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, November 18, 2015

Capehart Panamuse A-10 Amplifier Renovation Part 1

Radio/Phonograph console from 40's with field coil speakers.

"Panamuse" line had many models but almost use 2 chassis of power amplifier inside.

M-2 amplifier chassis called A-10:

9 tubes for 20 watt and two 12" "Precision tone loudspeakers" (Jensen).
Tubes: 6R7 phase inverter, 6C8G driver, 4 x 6V6G, 3 x 5Y3G.

M-3 amplifier chassis called A-9:

6 tubes for 10 watt for one 12 " speaker.
Tubes: 6R7 phase inverter, 6SC7 driver, 2 x 6V6G, 2 x 5Y3G.

More pictures in link below.

My friend have got 2 chassis of A-10 from ebay but had some different parts.

One chassis follow A-10 information above but other had 6J5 replace 6R7 position.

Different capacitors and the coolest part in 40's - Phase Splitter Autoformer. ;)

First one with 6R7, 6C8G and silver can autoformer.

Other with 6J5, 6C8G and black box autoformer.

Top view of 2 different chassis.

4 of 6V6G tubes in parallel push pull mode.

Parallel 5Y3G in rectify section.

Very old capacitor but still cool-looking until today.

Bottom view/ components inside.

All cloth wires from that day.

Almost wax capacitors were melt and capacitance had changed.

Old & cool style components layout on papers.

My friend need to renovate these amplifiers into new chassis and get rid of different parts.

Modify circuit both amplify and rectify sections

because of they had no field coil to use as filter choke and adapt to easily use in system.

Continue in part 2 after finish renovation these 75 year old amplifiers.

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