Model Forty Open-Reel Tape Recorder

The KLH Model Forty was a groundbreaking open-reel tape recorder with several notable features:

1. It was the first consumer product to incorporate Dolby B noise reduction technology.
2. The recorder featured a 3-motor, 3-head design and offered 2 tape speeds (7½ and 3¾ inches per second).
3. Its electronics were military-spec and built on glass epoxy boards, which was uncommon for consumer products at the time.
4. The device used all solenoid controls for operation.
5. It was a substantial piece of equipment, weighing approximately 50-60 lbs.
6. The Model Forty had a solid walnut cabinet and a thick aluminum faceplate, contributing to its high-quality construction and aesthetic appeal.
7. It was manufactured in 1968-1969.

According to the Wireless World November 1969 review, KLH claimed that the Model Forty set a new standard at 3¾ ips, comparing favourably with studio machines operating at 15 ips. Demonstrations at the time showed that recordings made on the Model Forty were indistinguishable from those made on professional machines, with some listeners noting that "the only difference they heard was $2,900!"

The review also mentioned an interesting feature: the Model Forty had only one VU meter that read both stereo channels, indicating the louder of the two at any given moment. The meter could be switched to either channel, though the reviewer expressed a preference for two separate meters.

The KLH Model Forty was priced at $600 (approximately £250 at the time), which the reviewer considered good value.

Despite its innovative features and excellent sound quality, the Model Forty had reliability issues. Many users reported problems with the transport switches arcing, cheap open frame relays failing, brittle plastic parts, and belt issues. These reliability concerns led to KLH buying back many units and struggling to sell them to dealers.

The KLH Model Forty was a pioneering consumer reel-to-reel tape recorder that offered studio-quality sound and innovative features but was plagued by reliability issues throughout its lifespan.

Here you find 23 models, 21 with images and 5 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from KLH R&D Co.; Cambridge (MA)