Ground Loop?
I have an amp that when used with my Soekris dam1021 DAC, there is a noticeable hum. If I use the same amp with other DACs, there is no hum.
In particular, I plug the DAM into the amp, power on the amp and there is virtual silence (a very slight hum, but requires ears being right up against the speakers to hear). But when I power on the dam, the hum gets noticeably louder.
I've read several people having ground loops when mounting the dam1021 with metal standoffs. I originally did just that. But switching to nylon standoffs didn't fix the problem. My RCAs are also insulated from the chassis.
I can't tell if the problem is with the amp or the DAC, as it only shows up when the two are used together. Either device with other components has no hum.
Anyone have any thoughts or ideas on the issue?
Thanks!
I have an amp that when used with my Soekris dam1021 DAC, there is a noticeable hum. If I use the same amp with other DACs, there is no hum.
In particular, I plug the DAM into the amp, power on the amp and there is virtual silence (a very slight hum, but requires ears being right up against the speakers to hear). But when I power on the dam, the hum gets noticeably louder.
I've read several people having ground loops when mounting the dam1021 with metal standoffs. I originally did just that. But switching to nylon standoffs didn't fix the problem. My RCAs are also insulated from the chassis.
I can't tell if the problem is with the amp or the DAC, as it only shows up when the two are used together. Either device with other components has no hum.
Anyone have any thoughts or ideas on the issue?
Thanks!
USB from PC, into an Amanero. I am using metal standoffs for the Amanero. But with the dam1021's isolated I2S, that shouldn't be an issue, right? Also, I'm pretty sure the USB receptacle on the Amanero is touching the case (meant to address that when I switched to nylon standoffs for the dam1021, but forgot). But still, shouldn't the isolated i2s fix that, if indeed it is a problem?
On the outgoing side, I'm using the raw outputs to RCA. RCA jacks are isolated from the chassis.
No serial connection to the dam1021 at the moment.
The chassis is definitely grounded. I think the dam's ground would be considered floating in my scenario, but here's the details in case I'm saying the wrong thing:
From the IEC: live and neutral go to a transformer. Earth goes to a screw in the chassis.
The transformer has a "screen" wire: that goes to the same chassis screw that IEC earth goes to.
The transformer has a pair of secondaries, those go to each side of a +/-12V power supply (this one).
From the power supply, the +12, Ground and -12V go to the DAM1021's J1 header.
Indeed, it certainly can't hurt! Will definitely do that.
What is that grey stuff on your dam1021 board? Are those sheets of EMI shielding material?
My DAM1021 Implementation
The layout is probably not the best but I got tired of waiting for 5-6 months to finalise the build. And in the end decided to at least put it into a box with some help so I can start listening to it properly without the test jig and walwarts
Next step is to integrate it with the remote control board and relay based power on circuit.
The sound is absolutely brilliant and really enjoying the DAC.
Thanks Soren, Normundss and DimDim for your help along the way.
- DAM 1021 V3
- Normundss input board
- Amanero
- Regulators and Transformer from Audiophonics
The layout is probably not the best but I got tired of waiting for 5-6 months to finalise the build. And in the end decided to at least put it into a box with some help so I can start listening to it properly without the test jig and walwarts
Next step is to integrate it with the remote control board and relay based power on circuit.
The sound is absolutely brilliant and really enjoying the DAC.
Thanks Soren, Normundss and DimDim for your help along the way.
My build (rev. 1 board)
My dam1021-01 rev. 1 has been playing for a long time but only recently I got time to put it in a proper enclosure.
My rev. 1 build including mods consists of:
2 Silchar r-core trafos feeding a Reflektor-D and a DIYinHK LT3032 150mA psu (soon to be replaced by a DIYinHK LT3042 1.5A psu hopefully to improve dynamics).
Reflektor-D (with jfet mod) is feeding Amanero combo384 (with external power mod and USB cable 5v lead cut off) Reflektor-D is also powering the isolators of the dam1021.
Mods so far: HiFiDuino's version of the vref mod 16 caps attached on back of the pcb, alecm/oneoclock's transistor mod, opamps removed, caps C135 and C143 removed since I only use the raw output.
Thanks to all the members in this forum for inspiration.
Are there any obvious mods that I'm missing? (replacing the 6 ceramic caps - marked with yellow - as proposed by søren/hifiduino), decoupling cap on the clock?
My dam1021-01 rev. 1 has been playing for a long time but only recently I got time to put it in a proper enclosure.
My rev. 1 build including mods consists of:
2 Silchar r-core trafos feeding a Reflektor-D and a DIYinHK LT3032 150mA psu (soon to be replaced by a DIYinHK LT3042 1.5A psu hopefully to improve dynamics).
Reflektor-D (with jfet mod) is feeding Amanero combo384 (with external power mod and USB cable 5v lead cut off) Reflektor-D is also powering the isolators of the dam1021.
Mods so far: HiFiDuino's version of the vref mod 16 caps attached on back of the pcb, alecm/oneoclock's transistor mod, opamps removed, caps C135 and C143 removed since I only use the raw output.
Thanks to all the members in this forum for inspiration.
Are there any obvious mods that I'm missing? (replacing the 6 ceramic caps - marked with yellow - as proposed by søren/hifiduino), decoupling cap on the clock?
If you aint using the buffered/balanced outputs then why not feed the board directly with +-5v on the secondary side of the 5v regs... lt3032 should be better than the on board 5v regs... altough i havent checked for the obvious place to connect the power input - but there is probably a few people here that have made that mod..
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