Quote:
Originally Posted by punk_guy182 /img/forum/go_quote.gif
Eveer thought of making your own amps and compete with Little Dot?
|
No, I think use MK IV as the base to mod and improve sound quality is much better and fun. For DIY projects, chassis and transformer is not easy to get quality like Little Dot.
MK IV basically uses MJ circuit similar to
this, just a few resistor value changes for 6AK5 and 6H30.
So far I have changed:
1. Added 1.2ohm/3W resistor on 6H30Pi heater (absolutely necessary)
2. Replaced 150ohm/1W plate and cathode resistor to 2W ones (highly recommended)
3. Replaced 7805 + 2 x 1N4001 for 6AK5 heater to LT1084 w/ bigger heatsink (recommended)
4. Changed 1000uf/35V and 220uf/25v 7805 power filter cap to panasonic FM (stock was UCC KYZ, probably OK quality)
5. Changed all 1/4w resistors to good quality dale, irc, and m/e ones, with hand matched on left/right channel. The only 4 left (2x 220K, 100K) near the dip switch are for lower impedance headphones, which I don't have to change. (not necessary if you already have IV SE)
6. Replaced the EF92 selection jumper to good quality switch.
7. Replaced the cathode capacitor 220uf/16V UCC SMH to Elna Silmic II 220uf/25V.
8. Shorted the input coupling capacitor 2.2uf MKP.
Next I will try to play with power filter caps (3 x 470uf/250V, 2 x 0.047uf) and output capacitor (2 x 330uf/200v, 2 x 2.2uf WIMA MKS4, 2 x 0.22uf) and the feedback capacitor 0.47uf/250v between 6H30 upper and lower section after my 6H30-DR and Silmic II caps burn in. The output cap probably will be the most bang of bucks. Ultimately I probably will build an external power supply or internal regulated power supply for 200V.