I have a friend who has a piezo that is about 105 db and we would like to lower that a lot. Is an L-Pad for a piezo any different that a conventional one? Any good reccomendations?
Yes, they are quite different. Because they are highly capacitive by nature you can/should use series capacitors to attenuate them. There is a table in Bost's original JAES article from the 1970's. I can't remember the exact values but small caps (bi-polar) under 1uF will achieve a uniform reduction in level. (Series resistance causes high frequency roll off.) Now, having said that, I think people have used L-pads too. Have you tried a Google search? There have been a few sections of DIY books that look at this issus.
But putting 0.47, say, in series will difinitely produce a noticable difference.....I think.
But putting 0.47, say, in series will difinitely produce a noticable difference.....I think.
Morning Ling, well it is morning here in Australia.
A resistor (30 to 50 ohms) feed to the speaker will cause a hi-frequency roll off of a few db at the top end. It doesn't matter which terminal +ive or -ive.
BTW I did google "pizeo tweeters" and found very useful site. It is the 3rd or 4th entry and is a forum from "audiokarma". The guy there is a bit digmatic and wrong in what he says about series resistance but he does have the L-pad circuit you are looking for. Try that and see if it is helpful. Good luck, Jonathan
A resistor (30 to 50 ohms) feed to the speaker will cause a hi-frequency roll off of a few db at the top end. It doesn't matter which terminal +ive or -ive.
BTW I did google "pizeo tweeters" and found very useful site. It is the 3rd or 4th entry and is a forum from "audiokarma". The guy there is a bit digmatic and wrong in what he says about series resistance but he does have the L-pad circuit you are looking for. Try that and see if it is helpful. Good luck, Jonathan
IIRC,Motorola suggests a small resistance in series with their piezo tweets,forget the exact reason why though.
Here is some information i put together based on my experience with piezos...
Piezo Super Tweeter
I like them and use them often in most, but not all, of my projects. Hope it helps.
Godzilla
Piezo Super Tweeter
I like them and use them often in most, but not all, of my projects. Hope it helps.
Godzilla
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