Modern Linestages

I have never seen the merits of arguing the virtues of passive versus active line stages and have had many of each. Presently, I have a BMC DAC! PRE which is the BMC dac with a passive insert to use as a line stage. It has two RCA inputs and one balanced input and only a balanced output. This all works with their amps to allows what they call Current Injection Analog Signal Processing.

All that I can really say is that this passive unit in this innovative circuit sounds great. I hear no compressed dynamics nor none of the purity of sound both of which I associate with passive units. All that I can say is that the total system sound exceeds any that I have had heretofore.

A line stage has 4 functions:

1) control volume
2) select input
3) add any needed gain
4) control the interconnect cable at its output

Of these, it is the the last that is the least understood. Audiophiles are very used to auditioning interconnects, and so do not think about what the benefit would be if the interconnect's artifact is eliminated.

You cannot eliminate this artifact with a passive; in fact you cannot *avoid* cable artifacts if a passive is in use. This has nothing to do with the quality of the passive control nor the quality of the cable. It has to do with the capacitive and resistive interactions of the source, the control, the capacitance of the cable and in the input impedance of the amplifier being driven.

The lower the source impedance, the lower the volume control impedance and the lower the amplifier input impedance, the less artifact the cable will have. However this set of parameters is almost impossible to meet due to the low impedances that are actually needed.

This is why a *quality* line stage will often be considerably more neutral when compared to a passive control, regardless of the quality of the passive.

Now I realize that this statement may be controversial to some, if this is the case for you I exhort you to examine the emphasis on the word 'quality' above.

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Onemug

Start a power cord thread and I've seen more peace and harmony in an Oakland Raiders parking lot after a game. :-)

Hilarious!! That quote goes in the Audiogon hall of fame.
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Atmasphere, could you perhaps comment on the original post. I notice that your top linestage retails for around $12k and weighs slightly less than 50lbs (a two box design no less). This is more or less in line price and weight wise with products being offered by VTL, Pass, EMM or EAR. As a thought exercise, what would your top linestage feature if you built it to a $35k price point?

"Charles1dadYou could certainly conclude also that the passive units are`nt passing the"complte" signal,thus there`s some degree of subtraction of musical information.Charles1dad"

This statement is not correct and only valid if one has not implemented the passive correctly.
As I've stated in my 2nd post on the 08-22-11, if followed then you will get it "all" as the source wanted you to hear it, even more than any actives preamps.

Once again here is the impementation that's needed to make a passive become electricly transparent to the source.

1: Is to make sure the sources ouput impedance is 5 x or less the attenuators input impedance.
2: To make sure the power amps input impedance is 5 x or more the attenuators output impedance.

Cheers George