Here's a little story about modifications of one of the most popular tube preamplifier that is coming from China - Yaqin MS12-B. Although it's interesting at the first look and quite good sounding, and total refreshment after solid state devices, I have decided to make a complete make over - inside and outside. Well, as much as I could or found it was necessary.
The changes include replacement of all main caps, excluding those of power, phono and power resistors, volume pot, RCA phono sockets, and last but not the least - the annoying aluminum handle!
Here’s the list of all parts used;
6x 1uF 5% 400V PETP K73-16 Capacitors
8X 0.01uF 200V PIO Capacitors K40Y-9
2x 0.1uF K75-10 hybrid
4X Takman REX25 carbon film resistor 1/4W 2%
Alps 50KAX2 LOG type Volume Pot
3X ELNA SILMIC II Caps 25V 220uF
1X ELNA SILMIC II Capacitor 50V 2.2uF
1X Panasonic FC Electrolytic Capacitors 2700uF/25V
22 ohm 10W High Power Resistor
Heavy Duty 30A ON OFF Toggle SWITCH
CMC RCA Sockets Silver Plated 805-2.5AG
wooden front plate and metal spikes
I have removed all Koreans Pilkor blue caps and put all NOS Russians (Soviet era) instead.
Phono RCA are on the left side of the housing now, that way it makes front mask free. For a fun and the new outlook I've placed the little metal dragon emblem on the new wooden fascia. 2012 is the dragon year in China and it's cool to mark the work that way. Although it’s more international unit now and has mixture of parts from China, Russia, USA and UK that makes it totally different device from what it was before.
Different look that is also much more practical, so no more obstacles of the aluminum handle.
But what’s most important – the sound! There is so much more transparency, beefier sound, details,... No more boomy bass and totally get rid of the muddy treble or harsh highs that was issue before. Sound is now very clear and crisp as it should be. With all these new capacitors this preamp simply shines. There is no annoying noise on high levels anymore, in fact – no noise at all, even with the volume pot turned to the end (on empty of course). AMAZING!
What I thought before that tubes makes the only difference and spent a lot of money buying and trying various lamps was totally wrong. Some, especially RCA clear tops do ring louder but none does make noise out on speakers - they are all dead quiet. So now no matter what production I put in they all sound better, much much better then before. However of all I have these are my favorites; Sylvania CHS-5751 W1 and Philips JAN 6189W.
No more talking, time to enjoy old music with a brand new sound
and outlook :)