Monday, December 15, 2008

Threshold FET-10/HL linestage review


The past few days I've been listening to the Threshold FET-10/HL linestage. This is an 'old' stereo unit built back in the late 1980s by the great Nelson Pass. It uses discrete FETs throughout with no op-amps in sight. It has tape outputs, selector switch for five inputs, a stepped Nobles balance and volume control. Be warned that there is no phono stage - that was available by purchasing the stand alone FET-10/Pc.

Opening the case of the 10/HL reveals an amazing layout - all discrete components, gold plated circuit boards and an attention to detail that would make a mil-spec electrical engineer gawk in admiration. Output capacitors are basic ERO polypropelenes and the resistors appear to be very nicely made metal-films. There is also an outboard power supply that keeps hum down to near zero.

In all honesty I wasn't expecting much from this linestage. I had faith that my trusty 6N6P based unit could trounce anything commercially made. After all I had MIT RTX coupling caps, all wirewound resistors, a SMD Goldpoint volume control and a choke-based tube rectified power supply. Surely some great parts combined with a simple topology would beat out an 80s produced solid-state piece!

Well, I'm prepared to eat a healthy helping of crow now. The FET-10HL is a wonderful performer and makes me question the need for ultra trick parts. I never knew that solid-state could sound this good.


First of all, it has the ability to resolve the smallest details in the recording. The brush of the cymbal, the breath against the microphone, the way the stick hits the drum and a myriad of other audiophile tricks that I crave in a high performance preamplifier. This is one high resolution piece of gear and on everyone of my recordings I heard details that I never knew existed before. But this resolution does not lose out in musicality. There is a natural sweetness to the treble and the midrange is remarkably grain free. The bass is deep and well defined, adding even more control to my EL156 single ended vacuum tube amplifiers. Instruments have body - maybe a bit less than the best vacuum tube preamplifiers - but more than enough to satisfy me. I wish the gain could be just a little higher for the use with a non-OS DAC, but it hasn't been a problem with my transformer-coupled RAKK DAC.

Considering the performance, a used FET-10/HL is an audio bargain. Prices vary since this was never a mass produced unit. However consider a power supply capacitor upgrade as part of the overall price. This will help for long-term reliability and if you're not handy with a soldering iron, have this work done by an experienced technician. Also a coupling capacitor upgrade may improve the sonics even more, but for now I'm quite happy with the stock caps.


System used:
Source: Philips DVD player and K&K RAKK DAC with passive output
Speakers: KEF C-75 or PSB Stratus Bronze
Amplifier: Threshold S/500 or Jenison Audio Ultra-SE1 EL156 monoblocks
Wire: Cardas 300-B Microtwin interconnects, Canare Quad speaker cable

.

1 comment:

Rob said...

Thanks for your nice review of this preamp. J. Gordon Holt Chief editor then of Stereophile reviewed it in Vol 10, september 1987 very favorable.
I'm comtemplating to buy one for accompanying my Threshold monoamps.