Topping D70S fried my speakers...

[Scrappy]

Seems highly unlikely. Most often “people” fry drivers.

I fry amp channels like it’s my job. Quite ironic considering what my job is...

 

[Doodski]

Neither can be done by a normal user, what did Sony and its dealer network did? Have they recalled them?

They had service bulletins out to each depot c/w a handful of other service bulletins for the series, instructions to solder the PCBs to chassis. I actually got out a large tinsmiths soldering iron and soldered a chassis and it flowed on the metal but whoa what a operation... No recall from what I am aware of. I was apparently known to the main service depot for star grounding them. Nobody advised me of anything other than some radical solder job to chassis bypassing a screw.

 

[Roland68]

Does that mean almost all AVRs are inherently dangerous? In other words, Billions of Dollars of units are sold every year, which can potentially burn countless tweeters.

Agreed, seems that glitches in digital volume control are common. Given that, the fail mode on these things being "return to full volume" is absolutely thoughtless.

But now everything is being thrown into confusion here.
The volume control in an AV receiver and a DAC have absolutely nothing to do with each other.
A digital control of the analogue volume control in an AVR takes place after the D/A conversion, before the power amplifier.
Volume reduction in a DAC occurs before the D/A conversion, not after the DAC chip.

Perhaps this is also the problem of understanding why using the digital volume reduction to directly control power amplifiers is not the best solution.
100% volume is always the normal state when the DAC chip converts the data (100%) unchanged from digital to analog.
So, in order to reduce the volume, the digital music data must be processed (reduced), the lower the volume, the more.
Why is anyone surprised that when an error/problem/reset occurs, the DAC switches back to normal and converts 100% of the incoming data stream?

 

[Scrappy]

Stop right there.

You switch on the source first, and the amps last, always. This little bit of expediency, along with always checking the volume level before turning on the next item in the chain would have saved his speakers.

Anyone turning one a dac or pre amp plugged into already switched on power amps needs their head examined.

Audio 101. Extra fun with big PA’s. Though modern digital boards are pretty quiet upon startup.

 

[sarumbear]

But now everything is being thrown into confusion here.

Indeed. I for one didn’t know that:

A digital control of the analogue volume control in an AVR takes place after the D/A conversion, before the power amplifier.
Volume reduction in a DAC occurs before the D/A conversion, not after the DAC chip.

I appreciate very much if you explain a further. Maybe a block diagram comperison?

Thank you in advance.

 

[Roland68]

Indeed. I for one didn’t know that:

I appreciate very much if you explain a further. Maybe a block diagram comperison?

Thank you in advance.

To be honest, this is currently too complex for me, but it is very simple.
The digital volume reduction takes place either directly in front of the DAC chip, or, assuming the appropriate functionality, in the DAC chip, usually in the DSP area directly after the digital input.
In the data sheet of the ES9038Pro you will find the volume control below the oversampling filter, directly after the input interface, before all further processing.
https://www.esstech.com/wp-content/uploads/2021/03/ES9038PRO-Datasheet-v3.7.pdf

There are a few threads here in the forum (of course also in others) that deal with exactly the topic and possible effects on the sound.
Regardless of that, I don't want to reduce my music data in any way .

 

[MAB]

To be honest, this is currently too complex for me, but it is very simple.
The digital volume reduction takes place either directly in front of the DAC chip, or, assuming the appropriate functionality, in the DAC chip, usually in the DSP area directly after the digital input.
In the data sheet of the ES9038Pro you will find the volume control below the oversampling filter, directly after the input interface, before all further processing.
https://www.esstech.com/wp-content/uploads/2021/03/ES9038PRO-Datasheet-v3.7.pdf

There are a few threads here in the forum (of course also in others) that deal with exactly the topic and possible effects on the sound.
Regardless of that, I don't want to reduce my music data in any way .

These are certainly some of the differences between a couple volume control implementations. Doesn’t matter though, they should all default to low or zero gain when power fault or glitch, or come up in mute. Lots of manufacturers do this, because it is just a good engineering practice. And, it is done in so many other industries on systems much more difficult to error-trap than a digital volume control!!!

 

[levimax]

Any device can fail in unexpected ways... I had a bad solder connection on a DIY pre-amp volume circuit (full analog with a fancy ALPS potentiometer) that intermittently would turn on with one channel at full volume.... and then would work fine on my bench. Even though I turned the pre-amp on first with volume set low, and then the amp, I didn't know there was a problem until the source started playing. I was lucky that I didn't blow out the speaker even though it happened twice. No matter how careful you are accidents can happen. The pre-amp had worked fine for 5 years in steady use before this happened the first time.

 

[MAB]

Any device can fail in unexpected ways... I had a bad solder connection on a DIY pre-amp volume circuit (full analog with a fancy ALPS potentiometer) that intermittently would turn on with one channel at full volume.... and then would work fine on my bench. Even though I turned the pre-amp on first with volume set low, and then the amp, I didn't know there was a problem until the source started playing. I was lucky that I didn't blow out the speaker even though it happened twice. No matter how careful you are accidents can happen. The pre-amp had worked fine for 5 years in steady use before this happened the first time.

