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diode clipping circuit or passive limiter


rosa
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Hello,

 

Can anyone suggest a circuit for a passive limiter, using diodes and resistors. I would like to know if it is possible to suppress audio signal peaks  higher than +18dbu. (6.16v?). I am using a mic preamp, with line level out, into a recorder and constantly get digital distortion when there are fast transients like hand claps or even laughter.  The recorder has a digital limiter but it does not help. There is a product available in the form of an xlr barrel, but I would like to know if it is a circuit I can put in a small box with ta3f in and out, or something I can add to the preamp out, internally. 

 

 

Thanks,

Rodrigo

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Digital limiters do not limit the analog input stage.

What mic pre amp and what recorder are you using? Connectors? Balanced, unbalanced?

You can buy or make some attenuation pads. Just five resisters in an balanced audio H-pad and less for an L-pad. They can easily fit inside an XLR  or 1/4" plug. Tight fit for a TA-3, but it's been done.

 

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thank you,

 

you are referring to this http://realoldiesradio.com/?p=212 , however I am searching for a circuit that will attenuate the signal once it reaches a certain voltage, depending on which diodes are used. https://www.quora.com/How-do-protection-diodes-work

 

I using the 633 with a 3 channel preamp made by vark audio.  

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No. I have had similar issues using other preamps, including a mixpre-d, and MP1, both with very effective  limiters, which did help but occasionally I would still get distorted pops.  I haven't had issues with radio mics, which makes me wonder if the lower frequencies of a boom microphone might cause the distortion. in all cases the audio levels were within safe range. 

 

I will build a simple zener diode clamper and see what happens.

 

thanks 

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5 hours ago, al mcguire said:

It seems you want to build your limiter, let us know how it turns out.

 

I would suggest a 10db pad on the Schoeps would be more effective.

 

https://www.bhphotovideo.com/c/product/1132547-REG/schoeps_pad_10ni_10_db.html/

 

 

That pad, as I understand it, would prevent distortion in the cmc or the preamp input. it isn't the the cmc or the mic preamp that is distorting.  

 

This seems to work well for many in a studio setting, but too bulky for a bag after converting to ta3, and they are calibrated to +18dbu, which would not allow me to adjust gain within the 633. 

 http://www.prismsound.com/music_recording/products_subs/overkiller.php

 

 

4 hours ago, John Blankenship said:

Do you have the same issue if you go directly into a mic pre on the 633?

 

no issues on inputs 1-3

 

 

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