VINTAGE TECHNOLOGY ARCHIVE / AUDIO / THRESHOLD / NS-10

Threshold NS-10 (1978)

Nelson Pass's first preamplifier to carry the Threshold badge, and the source of the company's "state of the art" boast.

Overview

Collectors repeat one claim about the Threshold NS-10: it is Nelson Pass's first preamplifier with the Threshold name on it. Two sources make the assertion, the Vintage Amp Repair archive and an Audiogon write-up that appears to quote the same text. The 1978 introduction date is corroborated by audioantiquary.com and hifi4sale.net. Threshold was founded in 1974, so the NS-10 showed up roughly four years into the company's life.

The NS-10 is a stereo preamplifier. The Music Room and Vintage Amp Repair describe it as a preamp in the classic sense, with line and phono stages in a single chassis. An Audio (November 1990, p.113) retrospective photo shows founders Nelson Pass and René Besné with the unit, and the caption notes that it contained advanced single-ended circuitry. That is one of the few period citations that survives for this model. Documentation on the NS-10 is thin.

According to highperformancestereo.com, Threshold kept the signal path as simple as possible. Only two common-emitter transistors are used in the gain stages of each channel. That's the kind of detail that gets quoted in service threads and owner forums. The same source describes the NS-10 as embodying design concepts and empirical performance that "set new boundaries for the classification 'state of the art'" - a phrase that also appears, nearly verbatim, on Vintage Amp Repair's page. It reads like marketing, and it shows how the NS-10 was positioned at the time.

An Audiogon post frames the NS-10 as the match for Threshold's first wave of amplifiers - the CAS 1, CAS 2, 400A, 4000, Stasis 1, Stasis 2, and Stasis 3. The same writer calls the NS-10 "one of those early over the top products from the mind of Nelson Pass." This wasn't a budget component.

Key Features

Class A Discrete Circuit with 50 MHz Bandwidth

A 1980 buyers'-guide listing describes the NS-10 as a "wide-bandwidth class A discrete stereo preamplifier" with a 50 MHz active circuit bandwidth. That is far beyond anything the audio band requires. Class A operation means the circuit conducts throughout the entire signal cycle, which avoids the crossover distortion that plagues class AB designs. It also means the preamp runs warm and draws constant current, and that's the trade-off owners accepted.

Phono Stage with Two MM Inputs

The NS-10 includes a phono stage, and according to HiFi Haven it accommodates two MM phono inputs. A listing title confirms it, describing the unit as a "Threshold NS10 preamplifier with 2 phono inputs." In the late 1970s that let a listener keep two turntables or two cartridges connected without swapping cables. The 1980 buyers'-guide listing reports RIAA deviation of −0.5 dB from 20 to 40,000 Hz on the phono input. The same listing notes ±1 dB deviation on the aux input over the same range.

Optional M1 Moving Coil Box

For low-output moving coil cartridges, Threshold offered an optional M1 moving coil box. A diyAudio thread ("Threshold NS10 renewed") mentions a unit for sale with "the rare M1 moving coil box in near mint condition." An Avito listing in Russian describes the preamp as having "MM, MC фонокорректором на борту" (MM, MC phono stage on board), which may reflect the M1 box option rather than a built-in MC stage. Buyers should verify whether a given unit includes the M1 before assuming MC capability.

Gain and Output Specifications

According to highperformancestereo.com, the NS-10 offers 40 dB of gain on the MM phono input and 20 dB on line-level inputs. Signal-to-noise ratio is listed at 70 dB (MM) on the same source, while the 1980 buyers'-guide listing reports 80 dB (A-weighted) overall. The discrepancy likely reflects different measurement conditions or weighting standards. Output is specified as 1 V nominal (pre out) with a 10 V maximum.

Compact Chassis with Three AC Outlets

The chassis measures roughly 3″ H × 16″ W × 9″ D per the 1980 buyers'-guide listing. That's a wide, shallow, low-profile box. Three AC outlets are provided on the rear panel, so owners could plug source components into the preamp's switched power.

Historical Context

Threshold was founded in 1974, according to bluemoonhouse-sophos.com, and the NS-10 arrived in 1978, the year audioantiquary.com and hifi4sale.net both cite as its introduction. Nelson Pass designed it, and Vintage Amp Repair, Audiogon, hifi4sale.net, and audioantiquary.com all credit him. The NS-10 was the first preamplifier to carry the Threshold name, and it was positioned alongside the company's early amplifier lineup - the CAS 1, CAS 2, 400A, 4000, and the Stasis series.

An Audiogon post describes those early Threshold products as "benchmarks not only for Threshold but the industry as well" - "truly breakthrough products, that firmly established high end audio as we now know it." That's enthusiast rhetoric, but it reflects how the brand was perceived in the late 1970s and early 1980s.

Collectibility & Value

The Threshold NS-10 doesn't command the same attention as the company's early power amplifiers, but it has a following among collectors of Nelson Pass designs and early high-end solid-state gear. Current asking prices start around €1,400 according to audioantiquary.com (product code USPR0036). That is a single-source figure, so treat it as indicative.

Jon Soderberg at Vintage Amp Repair is the name that comes up repeatedly across diyAudio, HiFi Haven, audioasylumtrader, and audiograffiti as the go-to technician for Threshold restoration. One audioasylumtrader listing notes that after Soderberg's repairs and upgrades, the NS-10 had approximately 200 hours of use and "performed flawlessly." A HiFi Haven post mentions a unit with "all new electrolytic caps" and a check-over by Stereo Rehab in Chicago. Recapping is the standard maintenance for gear of this age, and buyers should ask whether it's been done.

Schematic availability is limited. A diyAudio discussion notes that "Nelson's schematic" was found but is "lacking values and ratings," and users are still "looking for the actual schematic of the NS10 preamp." That makes DIY repair harder. Multiple units appear for sale across USAM, Audiogon, audioasylumtrader, audiograffiti (Italy), and Avito (Russia), so the market isn't dry. The documentation is.

One Audiogon owner reports running the NS-10 into a Threshold 400A amplifier with Alon Model 1 speakers, describing the system as "sounding as good as ever" after service.

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VINTAGE TECHNOLOGY ARCHIVE / 10-18-2026 / FEEDBACK