Yes, accidents certainly do occur. And having the volume control inadvertently playing your hifi at max gain is is an accident that can happen due to operator or equipment error. It is a known thing, to the extent that many gear manufacturers have simple fixes for that: if fail, then return to operation at low or no gain. As I said, lots of manufacturers do this on more difficult volume controls than on a DAC.

 

[restorer-john]

A digital control of the analogue volume control in an AVR takes place after the D/A conversion, before the power amplifier.

Ah no. Certainly not one size fits all I'm afraid.

Many digitally controlled analogue volume controls are implemented at the input stage, just after the source selection and any tone controls balance volume trims are do prior to A/D (if any).

At the end of the day, defaulting to 0dB should never happen on reset/power up, no matter what.

 

[MAB]

There are a few threads here in the forum (of course also in others) that deal with exactly the topic and possible effects on the sound.
Regardless of that, I don't want to reduce my music data in any way .

I get your point and Topping is thinking the same way; product should default to maximum fidelity (even if the human ear can't tell the difference!!!) The merest hint that you might be compromising SINAD is intolerable!

It is an inconvenience to have to turn the volume back up to your preferred hifi setting. It's existential to have your speakers blown just because the power went out for a few seconds. I really don't even want to be in the room when this happens, and I don't own anything that can play above 120dB. I love the high performing circuits, the form factors, and the minimalist designs of this Topping gear, but this is not the way to get to that performance.

I am not suggesting that the last iota of dynamic range be kept from the customer. Just want reasonable product design.

 

[MAB]

Sony had the STR-AVXXXX series that was known to switch ON in the middle of the night and auto switch radio stations as the volume went to 100% and stayed there. It was caused/found fault @ by PCBs grounds to chassis failures. Many people where awoken in the very early morning as their house changed temperature and the ground changed too. Brain failure due to poor ground.

Gosh, it makes the smoke detector that runs out of battery at 2AM seem peaceful (and, they do always give out at about 2AM local-time...)
I have a friend with a pair of Cerwin Vegas in his bedroom, don't even ask... I think it might give me a heart attack if those came on full-beans while I was sleeping...

 

[Sokel]

Accidents will always happen by misuse,I have already posted how two very nice 10 inch scanpeaks almost gone out of their boxes when my little destroyer turned the pot to max while playing in a previous set-up I had.
But that's completely different than the common sense to reset to low or nothing when anything strange occurs.
And sadly a lot of strange stuff happen in various points when VC is all-digital.

 

[MCH]

Risk evaluation needs to be done in a holistic approach and the result will depend on each case circumstances. Not knowing much about the technical details, I have problems to accept that an analog volume control is always safer than a digital one. Example: if your 4 yo toddler has been playing with your analog pot and leaves it maxed while the amp was off and you don't notice before you start playing your favorite Stooges album, there you go. The same situation with an endless turning digital pot, no problem.

 

[Sokel]

Risk evaluation needs to be done in a holistic approach and the result will depend on each case circumstances. Not knowing much about the technical details, I have problems to accept that an analog volume control is always safer than a digital one. Example: if your 4 yo toddler has been playing with your analog pot and leaves it maxed while the amp was off and you don't notice before you start playing your favorite Stooges album, there you go. The same situation with an endless turning digital pot, no problem.

Analog pots usually have a visual indicator (a dot,a line,something) and all it takes is a look at it to see if it's maxed.
As for the 4yo,look at the previous post.
The horror I still remember vividly!

 

[Roland68]

Analog pots usually have a visual indicator (a dot,a line,something) and all it takes is a look at it to see if it's maxed.
As for the 4yo,look at the previous post.
The horror I still remember vividly!

Thank you for saying that so clearly.
I would never turn on my amp, or start playing music from my source, without first checking the volume control position.

Why do some users of DACs with digital volume reduction feel that they are relieved of the obligation to verify the position of the volume control?
Because you would have to look at the digital display?

 

[Aerith Gainsborough]

At the end of the day, defaulting to 0dB should never happen on reset/power up, no matter what.

This. Even my lil' entry level AVR hard-defaults down to -40dB.
There is no excuse for a Topping DACs to not do the same.

Of course the user is also to blame somewhat. Ones does check the levels before feeding a signal, if one owns amp powerful enough tp destroy components.

 

[restorer-john]

Why do some users of DACs with digital volume reduction feel that they are relieved of the obligation to verify the position of the volume control?
Because you would have to look at the digital display?

Because those poor souls have no idea what the level is, until they turn it on. And then it's too late. Haha.

Get some real HiFi and stop p#ssing around in the shallow end I say.

 

[restorer-john]

There is no excuse for a Topping DACs to not do the same.

Hopefully those Topping guys will learn. Maybe, maybe not. But being a consumer beta tester with high fidelity equipment- no thanks- count me out of that chit.

 

[Koeitje]

Get some real HiFi and stop p#ssing around in the shallow end I say.

What is 'real HiFi'?