Hi-Fi Hall of Fame
2025 Inductee
Phase Linear 700 Power Amplifier

Introduction

Our next inductee is a power amplifier that shook up the Hi-Fi world when it was introduced in 1972. The Phase Linear 700 was the very first product from newcomer Robert (Bob) Carver, and it was truly impressive.

Let’s take a look at this iconic amp to see why it’s going into the Hi-Fi Hall of Fame.

Phase Linear 700 Introduction

Phase Linear Corporation was established in 1970 by two founders, Bob Carver and Steve Johnston. Their first product was the Model 700 stereo power amplifier, which appeared in 1972.

Delivering an unheard of 350 watts per channel, and priced at $749.00, slightly exceeding a “dollar per watt”, it offered remarkable power for its cost. The amplifier’s design was characterized by its distinctive brushed aluminum front panel and prominent dual VU meters. The high power output was made achievable by the advent of new high power transistors, which were originally developed for the high voltage demands of automotive electronic ignition systems.

The Phase Linear 700 almost immediately became a staple in recording studios and sound reinforcement setups, and was also popular with professional musicians and audiophiles.

Prior to the launch of the 700, the most powerful amplifier available to Hi-Fi enthusiasts generally put out less than 100 watts per channel, so the Phase Linear was a real quantum leap in power output. Another great aspect of the 700 was that the power transformer and output transistors were placed on the outside the chassis; this eased serviceability and reduced the operating temperatures. The 700 produced so much power, in fact, that the company ran advertisements explaining why owning a 700 watt amplifier was a good idea!

Impact of the Phase Linear 700

The Phase Linear 700 made a significant impact on the Hi-Fi community. When it was first introduced, there were few high powered amplifiers available. The top end amps from other manufacturers were generally capable of 50 to 100 watts per channel. There was the Crown DC-300, which was a consumer version of a studio amplifier. It produced 150 watts per channel.

Seeing the success of the Phase Linear, other manufacturers developed their own high power amplifiers. There was an improved version of the Crown (the DC300A), the Marantz 500, the Bose 1801, and the Dynaco Stereo 400, amongst others.

Another impact of the Phase Linear 700 was to make the preamplifier + power amplifier combination more popular with consumers. This included both transistorized and vacuum tube based equipment. By 1975, there were new models available from manufacturers such as Audio Research, Harman/Kardon, Marantz, and others.

These new amplifiers also enabled speaker manufacturers to produce some inefficient speakers; speakers that needed loads of power to play loud. These included the Acoustic Research (AR) 3a and LST, Magneplanar Tympani, ESS Air Motion Transformer (AMT), and Dahlquist DQ-10.

The Phase Linear 700 even impacted the receiver market. Within a few years, manufacturers were engaged in a power race, producing some high end receivers with very high power output.

Evolution of the Phase Linear 700

The original Phase Linear 700 appeared in 1972. It sold very well and so Phase Linear developed some evolved versions of the amplifier to improve the aesthetic and performance.

By 1975 the Phase Linear 700B was available. The new model had a symmetrical front panel, which many people preferred to the original’s asymmetrical design. It was equipped with larger VU meters, and a meter range switch.

In 1979 Phase Linear released the final iteration of the amplifier, which was the 700 Series II. It had an entirely new look, with a brushed gold front panel, and LED level meters replacing the old VU meters. It also had improved performance, with higher output and lower distortion than previous models.

The Rise and Fall of Phase Linear

In addition to the Model 700 amplifier, Phase Linear produced a number of extraordinary other products. Their second amplifier was the Phase Linear 400 which produced 200 watts per channel. It shared the same distinctive look as the 700. It retailed for just under $500, making it a great alternative for people, and was a big seller.

Phase Linear also produced the remarkable Model 4000 “auto-correlation” preamplifier in 1973. It was a design collaboration by Bob Carver and Bill Skinner. It was notable for several innovative features that set it apart from other preamplifiers, such as auto-correlation noise reduction, dynamic range expansion designed to restore the dynamic range of recordings that had been compressed during the production process, and some quadraphonic capabilities, as this was quadraphonic audio era. There were two versions of this product released, the original and the Series two.

In 1978, the company produced their most powerful amplifier, Dual 500 (also known as the D-500). Like the 700, it was a stereo power amplifier, and it put out a staggering 505 watts of clean power per channel.

Phase Linear also produced a remarkable loudspeaker, the Model III “Andromeda”, which was a three part (subwoofer and two panel speakers) system with multiple drivers.

In 1979 Bob Carver decided to sell the company to Pioneer, and Phase Linear entered into a period of decline. The company produced a few new products under the brand, but they were not as innovative or ground breaking as those produced during the Carver era. The company changed hands a few more times in the 1980s, and the brand was finally discontinued shortly thereafter.

Phase Linear 700: Induction into the Hi-Fi Hall of Fame

The Phase Linear 700 power amplifier was a game changer in the Hi-Fi world when it was introduced. There was no other amplifier that offered this amount of clean power. It triggered a race to produce ultra high powered amplifiers to drive the inefficient speakers that were popular in the 1970s.

The amplifier also established Bob Carver as a brilliant audio designer. He went on to develop many innovative and superb products for other companies, including Carver Corporation, Sunfire, and the Bob Carver Company.

More than 50 years after it’s introduction, the Phase Linear 700 remains a highly coveted and collectible amplifier.

For all of these reasons, the Phase Linear 700 is inducted into the Hi-Fi Hall of Fame.