Nattawut Uamkruea, blogger and audio gear maker who passionate in vacuum tube, audio & music.
Producing electronics projects since high school. Seriously upgrade and modify vintage audio equipment for “Real Sound” concept.
He is a co-founder of Soundaries and Sentimental Studio, all audio solution provider.
Experienced and lively explore the listening rooms & audio shops in Japan as his most favorite to do.

Wednesday, October 21, 2015

Altec 9476A Monitor Amplifier

I've got this pair of Altec 9476A from ebay without amplifier boards and metal covers.

But other components are valuable to rebuild.

See link below for complete operating instruction.

This is 8 watt monitor amplifier @ 4 ohm unbalanced or 150/600 ohm balanced load.

Use external module power supply (Altec 9550A) for two 9476A mounting on the tray.

Original schematic use 2N3055 power transistors operate in push-pull

and coupling with a huge value capacitor (5,000 uF) for 4 ohm load.

Really worth for money are input and output transformers,

Peerless 4814 (10k : 60k) input transformer

and Peerless 16688 (4 : 150/600) output transformer.

Output transformer can reverse to 600 : 4 ohm, easier to find coupling capacitor.

Pair of Altec 9476A amplifiers.

Coupling capacitor and filter capacitor are same value. ;)

Missing amplifier board at the slot.

RCA 2SK3027 replace 2N3055 ?

Bottom side of amplifier.

Peerless 4814 input transformer with complete audio frequency response.

Peerless 16688 output transformer, larger than spec !

I think build tube amplifier with these transformers in original casing will more interesting

than find an amplifier board or make a new solid state amplifier.

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