Preamplifier power supply

I think first you have to seperate the tube amps from the transistor units as they have very different requirements.First they need a stable B+ high voltage supply usualy upwards of 240volts for a preamp and a seperate low voltage supply for the heater circuit some using voltage regulation.Many designers prefer to incorperate in line inductors and by the time you get recifiers and storage caps for both high and low voltage circuits.Its getting both costly and heavy.Then you have to seperate the transistor guys into those that use switch mode supplys and those that like the high current transformer and massive energy storage supplys some also using inductors.Linn uses a lot of switch mode designs they sound good when effectively used but surely savings in cost as well as size,weight and efficiency are factors.I like to think the power supply is a critical part of the circuit and not the area to cut cost.

Hi Bill, you forgot to include Spectral. Still it is not very clear to me if a big bad MF of a power supply will ensure that you get: killer bass, bold dynamics, authority and spaciousness.
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?

Chris

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.