Topping E70 randomly went to MAX volume..

[Roland68]

Well, thinking about the classical combination of a pre-amp and a power-amplifier hooked up together, the question for me arises why pre-amp developers apparently get it done properly and one better shouldn't put the same amount of trust into a DAC. To my understanding, it is the same nominal problem in case of a failure, imagining a pre-amp would suddently output at full level.

Also, the same constellation essentially one has with a modern AVR. The only thing which separates the user from driving the amp at maximum volume is the DSP-based attenuation before the DAC. So again I wonder why it is never an issue there.

Maybe because the volume control in an AVR is after the D/A conversion and before the power amp?
In the AVR you have a digital control of an analog volume control in the small signal range after the DAC chip. Without specific control, no signal is output, or only at the lowest level. This is also the basic setting when switched off or when it is reset by an error. Just look in the service manuals of the AVRs. The difference to the DAC with a starting point of 100% volume should be clear.

 

[little-endian]

In the AVR you have a digital control of an analog volume control in the small signal range after the DAC chip.

Is that so? On my Denon, this "small signal range" at least from the end-user setting perspective is already more than 80dB after all and is also subject to change a bit depending on the channel level adjustments around a few dB, rather suggesting a DSP control, but I may be wrong about it. Update: looks I am as at least some if not most AVRs appear to actually use "digitally controlled IC with an analogue resistor network". Arguble whether those have exactly that kind of built-in safety when it comes to malfunctions over a DSP attenuation before the DAC or it is simply still a matter of philosophy (analog pot vs IC resistor vs DSP).

The difference to the DAC with a starting point of 100% volume should be clear.

Only partly as independently of how exactly it is implemented, I still see plenty of dynamic range to possibly 'malfunction' with an AVR also.

Without specific control, no signal is output, or only at the lowest level.

Sounds like a modest safety design so again the question arises what prevents DSP-only solutions from having similar precautions. One of these could be that significant changes of the gain setting are only allowed within a specific timeframe.

Otherwise, following your argument in reverse and assuming a DSP-only solution (as one doesn't really want analog potentiometers anymore), the only safety measure would be to only allow fixed outputs on a DAC, forcing end users to only hook up sensitivity-adjustable gear to it and at the same time forbid any usage of headphones as there the same issues potentially arises.

 

[MaxwellsEq]

All the more reason to use a proper preamplifier, with a proper volume control.

And NO. A D/A converter is NOT a preamplifier. Never was, never will be. A preamplifier of course can be equipped with a D/A converter. I have several such pieces and they are preamplifiers first and foremost. They have multiple inputs, various gain stages, tone controls, filters, extensive signal routing options, phono preamplifiers and a D/A converter too.

This!

 

[Trell]

This!

This is a long thread, for sure, on this topic.

One way to do this to reduce the sensitivity on whatever is on the other end of the DAC. This is what I did.

Another solution is to install passive attenuators between the DAC and whatever is on the other end. Not sure why preamp is better.

A third solution is to buy products like these from someone that can properly implement volume control. This is not common issue, really.

 

[MaxwellsEq]

Well, thinking about the classical combination of a pre-amp and a power-amplifier hooked up together, the question for me arises why pre-amp developers apparently get it done properly and one better shouldn't put the same amount of trust into a DAC. To my understanding, it is the same nominal problem in case of a failure, imagining a pre-amp would suddently output at full level.

Also, the same constellation essentially one has with a modern AVR. The only thing which separates the user from driving the amp at maximum volume is the DSP-based attenuation before the DAC. So again I wonder why it is never an issue there.

Because a DAC's correct default output setting is 0 (or perhaps better understood as maximum).

When people adjust the volume via their DAC+Digital-Attenuator they are effectively always turning it down!

Classic preamplifiers, both attenuate AND amplify.

 

[Overseas]

In this context, as a non technical person, I wonder about a 'myth' that is heavily argued against here on ASR. That is, a DAC in pre-amp mode sounding 'worse' than in fixed max output mode - which is proved for Wiim Pro by measurements. So, if DACs volume control is via Dsp, the myth has technical chances of being true, am I right?!

 

[Trell]

In this context, as a non technical person, I wonder about a 'myth' that is heavily argued against here on ASR. That is, a DAC in pre-amp mode sounding 'worse' than in fixed max output mode - which is proved for Wiim Pro by measurements. So, if DACs volume control is via Dsp, the myth has technical chances of being true, am I right?!

This thread is about that Topping E70 for some reason reset the volume to maximum, and that it's not an isolated event either from various posts here on ASR. As I recall, only Topping devices has been reported to have this bug.

 

[MaxwellsEq]

In this context, as a non technical person, I wonder about a 'myth' that is heavily argued against here on ASR. That is, a DAC in pre-amp mode sounding 'worse' than in fixed max output mode - which is proved for Wiim Pro by measurements. So, if DACs volume control is via Dsp, the myth has technical chances of being true, am I right?!

