Audio dropouts via optical output (Samsung NU7100 series)


Established Member
Just got a Samsung NU7100 series 49” which on the whole seems good value for money.

One thing I can’t get to work is sound via optical out. I’ve set it to output via optical out and to PCM but I’m getting frequent and very audible dropouts.

My Audiolab M-DAC which I’ve connected it to shows a 24 bit 48kHz signal. This is on normal Sat TV.

No dropouts over the TV speakers.

Any ideas? I was a bit surprised the TV was outputting a 24 bit signal for Sat TV.

I’d really hoped to plug the TV into the hifi :-(.


Established Member
I replaced the M-DAC with my Hegel DAC and now it works fine - weird.

Hi, I saw that you have a Hegel DAC. If you have, or can get, a Samsung Blu Ray player like the UDB-M9500, its optical output is capable of 24b, 192 kHz. The output format menu also has more options than the TV, including uncompressed Bitstream that doesn’t grey out.

It sounds so much BETTER than the TV that I switched to using the Blu Ray as the Smart Hub and stream from that. I never could tolerate the TV’s optical output sound. To me, it sounded worse than mp3, even though it is 24/48 PCM. I suspect that it is truncating the last 8 bits (like DAT) but it is also NOT uncompressed.

Furthermore, if you have a router that’s DNLA capable, you can play files up to 24/192 thru the player wirelessly, and, it sounds fantastic. I have a Hegel DAC as well, and I am familiar with it, but I am using a Chord DAC in my setup fed from the Blu Ray S/PDIF optical output because it up converts to 96 MHz and then interpolates with a Sin(x)/x reconstruction filter before shaping and analog filtering. This seems to completely eliminate ‘graininess’ in the geometry of the aural sound stage.

The main point is that the TV’s optical port and the codecs behind it are way inferior to those of a 4K Blu Ray player. Also, until you get into the Q80 to Q900 class, the HDMI-arc 2.0 port on the TV is simplex, i.e. output only, so you can’t source HDMI up to the TV on one HDMI cable to your DAC or A/V RCXR; you need to send it up on a non-arc HDMI input and play it down out of the HDMI-arc ‘output’ or play it thru the inferior (IMHO) optical port.

You may not be at this juncture (yet), but if you want to hear your Hegel DAC sound its best, consider getting the UBD-M9500 and then use its optical port straight to your DAC.

Just saying...


Established Member
Thanks for an extremely interesting post. I’d kind of assumed the optical out would give the best audio quality. I was initially thinking that the only audio out I was trying to send via the digital out is TV (using the onboard Sat tuner to avoid yet-another-box). But if I stream films off my Synology NAS or use a Fire stick (or Netflix) or something then I have the same issue.

I guess I could use the bluray player eg for DLNA streaming instead of the TV directly, but can you explain again how I could do this if I use the on-board Sat tuner in the TV? Having been mainly a projector user to date I’m not so up to speed eg with HDMI / ARC & co.

It would be nice to get decent audio quality from streaming films as the hifi system it is connected to, whilst only 2 channel, sounds very good in the room.

Reducing box count is also a factor - this is supposed to be a discrete system for the bedroom ....


Established Member
I think I can clarify my post but whether it helps or not depends on your current (& future) hardware. Here is how I would simplify my findings:

1). The optical output on my Samsung TV (& probably most, if not all), is limited. It main purpose is to drive a sound bar. It does not have much flexibility in format choices and it lacks in SQ. I know for sure that it won’t output digital data at higher than 48 kHz, and I do NOT believe that it is really outputting 24b wide data uncompressed data because of its poor SQ.

2. If you have a Samsung Blu Ray player with WiFi (like the UDP-M9500), since it has much more powerful dedicated audio processing capability, I find that streaming from the Blu Ray player allows an extremely wide choice of output formats on its optical port. 24b/96 kHz uncompressed PCM or uncompressed Bitstream data in many multi-channel channel configurations (like Dolby) is always available and sounds great.

3. In order to exploit the player’s better audio processing capabilities you need to source the stream directly from the Blu Ray player. It comes loaded with fewer APPs than the TV, but you can load up more.

4. If you are sourcing media directly from the TV (like with a SAT source), I don’t know of a way to get the Blu Ray player to handle that processing.

5. Instead, you will have to use the HDMI 2.0 audio out port on the TV and send that to a device that accepts digital data directly like an A/V receiver or a Digital-to-Analog Converter that ahas an HDMI input. The TV has a more powerful set of codecs to handle decoding the digital content for its HDMI outputs. There may be one (possibly 2) HDMI ports that is labeled HDMI 2.0 or HDMI 2.0a or HDMI-arc. That port will OUTPUT clean digital audio off the TV and down into whatever is processing that for your audio system.

6. In US 2019 models, the HDMI 2.0a ports are NOT duplex capable until you get up in the 75 inch range. For a smaller TV, you only get audio out, not in, on that port. To get full duplex (bidirectional paths), the ARC (Automatic Return Channel) enabled port on the HDMI 2.x port must be implemented, something that cost precludes for all but 75” and up models.

