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How to choose an attenuator

I have an Oppo Sonica DAC which has 4 Vrms through the balanced outputs and a Classe Amp2 (and a CAV-180 for that matter) which takes 1.4 Vrms maximum input without clipping. I was recommended to use 24dB attenuators to reduce voltage; but this seemed very high to me (based on online voltage to dB converters). Is there another criterion apart from the voltage?
Thanks in advance for any thoughts, as I am not very knowledgeable in this!
kislali
georgehifi's avatar
georgehifi
10,312 posts
 
Both your Amp2 and CAV180 have very high input impedances, perfectly suited for passive preamps (which a fixed attenuator is in a way) just that you can't adjust it.
 
Why not have it all, and have an adjustable one like the Schiit Sys, $49
http://www.schiit.com/products/sys

Cheers George
kislali OP
5 posts
 
Thanks georgehifi, but that comes with RCA. My whole idea was to be able to used the balanced outputs. When I use SE outputs the Vrms is down to 2 and is more manageable anyway.

There are 10, 15, 20, 25, 30 etc dB attentuators and I would prefer to just buy one pair with the correct values and forget about them.

According to a calculator (http://aetechron.com/calculator-Volt2dB.html) a 10dB correction should be right, but then there are other criteria like impedance so I get puzzled a bit.
willemj
1,036 posts
 
Why would you use attenuators if your Sonica has a variable output?
kislali OP
5 posts
 
I want to bypass the volume control of the DAC, and control the volume from the app, while the information is still purely digital.

Also, when I don't use the bypass mode then there is always the danger of someone (i.e. the kids or some guests) would put the volume too high and damage the system. Especially on the app it is very easy to do so just with a slip of the hand.
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