Mac MC240

1. Hi/Lo voltage 115/117 switch
2. Mullard 12AX7/ Amperex 12AU7/ RCA 12BH7 bk plate/ US brand 7027A instead of 6L6GC not Russian tubes
3. Home brew pure silver cable/ NBS Master speaker cable

Thanks Chang. For the Amperex 12au7, do I need the bugle boy or just amperex from USA (or Holland) is good? For the power tubes, I'll stick with my RCA 6L6GC black plate. Did you do the silver cable yourself? Or actually you have some for sale?

Thanks again.

We have 4 MC240s among our friends. The bugle boy nor Amperex (both made in Holland) makes no difference. If you want the best 12AU7s then go with Amperex 7316 tubes.
Cleaner without loosing the nice sounding. Even the Telefunken 12AU7s are nice too.
Reason why we didn't like the RCA 6L6GC bk plate vs say RCA or GE 7027A is the lower freq control. The RCA 6L6GC bk plate sounded very loose and lack of control for lower frequency response. The 7027As are much tighter and more dynamic and it is not thin sounding.
Yes, I'd designed and made my own silver cable after went threw over a dozen speaker cables and 50 interconnect RCA cables.
Just a hobbiest not a businessman.

Hope this helps.

Thanks again Chang. (By the way, are you the Chang of the "Chang" filter?) I'll have a look in my tubes drawer and see whethe rI have the 7316 (most probably not), then I'll take your advise to try the Telef diamond bottom 12au7. Really.....I have tried the RCA bk plate, but with another amp, they didn't sound as you said and I really enjoyed the low. It could be the 240 is "sweet" and "thick" itself and if using the bk plate, it will be toooooo fat and as exactly as what you said. For the 7027A, is it a driect replacement of 6l6gc (plug and play)? I'll look for them.

Thanks again.

Yes the 7027A are direct replacement in the case of MC240.
Telefunken 12AU7s are more smooth and refined but less dynamic and punchy when compared to Amperex 12AU7s.