BillFitzmaurice.info

Hello all,

last week my order of parts-express with my goldwood piezos for four DR200 arrived from US.

I tested them with pink noise first and noticed that some are a hint more sensitive than others.
Two piezos out of 100 are very quiet or didn't work.
The rest is working for the initial test.

Because of the different sensitivity I measured the capacity of every piezo.
Of the 88 pieces I get a range between 147 nF and 177 nF. The average capacity was 159 nF.

Because I don't want destroy the tweeters while cutting and painting the pastic horns, I opened all the piezo-tweeters.

Did you ever opend your piezos?

Out of 88 pieces, 41 have a deformed paper membrane. Some a little some extremely heavy (like you can see in the pictures). Do you know if I would hear the deformed paper membran later in the melded array?

Do you know a solution to fix these deformations?

I think the little deformation I can maybe carefully fix with my hands.
For the really bad ones I think the cables are to short and the piezo elements aren't centered. For these piezos I could try to desolder the metal connection and solder longer cables to the piezo elements.
I'm a electrical engineer so the soldering job wouldn't be a problem for me if the procedure could be the solution.

Thank you very much for your help and answers.

Best regards
Josh

I've been through plenty of piezos and opened enough too when spray painting arrays. I can honestly say I've never seen any like that. Given the small vibrations of the piezo and distance to the plug which sits into the cone, those deformations must have an effect on output.

From the Goldwood website:

"Goldwood offers a Lifetime Warranty against manufacturers defects on most the products we sell. You can buy with confidence knowing that our decades of experience in the industry will provide you with high quality products. We independently test all the products we sell and stand behind them 100%. You can view the warranty details below."

https://www.goldwood.com/warranty/

I wrote to the sales team of parts-express and waiting for feedback.

But maybe I should check the warranty options of goldwood, too.

Thank you Seth.


Best regards
Josh

Parts Express has awesome customer service. I had a few piezos in my order that were DOA and they credited my account. I over ordered anticipating there might be a few bad ones (allowed me to hit a price break point too), so in the end I had just enough good ones for my arrays.

Small sensitivity differences in piezos balances out in an array. When I'm checking phase with the reverse polarity rig and SPL meter i write down the loudness of each one. The deformation you uncovered may or may not be viewed as a manufacturing defect by the manufacturer. The diaphragm / surround is possibly not highly structurally loaded under working conditions, so durability may not be affected if not clamped properly between the housings. Given the lowish value and aggregation when working, if they're working when one tests them, stick 'em in an array would be my philosophy. One needs to satisfy ones self however. The manufacturer may have changed something or they may be chucking them out with less quality control due to all the BF purchasers, who knows.

Yes, I think that something in the manufacturing process went wrong, too.

I wrote to goldwood and they will talking to an engineer.
Goldwood told me that for my problem I have to find a solution with parts-express because I didn't order from goldwood.

I think that the small deformation wouldn't be a problem in an array because with a gentle tweezer fixing they schould be as normal.
But I'm concerned about the bigger deformated piezo tweeters which have not centered piezo elements because of too short cables.

But thank you all for your answers.