Dab out of synch

CjwontvCjwontv Posts: 368
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In my dining room I have a Denon M38dab mini system. In the kitchen there was an older FM only Denon, which has broken.
I was a bit pleased as I could only have both on fm because if I used DAB on the one there was a bad echoing delay.
I have just replaced it with a Denon M39Dab mini system.
If I play both on DAB on radio 2 there is also a slight delay causing an odd echo which I cannot bear.
How can this happen and what can I do?
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Comments

  • CjwontvCjwontv Posts: 368
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    They are connected to separate ariels. The dining room to a dipole ariel through a fm/DAB triplexer. The kitchen from a generic 10 year old fm ariel on the roof.
    Can that make a difference?
  • N.DeanN.Dean Posts: 1,684
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    The signals from the aerials arrive at the radios as the same time, but the radios take different lengths of time to decode the signal.
  • Peter the GreatPeter the Great Posts: 14,227
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    This is the problem with Digital i'm affraid. Different radios will have different delay and is nothing to do with the aerial.
  • CjwontvCjwontv Posts: 368
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    But if I put both on FM the echo is even worse. With the old Denon the FM was in synch.
  • chrisjrchrisjr Posts: 33,282
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    Are you 100% certain both are switched to FM? To be sure unplug the DAB aerials on both so there is no possibility you could have one on FM and one on DAB.

    There should be no delay at all on FM but if one were still on DAB then you will notice quite a considerable delay between FM and DAB.
  • CjwontvCjwontv Posts: 368
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    One Denon has separate inputs so removed DAB ariel from that one. Other is a combined ariel f plug
    Both say FM 98.3. On then front
    About 1/4 sec echo delay and cannot bear it!
  • N.DeanN.Dean Posts: 1,684
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    Cjwontv wrote: »
    One Denon has separate inputs so removed DAB ariel from that one. Other is a combined ariel f plug
    Both say FM 98.3. On then front
    About 1/4 sec echo delay and cannot bear it!

    I can't explain this, unless your ears are much closer to the speaker of one radio than to that of the other.
  • chrisjrchrisjr Posts: 33,282
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    N.Dean wrote: »
    I can't explain this, unless your ears are much closer to the speaker of one radio than to that of the other.
    Then the OP must live in one hell of a big house. Quarter of a second at the speed of sound is the thick end of 85m :D
  • VectorsumVectorsum Posts: 876
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    On threads elsewhere, folk are complaining about unexplained poor FM performance in good signal areas from Pure DAB/FM sets. The general conclusion was that after a couple of RF stages, the sets were sampling the output of the last IF and implementing the FM demodulation in software. This causes a delay, as does any digital processing to cancel noise. If the Denon is built similarly this could be the explanation for a ~250ms latency, if the other Denon implements the FM discriminator in hardware.
  • N.DeanN.Dean Posts: 1,684
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    ........
  • N.DeanN.Dean Posts: 1,684
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    chrisjr wrote: »
    Then the OP must live in one hell of a big house. Quarter of a second at the speed of sound is the thick end of 85m :D

    I agree.
  • N.DeanN.Dean Posts: 1,684
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    Vectorsum wrote: »
    On threads elsewhere, folk are complaining about unexplained poor FM performance in good signal areas from Pure DAB/FM sets. The general conclusion was that after a couple of RF stages, the sets were sampling the output of the last IF and implementing the FM demodulation in software. This causes a delay, as does any digital processing to cancel noise and could be the explanation for the ~250ms latency if the other set were implementing the FM discriminator in hardware.

    Aha. That makes sense.
  • technologisttechnologist Posts: 13,341
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    There is No specification for how long a ( DAB) radio takes to decode the signal... So certainly different radios may / will have different delays .. And even two identical radios could have a delay between them...
  • omnidirectionalomnidirectional Posts: 18,799
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    Vectorsum wrote: »
    On threads elsewhere, folk are complaining about unexplained poor FM performance in good signal areas from Pure DAB/FM sets.

    I've found my Pure Evoke Flow suffers from poor FM reception when plugged in, but disconnecting the plug and using battery power greatly improves the signal.
  • CjwontvCjwontv Posts: 368
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    Ok. So the 1/4 sec was a guess. It would need professional devices to be accurate.
    The radios are about 15 ft apart.
    The sound is like an echo, especially speech. You can easily hear individual words starting in one room then in the kitchen.
    If a say BBBBBBB as fast as possible that's the speed of the delay.
  • VectorsumVectorsum Posts: 876
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    I've found my Pure Evoke Flow suffers from poor FM reception when plugged in, but disconnecting the plug and using battery power greatly improves the signal.
    It isn't a signal level thing. On my particular One Flow it's like a constant impulsive interference that doesn't vary with FM signal conditions. It's as if there's a systematic error in the ADC every few milliseconds, that has the same effect as impulsive interference.

