Correction.
Any reasonable quality amplifier will work well past 20 KHz. Human hearing is
greatly diminished above 15 KHz, depending on age. To reproduce high frequency
'attacks' the amplifier has to be able to handle frequencies into the 100+ KHz.
The low distortion figures for 20 KHz specifications require an amplifier that
can apply significant negative feedback at that frequency. It would not work
if the amplifier was frequency limited to 20K. In short, it will amplify 23
KHz at a slightly higher distortion.
You are better off driving the transducer with a square-wave signal that is
filtered above the fifth harmonic. It is a lot more power efficient. Low
distortion is not needed.
Unfortunately you can not make a CD with 23 KHz tone. The sampling rate is
44.1 KHz. Nyquist's theory limits the maximum reproducible frequencies to a
little over 20 KHz.. If you somehow could make a CD with 23 KHz tone, it would
play back at about 1 KHz due to aliasing.
;-)
Leslie
with a few years in telecommunication research in my checkered past...
________________________________
From: Joel Aronson <[email protected]>
To: "[email protected]" <[email protected]>
Sent: Monday, July 8, 2013 5:57 PM
Subject: Re: Stus-List Anti-Barnacle Waves - Was: Music in cockpit
Bob,
Most good audio equipment produce sounds up to 20k. You would need a custom
amp and speakers.
Joel
Sent from my iPad
On Jul 8, 2013, at 8:53 PM, Bob Moriarty <[email protected]> wrote:
Professor Dreuge & Any Audio Engineers,
>
>
>Some of the abstracts in your link mention 23 kHz as a sort of sweet spot for
>barnacle repulsion. The spec sheets on the sound exciters all specify an audio
>range with the upper limit at 20 kHz - which is the upper limit of audio
>perception by humans.
>
>
>I'm an audio newb with a tin ear. Is it likely the sound exciters - or most
>any speaker for that matter - could produce output at 23 kHz? Would it be
>simple to create a CD with a 23 kHz sound track that could be played through a
>boat's sound system (to sound exciters attached to the inside of the hull)?
>
>
>I have more dumb questions for later.
>
>
>Bob M
>Ox 33-1
>Jax, FL
>
>
>On Mon, Jul 8, 2013 at 11:09 AM, <[email protected]> wrote:
>
>Bob,
>>
>>
>>Have a look at the article I found online regarding "Inhibition of barnacle
>>cyprid settlement using low frequency and intensity ultrasound."
>>
>>
>>http://www.ncbi.nlm.nih.gov/pubmed/22296259
>>
>>
>>
>>
>>Ted,
>>
>>
>>Also a big thanks. I just installed a stereo in my cabin, and while I wanted
>>speakers in my cockpit, I was very reluctant to cut speakers holes.
>>
>>
>>
>>
>>-
>>Paul E.
>>1979 C&C 29 Mk1
>>S/V Johanna Rose
>>Carrabelle, FL
>>
>>On Jul 4, 2013, at 12:00 PM, [email protected] wrote:
>>
>>Date: Wed, 3 Jul 2013 22:39:53 -0400
>>>From: Bob Moriarty <[email protected]>
>>>
>>>To: [email protected]
>>>Subject: Re: Stus-List Music in cockpit
>>>Message-ID:
>>><cam7ccy+hxy1eumfmhej+u9tyh3sstzcq_ry5oazvdp_opjp...@mail.gmail.com>
>>>Content-Type: text/plain; charset="iso-8859-1"
>>>
>>>
>>>Ted,
>>>That is really cool and interesting. Thanks for posting the youtube and the
>>>details.
>>>I wonder if there's any sort of rock'n'roll or other music that barnacles
>>>and slime find repulsive.
>>>I say that mostly in jest, remembering the "magic ultrasound barnacle
>>>repeller system" from years back.
>>>Not trying to change the subject. I'm going to give your discovery a try.
>>>Bob M
>>>Ox 33-1
>>>Jax, FL
>>
>>_______________________________________________
>>This List is provided by the C&C Photo Album
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>>[email protected]
>>
>>
>
_______________________________________________
>This List is provided by the C&C Photo Album
>http://www.cncphotoalbum.com
>[email protected]
>
_______________________________________________
This List is provided by the C&C Photo Album
http://www.cncphotoalbum.com
[email protected]
_______________________________________________
This List is provided by the C&C Photo Album
http://www.cncphotoalbum.com
[email protected]
