Sunday, May 3, 2009

A visit with the Threshold FET-10/PC phono preamplifier

The Threshold FET-10/PC is a standalone phono preamplifier that was meant to be partnered with the FET-10/HL linestage. With the use of internal dip switches it features adjustable gain for MM or MC cartridges and adjustable capacitance. Designed by the great Nelson Pass in the mid-80s, the 10/PC is a statement piece and the build quality certainly shows that - outboard power supplies, hand selected parts, a frickin' gold plated circuit board, and a RIAA curve that is within .25dB.

I bought my FET-10/PC via Ebay to match my FET-10/HL linestage. Upon receiving the phono stage, I opened up the case and like the linestage was amazed by the build quality. I read the manual and made sure to set the gain to 40dB to match my Ortofon 2M Blue MM cartridge.

How does the FET-10/PC sound? - so far it doesn't sound much like anything at all. It is very neutral, transparent and has excellent control over the sound coming from the Ortofon 2M Blue. Bass is very deep with excellent 'slam' and dynamics. The midrange has a bloom that is very natural and pleasing to the ear. No major faults come to mind - though a good tube unit may have a smidgen more body at the expense of detail. And the details! I heard little things on recordings that were just plain not there on my other phono preamplifiers.

In comparison it makes the Graham Slee Era Gold V sound ever so slightly artificial. The Bottlehead Seduction is just a little less detailed but perhaps a bit more musical.

I'm very impressed with the FET-10/PC and I'm certainly enjoying the complete Threshold amplification chain. Future cartridge purchases can only make the sound even better and this unit will be a good basis for my planned analog upgrades.

Setting up the FET-10/PC:
As for setting up the impedance and capacitance loading - with the top open and the front of the preamplifier facing you, locate the two red 8 position dip switches on the far left side. If a dip switch is set to the left, it is ON. If it switched to the right, it is OFF.

Resistance Loading:
#1 - 22 ohms
#2 - 47 ohms
#3 - 100 ohms
#4 - 1,000 ohms

1-4 OFF = 47k ohms (ie, MM cartridge)

Capacitance Loading:
#5 - 1,000 picofards
#6 - 250 picofarads
#7 - 150 picofarads
#8 - 100 picofarads

5-8 OFF = 50 picofarads

To set the gain, locate the two jumper sliders on the middle left of the board. These are colored blue and each cover two pins of a three gold plated prong.

For highest gain, each jumper slide is positioned towards the center of the preamplifer. In this case the exposed pins are those nearest to the front and back of the preamplifier.

For 20dB less gain, the jumpers are located away from each other and toward the back and front of the preamplifier. The exposed pins will be nearest to the center of the preamplifier.

preamp: Threshold FET-10/HL
amplifier: Threshold S/500
analog: VPI HW19 MkIII - Rega RB300 with Incognito wiring - Ortofon 2M Blue
speakers: UREI 813A loudspeakers
phono preamp(s): Graham Slee Era Gold V phono and Bottlehead Seduction with C4S mods
speaker cable: Canare Quad
Interconnects: Cardas Crosslink and Belden