2. amps-preamps
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Passive Stage preamp vs Active Stage Preamp

As you all probably know lots of integrated amp designs (solid state) exersise the passive preamp part design which are basicly either transformer or a high quality potentiometer and simple input circuitry.
Many of us know that most of the CD players have a sufficient enough output voltage to feed the power amp (from 1V upto 3V) Same thing with DACs. Analogue phonos are able to produce the same kind of outputs.
The input sensitivity of power amp <=500mV
For somehow I've been experimenting with loaned WADIA No 15 DAC with variable output that has just a passive potentiometer and connected a variable output directly to my Bryston 3b-st. The result was deeper soundstage and details vs. setup through Bryston 11b preamp. The only drawback was that the volume range is much smaller than with preamp.
Can anyone summarize all advantages and disadvantages in using passive preamps vs. active?
Does it make a sence to try a passive stage preamp in my current solid state setup which is Theta Data II -> EAD DSP700 ->...
and analogue J.A. Michell GyroDec -> Delphini phono ->...
and ending with Bryston 3b-st?
Also if such exists, describe an importance of using active stage in tube setup.(Impedance matching?)
128x128marakanetz
sean
6,231 posts
 
I'm pretty much with Albert on this one. While i haven't played with a LOT of passives ( a few ), i have always had better results with an active unit. Don't know the specifics as to why, as i've tried TONS of various cables, source / amplifier combos, etc...

As to the rated sensitivity of an amp, don't take that spec as being written in stone. A single tone can generate a higher output level than a broadband dynamic signal. Since music is a broadband dynamic signal, you might need more than the specified amount of input voltage to reach full output even though the amp meets spec under test conditions on the bench with individual narrow bandwidth tones. Sean
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sqjudge
96 posts
 
It has been shown that any realtime electrical signal (music)can be broken down into a series of sine waves of varying amplitude, frequency, and phase using the Fourier transform. Fourier analysis shows that music is composed of a linear sum of many sine waves. If an amplifier is linear and has sufficient bandwidth to pass all audio harmonics, then it will clip with a sine wave at the same peak to peak value as it does with music. The confusion can result when comparing the RMS value of a sine wave to the RMS value of music. This is usually not a problem in a CDP because the voltage output is usually specified as an RMS value at 1 KHz and at 0 db recording level. I agree that the 0 db output level must be greater than the input sensitivity of the amp because music is not recorded at 0 db on a disc.
arupg
42 posts
 
I agree with Aisip. I use an Audio Synthesis "ProPassion" which is dual mono, single input, single output. This is a killer device. You need a strong drive, i.e. above 6V to get the max and when this happen, god bless you.
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