So, in summary, if you don’t have a WiFi 4K Blu Ray player, and you don’t have an HDMI 2 capable A/V Receiver, you will be stuck with the limitations of the TV’s optical port.

If you get or have a WiFi enabled Blu Ray player (hopefully 4K), then any thing which can be sourced directly from the player will then give you a much better SQ output on its optical port and have a much wider set of format choices on your menu.

For the SAT TV mode, AFAIK, the Blue Ray player cannot be inserted in that loop. You can still bypass the optical port if you get or have an HDMI 2+ A/V Receiver or equivalent. HDMI 1.0 won’t handshake with the 2.0 port from the TV.

There are two points here that make me ponder.

A). Your problem as stated is dropouts and not stated as continuously poor SQ.
B). HDMI 2.0, 2.0(a) and, especially HDMI 2.1 are fully capable but rigidly enforce the HDCP copyright protection safeguards.

Problem A may be as simple as replacing your S/PDIF optical cable. Or, it may be much more troublesome if it is in anyway being affected by the HDCP (High-Definition Digital Copyright Protection) data police.

Media ownership and theft thereof is where the biggest legal fees go.

The manufacturers have responded to that threat by implementing HDCP and extended it thru the progression from HDMI 1.x thru HDMI 2.1.

What this does is create a Nanny State of paranoid control inside of the TVs.

For example, if you feed your TV with both HDMI 2 and HDMI 1 inputs (even HDMI 3 from game boxes), the nanny will sooner or later notice that you are possibly trying to hijack 4K quality because you have HDMI 1 ports activated.

Those ports may be attached to equipment that lack the HDCP handshaking expected, so it will say, “Whoa. Hold on there Sir. I am going to downgrade my video to 1080P and do harm to the audio output as well because your ‘older’ equipment may be making illegal dupes!

Nanny will rule the roost, att least until you run out and buy all HDCP/HDMI 2.1 compliant equipment in your stack.

The manufacturers have turned the liability of being sued for copyright violation and the cost of implementing the much higher BW ‘new’ fully compliant HDMI standards into a feeding frenzy bonanza where all of their (& others) HDMI 1 equipment is suddenly rendered obsolete, forcing you to buy not just the 4K TV, but to upgrade every component.

It puts a new meaning on ‘Fire Sale.’ You might as well have a fire destroy every device that connects to your new 4K (or 8K) TV so you at least get some insurance recompense.

As far as the MFGRs are concerned, its a Bright New Day! They figure we are all Nits, and we we sheep-walk to the order bar and re-buy EVERYTHING. They give us more nits of brightness while viewing us as dim-nits.

If you replace the IR optical cable, and still get dropouts, there is one last cheap fix that may slightly be possible. The total GPU/codec horsepower is limited, and if you have all of the extra modes under Picture/Expert Settings turned on, turn them all off and see if that makes any difference.

If after swapping in a new optical cable and disarming process demanding expert picture processing settings, you still get audio dropouts, I think you will have to expend more money.

Best wishes
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Established Member
Thanks for the very detailed response. I did some more tests on SQ (for example streaming from the same Logitech Media Server instance via the TV and optical out and a Logitech Squeezebox Touch also optical, both to the Hegel DAC. The SQ from the Squeezebox was far higher so either the TV code for playing back FLAC is poor or the TV digital out is poor, or both.

So I suspect your assertion that the TV optical out is poor is correct.

However to get around this, based on your note above, I’d have to increase the box count noticeably, either separate Sat TV box and possibly BluRay player (as I don’t believe either device alone could do everything I need), or amp with HDMI input (I don’t have a DAC with HDMI input).

I still have no idea on the dropouts but it maybe the Audiolab was handshaking at the wrong frequency or bit rate or something. I tried two completely different optical cables that work flawlessly elsewhere.

Given box count and small format is quite a strong driver for this system, I may have to live with it as-is. But at least I understand a lot more around this now, so very many thanks for that.


Established Member
Thanks for verifying the poor SQ direct from the TV optical port.

As for the Blu Ray player, whether it helps or not, may be a moot point. The M9500 is the last Blue Ray player Samsung released, and that was in 2017. It appears that they are closing down that division.

You might want to check out the Samsung ‘One Connect Box.’ I don’t have one but it may be the magic interface. If it also has an optical output port, your problems may be solved, but I haven’t looked at it.

Your drop outs are seemingly not a common problem. Since an optical port is one directional, the receiving end has to extract the data by ‘slaving’ its clock to synchronize with the TV’s master clock frequency.

The lock-in range of a downstream clock to vary until it matches the upstream clock that it has no control over is usually pretty wide, but maybe, in your case, your dropouts have to do with a possible issue.

First, DAT is a 16b, 48 kHz data format. Some broadcasters use this for their Audio.

What I suspect (zero hard data) is that, when the Samsung codecs get a 16b incoming signal, they might just be appending 8 zeros!

Please do not trust this as data - it is just a hypothesis at this point.

However, let’s just imagine that you have a 24b PCM DAC that is trying to clock onto a data stream that ‘claims’ it is 24b, but has only 16 bits of data.

