Question about Teac DRH300DAB Receiver
Hi ... I recently purchased a TEAC DRH300DAB unit and overall I am very happy with it, but ...
on 2 pairs of headphones that I have, there is a low level hum which is audible at low volumes. Is this due to impedance rating? If so, do I need 'phones with a HIGH impedance or LOW impedance ... please advise!
I have no problems with my Mission bookshelf speakers.
I've had one of these since late 2007 and the problem you've identified is one of a number of design problems with this product; Teac UK were - and still are, really - in complete denial about the shortcomings and, indeed, their support manager sent me a recorded delivery letter which verged on the insulting!
The headphone hum, buzz and clicks (when changing sources) are not to do with the type of headphones (although better ones with a decent LF response will reveal the hum better, of course). The problem is almost certainly due to poor power rail decoupling/isolation within the unit. I suspect the VFD could be involved, but other factors could be the layout of the PCB, inter-board wiring, etc. I have a service manual and keep meaning to investigate - but I need to mod the LS terminals for banana types to allow quicker dis/connect for tests first.
Other problems include DAB mutes up to 5s when any station (not just the one you're listening to) on the same multiplex changes bitrate. Again, Teac said there's nothing wrong - but research involving the manufacturers of the Gyro 1122 tuner module the DR-H300DAB uses tell a very different story.
Then there's the problem of some CD tracks being clipped at the start....
Posted on Jun 02, 2009
The impedance of the headphones will not produce problems such as hum. The amp will be able to drive any impedance headphones anyways. I WOULD be concerned as to why the hum is there however. It may be that you are noticing it because they are headphones. If you go right up to your Missions, and put your ear almost in the woofer... can you hear the hum. Headphones can reproduce mains hum quite easily, whereas, you may not get the same levels of reproduction from a bookshelf speaker.
Do a few checks first to ensure that it is not a connecting lead for your system inducing hum in. Best way to do this is to select tuner, and turn the vol right down. If it is only audible with signal from an external source, try rearranging the leads to the rear of the amp away from mains cables, fluorescent lights, TV's, anything that may produce the hum.
If nothing seems to change or alter the problem, and it is there at with the vol turned right down, I would suspect that the amp has a power supply regulation problem that will need to be sorted out. If it is new, I suggest returning it to the retailer for them to resolve the problem for you.
I am more than happy to answer any other questions you may have about it, just give me a hoy :) Thanks for using FixYa, If you consider the advice I have given you as sound, a FixYa rating is a great reward for my efforts to help you. Cheers.
Posted on May 31, 2008
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Posted on Jan 02, 2017
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