Piezos from monday morning shift...

[N.Webber]

Modifying first two of my 290s to 280s.
Taking the piezos apart in order to saw their horns to make up the array
I found 8 (out of 24) to have the membrane dented or pushed and not seated properly:


Yes, I know all the Chinese quality horror stories, still, anyone else (if checked this)
encountered such a high rate of defects or have I just picked the top of the 'end of shift' batch?

Luckily they are from a near local supplier so no big deal; I'll just go and swap them.

[David Carter]

Wow! I've never seen this on mine. But then again, I haven't looked closely, so I wonder what I've been missing.

[Bill Fitzmaurice]

I've pulled apart hundreds of piezos and have never seen damage like that.

[Les Webb]

I've pulled apart hundreds of piezos and have never seen damage like that.

+1

I may not have taken apart as many as Bill but I've taken apart well over a hundred. Never seen anything like that.

[Tim A]

I've pulled apart hundreds of piezos and have never seen damage like that.

+2

[fender3x]

Modifying first two of my 290s to 280s.
Taking the piezos apart in order to saw their horns to make up the array
I found 8 (out of 24) to have the membrane dented or pushed and not seated properly...

Yes, I know all the Chinese quality horror stories, still, anyone else (if checked this)
encountered such a high rate of defects or have I just picked the top of the 'end of shift' batch?

Luckily they are from a near local supplier so no big deal; I'll just go and swap them.

I have had a similar problem...though not so many...with Pyle tweeters. The design is pretty much the same. Goldwood elements fit Pyle horns. But the quality control seems to vary quite a bit from mfg to mfg. You might want to see if there is another mfg's tweeter of the same model that you can get easily in Israel.

[AntonZ]

Same source as my cheap piezo's, probably. Mine had similar cone damage, as well as glue dripped onto the cone, gluing it to the horn.

[DAVID_L_PERRY]

Wow....I always removed the elements and only ever found a couple faulty, and that was just where the cone had come loose on the WLE models.....another fault was badly glued housings (again on the WLE models)

Very interested to hear your view on the piezo array when you get them fitted and eq'd (providing you can find enough that work........ )

If you keep having problems getting them I would be happy to get some from CPC and send them to you but I have no idea what shipping costs would be.

Dave

[N.Webber]

Thanks for the offer David, I'll see (hear actually…) how these sound and see…

What does bother me a little is that maybe the membrane issue in such scale
is actually a symptom of the overall quality of these drivers.
This poor quality may reflect also as noticeable differences in
sound/response/sensitivity even between the 'good' (looking...) elements.

I intend to bench test all the elements that will go into the arrays for maximum consistency.
Hopefully after taking out all the 'off-key' ones I'll end up with enough good ones…

By the way, notice that all the bad drivers have the defect at about the same place/orientation,
just opposite the terminals.
Something must be basically wrong in the assembly routine or in the assembler's coordination…
Or, maybe it's just another 10 years old kid who doesn't know better

[AntonZ]

Here are some pics of the two models of piezo's that I got. Model with the red dot is good quality, the other model is rubbish (at least in the 20 pieces that I got).

The cheap model consistently has slightly sleeker looks. The one that looks a bit simpler in construction, and also shows some heat/glue in the horn, is far better. Louder, more consistent response, no faults in a batch of 20. The cheap model was perfect for practicing, but my next order will be the "expensive" model (costs 4 to 5 times as much, well worth it if you ask me).

[Bill Fitzmaurice]

Here are some pics of the two models of piezo's that I got. Model with the red dot is good quality, the other model is rubbish (at least in the 20 pieces that I got).

The cheap model consistently has slightly sleeker looks. The one that looks a bit simpler in construction, and also shows some heat/glue in the horn, is far better. Louder, more consistent response, no faults in a batch of 20. The cheap model was perfect for practicing, but my next order will be the "expensive" model (costs 4 to 5 times as much, well worth it if you ask me).

Your results are the same as mine. Here the better ones are sold under the Goldwood label, the bad ones under the Pyle label. Oddly enough there's no appreciable price differential.

[AntonZ]

Your results are the same as mine. Here the better ones are sold under the Goldwood label, the bad ones under the Pyle label. Oddly enough there's no appreciable price differential.

Odd indeed. Cheap model: some 0.60EUR each, the good model is about 3 EUR. No brand as far as I'm aware, but model nr MPT-016.

[DAVID_L_PERRY]

The piezo with the mould line around the top is the same as the WLE piezo's that I got in the UK....crap, crap crap....build quality was rubbish, sound was inferior...nothing in its favour other than it was cheaper....but then piezo's are so cheap anyway even the expensive ones are still cheap...

[thijs666]

Cheap model: some 0.60EUR each, the good model is about 3 EUR. No brand as far as I'm aware, but model nr MPT-016.

Anton, could you please tell me where you got those? Planning on building 4 DR250's

[Nordskov]

Cheap model: some 0.60EUR each, the good model is about 3 EUR. No brand as far as I'm aware, but model nr MPT-016.

Anton, could you please tell me where you got those? Planning on building 4 DR250's

Try Sabbelbacke. He's located in Germany.

The MPT-016 are from Monacor. I don't know if it's an OEM.


Nordskov