I wonder if it isn't the pot but some DC offset. I have had a couple of op amps that caused problems. But if you aren't moving the volume control, and you get no noise, I am not sure of the problem.
Come to think of it it might be that during my "grinding" the CNC case process I didn't removed all of the "aluminum dust" from the case (mind you they are tiny), maybe they got stuck in the volume pot.
Yeah that what's I tried at first, works for other amps but not this one. I guess the high gain of the opamp is too much here. Though I can live with it as long as I don't turn the volumes over 11 o'clock which I rarely do except when I listen to some really quiet classical pieces. But just a report for those interested in the Sparkos opamp.
You might try changing the ground configuration. Perhaps try the bypass dummy adapters. Always check for proper configuration by turning on the amp prior to re-installing the cover and confirm that the blue light only blinks when you turn the amp on. If it stays on, there is something wrong, most likely an opamp installed incorrectly.
If you hear static without turning the volume knob, you most likely have a defective opamp. Easy to check by replacing each pair with a different pair, one pair at a time. I would start with swapping the pair of L/R opamps first. Even if it only happens when turning the volume control, as John suggested, it is likely the presence of some DC offset voltage. Again, try swapping the opamps by pairs.
You might try changing the ground configuration. Perhaps try the bypass dummy adapters. Always check for proper configuration by turning on the amp prior to re-installing the cover and confirm that the blue light only blinks when you turn the amp on. If it stays on, there is something wrong, most likely an opamp installed incorrectly.
If you hear static without turning the volume knob, you most likely have a defective opamp. Easy to check by replacing each pair with a different pair, one pair at a time. I would start with swapping the pair of L/R opamps first.
I'm pretty sure it is working normally: no bluelight, same configuration as before other than changing the 2 single OPA627 to the Sparkos Dual (bypass 2 ground, discreete buffer). I tried some other configuration but it doesn't help. Also it is opamp specific (the Sparkos), the 627 also have slight noise but they are just no loud enough. Note that all the noise I mention only appears when turning the volume pot, otherwise it is dead silence.
I'm pretty sure it is working normally: no bluelight, same configuration as before other than changing the 2 single OPA627 to the Sparkos Dual (bypass 2 ground, discreete buffer). I tried some other configuration but it doesn't help. Also it is opamp specific (the Sparkos), the 627 also have slight noise but they are just no loud enough. Note that all the noise I mention only appears when turning the volume pot, otherwise it is dead silence.
Hi guys, can I ask for some help? I just bought an ibasso p5 secondhand. Problem is, when I plug the power supply to the amplifier, there is a hissing sound. There is no hissing at low volumes and the hissing grows a little louder as I turn the volume knob higher.
However, there is no such problem when the power supply is not plugged in or turned off.
What's wrong?
Hi guys, can I ask for some help? I just bought an ibasso p5 secondhand. Problem is, when I plug the power supply to the amplifier, there is a hissing sound. There is no hissing at low volumes and the hissing grows a little louder as I turn the volume knob higher.
However, there is no such problem when the power supply is not plugged in or turned off.
What's wrong?
What batteries are you guys using, I tested a few and it makes a good difference. 9v batteries come in 4 voltages(even though all just advertise as 9v), They are 7.2v/7.4v, 8.4v, 9.6v. I tested all and 9.6v sound noticeably clearer, more detailed but smoother more refined and open as well, a no going back sonic upgrade.
There are two types of 9.6v batteries on the market, NiMH and LiFePO4 (Lithium Iron Phosphate, a special type of Li-Ion). I highly recommend LiFePO4, they do not drop in voltage in use, like NIMH they will stay at their rated cell voltage in use until close to depleted, while normal Li-Ion batteries linearly drop in voltage while used.
LiFePO4 are a better option than NiMH as they use less cells and higher mAH, 9.6v NiMH use 8x 1.2v cells total 260mAH, while 9.6v LiFePO4 use 3x 3.2v cells total 320mAH, less cells means lower resistance and higher max current output, 9.6v NiIMH battery has 520mA max dischargeable current, compared to 640mA for 9.6v LiFePO4.
Only Soshine makes 9.6v LiFePO4 and I can highly recommend them, you need the special 9.6v LiFePO4 charger that comes with them so don't think to buy the batteries alone, they won't charge properly in NiMH and Li-Ion chargers.
I bought from: https://www.aliexpress.com/item/LiFePO4-Li-ion-Ni-MH-Battery-Soshine-Professional-9V-6F22-Rechargeble-2-Battery-1-Charger-Suit/32657450132.html
Will give your sound quality a decent boost! I'd say 10-15%, well worth the $20.
Hi Paul,
sorry it took a while to reply. After testing, this problem only occurs with my Grado SR-80e. I tried it with a few other earbuds and IEMs and also the Sennheiser HD600 and there is no hiss. It seems to be a problem with my grado. Would you happen to know what's wrong with it?
Id say no, they require to be charged to 11.2v and the P5 isn't regulated for that, probably even 9.6v NIMH batteries will not charge properly in P5 as they need to be charged to 11.6v, so both 9.6v NIMH and 9.6v LiFePO4 need different chargers to one another(unless charger is specified for both) and LiFePO4 obviously needs a different charger than regular Li-Ion.
Id say no, they require to be charged to 11.2v and the P5 isn't regulated for that, probably even 9.6v NIMH batteries will not charge properly in P5 as they need to be charged to 11.6v, so both 9.6v NIMH and 9.6v LiFePO4 need different chargers to one another(unless charger is specified for both) and LiFePO4 obviously needs a different charger than regular Li-Ion.
I hear an electrical buzz/hum when I use the PS with P5, through IT03, you can't really hear it with music playing, unless it is quieter music with empty pauses. Also when I turn up the P5 volume with no music playing and I touch the PS casing I get very loud buzzing through IT03 when I touch PS.
Is this normal or is it due to PS being 220v(China) being used with 230-240v(Australia) power?
I hear an electrical buzz/hum when I use the PS with P5, through IT03, you can't really hear it with music playing, unless it is quieter music with empty pauses. Also when I turn up the P5 volume with no music playing and I touch the PS casing I get very loud buzzing through IT03 when I touch PS.
Is this normal or is it due to PS being 220v(China) being used with 230-240v(Australia) power?
What type of grounding do you have? The PS is fine with 230 volts. I have tried the IT03 with the P5 and PS in the past and experience no buzz or hum. I would suspect a grounding issue. Do you have both the source and the P5 hooked up to the AC at the same time?
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