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VOX AC 50


This VOX AC50 started its career with an ambitious local pop band. They sold it on to a Ten-Sing group and its life as a public performer ended thereafter. I bought it from the carpenter who built the loudspeaker cabinet. They are both gone from this world. The Gibson Les Paul 55 remake was sold to and "used up" by a bandleader. It had a good life and may still be around.

Recent Technical Situation

The amplifier had been in storage for over 30 years. Time and people came together to work on the internals. Electronic Engineer Amund Amundsen who lights up when the tubes glow came in his VOXwagen. Three housevisits later the AC50 played again.

Day one, assessment day:

After cleaning of chassis and fuse contacts, power was switched on with the valves connected.

The green resistor had taken the heat and swelled. The GZ34 tube was defect. Modern replacement parts were ordered and arrived the next day from ELFA Distrelec; a GZ34 tube was cribbed from a defect AC30 within reach.

Day two, repairs:

The modern parts were much smaller than the old ones so aluminium was bent to compensate. It is only right to say that the engineer would have soldered the joints better than me.

Parts list:

4 Aluminium Electrolytic Capacitor 68 uF, EEUEE2G680, Panasonic Automotive & Industrial Systems

1 Fusible resistor 22 Ohm 5 % 5 W, ULW5-22RJT075, Welwyn

Heat-shrink tubing black 6 mmx2 mmx1.2 m, 5677572005, TE Connectivity

4 200kOhm 1W / 5% resistors were procured late in the evening from Amund's brother in law.

Day three, final check:

We were all nervous as the voltages had been read both as 6-700 and more volts. An 8 ohm Electrovoice EVM-12L 12" guitar speaker mounted in a Valand-Stange cabinet was connected. For a period feel, a mid-sixties Guild Capri was hooked up to the brilliant channel.

The AC50 was playing again, so sweetly and so powerfully. Handle with care.

The chassis in its original cabinet, and photos were taken:

Helpful sites

http://www.voxshowroom.com

http://www.voxac50.org.uk

https://www.elfadistrelec.no

Dating this AC50

Black plastic mains switch from 1965/66.

Voltage selector from 1965/66.

Serial number 02175 late 1964?

It is likely that this AC50 and my AC30 were shipped and sold at the same time, from the same shop to the same band. Comparing details shows only one diffference; the rotary voltage selector on the AC50 and a blanked out selector on the AC30. There is nothing underneath this original VOX blanking plate. Was this for the export only models?

The AC30 was dated from its original loudspeakers, and gives February 1966 as its production date. San Fransisco's "Summer of Love" was 1967.

Dating! the band, The Moonspinners.

Established 1965, Haugesund. First year bassist Leif Hausken was a cousin probably once removed. Have I got "his" AC50? AC50 and VOX cabinet showing in old photos at http://www.rogalyd.no/artist/the-moonspinners

pop band The Moonspinners

Dating (again an exclamation mark!) Key-Stone Singers:

Established 1968, Haugesund.

http://www.rogalyd.no/artist/keystone-ten-sing

Spot the AC50 and speaker cabinet from the photos at the top of this page.

A VOX speaker cabinet from the same story, 1973.