Originally Posted by HeadphoneAddict /img/forum/go_quote.gif PS: Mine doesn't hum - I wonder if that is one of those dreaded QC issues you feared (murphy's law), but it might be a simple warrantee replacement issue.
The hum might be related to this particular AC wall socket area that I was using... I've had other pieces of equipment hum when getting AC power from that outlet before. I have to test it in another part of the house (different AC circuit). I have tons of stereo audio/video equipment plugged into that one area socket that I was hearing the hum from. Maybe related with a ground loop. But then again, I did not have any ground looping condition that I knew of and was using optical input with no grounds to anywhere else to form a ground loop.
Originally Posted by unbiased /img/forum/go_quote.gif The hum might be related to this particular AC wall socket area that I was using... I've had other pieces of equipment hum when getting AC power from that outlet before. I have to test it in another part of the house (different AC circuit). I have tons of stereo audio/video equipment plugged into that one area socket that I was hearing the hum from. Maybe related with a ground loop. But then again, I did not have any ground looping condition that I knew of and was using optical input with no grounds to anywhere else to form a ground loop.
If you are using an optical input I really don't think you would have a ground loop unless the case of the D1 was sitting on something metal - that would be about the only other way you could set up that sort of condition.
It sounds like you are getting hum another way, via induction, especially if you have large transformers nearby in your stereo system. It is probably getting picked up by the cable between the wall and the D1.
Originally Posted by ehlarson /img/forum/go_quote.gif If you are using an optical input I really don't think you would have a ground loop unless the case of the D1 was sitting on something metal - that would be about the only other way you could set up that sort of condition.
It sounds like you are getting hum another way, via induction, especially if you have large transformers nearby in your stereo system. It is probably getting picked up by the cable between the wall and the D1.
Yeah, might have been some stray fields causing it. Tonight I came home from work and just tried it out upstairs on another outlet and could not get it to hum. I brought it back downstairs to the same outlet that I heard the hum from and tried it again. No hum this time. The only thing different is that I have since new with hum, swapped out the stock op amps.
Yes there was no metal touching the D1 from any other equipment when I heard the hum. I was even holding it up in my hand at some times turning the volume control to hear the hum. It was odd in that the loudest hum setting was volume control from about 11:00 to about 02:00 position. If I turned it full max, the hum diminished almost totally. No hum at minimum volumn setting neither. Odd behavior. Maybe it was a loose connection on one of the op amps and when I started swapping them, I cleaned up the connection. I still dunno at this time. Will be watching it though to see if the hum comes back and when. It only hummed with the AC power supply of course. With the battery power here is/was no hum at all.
Originally Posted by HeadphoneAddict /img/forum/go_quote.gif Stock the D1 is a bit bright. I think that's why it synergized with my E500 and stock HD600 so well at the time. There was a big change by 70 hours and the caps and stuff need burn in too, not just the opamps. My D1 took 350 hours to fully burn in, and I posted about 5-7 updates in the other thread, if you search for my posts in that thread I think they will help you know what to expect over time.
Since I started with mine before all the opamp rolling was being sorted out, I burned it in with the stock opamps - the brightness/harshness really improves, but doesn't totally go away till you swap out the stock opamps.
However, the AD6234 (see other thread) is a good DAC opamp, and you'd do well to keep it there. HiFlight says it will be a little bright if you put the AD6234 in the LR. If you think it is still too bright in the DAC a 6643 will smooth it out.
The LR and buffers need most of the work since you got a good DAC chip. Using a 6643 or the 49720 as buffers will smooth out the sound, and then your spare OPA2111 can be used in the LR. If that is still too harsh/bright, a 6241HV with 6643 as buffers will give a nice "tube sound".
I have all these to try as soon as I am feeling better, then I'll dig into my D1 again. I haven't been well the past 2 months, and it's taking me longer to get the energy to get up and do anything.
I'd really like to keep the opamp rolling stuff to the other thread, but all of this is already in the other thread - I just memorized it.
Sorry did not see this post right away, but yes, I visited the other D1 thread and found out the DAC amp in my stock D1 is a Linear Technologies chip LT6234. I don't know if it is really better or not than the original AD chip that was in the earlier batch of D1's.
Just wanted to say I'm enjoying the D1, letting it burn-in, and trying to wait until the 200 hour mark to do some in-depth reviews. What a versatile little unit.
Originally Posted by jerikl /img/forum/go_quote.gif Just wanted to say I'm enjoying the D1, letting it burn-in, and trying to wait until the 200 hour mark to do some in-depth reviews. What a versatile little unit.
I'm not that patient when it comes to this sort of waiting, so I started rolling the op amps I bought. I have just brought my iBasso D1 up to the level of (or better than) my other headphone amp and the ZERO 24/192 home DAC/amp sound quality! How?
Sounds so smooth, musical, wonderful now. No harsh edginess! No overbright harshness! No loss of detail. Good lush liquidy smooth sound through my HD650 headphones. I think this D1 sound can stand up to the best out there! It sounds so right on the money with these op amps installed that I don't have any desire to try changing to anything else! I think I hit the jackpot with these op amps. For a mellower sound, you can use an AD4841 opamp in th DAC spot. This mellows off the highs a wee bit more and still sounds good.
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