Hi,
I am writing from Turkey. We have submitted the observations and video recordings related to the issue described below to Denon via the Turkish service, but we have not yet received a response.
I would like to understand how you would interpret this issue technically, and whether other Denon users have experienced the same problem.
I purchased a brand new PMA-A110 from an authorized dealer about a week ago.
Currently, I have both the PMA-1700NE and the PMA-A110 in my system.
The Problem:
When a turntable is connected to the MC phono input of the PMA-A110, a noticeable and disturbing 50Hz hum noise is heard through the speakers. I analyzed the recorded noise on a PC and confirmed that the fundamental frequency is exactly 50Hz. The hum becomes clearly audible once the volume knob reaches around the 10 o’clock position, and its intensity increases as the volume is raised. It is also audible during playback, especially in records that contain quiet passages, such as solo piano.
When using the MM phono input, the hum is still present but relatively less pronounced.
In CD and AUX modes, the device is operational, and while no music is playing, the hum becomes just barely audible at very high volume levels and with careful listening.
In contrast, there is no hum at all in USB-DAC mode.
Based on my observations, I suspect that the problem is caused by excessive leakage from the internal transformer/PSU.
For reference, I am using my Pro-Ject X8 turntable with its original XLR-to-RCA cable, and I have also connected the ground wire. However, connecting or disconnecting the ground wire makes no difference whatsoever.
When I listen to the same turntable through the PMA-1700NE, there is no hum at all.
To be absolutely certain, I brought the PMA-A110 to a hi-fi store with professional-grade electrical infrastructure. There, under entirely different wiring conditions, with a different turntable and ground wire, the result was the same: a pronounced 50Hz hum.
I also checked the grounding integrity of the device externally from the chassis using a multimeter. The following resistance measurements were taken:
These measurements indicate that the device's physical grounding connections are electrically intact.
The PMA-1700NE gave identical readings under the same conditions.
Have any of you experienced a similar issue with the PMA-A110?
Or could someone try to reproduce this issue and report back here?
I am writing from Turkey. We have submitted the observations and video recordings related to the issue described below to Denon via the Turkish service, but we have not yet received a response.
I would like to understand how you would interpret this issue technically, and whether other Denon users have experienced the same problem.
I purchased a brand new PMA-A110 from an authorized dealer about a week ago.
Currently, I have both the PMA-1700NE and the PMA-A110 in my system.
The Problem:
When a turntable is connected to the MC phono input of the PMA-A110, a noticeable and disturbing 50Hz hum noise is heard through the speakers. I analyzed the recorded noise on a PC and confirmed that the fundamental frequency is exactly 50Hz. The hum becomes clearly audible once the volume knob reaches around the 10 o’clock position, and its intensity increases as the volume is raised. It is also audible during playback, especially in records that contain quiet passages, such as solo piano.
When using the MM phono input, the hum is still present but relatively less pronounced.
In CD and AUX modes, the device is operational, and while no music is playing, the hum becomes just barely audible at very high volume levels and with careful listening.
In contrast, there is no hum at all in USB-DAC mode.
Based on my observations, I suspect that the problem is caused by excessive leakage from the internal transformer/PSU.
For reference, I am using my Pro-Ject X8 turntable with its original XLR-to-RCA cable, and I have also connected the ground wire. However, connecting or disconnecting the ground wire makes no difference whatsoever.
When I listen to the same turntable through the PMA-1700NE, there is no hum at all.
To be absolutely certain, I brought the PMA-A110 to a hi-fi store with professional-grade electrical infrastructure. There, under entirely different wiring conditions, with a different turntable and ground wire, the result was the same: a pronounced 50Hz hum.
I also checked the grounding integrity of the device externally from the chassis using a multimeter. The following resistance measurements were taken:
- GND terminal ↔ chassis: 0.03 – 0.04 Ω
- RCA ground ↔ chassis: 0.03 – 0.04 Ω
- RCA ground ↔ GND terminal: 0.03 – 0.04 Ω
These measurements indicate that the device's physical grounding connections are electrically intact.
The PMA-1700NE gave identical readings under the same conditions.
Have any of you experienced a similar issue with the PMA-A110?
Or could someone try to reproduce this issue and report back here?
