Sound Technology Test Equipment

In the 1970s and 1980s Sound Technology test equipment was the best you could get but somewhere along the line the company faded from the headlines. The first dedicated audio test equipment I used professionally was the Radford low distortion oscillator and matching Distortion Measuring System in the 1960s. When I moved to Cambridge Audio at the start of the 1970s I was introduced to the Hewlett Packard 334A which was a dramatic step forward because it had automatic tuning so having set the level the distortion figure could be read directly.  When used with the Radford LDO it could be usefully used to read down to about 0.01% distortion.

However there was a dramatic change around 1970 when Sound Technology appeared on the scene.  A group of ex-HP engineers had got together to design some excellent equipment which was both accurate and quick and easy to use.  The first product was the model 1000A FM Stereo Alignment Generator. We bought a load of these instruments to use in the factory and also became the UK distributors of the product line.

The 1000A was quickly followed by the model 1700A which was a state of the art audio measuring system which could read distortion (THD) down to 0.001% and whose auto-tuning was super-fast.  Indeed we ran an advertisement for the 1700A which read “Testing, testing, tested”.  Once again Cambridge Audio used this system throughout the factory; after which it was sold to Lecson, Quad and others and rapidly became the industry standard instrument. The oscillator section was available as a separate instrument the 1400A. The 1700B appeared next which offered several upgrades.

I personally used the 1700B until I changed to the Hewlett Packard 8903 in the 1980s and then to Audio Precision gear in the 1990s.  I found Sound Technology equipment very easy to use and very reliable.  Indeed I only sold my last 1700B about a year ago and actually found I still had three of the model 1000A generators at the back of the garage.

Sometime in the 1990s the company moved into computer based testing and whilst they still service old equipment they don't appear to provide support or manuals

“Googling” the company brings up very few hits and servicing information seems to be hard to find so I have scanned copies of the User/Service Manuals for the models 1000A; 1100A and 1700B together with the original literature; some reviews and some advertisements.  If you need them go ahead and download them in PDF format.

And if anybody can add anything to my short story of Sound Technology please contact me and I’ll add what you know to this page.

A lot of this equipment is still in use but there is virtually no information on the web. Here you'll find manuals and literature and in time I'll add more information. The pictures below show the 1700B Distortion Analyser and the 1000A Stereo FM Measuring System. Below the pictures you'll find PDFs of the manuals and some literature.

Some new pieces of literature below have been added courtesy of Fred Rosenberg. Thanks Fred !

If you would like to upgrade the ST 1000A there is a great article here by Brian Beezley. I've tried the mods and they are really worth doing.

The famous 1700B Distortion Measurement System followed the 1700A and was the ultimate measurement system in the early 1970s

Inside the 1700B

The ST-1000A FM Alignment Generator was Sound Tech's first instrument and was an immediate sucess.

The picture shows the grey box which was an optional module which offered much higher specifications for the stereo separation between channels

I wonder what ever happened to Willene who assembled this 1000A ? She'll definitely be retired by now.

The RF Generator box showing the external adjustments

An inside shot showing the piston type attenuator

The inside view of the one transistor RF oscillator

The 1400A low distortion Oscillator was the oscillator section of the 1700A built into a separate case.

The 1701A Distortion Measurement System was a Pro Audio version of the model 1700A with the addition of an Intermodulation distortion measurement system installed in the middle of the top panel.

A rather battle weary model 1710A which added the IM distortion and a pro-sound output level attenuator

Another popular product was the 1200A Test Panel which could be used with the 1700A & B. It greatly simplified the task of wiring up a test system since the test equipment and the item under test could be wired direct to the 1200A then all the usual inconvenient cable swapping was avoided by the use of the comprehensive front panel switches. I must admit that I looked at the design and the price tag then promptly built my own copy.

The model 1020A FM Alignment Generator was the follow on model to the 1000A and was styled in the Sound Technology family look. It is a very rare beast and I've only ever seen a couple in the UK. Here an example shown with the IF Conversion accesory box sitting on top. The original brochure from the early 1980s can be downloaded below together with some servicing information. These are rather poor copies of the schematics & board layouts. Not ideal but enough to get you out of trouble

A couple of close up pictures of the front panel of the Sound Tech 1020A

The model 1510A Tape Recorder Test System was a sophisticated test system for tape recorders and record players and ST supplied matching Test Tapes and an LP Test Record.

It can measure:

  • AC Volts
  • Phasing
  • 2nd harmonic distortion vs level
  • 3rd harmonic distortion vs level
  • Frequency response
  • Channel separation
  • Noise, composite and spectral
  • Change in speed and drift
  • Wow and flutter, average and spectral
  • Dropout vs time

The 1510A is a microprocessor-controlled analyser which runs automated tests and displays both alphanumeric and graphically displayed test results on the built-in CRT monitor. Photocopies of the model 1500A and 1510A operating and service manuals can be bought from

We now have the Operating Manual for the 1510A thanks to Duke Aguiar of Duke Aguiar Engineering Services in Thousand Oaks, California. (email: You can download it below.

ST offered two matching transformers to cover 50 ohm; 75 ohm and 300 ohm applications. Inside the box was a simple balun transformer. It has previously been very difficult to get the manuals and circuits of these products so I've added some of them to this site together with a few other downloads that might interest particular visitors. If anyone has any documents they'd like to add I'll be happy to host them here.

RADFORD .......For those people interested in these iconoc British test instruments I've put a manual below

Downloads <click on the logo to download>

The full manual for the ST-1000A

Literature etc for the model ST-1000A

Circuit Schematic for the model ST-1000A

The full manual for the model 1700B --This is a huge 40 Mb document so it might take a minute or two to download

Literature etc for the model 1700B

The original brochure for the model 1020A FM Alignment Generator


Some basic service information (schematics & board layouts) for the model 1701A Distortion Measurement System. Only a few of the circuits but includes the important oscillator circuits. The rest of the circuits are very similar to the model 1700A and B including the power supply which is not shown here


Operating Manual for the 1510A Tape Recorder Test System

Service Manual for the RADFORD Low Distortion Oscillator Series 3 version

Operating Manual for the 1020A

Manual for the 1100A Alignment Unit

How to make Audio Measurements

How to align Stereo Receivers

FM Alignment Generator Overview

Buckhard Notes on 1000A Generator

Electronics World Review of 1000A Generator

Pacific Stereo Sales advert

Open Letter Sales advert



• Copyright 2009, 2010
Stan Curtis the hi-fi guru -Sound Technology test equipment - 1000A - 1100A - 1700A - 1400A - 1700B - 1701A - 1710A - 1400B - 1500A - 1510A - 1200A - 1020A -