Grimm Audio PW1 MM/MC Phono Preamplifier

Designed by Peter van Willenswaard. Since harmonic distortion on LP’s is quite high by nature, THD requirements were modest leaving Peter free to focus on minimizing the amount of active components while optimizing their ‘electric environment’ in conjunction with each other. The power supply was an integral part of the design. Passive components like capacitors and resistors were carefully picked.

The result is a well balanced design with Peter’s signature sound, that is very spacious, detailed and open, but at the same time rhythmically addictive and emotionally involving. The industrial design had to justify this quality. Michiel Uylings of MU1 fame matched the sonics with a simple but powerful cabinet shape and Grimm Audio’s design team made the copper shielded interior look like a piece of art. 

Extensive setting options

In terms of settings and adjustments to different types of elements, a lot is possible with the PW1. The nominal MM sensitivity is 5 mV for 350 mV out. An additional 10 dB gain is available for the MM input if you want to use it with high-output MCs, the sensitivity is then around 2 mV. Mind that MM cartridges can deliver almost 100 mV with very deeply modulated LPs, resulting in 7 Vrms output. Both the MM input and the output electronics are able to cope with these extremes. In fact, the output of the PW1 can hardly be overdriven with its maximum level of a staggering 10 Vrms (+22 dBu)!

A separate input is provided for MC cartridges, that offers optionally 20 or 30 dB gain. If all the gain available on the PW1 is switched on, a maximum gain of 77 dB is achieved on MC, or more than 7000 x. This means that MC cartridges with ultra-low output (in the order of 0.05 mV!) can also be used. And without noise problems, because the inherent noise of the MC section is, as mentioned, extremely low.

In order to fine-tune the behavior of pickup elements, a series of capacitors and (for MC) termination resistors are provided on both the MM and MC inputs. For MM cartridges, capacitors of 47, 100 or 220 pF can be added to the load. 

MC cartridges are quite insensitive to capacitive termination, but if one likes 330 pF and/or 680 pF can be added. The main load setting for MC is the resistive one. Most MC’s feel comfortable with a load resistance in the order of 5 to 10 times their own internal resistance. The PW1 has a range of options for this purpose: 33-100-330-1000 ohms and of course all combinations thereof. Disabling all extra load is also possible, the load resistance is then 47 kOhm and many MC elements feel very happy with that.

• Unique minimalistic electronic design

• 2 x RCA inputs (1 x MM, 1 x MC)

• 1 x RCA and 1 x XLR outputs

• Gain and load settings under bottom plate

• Internal silent linear power supply

• Copper shielded interior

• 5 year limited warranty

• 355 x 85 x 295mm (WxHxD)