16/09/2024
Right then..... Now the KEFs have gone to their new owner; it's fine to embark on the next project.
A 1972 Rank Audio RA-210 amplifier. This lovely little amplifier is a rebranded Rotel RA-210. A Wooden cased, aluminium fronted compact thing.
It's a very basic and very simple little amplifier. 8 watts....yes...that's 8 watts per channel into an 8 ohm load. It won't blow your windows out or rattle your neighbours.
The best thing about this particular one is that it is fully boxed with all paperwork.
Does it work?..... Yes.... although taking into the age of it; I'll be promptly replacing every last capacitor in it. Thankfully; as it is considered a low end amplifier; every electrolytic capacitor used in it are common values (1μF, 10μF, 33μF, 47μF, 100μF, 470μF and 1000μF). This makes replacing them easy as there are no funky value ones. I'll be replacing the 2 main filtering capacitors (1000μF) with 105°C Axial Nichicon ones.
The rest of the electrolytics will be replaced with Nichicon FW series Audio grade capacitors. This will massively improve the sound quality. It may seem like overkill to install premium capacitors in such a basic amplifier but I strive for exceptional quality when I refurbish the kit and I have these capacitors in and I want the very best reliability and sound quality for this little amplifier. Using cheap capacitors just isn't an option.
Now the polyester capacitors used should all be fine as these rarely drift from their factory value. That said; I'll still check them all. Same goes for the resistors.... especially the ones for the power amplifier section. I'll also check the idle current and DC offset for the Matsush*ta brand 2SD317 output power transistors. These can be somewhat problematic due to power on/off cycles and thermal breakdown. I may end up replacing these with the more rugged Hitachi 2SD476. I'm not too sure yet.
Audio inputs are DIN opposed to RCA. A simple DIN to RCA female cable will sort this. Speaker outputs are by means of a 2 pin din. This will remain unchanged.
Switches and pots will be cleaned.
Speaker wise. There are some nice vintage options that could be used. The Wharfedale Denton 1 and 2, The MK I Lintons, The Denton XP, Sheldon XP, Celestion Ditton 11 and Ditton 15, KEF Cadenza and Corelli to name some. These will all happily run with very little wattage. Impedance wise. 8 ohms is preferable although this amplifier will run 6 ohms and sailing close to the wind; 4 ohms.
I wouldn't recommend 4 ohms as the amplifier would run rather warm and will be pushing the output transistors close to their limit. Anything lower than this would obliterate the output transistors and release the magic smoke with spectacular results.
I'm going to ensure this little amplifier is refurbished to the same high standard as all the kit I refurbish.
This would suit someone where space is limited and they don't want to eject the pictures off their neighbours walls and they want to get into viny.
This amplifier has a very small footprint and won't take up much space.
Anyway....
Until this amplifier arrives and I get my grubby little paws on it; here's a picture of the amplifier. The exact one we're getting in..
Watch this space....
