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In Reply to: RE: Tried without a preamp posted by Tre' on January 28, 2017 at 17:17:28
if we assume Mikey left it stock the input impedance on the duece is a meg but it needs 1.5 volts for full out. The Bifrost is listed as a max out of 2V @75 ohms. So it is likely that on most CDs he often cant even drive the amp to full out. Not good. You want to be able to always drive the amp to full out plus 6dB in my opinion active or passive. If he listens to classical, jazz or other less or non compressed recordings then I see a problem.
I'm a passive user and have a DAC that does 2.35VRMS @50 ohms. My amps need only a volt for full out and I have many CDs that cannot drive the amps to full out with my Placette all the way up. Luckily my speakers are 91dB efficient and in my biamp I can do 250/ch LF, 100/ch HF.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
Follow Ups:
CD's and digital files are normalized. The loudest moments will be at full digital level regardless of the dynamics of the music.2 volts will drive his deuce to beyond full power.
"You want to be able to always drive the amp to full out plus 6dB in my opinion active or passive"
Why? I do my best to never over drive any stage of my system.
Bad things happen when a tube is over driven.
I know some amps are rated for so called "headroom" but 6db would be 4 times the rated power. 240 watts per channel? I can't imagine how distorted that would be for the deuce.
I'm I missing something?
Edit; I reread your post.
"..if we assume Mikey left it stock the input impedance on the duece is a meg but it needs 1.5 volts for full out. The Bifrost is listed as a max out of 2V @75 ohms."
Do you think the Bifrost will not output 2 volts into 1 meg ohm?
It will. The higher the impedance it has to drive, the easier for it.
It's own source impedance dominates but technically the higher the input impedance, the higher the output voltage will be. Not lower.
In practice, because it's own output impedance dominates the equation, the output voltage will be virtually the same.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 01/28/17
You are assuming every CD you play outputs 2V. My post says they dont because they dont. You should measure that and see how seldom even a volt comes out of your DAC. When you had a cassette deck were the VU meters always at zero? No seldom or never. When they were at -6db if zero db is full out (2V) then -6 is a volt.
Also in my post I told you my higher out, lower Z DAC than yours very seldom (meaning almost never) drive my amps that need only a volt for full power to put out their full power.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
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