Affordable, Quality Audio Repairs & Restorations

Phone: 519-513-1084

Email: repairs@dnaelectronics.ca

Address: 15 Shaftsbury Dr. Kitchener, ON, Canada

Quality, Reliable Restorations by Experienced Father & Son Technicians. We Take Pride in our Workmanship.

Receivers | Power Amplifiers | Integrated Amplifiers | Preamplifiers | Tuners

D 'n A Topics & Resources

Restoration Information

General information about our restoration work, and pricing information for various models.

Audio Specifications Database

We are compiling a database of audio equipment specifications gleaned from our annual equipment directory magazines, owner's manuals, service manuals, etc.

Audio Picture Gallery

Pictures of some of the equipment we've worked on, with occasional commentary.

Our Testing Procedures

We test the audio components we restore to ensure they perform at least as well as expected. This is both an overview of our measuring procedures, and an attempt to make clear exactly what is being measured.

FAQ

Answers to some frequently asked questions.

Phase Linear Dual 500 Gallery

The Phase Linear Dual 500 is a class B amplifier rated at a whopping 505 Watts per channel. You can check out the specs here.

Although the front panel says the amplifier is "Series Two," to the best of my knowledge there has never been a Series One Dual 500.

If you have a Phase Linear Dual 500 amplifier that is in need of repair, call us at (519)513-1084, or email your enquiry to repairs@dnaelectronics.ca.

Phase Linear Dual 500 Power Amplifier picture

The LED display PCB.

In order to get 505 Watts per channel at the rated distortion with both channels driven out of this (or any other very high power) amplifier, you will need a dependable 120 VAC source. If the AC line sags, so will the amp's output.

The power transformer is very big. The picture doesn't really do it justice.

The replacement filter cans. Originally, the Dual 500 has two 13000 uF cans (13000 uF per rail). We paralleled two 8200 uF 200V cans per rail, for 16400 uF per rail.

In the HI-Z mode, the rail voltages are ±120 volts. In this mode, the replacement capacitors store 118 joules of energy per rail! In the LO-Z mode, the rail voltages are ±85 volts. We used copper sheet metal to strap the terminals of the new capacitors together.

The front panel has LED power meters, level controls, a power switch, and a speaker impedance switch labelled HI-Z / LOW-Z. With speaker loads greater than 4 Ω, you use the HI-Z mode. With 4 Ω speakers, you use the LOW-Z mode. In the LOW-Z mode, the rail voltage drops from ±120 volts to ±85 volts.

When the amp clips into an 8 Ω load for any length of time, it automatically switches to the LOW-Z mode. This causes the rail voltages to drop considerably, and the amp clips even worse (assuming the operator does not reduce the output level).

Sponsored Link

Although they manufactured preamplifiers and tuners, audio power amplifiers were Phase Linear's bread and butter.

The cooling fan comes on when the heatsink reaches about 58° C. The Dual 500 has sixteen output transistors per channel! They are all NPN.

D 'n A Electronics is a Father & Son business located in Kitchener, Ontario, Canada. We specialize in restoring hi-fidelity audio power amplifiers, integrated amplifiers, preamplifiers, receivers, and tuners. We've been repairing vintage audio equipment since long before it was considered vintage! It is our goal, and pleasure, to reliably restore hi-fi audio equipment to original operating condition (or better!). We accept shipments from across Canada, and many customers from Kitchener, Waterloo, Cambridge, Guelph, Hamilton, London, Toronto and surrounding areas find us to be within convenient driving distance. Thank-you for visiting our website, we look forward to serving you!