT-1005 and GT-1016 in the Parts Express page, but not a 1167. Is the 1167 preferred over the 1005 or 1016?

Thanks! MY

[Bill Fitzmaurice]

For US and Canadian builders the piezos sold by Parts Express appear to be the same as those sold by CPC in the UK, and are what I use.

I see the Goldwood GT-1005 and GT-1016 in the Parts Express page, but not a 1167. Is the 1167 preferred over the 1005 or 1016?

Thanks! MY

Goldwood doesn't make an 1167. Pyle sells a version, the last time I tried them I had to reglue all of them, I believe they are the same as the WLE stock.

[Strapping Young Stu]

Its quite complicated, will post pics in a bit

Stu

[rafaro]

Brief research in the internet (not much available) powerline piezo used
a PTC (thermistor) resistor which increases resistance as power is applied.
At about 100 watts increased resistance shunts power to the parallel wired tungsten bulb which increases resistance as power increases and acts as a soft clip power limiter to 400 watts and then goodbye piezos. Real neat !! But what are the specific PTC resistor, and bulb parameters. Obviously this very useful circuit means we can wire all piezo in parallel for greater SPL and yet obtain power protection. I know Bill is watching!!

Additionally better suspensions and damping may help improve the performance of the non CTS piezos now available. Seems most I see are using the floating piezo crystal attached to the diaphragm cheap and easy (see patent number 3548116) but ?? quality of sound.

So Stu the ball now is on your side.

[Bill Fitzmaurice]

While the benefits of the Powerline are palpable in a single driver application they have less and less value as more drivers are added to a vertical array. I seriously doubt they are worth the considerable extra expense they'd entail in an array of four or more drivers.

[Strapping Young Stu]

Ok I have taken some closer photos of the insides but I agree with bill, I think the mod would be a) too complicated to achieve and b) not worth the trouble

The physical element of the horn is from what I can tell identical to regular piezos

The horn is slightly differently constructed giving a slightly different quality to the sound, but this is why I have investigated the tonal qualities of the 1177 vs the 1005 vs the powerline 1165 so that you can judge better which piezos you want to use for your application.

The Bulb and I think resistor/capacitor (looks like a small button camera battery) are wired across the negative input of the piezo, there is nothing written on the bulb or the resistor/capacitor so I dont know what their values are.

In addition there is a small amount of what looks like wadding, behind the piezo, behind which are 3 strips of fabric which act as supporting elements

I cant see that you would be able to mod anything except add some wadding in behind the piezo to try and damp the rear output down.

I will see about trying a little of this to see if it improves performance but since it is a mod, it is likely to make things worse rather than better.

Ultimately if you are using an array of piezos you have both much higher sensitivity than the powerline, a flatter response, and high power handling anyway. So what do you need the protection for?

Stu

[Dave Non-Zero]

@Dave, im not into selling stuff that works,

Stu

Haha does that mean you only sell broken stuff?

[Strapping Young Stu]

Haha nope, I dont have any stuff that doesnt work, if it doesnt work it gets recycled or chucked

I am a "collector" - if I superceed something with something else thats the only time I sell - or if i decide that I wont use it again and its just gathering dust when someone else can use it.

For instance I had 1x15+Horn reflex cabs for monitors, now I have Wedgehorn 10s so the other monitors got sold

I am selling a randall bass setup atm along with a Digitech BP200 bass multi FX and an alesis micro EQ and micro enhancer, due to the fact that I use a Sansamp programmable Bass DI in the studio on the rare occasion that I play bass, and that I am now going to be using Omni 10.5s for my keys from now on.

I used to want to play bass, and keys and sax and drums, AND run a PA, and do DJ work, and do a whole host of other things in music, what I have realised is that the only work I get is as a keys player and arranger/composer/AE, so its useful to have a drum kit that works for recording (and obviously for me to keep my hand in as a session drummer), and a bass setup that I can use to get a consistently good sound, and a guitar amp for generic guitar recording (which is made easier by the fact that my dad owns a lot of guitar gear for his own private use - i.e. doodling in his spare time)

So all in all I abandoned the sax, even though I was ok, and abandoned the bass as a bad job since its never going to come naturally to me.

So all I really need is

PA for me and my bands
A recording system that works for the studio.
A keys setup and lots of boards to do everything I need to do.

Now that I have realised that, I will probably end up with a lot of my gear eventually finding new homes.

Stu

[rafaro]

Not interested in using powerline piezos too expensive for array use but certainly much can be learned from them. Their protection circuit allows parallel connections of all piezos with resulting greater SPL output AND still have overpower protection. Use of Motorola damping and suspension may mean better less distorted sound with taming of intrinsic freq peaks and resonances.

Piezo "Crystals" may look identical but quality may vary depending on density and uniformity which can not be seen by naked eye. So it may mean that the big difference in SPL from motorola/CTS vs other makes may indeed be a better piezo crystal which can not be modded. BUT
it costs nothing to acquire more knowledge about an intrinsic component in our speakers and perhaps learn enough to be able to mod them for better performance inexpensively!!

So please Stu post your close up photos.