Denon DM38DAB Headphone Hum Issue

[admin_exported]

I've just purchased a Denon DM38DAB without speakers specifically to listen to using headphones when I'm bed to either the radio or CD. Having read about DM37DAB issues with headphone hum I was disappointed that mine is suffering at volume levels around 7-9 with a constant mains hum.

This makes the system unusable for me so I called Denon this morning. First off I had the reply 'there's been no reported problems with the DM38 model sir' - but he did acknowledge that it had been an issue with the 37 model. What struck me was that he then dismissed the hum as 'going away if you increased the volume'. Well excuse me but music does tend to have quiet bits and filling this glorious silence with intrusive hum is not my idea of hi-fi.

The tech support guy promised to ring me back today after he had discussed this with the European office but at this stage I'm inclined to return it to the shop as not fit for purpose. How can you have a hi-fi product with a noisy headphone output? I suspect the hum is due to bad design and is always there but being masked by the use of speakers at higher volumes.

 

[8009514]

I can understand your frustration over this. Headphone hum has come up several times before on this forum ref. the DM37. Whether its a batch or design flaw is difficult to say. I've certainly never had it on my 37.

The Denon guys must surely look at the forums and note what people are saying, so it should certainly have been an issue to be addressed and sorted out for the new model. I've taken a look at the 38 while I was passing Sevenoaks sound and noted that it still incorporates the speaker terminal with a flange on it. Thus making it impossible to use a spade connector. That was the most frustrating issue for me.

Hope you get it resolved

Rich

 

[Anonymous]

I did get a call back - he asked me what headphones I was using - then he referred it to the German head office to see if they could replicate the hum. In the meantime I went back to the dealer and listened to the display model and didn't hear the hum - probably because of the background noise in the shop. The dealer was happy if I wanted a refund but I'll stick with it until I hear back from Denon.

In the meantime I'll try fiddling with the mains wiring to see if that makes a difference - but I suspect it's an internal issue.

 

[Sizzers]

Hum or no hum, if you're a dedicated headphone listener then I would invest in a headphone amp. Problem solved and far better SQ.

 

[Anonymous]

Forgive my ignorance but I assume the headphone amp connects to an alternative output therefore may avoid the hum?

Could you suggest a suitable headphone amp please?

 

[Sizzers]

You can connect the amp to "Aux Out" using 2 interconnects. Best place to go for advice on a suitable amp is to post in "Headphones" forum and ask idc; he's exceptionally knowledgeable and very helpful.

 

[Anonymous]

As an update I borrowed a Pro-Ject Head Box II headphone amp and plugged it into the AUX out on the DM38 - and there's no hum at all! It is however an expensive upgrade to something that should work already as I can't tell a huge difference in quality (but maybe that's just my old ears!). I could spend the extra £100 on a better all-in-one.

I tried a few other fixes for the DM38 hum:

1. Tried a different mains lead - hum

2. Plugged into a different socket rather than via an extension lead - hum

3. Found that if you switch between sources when you get to the USB input the hum vanishes. If you put in a USB stick then as soon as it detects the stick you hear a relay click then the hum comes back. So it seems that whenever the DM38 headphone amp connects to a source then you get the hum. Therefore it's reasonable to suspect an internal fault.

I might return the Head Box and see what Denon have to say next week - but I can see myself returning the unit for a full refund (which the retailer is ok with as I checked) even though I do like it.

 

[Anonymous]

I had mains hum on my dm37, sent it back for repair, came back working ok, but hum still does appear occasionally but mostly ok, there of course should be no hum

I would have expected the dm38 to have had no hum and also that the volume increments were changed with far smaller steps, and the speaker connectors changed so you could use spade connectors, I would have thought all these points would have been addressed as they should not be there anyway especially as it is made by denon

 

[Anonymous]

David Butler:

As an update I borrowed a Pro-Ject Head Box II headphone amp and plugged it into the AUX out on the DM38 - and there's no hum at all! It is however an expensive upgrade to something that should work already as I can't tell a huge difference in quality (but maybe that's just my old ears!). I could spend the extra £100 on a better all-in-one.

I tried a few other fixes for the DM38 hum:

1. Tried a different mains lead - hum

2. Plugged into a different socket rather than via an extension lead - hum

3. Found that if you switch between sources when you get to the USB input the hum vanishes. If you put in a USB stick then as soon as it detects the stick you hear a relay click then the hum comes back. So it seems that whenever the DM38 headphone amp connects to a source then you get the hum. Therefore it's reasonable to suspect an internal fault.

I might return the Head Box and see what Denon have to say next week - but I can see myself returning the unit for a full refund (which the retailer is ok with as I checked) even though I do like it.

I have a DM37DAB and it has a very slight hum when the ambient is quiet. However, I had managed to reduce the humming by turning off the flourescent display. It worked on mine.

 

[soulsonic34]

Funny that, I'm now getting the infamous headphone hum having owned the DENON M38DAB for little over two years.

Just noticed fault it this morning (Monday, 20th May 2013) when watching a video on a USB stick connected directly to my Samsung LCD TV. All audio is routed to my DENON M38DAB amp. Upon hearing the hum I thought I'd initially thought I had a loose connection between my heapdhone and the amp's headphone socket. Wriggled it a bit having no difference. Tried a headphone extension cable, same result. Tried another headphone cable with same results with a constant hum being heard through both channels.

Switched to a different pair of headphones and the hum disappeared. Swiched to another pair of headphones and the hum reappeared. Switched to a third set of headphones and hum disappeared.

My conclusion is that the hum is largely dependant on headphone used, which may attributed to the headphone's sensistivity to electrical current

Working headphones i.e no hum heard: Philips Uptown headpones, Sennheiser HD 203 and Klipsch Image X1 earphones

non-working headphone i.e audible hum - AKG 450, Sony MDR-XB500, Shure-SE110

Not quite sure what to make of it all.