Please, after buying this item, check out my other items for more of these MB-20. I will always combine shipping to save you money.
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1950s Ampex
Monitor Amplifier and Power Supply.
Schematic has it as a 402P (3680) which is very rare.
Being offered for parts or repair.
According to the last owner, this has been in storage since 1971.
Good news is, it has the schematic attached to the bottom plate.
One transformer is not original.
Here is some info I found about this from a past sale- This is the only info I can find on this. These are not my words, but the words of another seller from the past.
AMPEX 3680 full tube power monitor amp including Power Supply Unit Section 402P.
Vintage, Made in the USA in 1953.This is a special order for the US Army with model name OA-584/TNH-2 Description: Very rare professional studio power amplifier by Ampex. It was produced in 1953 in limited numbers of no exceeding a few hundred units at the most. Most of these were ordered by the US Army. The 402 P unit includes power amplifier model 3680 + 2 power supply units model 3741. One psu is devoted to the 3680 power amplifier and the second one can provide power to a 402, 403 or 350 Ampex microphone preamplifier. This is the best power amplifier Ampex ever produced. Ultra linear, 3-dimensional, absolutely silent, with full-bodied sound. It's obvious that Ampex used the best materials in making these few hundred 3680's. Forget about the onboard speaker. Use the 8ohm speaker output and simply connect it to an efficient studio monitor and wow...! This is an incredible studio monitor amp with huge headroom and VERY loud. From a large collection of tube related gear. This is not tested in any way. Needs work. As-is Sale. Please see the photos. Dated 1953.
Shipping will be a calculated for a very well packed and extra insulated package.
Being offered at a very fair Buy It Now.