Hi everyone,
I'm a newbie here, so having newbies' questions ; maybe already been discussed thru the 107 pages ...?
So, got this MHHA, mine is a copy of this just acceptable amp (like Bravo/Indeed/Muse ...).
Sure everyone here started the same tweaks, changing those VERY BAD parts :
1. chinese 6N11 tube >> RCA made ECC88, waiting for a NOS Sylvania made 6DJ8
2. under rated / low cost power caps >> Panasonic/Elna 35/50V ones + bypass caps (if not)
3. standard IRF630 MosFETs >> more 'musical' IRL510 ones (or IRL530 or 2SK310 ...)
4. standard Elna RJJ output caps >> 'dedicated for audio' ones
(mine are NOS Elna like ROA/RW5 miniaturized, 105°C, bypassed w/ ERO/Vishay MKP1837 22nF)
5. output Dale metal layer resistors >> Welwyn wirewound 47R
6. input ground resistor 8,2K >> 91K 1/2W
+ also have to change the input resistor (!!!) to a Cap (obviously) : NOS Sprague 150nF 100V will fit
+ the mediocre potentiometer (to small ALPS RK09)
So ... my question is : since I changed the MosFET, the IRL and the LM317 became hot, I mean VERY HOOOT !
Is it something I could fix or did I make something wrong ? I changed to massive heatsinks, still hot (maybe > 40°C).
I checked and ajusted the bias, but : I can read 13,5V here, or 15V there, dunno what value's the best ...
(but my sh## was initially set to ~10V @ R and 6V @ L !... did I say BAD ?)
My power supply is 19V, not 24V (I'm in France, EU, and the stuff came from China with a plug only for UK I guess) ; I have a 24V tomorrow.
Whatever if I can fix that or not, these little mods really worth to switch on the iron !! Now closer to an audiophile product.