Check your piezo's, Damp your cabs, Follow the plans!

Helpful hints on how to build 'em, and where to get the stuff you need.
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LelandCrooks
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#16 Post by LelandCrooks »

You can hear high order harmonics. Run a sweep from 2k to 15k. The harmonics will jump out of the horn. Above 12k they're usually quiet and harmless. Anything below 8k is grounds for dismissal.
If it's too loud, you're even older than me! Like me.
http://www.speakerhardware.com

nola50
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#17 Post by nola50 »

I am about to start two J12Ls with full Piezo arrays. Is testing Piezos still recommended? I'm getting them from PE.

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LelandCrooks
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#18 Post by LelandCrooks »

Yes.
If it's too loud, you're even older than me! Like me.
http://www.speakerhardware.com

nola50
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#19 Post by nola50 »

Soooo... If I need 32 of them, how many should I get to allow for perfection- 10% or 20% or?

Grant Bunter
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#20 Post by Grant Bunter »

nola50 wrote:Soooo... If I need 32 of them, how many should I get to allow for perfection- 10% or 20% or?
6-10 extra should be fine...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

nola50
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#21 Post by nola50 »

Apparently my PC does not generate enough power to drive the Piezos to any great volume. What is a good suggestion for amplifying the test sweeps from the Audion Sweep Gen free program?

Bruce Weldy
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#22 Post by Bruce Weldy »

nola50 wrote:Apparently my PC does not generate enough power to drive the Piezos to any great volume. What is a good suggestion for amplifying the test sweeps from the Audion Sweep Gen free program?
I did it with the output from my iPhone.....you should have plenty with the PC.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

nola50
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Re: Check your piezo's, Damp your cabs, Follow the plans!

#23 Post by nola50 »

Once the volume was cranked up, it all worked just fine.

Out of 42 I have 3 that are questionable after checking them all twice.

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fender3x
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#24 Post by fender3x »

please delete me, let me go...
One man's magic is another man's engineering. --Heinlein

1 x DR250
1 x T39
1 x Omni 10

Grant Bunter
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#25 Post by Grant Bunter »

fender3x wrote: Wed Aug 10, 2022 5:47 pm please delete me, let me go...
Haha!
If you'd have said (typed) nothing, it would have just sat there.

Still, there's valid info in the thread...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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fender3x
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Re: Re:

#26 Post by fender3x »

Grant Bunter wrote: Thu Aug 11, 2022 4:34 am
fender3x wrote: Wed Aug 10, 2022 5:47 pm please delete me, let me go...
Haha!
If you'd have said (typed) nothing, it would have just sat there.

Still, there's valid info in the thread...
I just meant JUST my post.... I posted in error, and deleted text with the edit function but could not delete the post. The info in the thread is definitely helpful! I just finished testing 50 piezos with the info here. Thanks to this thread I know that...
None had reversed polarity
All of them had capacitance between .167 and .120.
All worked.

Maybe I could contribute a rattle test. One that had capacitance of .162, worked and did not have reversed polarity was quieter than the others. It also had something rattling inside. On opening it, the paper cone was bent out of shape. It's my only bad one. Pays to get them from Speakerhardware.com or from Parts Express I guess.
One man's magic is another man's engineering. --Heinlein

1 x DR250
1 x T39
1 x Omni 10

himhimself
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Re: Re:

#27 Post by himhimself »

fender3x wrote: Sat Aug 13, 2022 11:19 am The info in the thread is definitely helpful!
For sure. This post helped me build my little test rig that made checking the piezos for my otop arrays easy. Found a fair number of bad ones that Parts Express forgave.
2xT30 (20", 3012LF)
2xT30 (21", 3012LF)
4xOtop J-array (Beta12, melded/straight piezos)
Truck Tuba (MCM)
Next up: 2xJack12 or family of table tubas

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