Topping D70S fried my speakers...

[sarumbear]

Thanks for the post OP. It takes a lot of guts to admit a mistake, but your post can help people avoid a similar issue. Hats off to you.

Have I missed a post where the OP said he made a mistake?

 

[sarumbear]

The DAC directly to power amp has been known as risky for a very long time. Whether it's ignorance or knowingly taking the chance and doing it anyway ..... yup, it is a mistake. I was just giving props to the OP. I don't think most people would admit the mistake, especially here at the snake pit of vipers. Yeah, Topping should get their poop together, but it's not like this issue has not been known for a very long time. Ignorance nearly always fails as an excuse.

It’s a DAC with a preamplifier. It has a volume control — with a remote! It’s perfectly reasonable to connect it to power amplifier. The unit should never have switched on at 0dB. That is 0dBFS, a value that has no use in an audio unit that has a level controlled output — period!

The unit’s software farted and burned the tweeter. It’s a fault of the device.

Yes, the OP “could” have expected that a cheap Chinese unit may be unreliable and took precautions as you said but that doesn’t change the quality of the unit.

Just because a device has excellent value on one aspect doesn’t make it excellent all round.

 

[Marc v E]

It’s a DAC with a preamplifier. It has a volume control — with a remote! It’s perfectly reasonable to connect it to power amplifier. The unit should never have switched on at 0dB. That is 0dBFS, a value that has no use in an audio unit that has a level controlled output — period!

The unit’s software farted and burned the tweeter. It’s a fault of the device.

Yes, the OP “could” have expected that a cheap Chinese unit may be unreliable and took precautions as you said but that doesn’t change the quality of the unit.

Just because a device has excellent value on one aspect doesn’t make it excellent all round.

Good reasoning. However, I cannot think of even one dac that defaults back to a lower value than 0db. Can you name one?

 

[sarumbear]

Good reasoning. However, I cannot think of even one dac that defaults back to a lower value than 0db. Can you name one?

I don't have any experience other than my own two devices. My Benchmark AHB2 had fixed position rotary level control that stayed at the level when you turned it off. I replaced the AHB2 (but kept it) with Topping D90SE. However, not liking the way Topping manages audio levels, I commissioned a custom remote controlled passive volume control that works like AHB2 and use it before the power amps. (I posted about this earlier.)

 

[sq225917]

My gustard A18 reverts to last known volume level after any power off, front or back panel power-down, or even just pulling the plug.

And even then I'd turn it on before my amps, and my amps are designed to reset into standby only after a power cut.

 

[Trell]

My gustard A18 reverts to last known volume level after any power off, front or back panel power-down, or even just pulling the plug.

And even then I'd turn it on before my amps, and my amps are designed to reset into standby only after a power cut.

My RME ADI-2 DAC FS slowly ramps up volume to last level so that I have some time to turn it down or off. Same when switching outputs, say, between monitors and headphones. RME implemented this to save the listeners hearing as well as connected monitors/headphones/IEM.

 

[Roland68]

It’s a DAC with a preamplifier. It has a volume control — with a remote! It’s perfectly reasonable to connect it to power amplifier. The unit should never have switched on at 0dB. That is 0dBFS, a value that has no use in an audio unit that has a level controlled output — period!

The unit’s software farted and burned the tweeter. It’s a fault of the device.

Yes, the OP “could” have expected that a cheap Chinese unit may be unreliable and took precautions as you said but that doesn’t change the quality of the unit.

Just because a device has excellent value on one aspect doesn’t make it excellent all round.

That's exactly the mistake, it's a DAC and is therefore one of the source devices. All source devices in the world deliver full volume at the output. This has been the case for over 50 years and is also intended to be so.
The Topping D70S is one of the normal DACs and does not have an integrated preamp, nor can the device be categorized as a preamp in any way.

In the last 5 years I had over 50 current DACs to test here, both the more current models from SMSL, Topping, Gustard and Sabaj, as well as German, European and US devices for several thousand $/€.
I didn't have to turn up one of them, they were all on maximum volume. This is standard with every normal DAC and every source device.

 

[sarumbear]

All source devices in the world deliver full volume at the output. This has been the case for over 50 years and is also intended to be so.

Is that so? Let’s look at some source devices, shall we? Starting from 50 years ago, moving forward to current.

 

[Roland68]

Is that so? Let’s look at some source devices, shall we? Starting from 50 years ago, moving forward to current.

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4 tries and 4 misses.
- With the Denon SACD player, the volume control is only for the headphones, analog of course
- Ditto for the Revox for headphones and monitoring, also analogue
- The Benchmark DAC3 HGC is a DAC with a built-in headphone amplifier and a built-in "real" preamp, where the volume is of course analog controlled with a potentiometer
- With the Nakamichi 1000, the output is controlled for monitoring and recording, you can read about it in the manual under point 15 of the control functions. It was never intended to control power amps and since it was a professional level device at the time it's a bit ridiculous to use it as an example (most professional devices have an output level control).

