Audio Innovations Series 1000 and Second Audio

[mike4kim]

Hi,

I am new to this forum.
About 30 years ago, I have bought AI Series 1000 Pre-amplifier, and Second Audio 2A3 8-pin version Mono Blocks.
During last 30 years, I enjoyed the sound quality of the system with great satisfaction, but recently the system started to show its age.
Loud hums and noises when powered on, which made me think of the valve replacement. Then I found that 2A3 valves on the mark are 4 pin based.

To bring my system to the repair shop, it might help to replace sockets and valves if I can bring the schematics of AI Series 1000 Pre-amplifier and Second Audio Power Mono Blocks, since Audio Innovations products were not popular in my country, South Korea.

Is there a way to get it?
I hope I could get some help on this.
Thanks

 

[Eli Duttman]

Power supply electrolytic capacitors that old are always suspect, when hum develops over time.

No ifs, buts, or maybes the 2A3 has never been anything other than UX4 based. The 6B4G is Octal based and, except for the base and filament voltage, electrically equivalent to the 2A3.

 

[euro21]

The power amplifier is the beautiful Audio Innovations "The second" 2A3 push-pull amp.

Audio Innovations - Page 4 - Owners Clubs and Forums - HiFi WigWam

The power tube probably Svetlana 6BG4 (similar characteristic, than 2A3), which originally has octal base and 6.3V filament.

 

[mike4kim]

Thanks a lot for quick reply.
The valves are as shipped, and show as attached photo. The letter on valve shows '2A3 Octal' by Shuguang.

 

[Koonw]

Second Audio Power Mono Blocks schematic

 

[Hooch500]

You can contact Guy Sergeant at info@puresound.info if you need tech help.

FWIW they are fabulous sounding amps - I should have hung on to mine.

 

[mike4kim]

My Second Audio valves as shipped by AI

Here goes the photo of 2A3 valve on my Second Audio as shipped by AI.

It says 2A3 Octal, made by Shuguang of China.

 

[mike4kim]

Thanks for the help

Thanks a lot for the quick replies, which gave me an understanding of what I have to do. Also, the schematics of Fist Audio will help me fix the issues.

Have a good day.