    Just did a side-by-side comparison using a good quality FM tranny (Morphy Richards 27006) and I'd say that the One Flow's software demodulation delay is equivalent to a good sized conference room, i.e. about 50-75ms. It isn't really noticeable and you have to listen to recognize it (in fact I'd never noticed before). My sympathies to Cjwontv as I'd be driven doolally by a 250ms delay too.
  • CjwontvCjwontv Posts: 368
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    Good idea. Just got my Roberts FM radio from the bathroom. Matches the original room FM signal. Horrible echoing delay with the new kitchen Denon. So the new one is slow.
    Would this be grounds for returning it?
  • chrisjrchrisjr Posts: 33,282
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    Cjwontv wrote: »
    Good idea. Just got my Roberts FM radio from the bathroom. Matches the original room FM signal. Horrible echoing delay with the new kitchen Denon. So the new one is slow.
    Would this be grounds for returning it?
    Only if it was a fault. If it is working to it's design specification then there is nothing wrong with it.

    Just out of idle curiosity why have you got two radios on in two separate rooms all the time?
  • CjwontvCjwontv Posts: 368
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    Just in the morning. Make breakfast in kitchen. Eat in dining room. Wander in and out. Serving hatch so unable to acoustically separate. Radio on, but can't hear just the one if in the other room.
    Still it's 45 mins and would like 2 radios to play at the same time. Not unreasonable.
    Bbut II ccoulnt llisstten Tto itt llikke ththiss.
    Boy spellchecker can be annoying sometimes!
  • chrisjrchrisjr Posts: 33,282
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    Now here's a thought. Stick the kitchen unit near the serving hatch. Switch it to Mono and point one speaker into the kitchen and the other through the hatch into the dining room. :)
  • Phil DoddPhil Dodd Posts: 3,975
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    chrisjr wrote: »
    Now here's a thought. Stick the kitchen unit near the serving hatch. Switch it to Mono and point one speaker into the kitchen and the other through the hatch into the dining room. :)

    A sensible idea. My solution is to use 10 metres of screened multi-core cable. It starts out in the sitting room, goes through the middle room, and into the kitchen. In the sitting room, it can connect to a line-out on the radio, or to the computer sound card. In the kitchen, it connects to some powered speakers. When moving from 1 room to the other, I only have to switch the speakers on in the kitchen.

    It is best to solder stereo jack plugs onto each end of the cable.

    If buying stereo powered speakers, go for either two including bass units, or the ones known as 2.1 , which are a bass unit with 2 slim stick-like high-frequency units. Avoid the cheapest ones, which are the two sticks by themselves, as they have no bass and are no good for music.

    So have 1 radio, and pipe the audio through from room to room...
  • Mrs MillsMrs Mills Posts: 873
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    Phil Dodd wrote: »
    A sensible idea. My solution is to use 10 metres of screened multi-core cable. It starts out in the sitting room, goes through the middle room, and into the kitchen. In the sitting room, it can connect to a line-out on the radio, or to the computer sound card. In the kitchen, it connects to some powered speakers. When moving from 1 room to the other, I only have to switch the speakers on in the kitchen.

    It is best to solder stereo jack plugs onto each end of the cable.

    If buying stereo powered speakers, go for either two including bass units, or the ones known as 2.1 , which are a bass unit with 2 slim stick-like high-frequency units. Avoid the cheapest ones, which are the two sticks by themselves, as they have no bass and are no good for music.

    So have 1 radio, and pipe the audio through from room to room...

    Agreed.
  • KnobTwiddlerKnobTwiddler Posts: 1,925
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    Buy a small FM transmitter - connect it to you DAB radios audio output and listen on FM radios - that's what I do - problem solved.:D
  • Sky_TechSky_Tech Posts: 134
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    Not sure if this still the case, but ClassicFM used to synchronise the the FM signal, the DAB signal and the Satellite signal so they were all in sync.
  • wns_195wns_195 Posts: 13,557
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    It is true that some DAB digital radios (including Sony and Intempo) have a slight delay on FM. It has nothing to do with how far you are away from one radio. If you tune into the same radio station via its FM frequency on a normal radio and a DAB digital radio, there will be a delay on the DAB digital radio. I don't see why digital tuning should be the reason, because there are FM radios that have digital tuning that don't have a delay. Many car radios don't have a delay.
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