 

[RosalieTheDog]

That's exactly the mistake, it's a DAC and is therefore one of the source devices. All source devices in the world deliver full volume at the output. This has been the case for over 50 years and is also intended to be so.
The Topping D70S is one of the normal DACs and does not have an integrated preamp, nor can the device be categorized as a preamp in any way.

In the last 5 years I had over 50 current DACs to test here, both the more current models from SMSL, Topping, Gustard and Sabaj, as well as German, European and US devices for several thousand $/€.
I didn't have to turn up one of them, they were all on maximum volume. This is standard with every normal DAC and every source device.

It's true that it doesn't have an integrated preamp, but you do specifically tell the device which 'role' it's supposed to play in a one-time set-up (or through a menu only accessible by turning it off and on). The D70s can be run in "preamp" and "DAC" mode. In a DAC mode you cannot adjust volume, in a "preamp" mode you can. I think it's reasonable to expect the device to remember its volume settings in "preamp mode", especially since in fact it does! It does remember the volume setting. And for some reason it didn't for one fatal time.

Edit: Anyway, it really does seem to me to be a troubleshooting issue rather than one to have a general discussion about. Relevant questions being: what input was used, what happened prior to the unit malfunctioning ...

 

[sarumbear]

4 tries and 4 misses.
- With the Denon SACD player, the volume control is only for the headphones, analog of course
- Ditto for the Revox for headphones and monitoring, also analogue
- The Benchmark DAC3 HGC is a DAC with a built-in headphone amplifier and a built-in "real" preamp, where the volume is of course analog controlled with a potentiometer
- With the Nakamichi 1000, the output is controlled for monitoring and recording, you can read about it in the manual under point 15 of the control functions. It was never intended to control power amps and since it was a professional level device at the time it's a bit ridiculous to use it as an example (most professional devices have an output level control).

You said no source for 50 years had volume control. Now quantifying with digital only. What digital source existed 50 years ago? Besides, all devices I posted are consumer devices. Correct your historical knowledge, please.

What does “real” preamp means? You seem to be finding excuses to win an argument. I wish you all the best but I’m not prepared to argue against what seems to me, demagogy.

 

[MAB]

We seem to have gotten distracted here making excuses for poorly implemented volume controls. This isn't a DAC vs. "real" preamp issue. It's not even a DAC issue. This is the development of electronic volume controls with no reasonable error-trapping. (Lots of products error-trap for common faults, like tractors! If the operator is tossed off of the machine, the throttle is cut, it doesn't go to full power or some other setting, if it did I would have to conclude that the engineering team had no actual experience with tractors!!!) Back to audio, since the volume control was invented, it has been subject to accidentally being turned to max. In the old days, it was typically operator error; like when switching sources, or unplugging headphones, drinking too much, etc... Now, we have digital volume controls that don't stay put in the presence of a glitch and it really doesn't matter if it is a DAC, preamp, etc... Experienced manufacturers understand this. I had a Sonic Frontiers preamp that reduced the volume in the case of a power interrupt. It had an intelligent headphone jack too so that unplugging the phones didn't accidentally blow your speakers if the gain was different. My Proceed DAC would come up 75dB down if power was interrupted. I just looked at a few DAC/preamps (yes, DACs are real preamps and have been for some time), and they all have some error trapping to prevent the user from having and accident, and to prevent the device from causing an accident all by itself. For instance, PS Audio Stellar DAC/Preamp:

The volume is adjusted by rotating the volume knob. The range is 0 - 100. If you are listening to playback through speakers, the volume will stay where you leave it even after you power the unit off with the blue logo button. If you use headphones and the volume is set above 25, the volume will automatically reduce to 25 when the headphones are unplugged, protecting your speakers. If you power the Stellar Gain Cell DAC off using the rear power switch, once powered back on the volume will default back to 25.

We love to bash PS Audio here, but at least their product team knows how to implement a digital volume control.

Devices resetting to full power are kind of like loaded guns, and should be the exception. I can't think of a single reason why a digital volume control resetting to max volume would ever be a good idea.

OP got screwed by inexperienced and thoughtless product implementation.

 

[pma]

It must have been more than 30 of my posts saying that a dac plugged straight on an amp is an accident waiting to happen sooner or later.

You are absolutely right. There is always a possibility of SW malfunction. Much higher probability than a failure of a good pot.

 

[sarumbear]

You are absolutely right. There is always a possibility of SW malfunction. Much higher probability than a failure of a good pot.

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.

 

[MAB]

You are absolutely right. There is always a possibility of SW malfunction. Much higher probability than a failure of a good pot.

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.

 

[Doodski]

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.

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.

 

[sarumbear]

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.

That is bonkers. Even more so that it seems to be a hardware bug. What was the solution?

 

[MAB]

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.

Great point, that's lots of home theater tweeters that are NOT getting blown! My AVR also comes up from a power interrupt at zero gain. Again, it isn't the volume control that is the problem, it is incorrect application of the volume control, in this case coming back after a reset at full-gain.

 

[Doodski]

That is bonkers. Even more so that it seems to be a hardware bug. What was the solution?

I star grounded them in-warranty and some re-soldered the boards to chassis.

 

[sarumbear]

I star grounded them in-warranty and some re-soldered the boards to chassis.

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