Forte F44 Preamplifier
The Forte F44 is a basic stereo preamplifier combining sophisticated circuit design with exceptional ease and convenience of operation. A true product of audio's digital era, it has six sets of line-level inputs but no phono jacks, though it does provide for such addons as an outboard phono preamp.
Operating convenience has not been overlooked in the design of the F44. Its infrared remote control covers all the normal operating functions, including input selection, volume adjustment, and muting, and there is a Standby button for use with future Forte components such as a video switcher (a Data Bus connector for that purpose is on the back of the preamplifier). The front-panel control knobs are turned by internal motors when operated from the remote, in total silence and with no switching transients. A major advantage of this system is avoidance of the dynamic-range limitations and distortion typical of voltage-controlled solid-state attenuators. The white bars on the control knobs clearly show their settings even at a moderate distance.
The F44's inputs are designated as CD, Video, Tuner, High Level 1 and 2 (for other high-level sources), and Tape. A separate Record switch connects the signal at any of the inputs, independently of the one selected for listening, to the tape-recording outputs. In its off position this switch completely isolates the tape outputs from the input signals. The Record switch is not duplicated on the remote control.
The Forte F44 has no power switch. It is designed to be energized permanently once installed, and since it consumes only a few watts of power and runs perfectly cool, this is quite practical. The selected input signal goes through the volume control before being amplified, insuring against unwittingly overloading a low-level stage. The F44's cascode Class A amplifiers are direct-coupled.
An unusual feature of the Forte F44 is its provision for balanced inputs. In addition to the standard unbalanced inputs and two sets of output jacks, the rear apron contains balanced jacks for the CD inputs and a pair of balanced output jacks. The balanced outputs are not normally functional, but the user's manual explains how to switch jumper blocks on the main circuit board to replace the standard CD inputs with their balanced equivalents, which can provide better interference rejection than the standard unbalanced connection.
The Forte F44 has a relatively low input-impedance rating of 12,000 ohms unbalanced and 4,400 ohms balanced. Its output impedance is specified as 100 ohms unbalanced, 200 ohms balanced. Frequency response is rated as flat to DC (0 Hz) and down by 1 dB at 200,000 Hz. Distortion is specified as 0.005 percent from DC to 20,000 Hz at 3 volts output into a 10,000-ohm load, and noise is rated at lower than -100 dB relative to 0.5 volt.
In our measurements, the Forte F44's frequency response was flat within +/-0.01 dB from 20 to 20,000 Hz, going to +0.04 dB at 10 Hz and to -0.75 dB at 200,000 Hz. Its maximum output level was one of the highest we have measured from a preamplifier. Driving an EIA standard load of 10.000 ohms in parallel with a 1,000-pF capacitance, the F44 delivered slightly more than 11 volts from 20 to 20,000 Hz at 0.5 percent distortion (the onset of clipping).
The crosstalk between inputs was -77 dB from 20 to 100 Hz and increased at higher frequencies, to -40 dB at 20,000 Hz, because of capacitive coupling between the input-selector switch contacts, and perhaps the circuit-board traces as well. We used the CD input for this test, and the closest contacts to its switch terminals were those of the Video inputs. The other inputs had somewhat less high-frequency crosstalk from the CD inputs, typically about -72 dB at 1,000 Hz and -50 dB at 20,000 Hz. The crosstalk between channels of the same input was a constant, and far more than adequate, -81 dB from 20 to 20.000 Hz.
Distortion was very low, even compared with the F44's impressive specifications. Up to 8.5 volts output, it was about 0.0025 percent. At a 5-volt output, far more than will be needed to drive any power amplifier fully, distortion was 0.002 percent from 20 to 1,000 Hz, rising slightly to 0.0032 percent at 10,000 Hz and 0.008 percent at 20,000 Hz. All these distortion levels are inaudible.
The Forte F44's performance was as effortless and ideal in a music system as it was on the test bench. It is hard to imagine how anyone could find it wanting in any respect, except possibly in the lack of a built-in phono preamplifier. For many people, in this digital age, that should not present any problems.
The controls were silky smooth in their operation, and there was absolutely no trace of switching transients when we changed inputs. Personally, I do not believe that a component of the caliber of the Forte F44 could possibly have a distinctive sound character (a high-performance preamplifier certainly should be sonically neutral), and it did not in our listening tests.
The Forte F44, priced just above high-quality mass-market components, represents a solid value. If you don't need features that it lacks, it is hard to see how it could be surpassed in its price class.
