Threshold Fet9usedThreshold FET 9 Preamplifier with MM/MC PhonoThreshold Fet 9 MM/MC Phono. Excellent physical and sonic condition. Ships in original factory box/ packing materials with owners manual, sales brochure, power cord, also included factory service m...1.00

Threshold FET 9 Preamplifier with MM/MC Phono [Template]

no longer for sale

Threshold Fet 9 MM/MC Phono. Excellent physical and sonic condition. Ships in original factory box/ packing materials with owners manual, sales brochure, power cord, also included factory service manual with adjustment specs and circuit schematics. All electrolytic caps replaced 2017. Power supply B+/B- rails adjusted to factory spec +- 17 volts. I've been in this hobby 45 years, and have accumulated too much gear. I'm selling some of my treasures, and I consider any pre/amplifier designed by Nelson Pass to be a treasure. Numerous reviews on the web. 

Here is some info I found on Audiogon:

The FET Nine from Threshold as well as the FET Ten were the last of the Nelson Pass designed preamps to emerge from the original Threshold Company co-founded by Nelson Pass.

The Fet 9 is a high end preamp of extraordinary build and sonics. This preamp has few peers in the lofty world of high end. It competes quite well with preamps from Krell,Levinson,Klyne and Coda.

This preamp has provisions for three line inputs, plus an absolutely stellar phono section and can accommodate two tape units as well.

Blessed with an outboard power supply to keep any transformer interaction away from the preamp.

The phono section can bet set up for Moving Magnet and Moving Coil and the appropriate loading values can be set as well.

One look at the interior of this preamp with its gold circuit boards and wiring layout, immediately makes the statement that this is a no nonsense preamplifier. The build quality with its thick front face plate to its all steel chassis puts this in rare company indeed.

Dual channel, non-Inverting, field effect transistor preamplifier designed to provide gain and equalization for all moving and stationary coil "magnetic" cartridges and conntrol and routing functions for high level signals. Gain, impedance, and capacitive cartridge loading characteristics are internally selected.

Three high level inputs are provided plus record and monitoring for two recorders. Front panel controls provide program selection, record signal routing, monitor signal selection, channel balance, and audio level.

Phonograph Cartridge Section:


Impedance loading variable in increments

between 22 Ohms and 47,000 Ohms

Capacitive loading variable in increments between 50 picoFarads and 1,000 picoFarads. Gain factor selectable at 40 dB or 60 dB.

RIAA Equalization:

Passive and active topology computer designed to 0.025% accuracy. Selected precision components used in construction hold deviation to within 0.25 dB of model.

Distortion: No greater than 0.02% @ 1 volt stage output.

Noise: No greater than - 80 dB referenced to (1 millivolt input @ 1,000 Hz.)

Crosstalk: No greater than - 70 dB @ 20,000 Hz with 1,000 Ohm source.

High Level Section Frequency Response:

Virtually flat within a bandwidth having - 3 dB points at 1.5 Hz and 125,000 Hz.

Distortion: No greater than 0.02% @ 3 volts RMS out 20 Hz through 20,000 Hz into 10,000 Ohms

Crosstalk: No greater than - 75 dB @ 20,000 Hz with 1,000 Ohm source.

Noise: No greater than -100 dBA referenced to 1 volt input.

Input Impedance: 25,000 Ohms.

Output impedance: 100 Ohms. Maximum output swing: 20 volts peak-to-peak.

Gain: +20 dB

Dimensions: 19" wide, 1.75" high (add .25" for feet), 6.5" deep (rear surface of faceplate to end of connectors). Approxiimate weight: 4.5 pounds.

The Threshold FET nine is a unified preamplifier system containing both moving coil/moving magnet phonograph cartridge gain stages and high level control stages in a single, single rack height chassis with external power supply. All gain stages of the FET nine are operated in the pure class A mode.

The cartridge gain stage of the FET nine employs the same basic topology as the FET ten/pc. However, the extravagance of space and component expense implicit in production of parallel stage elements has been dispensed with. This allows the FET nine to exhibit the musical transparency of the FET ten in essentially half the physical size and with minimal amounts of measured noise and distortion.

The moving coil/moving magnet cartridge preamplification of the FET nine is provided by a single stage whose gain and loading characteristics are internally adjusted to the requirements of the carrtridge in use. The input of this stage is specifically designed to exhibit no source/load interaction and assures that subtle colorations will not be added to the character of the selected cartridge.

An exact inverse to the RIAA recording curve is achieved through a combination of passive and active equalization, This de-emphasis circuit is designed to a computer model accurate within 0.025% deviation, Production of the circuit as realized in the FET nine employs individually selected precision tolerance components, This assures that phase and amplitude relationships within the music signal of an analog disc recording are accurately maintained during playback, As a result the cartridge gain stage of the FET nine reproduces all characteristics of the cartridge in use with precise linearity,

In addition to the phonograph cartridge input deescribed above the FET nine provides three high level inputs plus record and monitor facilities for two associated tape recorders, This allows for connection and control of up to six pieces of ancillary equipment.

The high level gain stages of the FET nine include cascoded MOS-FETs, The cascode circuitry employed suppresses voltage variations and maintains operating linearity of the MOS-FETs at an optimum level while holding distortion to tiny percentages with simple, direct gain paths, Careful selection of internal operating impedances assures that all equipment will be appropriately loaded without the use of "buffer" amplifiers between the primary signal sources and the connected recorders, This places the recorders a step closer to the original source and assures that the recorded signal will not be subject to subtle degradation,

Biasing of all signal carrying gain devices in the FET nine is performed outside the signal path by precision monolithic J-FET constant current sources. These shield the active components in audio path isolating them from modulation effects during transient supply demands. This provides a substantial dynamic capability and assures that the full potential of source equipment and material is effortlessly realized.

The FET nine is powered from an external power supply module which is identical to those used for the FET ten system, The supply utilizes a large transformer followed by forty-two hundred microFarads capacitance provided by computer-grade capacitors, This smoothing of the supply voltage is then followed two discrete class A voltage regulators, The supply rail regulation of this design in conjunction with extensive film capacitor bypass and the extremely high power supply rejection ratio built into the gain topologies insures no interaction between either of the gain stages or the outside power environment. This preserves the neutrality of the FET nine gain stages by their complete isolation from any fluctuations that may occur in their power sources.

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