There are many threads on this. Early examples were questionable. With modern DACs there is no real-world problem. Search for this subject for more details.

 

[Overseas]

So, no answer for me.
Everything is questionable.
No guarantees in life and blue is the new red. Got it.

 

[Atanasi]

As I recall, only Topping devices has been reported to have this bug.

Older E1DA dongles had a similar glitch where disconnecting USB data but keeping the power up would output white noise at full scale. Newer revisions have fixed this. It's not exactly the same bug but shows various ways for full scale output to happen.

 

[JSmith]

So, no answer for me.

Amir now shows in his reviews;

As we can see, SINAD is still 100dB at a low volume.


JSmith

 

[MaxwellsEq]

So, no answer for me.
Everything is questionable.
No guarantees in life and blue is the new red. Got it.

I answered your question. This is a thread about bugs causing DACs to go to their native 100%.

If you want to know whether the attenuators added in to most modern DACs produce audible depredation, search for threads on that topic. But the short answer is: probably not in a way you can hear it.

Edit: @JSmith got there first.

 

[soerenssen]

I'm currently searching for a DAC/pre-amp for a Kef Reference 3 Meta + NCx500 combo.
I was considering Topping DACs too, but after reading I'm not so sure anymore. This is definitely not what anyone would want to experience in his home.
Does it mean that it's safer to discard Topping products altogether?
How can this issue be avoided with other DACs like an RME?

 

[Roland68]

I'm currently searching for a DAC/pre-amp for a Kef Reference 3 Meta + NCx500 combo.
I was considering Topping DACs too, but after reading I'm not so sure anymore. This is definitely not what anyone would want to experience in his home.
Does it mean that it's safer to discard Topping products altogether?
How can this issue be avoided with other DACs like an RME?

You don't have to do without a DAC, you should just refrain from using a volume control that is based on the DSP function of the DAC chip. Especially without additional security measures. (Almost) everything should have been written about this in this and the other threads on this topic, keyword attenuators, preamplifiers, etc.
With RME you don't have this problem because RME has its own digital volume control in front of the DAC chip. However, we are also talking about a professional device from one of the leading manufacturers of professional audio equipment.

 

[MaxwellsEq]

I'm currently searching for a DAC/pre-amp for a Kef Reference 3 Meta + NCx500 combo.
I was considering Topping DACs too, but after reading I'm not so sure anymore. This is definitely not what anyone would want to experience in his home.
Does it mean that it's safer to discard Topping products altogether?
How can this issue be avoided with other DACs like an RME?

A DAC's default setting is 100%. Any DAC with DSP based attenuation could have a glitch making it default to the standard 100%. It therefore comes down to flawless software or luck. The classic solution is a preamplifier between the DAC and power amplifier.

 

[JSmith]

How can this issue be avoided

One can also buy an amp that has it's own volume... run the DAC at full output and turn up the amp to the loudest you would ever want to have it, then adjust using the DAC volume control and leave the amp volume as is. If something happens to go awry, at least you then know you won't damage your speakers if the DAC defaults to full output. Also, it's more likely to happen after a power cycle if setting somehow become reset, rather than during usage, so always check the volume on the DAC before turning on the amp.


JSmith

 

[Sokel]

One can also buy an amp that has it's own volume... run the DAC at full output and turn up the amp to the loudest you would ever want to have it, then adjust using the DAC volume control and leave the amp volume as is. If something happens to go awry, at least you then know you won't damage your speakers if the DAC defaults to full output. Also, it's more likely to happen after a power cycle if setting somehow become reset, rather than during usage, so always check the volume on the DAC before turning on the amp.


JSmith

Why not just set the DAC to max (or -3db to avoid most of the intersample overs) and just use the ease of the remote control or the big knob of the integrated.
Unless the gain structure is not the optimal one,this has to be calculated and measured.

It's not about audibility of course,it's more like the fact that someone pays for certain performance and it's nice to see it when measure it regardless that audibility issues are far-far away.

 

[JSmith]

just use the ease of the remote control or the big knob of the integrated

Agree, if it has one... but I meant really amps like the LA90, Fosi etc. that are more a "power amp with a volume pot" rather than a traditional integrated. It would be easier in those cases to use the DAC volume as they don't come with remote volume control.


JSmith

 

[BR52]

I use the E 70 since month’s in preamp mode. Is still running flawless.

 

[JeremyFife]

Which thread? I'd like to read..

I've had this setup for 5 days or now so and haven't had any issues with the E70, not sure how this issue came out of no where. Even worse was that the volume control LOCKED to 0db regardless of me trying to turn it down instantly.

Think I'll leave my Windows volume at 50% for a couple days, make sure it doesnt happen again.

This Thread 'Topping D70S fried my speakers...' https://audiosciencereview.com/forum/index.php?threads/topping-d70s-fried-my-speakers.38706/