Michael Yee Audio

 

 

The PFE-1...

pfe1 top view

Manual for the PFE-1

Yes, phono still does sound better than compact disc when it comes to imaging and body of sound. These are the all-important reality factors. So keep your records... the compact disc still needs more time.

The Michael Yee Audio PFE-1 (Phono Front End) is a universal phono front end which amplifies either a moving coil cartridge or a moving magnet cartridge up to line level, with RIAA equalization. There are user-defined internal switches to set the gain (40 - 60 dB) and switches to set the input termination (15 Ohms to 100K Ohms).

The PFE-1, as with all of our components, utilizes Tonal Imaging technology. Simply put, this allows us to offer a cutting-edge phono front end, comparable with the best, for a suggested list $900.

Special Design Features:

SINGLE-STAGE GAIN

A unique and crucially important feature of the PFE-1 is the use of only one "gain block". Other systems which offer gain from moving coil up to "line level" use two or more "gain blocks". If two amplification stages are used, the distortion of the amplifiers is multiplied, not just added together. For this reason the PFE-1 has a carefully designed, fully-discrete 14-transistor amplifier to form its single "gain block".

PHASE-COMPENSATED FEEDBACK
RIAA EQUALIZATION

There are two primary ways to implement the RIAA equalization needed for the playback of records, passive equalization and active equalization. Both until now had disadvantages.

Passive equalization is perhaps the simplest method to achieve the RIAA curve. This involves the accurate attenuation at given frequencies using a fairly simple network. The major disadvantage of this system is the attenuation of the signal can cause clipping and degradation of noise performance. The noise performance is compromised since the resultant signal, after attenuation by the RIAA network, is often at very low levels and needs to be amplified again. The noise therefore will also be amplified.

Active equalization is probably the most widely used method and involves the insertion of an RIAA feedback network in the feedback path of the amplifier. In this case, the signal is amplified only the amount needed, so no attenuation is necessary. However, the interaction between the amplifier and the RIAA network causes phase anomalies. The RIAA network causes "poles and zeros" in the loop gain, with associated phase responses. These undesired phase changes result in summing errors at the feedback summing node.

The PFE-1, with Phase Compensated Feedback, has a response pole for every zero and a zero for every pole caused by the RIAA equalization network. This ensures the RIAA network is always "in phase" at the feedback summing junction. This dramatically improves the imaging qualities while also improving the accuracy of the RIAA equalization.

USER-DEFINED INPUT IMPEDANCE

In the past, input termination has been critical. It was typically necessary to "tweak" the loading of a moving coil cartridge, always balancing the irritating sound of a load which is too light (high impedance), or with the nasal sound of a cartridge too heavily loaded. We feel that these compromises were due to poor-sounding electronics. You will find that the loading is not critical with the PFE-1. We have however enabled the user to program the input impedance very easily and accurately, if desired, from 15 Ohms to 100K Ohms in 60 steps.

USER-SELECTED GAIN

There are 16 user-defined gain settings between 40 and 60 dB (@ 1000 Hz). The lower gain settings are appropriate for moving magnet and high output moving coil cartridges (>2 milli-Volt output). The higher gain settings are intended for very low output cartridges

DIRECT DRIVE OUTPUT

D.C. blocking is perhaps the most critical use for capacitors. The PFE-1 has no capacitors in the signal path, instead a D.C. correction circuit is utilized so no D.C. blocking capacitors are needed in the signal path.

DUAL MONO DESIGN

The dual-mono design offers supreme isolation between the two channels. The grounds of the two channels are connected to each other through the chassis but this too is user defined. The two channels can be completely isolated from each other if desired. This flexibility is an asset for systems with difficult grounding requirements.

CLASS A OPERATION

The PFE-1 operates all the stages in class A mode for the elimination of crossover distortion.

REMOTE POWER SUPPLY

The remote power supply (PSU-1) provides additional line regulation and freedom from electromagnetic interference. It can be located up to six feet from the preamp unit. The PSU-1 adds an additional 8800 micro-Farad in capacitance and adds another stage of voltage regulation.

CONSTRUCTION

The PFE-1 is American-made of very high quality materials- anodized all-aluminum cases, alloy allen-head machine screws, gold RCA jacks, for a high degree of look and feel.

TECHNICAL SPECIFICATIONS:

Dimensions: Amplifier 10.9" X 2.2" X 7.0"
PSU 4.7" X 7.4" X 3.2"

Power Req.: (50-60 Hz) 120 Volts 0.1 Amps RMS
230 Volts 0.05 Amps RMS

Gain: selectable (16 steps) 40 - 60dB

Frequency Response: 20Hz-20kHz 0.02dB

Input Impedance: selectable 15 Ohms-100k Ohms in 60 steps

Output Impedance: 100 Ohms

Shipping Weight: 10 lbs

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