The Phase Locked Loop (PLL) that is tracking the input frequency could be having a hard time knowing that the last 8 bits are NOT data, and I could see how it might mistake that for a header frame.

The point is that pseudo 24b data that is really only 16b can possibly confuse the PLL inside a DAC if the header claims it is a different resolution than it really is.

Not all DACs would behave this way. You might want to borrow another different brand DAC with an optical port and see if that makes any difference.

To me, that would also explain why the internal audio doesn’t drop out. The decoded data, if it is only 16b internally, will work just fine if fed to a 16b DAC, but, when it is unconverted to quote-unquote 24b, unless upsampling and interpolation is used to increase effective resolution, just adding trailing zeros would be very bad.

Also, if you have a scope and an IR diode, you could actually capture a bunch of data and look at it on the scope.

To me, the TV’s optical output sounds much worse than CD quality (16b, 44.1 kHz) or even DAT (16b, 48 kHz). The SQ to me sounds like it is still compressed and very harsh, especially during very busy passages.

The Blu Ray player’s optical output sounds really good. I’ve verified that it can output true 24b, 96 kHz data when streaming from a DLNA server over WiFi direct to the Blue Ray player.

Call up some friends and have a BYOD party - Bring Your Own DAC. Invite them over. If even one DAC does not drop out, this hypothesis is proven.

Sorry for this issue.

How long in duration are the dropouts? Are they periodic?

In USB, before there was so-called Synchronous/Asynchronous PLL capability, there were all manner of data dropouts. For me, my Hegel DAC did not like playing with a laptop generated PCM data stream. My experience with mine was that it really wanted a clean, jitter free data source, but it was an older model.

Best of luck with your optics!


Established Member
The dropouts were fairly regular - every few seconds for half a second or so. The one connect box is interesting - but I checked and with this model upgrade Samsung dropped support for it.

So I think I’m stuck with the current setup if I want to keep the box down (I like the Hegel as it also acts as a pre-amp).

I guess a kludge is to use a laptop with HDMI to the TV and USB to the Hegel. Works for blurays, Netflix and streaming off the Synology.

Not sure it is worth getting a separate Sat TV box - it is quite convenient using the built in sat tuner in the TV, even if it needed a PhD in lateral thinking to get it set-up correctly.


Established Member
OK, I think you have likely verified that it is a clock frequency locking problem. That hop-skipping type of pattern is what an out-of-range PLL (Phase Lock Loop) could do.

(BTW, I made as post about “Q70R Optical Sound Quality Is Poor,” or something close to that wording. You might want to repost your own results there as this is a big issue that hasn’t received enough attention yet. Your independent results are important.)

One way this could happen is if the DAC were being told that it is receiving 16b data when its receiving 24b data. Another way (depends on PLL implementation of clock extraction) is if you have 4 bytes of data only 3 of which are non-zero. I mentioned this before.

So, there may be a very cheap way to get rid of those dropouts.

There are many “Jitter Cleaners” on the market. Some are USB In/Out, some are Optical In/Out, and some have Optical In/USB out.

The idea is this. “What’s the cheapest way of swapping in a DIFFERENT PCM synchronous/asynchronous data extractor, for your system?”

The theory is that some are more robust than others in tolerating PCM data streams that are ‘weird.’

These things claim to have a ‘better’ clock than the source clock, whatever that is, and they actually do make a difference (the good ones) if you put one in between a laptop with a lousy clock and your Hegel DAC.


There are some patent issues with one or more specific implementations of how to match the frequency precisely of a much lower jitter clock to that of a noisy clock. If MFGR X didn’t pay the royalties for Asynchronous/Synch method “A”, then they use method “B.”

And suffer.

The jitter cleaners are pretty cheap. The optical In/Out obviously need a PS, and they will cost a bit more for that.

The Optical In/Usb out will run off of your USB port straight into the Hegel.

I would try that approach. Or have your Bring Your Own DAC party and swap in different DACs.

Looking at 4K but hearing circa 1930s radio broadcast dropouts isn’t what you paid for.

Go for it!
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Established Member
I’ve got a Halide Bridge which is essentially a jitter corrector (it does work very well, although a good DAC with asynchronous USB is now as good / better. That works the wrong round though (USB to Optical). Could you give me some pointers to a corrector / cleaner that starts with Optical, as far I haven’t managed to track any down ....


Established Member
Here’s one. It has optical in, optical out + 75 Ohm coax out; needs 5V walmart PS.

iFi - SPDIF iPurifier High-Resolution REclocking Jitter Eliminator

This should just splice in between the S/PDIF optical out port on the TV and your fiber cable from your Hegel.

(I know that the picture is confusing. The combined optical + 75 Ohm RCA phono plug connectors are weird, but you will be able to plug it into your Hegel even if it does not directly plug into the TV).

Let me know if this works out.

Best wishes!
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Established Member
Experimented with a different amp (Denon PMA-30 which has a built in DAC). It sounded surprisingly good and none of the original problems I had with dropouts. So the issue is clearly the Audiolab couldn’t deal with whatever the Samsung was doing to the optical out. It sounds “good enough “ so I’m going to call it quits before I start adding to the box count. Thanks for all the advice and suggestions.

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