Contact Information
Web Site Search
Intercom Repair Request Form
NuTone IK15 & IK25 DoorCom Systems
Vintage NuTone Intercom Catalogs
Donations

Rebuilding a NuTone 2400 Stereo Music Intercom System Amplifier and Tuner

Wednesday
Oct102012

Workon the 2400 begins

Back in 1962 one of the coolest and rarest NuTone Intercom models was the 2400 Stereo Music Intercom System. The 2400 consisted of 4 main components, a stereo amplifier, stereo AM/FM tuner, stereo turntable and either the optional stereo reel-to-reel tape player or a the less expensive LP record storage unit.

The stereo amplifier and tuner are vacuum tube designs, which makes them exceptionally rare and cool today. What most people don't realize is that back in 1962 FM radio was still a fairly new idea as was stereo music. NuTone's decision to design and build a stereo music intercom system would be equal to Apple's decision to design and build the first iPod. The model 2402 stereo AM/FM tuner places NuTone in the same company as Fisher, Magnavox, Sherwood and Scott for designing stereo tuners.

This 2401 amplifier and 2402 tuner arrived at the shop in basically all original condition. Neither unit works and they definitely are in need of rebuilding. Working on tube equipment is different than modern solid-state models. The 2401 and 2402 are hand assembled models with point-to-point wiring and they use electronic components that are unique and difficult to replace with today's modern parts.

The first order of business was to clean both units, they were covered with 50 years of dirt and dust. A simple and gentle method of cleaning these units is to use a soft bristle brush and a vacuum to sweep away the dirt.

 

After the cleaning it's time to test the tubes. The 2401 amplifier has 10 vacuum tubes, 6 of the tubes tested bad. One interesting discovery was that the 4 pre-amp tubes have been replaced with higher quality tubes. NuTone typically used Mullard brand tubes in their intercom sets, original tubes will be stamped with the NuTone logo. In the 2401 I found that the 4 12AX7 preamp tubes were vintage Telefunken brand German tubes.

 

Telefunken tubes are highly sought after by audiophiles for their high quality and smooth sound. Finding this high level of tube in the 2401 must mean that a previous owner cared a lot about have their system sound as good as it could.

Testing on the 2402 tuner was next. The 2402 has 11 vacuum tubes, 7 of the tubes tested bad. This was not to surprising because all the tubes in the tuner were original NuTone labeled tubes.

Along with the replacement tubes other various parts are planed to be replaced. These models use various capacitors which after 50 years need replacement. In the 2401 there is a Selenium Rectifier that must be replaced with a modern Silicon diode.

Tubes and parts have been ordered and should be delivered next week, more to come...

See all of the 2400 project pictures here.