Preamplifier power supply

Oversize is a relative term. If a preamp has a high-power amp's supply, then yes, based on power it would be overkill.

As an EE that specializes in power supply design, my personal opinion is that a large power supply is a good thing. The reason is that large transformers have a low internal impedance which allows them to pass current very quickly to the circuit. This speed and availability is what makes them better than a small transformer with thin wire.

Sometimes, sounding "dynamic" is due to a lack of bass. So yes, a small power supply can sound more "dynamic" than a large one - but that is simply because tonal balance is relative to itself and not because of power supply design. The two should not be confused.

Arthur

I have an AudioPrism Mantissa preamp. It's getting a bit long in the tooth now, but still a very nice product overall. It has an external power supply. There was also an upgraded version that had a beefier power supply available.

Now AudioPrism has long had a reputation as understanding power supplies and power filtering, so I kind of trust them on this one. Anyway, the difference between the original power supply and the upgraded one, in terms of sonics, is quite easily heard. More dynamics and ectension. An overall sense of increased ease and blacker backgrounds.

It's more than just boosting capacitance or the size of the transformer though. There's probably more discrete filtering in there and probably additional isolation between the sections feeding power to the analogue circiutry also.

Beefier supplies also tends to mean better design and implementation. Or at least more complex design and implementation that should lead to better sonics, for the reasons I cited above.

Enjoy,
Bob

Btw, some of the fellow Audiogoners use passive preamps (resistor or transformer based) with NO power supply at all --> do they have poor dynamics and bass response?

This is a terrible mistake. You will not achieve high input impedance and low output impedance with a device like this. In the worst cases the sound will change character audibly with volume as the circuit will act like a filter when it couples with the source and power amp. Remember a preamp is also a "buffer" - it allows the source to see high impedance (making the source have an easy life) while driving the power amp faithfully with whatever it needs - irrespective of small load variations. Buffering and high S/N cannot be achieved without active circuitry. Volume adjustments require around 120 or more decibels of control - it is not a simple task if you want to do it with high channel separation and high S/N and low distortion/transparency.

Shardone, with transformer based passive preamp you will get high input but low output impedance. I think with saying that a passive preamp is a "terrible mistake" some of us would feel offended (btw, myself not included).

Chris