Originally Posted by AgentXXL
The 'component spec changes' you mentioned - were they just in the op-amps used? If so, would you mind telling us what you used and why? While I'm still reluctant to make any changes to my new E9 right now, I'm definitely curious as to what you chose and why.
PS: the build looks great!
For op-amp choices, I would suggest looking at some of the op-amp rolling guides on head-fi and diyaudio. You won't be short of choices depending on the sound signature you are looking for. Also keep in mind op-amp sound signature may differ between amps as well.
For my build, I stuck with the JDS labs recommended op-amp (TI OPA2227) at the time of the build. Planning to roll the op-amp in the near future.
Just going based on memory, I made the following changes.
1. R3 resistor: 1.65k ohm 1/8w
2. R4 resistor: 11k ohm 1/8w
Combination of R3 and R4 resistor would get 7.67 gain. I wanted a gain between 7 and 8.5 and decided to settle in between. This is enough to keep most op-amps stable and drive my beyerdynamic DT770-250.
3. RB-L/RB-R: 20k ohm 1/8w
RB resister value is lower to reduce the bass boost effect when the bass boost switch is activated.
4. Ceramic capacitors : Switched a few of the capacitors to ceramic in attempt to lower noise. Can't remember which ones I switched.
1. NJM 4556 Op-amp - Higher current op-amp
2. Add second TLE2426 splitter with 0.1uf capacitor
3. AC/DC adaptor 18v to 24v, 500 to 750ma
Hoping the above changes will increase current enough to drive low sensitivity headphones.
The Cmoy in the current state definitely sounds better in comparision to the Fiio E11. Compared to the JDS labs pre production C421 amp (AD8620 op-amp), the Cmoy falls behind in reproduction of details and not as smooth through the entire frequency range. I am still very impressed with the Cmoy based on value. lol.
Edited by 2000impreza - 2/5/12 at 4:25pm