What is a pre preamp? Is that like a step up transformer??
9 responses Add your response
It replaces an SUT but works differently. A pre-preamp or head amp is an active gain stage. It does not have the RIAA equalization and gain stage of a phono pre, but allows a LO MC to be plugged in to an MM phono input. An SUT is passive; it multiplies voltage according to the ratio of the windings of the primary and secondary.
A "pre preamp" or MC head amp functions in place of a "step up transformer" but is an active powered circuit adding gain, usually in the 10-20dB range, but no RIAA equalization, allowing an MC cartridge with an output of less than say .8mV to be used with a phono stage designed for MM cartridges with outputs in excess of 1-5 mV. One way to gage the appropriateness of a given head amp/cartridge/phono stage is to figure that one usually need at least 40dB of gain for a 1mV output cartridge, bearing in mind that every halving of cartridge output would require additional 6dB of gain. Some would argue that, depending on listening habits, circuit noise, overall gain of electronics and sensitivity of speakers, that 40dB of gain would be better matched to a 2mV (or even 4mV) output cartridge. This would translate to an optimal match of 34dB of phono stage gain with a 4mV output cartridge, 46dB of gain with a 1mV cartridge, 52dB of gain with a .5mV cart, 58dB of gain with .25mV cart, and 64dB of gain for a .13mV cart.
As usual, there are diverse preferences for step up transformer versus active head amp, or simply a high gain phono stage.
There aren't many stand alone active pre preamps on the market. The ZYX Artisan is highly regarded although I haven't used it. I prefer to have a phono stage that has enough gain to handle the cartridge without adding another gain stage and requisite pair of interconnects.
FYI, Hagtech's Piccolo is his own make and although I haven't tried it I would guess it is his usual excellent value, sold direct only. In his own words, he prefers step up transformers to active stages despite his own product. Raul here is adamant about the evils of SUTs. different strokes.
BTW, I forgot to mention above that there are at least two standards for measuring output of cartridges that can confuse your calculations by about 30%. The operative is voltage@5cm/sec or 3.54cm/sec.