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Good, And well put Zen,
, now guys He is pretty right, its just a matter of what one likes. No need to start a argument. We had enough of that in the cable thread, ( soon to be closed ) It all has to do with personal taste, and to some ( YES SOME ) who has spent more money.
I'm still running my alps 20$ pot i bought from peter 4 years ago, passivly between my Sony CDP-620es cdplayer and my Mini aleph's.
that's right a 20$ Alps pot, ( thanks peter )
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Its a transformer so the input impedance depends on the input of the next stage, and the output on the source impedance, and with 6db gain the input impedance drops to 1/4 the amp input impedance which might overload the source. (this is worst case, without the schematic its hard to say what the attenuater is doing). And with no buffering any noise on the output of the pre will get back to its input.
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Wish I could say $10,000 was irrelevant!
Minimal design (high school physics), 2 $500 xformers, 3 selector switches, a chassis some wire and some connectors= about $1500. Lets say the dealer takes $4k, thats about $4500 profit per! ( Im not including marketing or the graft paid to the reviewer but come on somethings not right with these numbers)
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They still are, as the max output volume level will ultimately depend on speaker efficiency for a given amp.
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Ok, didnt know the attenuation was done by xformer taps. Still: "In the case of operation with 6dB of gain and with 10kOhm load on the output the worst-case load impedance on the source will be 2500 Ohm plus copper losses. This is a very severe loading and many items of consumer electronic will not be able to drive such a load adequately! "
Sure the less efficient the speakers the more likely you are to overdrive your amp, but if your pre mathces your amp sensitivity you will never over drive your amp no matter what your speakers are. So a lot of systems dont need a pre with gain. Do you find your system isnt loud enough without the 6db gain? If it is, you dont need the gain and could have gone the passive resistive route. (transformers will always effect the sound more than resistors).
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Can keep the impedance of entry fixed like a stepped ladder attenuator with resistors?
An externally hosted image should be here but it was not working when we last tested it.
Shallco or other switches attenuators don't use DC in the signal path, so "zero" noise, & I am sure that a very good passive resistor added less noise than a LDR....
Merlin El Mago
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Everybody whom I know, including 6moons reviewer, preferred 6dB setting. My personal units are permanently set for 6dB gain.
Exactly, with 12dB gain on the amp, 95dB efficient speakers and passive DAC output the system wouldn't be loud enough without 6dB gain in a linestage. Don't forget that 6dB difference in CD recording level is quite normal.
I was comparing TVC to Placette and preferred TVC as more neutral solution.
http://www.diyaudio.com/forums/chip-amps/73538-search-perfect-attenuator.html
Not really completely, it was confirmed by manufacturer that 30mV offsets are still acceptable.
I would say "zero" noise added to the resistor due that switches do not use DC.
Wich resistor have more noise: one resistor than only pass DC signal or another resistor that pass DC signal + DC noise?
Merlin El Mago
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