Heathkit Virtual Museum

W-5M 25-Watt Amplifier

W-5M 25-Watt Amplifier


  • Extra performance through special-design output transformer
  • Full 25 watt output with KT66 tubes
  • Simplified balance circuit requires only voltmeter for adjustment
  • Fine bass response, high frequency response, and phase shift characteristics
  • Reduced IM and harmonic distortion

The W-5M Amplifier is considered top value in its power class by leading independent research organizations. It incorporates all the latest advance-design features for the super-critical listener. You can enjoy virtually distortionless reproduction from one of the most outstanding high fidelity amplifiers available—at any price! This amplifier employs a specially designed Peerless output transformer and uses KT66 tubes. Involving entirely new techniques in transformer design, this Peerless unit prevents loss in frequency response, especially at moderate volume levels, in addition to allowing increased power output. The circuit is rated at 25 watts, and will follow instantaneous power peaks of a full orchestra up to 42 watts. Featured also, is the "tweeter saver" which suppresses high frequency oscillation, and a new type balancing circuit. This is easier to adjust, requiring only a voltmeter, and it results in a closer "dynamic" balance between output tubes. Overall results are improved phase shift characteristics, reduced IM and harmonic distortion, and improved frequency response. With complete stability under all dynamic operating conditions.

The frequency response of this amplifier is ± 1 db from 5 to 160,000 CPS at 1 watt and within 2 db from 20 to 20,000 CPS at full 25 watts output. Harmonic distortion is 1% at 25 watts and intermodulation distortion is 1% at 20 watts (60 and 3,000 CPS, 4:1). Hum and noise are 99 db below 25 watts for truly quiet performance. The specifications above were taken with the most modern and accurate test equipment available in 1958. They are actual measurements taken on a typical amplifier, under carefully controlled conditions, not representing the most favorable operating conditions nor advertising information.

All connectors and terminals are located on one side of the chassis apron for convenience. The circuit is fused, and two AC outlets are provided for accessory equipment. One outlet is switch-operated and can be used to automatically turn off record player motor when amplifier is turned off. Provision is made for matching 4, 8 or 16 ohm speakers at a terminal strip on the chassis. The chassis is finished in satin-gold enamel, and all terminals and tube sockets are marked as to type and function. An attractive cover fits over all above-chassis components. This not only "child-proofs" the unit, but it results in a most attractive "finished" appearance. The bottom plate also has large rubber feet to prevent marring of furniture. It is suitable for use in or out of a cabinet. Rich black and gold color harmonizes with the Heathkit model WA-P2 Preamplifier, the Heathkit model FM-3A Tuner, and blends with any room decoration.

Conservatively rated, high quality components are used throughout to insure years of trouble-free performance. Its specifications, completely outlined above, clearly indicate the superiority of this amplifier for the individual who wants "something special" in top-quality audio. The construction manual is written so that no technical background or training is required for assembly. Complete step-by-step instructions are provided for every stage of construction, and large pictorial diagrams illustrate exactly where each wire and component is to be placed.

Specifications—Power Output: 25 watts. Frequency Response: ± 1 db from 5 to 160,000 cps at 1 watt. Harmonic Distortion: 1% at 25 watts. Intermodulation Distortion: 1% at 20 watts (60 and 3,000 cps, 4:1). Hum: 99 db below 25 watts. Damping Factor: 40:1. Input voltage for 25 watts output: 1 volt. Tube complement: 2-12AU7, 2-KT66, 1-5R4GY. Output Transformer: Peerless, Special Design. Power requirements: 105-125 volts, 50/60 cycles, 140 watts. Dimensions: 13 3/32" wide x 8½" deep x 8¼" high. Shipping Weight: 31 lbs.

Back to HiFi & Stereo Kits

Copyright ©2023 by Cyberventures Unlimited.Terms of Use