A push-pull design can be quite spectacular with the right set of speakers. If you're looking to drive high-efficiency, vintage speakers, you can hardly do better than this pair at this price. This exquisite example of the Heathkit W4-AM features a grey hammertone finish, as opposed to the gold tone used on the earlier models. Rest assured, these amps have been fully serviced by a qualified, seasoned tech.
- Production
- 1957-62
- Condition
- 9/10
- Orig. MSRP
- $39.75 (ea)
- Restoration
- Full service check
- Cleaned controls, switches, and chassis
- Recapped as necessary
- New tube complement
- Factory Specs
Type Monaural Amplifier
Circuit Design Williamson-type
Class Class A
Power output 27 watts into 8Ω (mono)
Frequency response 20Hz to 20kHz
Total harmonic distortion 1.4%
Damping factor 28.5
Input sensitivity 2V
Signal to noise ratio 95.2dB
Speaker load impedance 4Ω to 16Ω
Tube Complement 2x 6SN7, 2x 5881, 1x 5V4G
Dimensions 15.25"W x 7"D x 8.5"H
Weight 28 lbs.
- Documentation
Heathkit W4-AM Owner's Manual
- The History of Heathkit
- The Heath Company was founded as an aircraft company in 1911 by Edward Bayard Heath with the purchase of Bates Aeroplane Co, soon renamed to the E.B. Heath Aerial Vehicle Co. Starting in 1926 it sold a light aircraft, the Heath Parasol, in kit form. Heath died during a 1931 test flight. The company reorganized and move...
[ Read More ]
- Liner Notes
The Heathkit W4-AM is a Williamson-type amplifier. The Williamson amplifier is a four-stage, push-pull, Class A triode-output valve audio power amplifier designed by D. T. N. Williamson during World War II. What makes the Williamson design so good? First, it relies on a large amount of negative feedback including a feedback loop that encompasses the entire circuit including the output transformer. This feedback path is from the highest impedance tap on the secondary of the output transformer to the cathode of the first audio stage. Second, no transformer coupling is used between stages, eliminating a major frequency dependent component. And third, a clever circuit is used to convert the single ended audio into split phase audio without the need of an interstage transformer.
Literally thousands of people have built and used Heathkit Williamson-type amplifiers. They represent a large majority of the units of this type now in use throughout the audio-conscious world. Your Heathkit model W4-AM amplifier incorporates all the worthwhile improvements and modifications resulting from this unequaled background.
- Stock No.
- 7438282064093
A push-pull design can be quite spectacular with the right set of speakers. If you're looking to drive high-efficiency, vintage speakers, you can hardly do better than this pair at this price. This exquisite example of the Heathkit W4-AM features a grey hammertone finish, as opposed to the gold tone used on the earlier models. Rest assured, these amps have been fully serviced by a qualified, seasoned tech.
Production
1957-62
Condition
9/10
Orig. MSRP
$39.75 (ea)
Restoration
- Full service check
- Cleaned controls, switches, and chassis
- Recapped as necessary
- New tube complement
Factory Specs
Type Monaural Amplifier
Circuit Design Williamson-type
Class Class A
Power output 27 watts into 8Ω (mono)
Frequency response 20Hz to 20kHz
Total harmonic distortion 1.4%
Damping factor 28.5
Input sensitivity 2V
Signal to noise ratio 95.2dB
Speaker load impedance 4Ω to 16Ω
Tube Complement 2x 6SN7, 2x 5881, 1x 5V4G
Dimensions 15.25"W x 7"D x 8.5"H
Weight 28 lbs.
Documentation
Heathkit W4-AM Owner's Manual
The History of Heathkit
The Heath Company was founded as an aircraft company in 1911 by Edward Bayard Heath with the purchase of Bates Aeroplane Co, soon renamed to the E.B. Heath Aerial Vehicle Co. Starting in 1926 it sold a light aircraft, the Heath Parasol, in kit form. Heath died during a 1931 test flight. The company reorganized and move...
[ Read More ]
Liner Notes
The Heathkit W4-AM is a Williamson-type amplifier. The Williamson amplifier is a four-stage, push-pull, Class A triode-output valve audio power amplifier designed by D. T. N. Williamson during World War II. What makes the Williamson design so good? First, it relies on a large amount of negative feedback including a feedback loop that encompasses the entire circuit including the output transformer. This feedback path is from the highest impedance tap on the secondary of the output transformer to the cathode of the first audio stage. Second, no transformer coupling is used between stages, eliminating a major frequency dependent component. And third, a clever circuit is used to convert the single ended audio into split phase audio without the need of an interstage transformer.
Literally thousands of people have built and used Heathkit Williamson-type amplifiers. They represent a large majority of the units of this type now in use throughout the audio-conscious world. Your Heathkit model W4-AM amplifier incorporates all the worthwhile improvements and modifications resulting from this unequaled background.
Stock No.
7438282064093
