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Old 11th July 2008, 07:54 AM   #11
Vix is offline Vix  Yugoslavia
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It looks to me that you should simply build the Boz as in original schematics, adjust for 40 mA bias, and use some input attenuation, if overload is an issue. You can use 47 K pot first, and then, after you have found the appropriate setting, measure the resistance and replace the pot with fixed resistors. Then, use the pot at the output as a volume control.

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Old 11th July 2008, 05:07 PM   #12
rtate is offline rtate  Canada
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How do I determine a value for input attenuation?

I have read post stating anywhere from 47k to100k to 470k
The different values must make a difference....
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Old 11th July 2008, 05:31 PM   #13
AndrewT is offline AndrewT  Scotland
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Attenuation is a ratio, not a value.

-20dB = 1/10
-40dB = 1/100

The resistances in the attenuator create that ratio.
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Old 11th July 2008, 06:14 PM   #14
rtate is offline rtate  Canada
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So for a CD player with a specified output of
2Vrms , what value resistance would be needed to get the proper ratio?
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Old 11th July 2008, 06:47 PM   #15
AndrewT is offline AndrewT  Scotland
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to get a ratio you need two resistances.

1r0 and 100r gives -40dB
similarly 5k0 and 500k gives -40dB.
or any value in between can be arranged to work as a -40dB attenuator.

The pot/attenuator is a variable PAIR of resistances that usually give attenuation ratio between 0db an -80dB.
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Old 11th July 2008, 07:01 PM   #16
Manu is offline Manu  Europe
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Quote:
Originally posted by rtate
How do I determine a value for input attenuation?

I have read post stating anywhere from 47k to100k to 470k
The different values must make a difference....
Your ear will determine what is best for you.
As VIX said, start with 47K ...
and if your layout allows it, try different values ...
My experience is that too much input attenuation makes sound less dynamic...

How should, I say thats not math, thats life...

Manu
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Old 11th July 2008, 07:04 PM   #17
rtate is offline rtate  Canada
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other articles that i have read say that input attenuation will limit the bandwith by rolling off the HF above 15kh
Is this true in this case?
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