Topping D70S fried my speakers...

[restorer-john]

0db is straight DAC. It’s very common to use a Topping D10 to drive Genelec’s and rely on your source to control volume. Granted Genelec have good protection, I would have thought Revel’s would as well.

Protection in passive speakers is usually done with a polyswitch in the tweeter line. But they take time to go high and 'audiophile' brands like to leave them out. Tweeters cannot absorb massive bursts and will actually vaporise the lead-in wires in a fraction of a second. Poor OP.

 

[NiagaraPete]

Okay, how the hell does a DAC fry a passive speaker? Where is the amp?

 

[Jinjuku]

Sorry to hear what happened. I can only echo others are saying. Connecting a DAC output direct to a power amplifier is never safe. You are basically trusting a software that is developed by a small team or even one person and not tested properly, at least not by a professional test team. Remember, even software written by major developers like Apple & Microsoft occasionally fails.

This is why I use a custom passive volume control based on a motorised Alps potentiometer, similar to this one. There are also ready made devices based on this concept.

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Then there is software written for xray machine the Therac 25 that killed patients due to a software bug. Takes zero day to a whole other level.

 

[Chrispy]

Okay, how the hell does a DAC fry a passive speaker? Where is the amp?

Per his signature it's a Audiophonics LPA-S400ET

 

[NiagaraPete]

Per his signature it's a Audiophonics LPA-S400ET

Then we should be looking at that, and not blaming the DAC as the absolute problem.

 

[Chrispy]

Then we should be looking at that, and not blaming the DAC as the absolute problem.

Why? It's the volume setting that would do it with other pre-amp signals too....I like the feature of being able to set a start up and max volume for sure.

 

[restorer-john]

Then we should be looking at that, and not blaming the DAC as the absolute problem.

Huh? It’s a power amp. It amplifies whatever you feed in.

 

[NiagaraPete]

Huh? It’s a power amp. It amplifies whatever you feed in.

And if the amp went into fault? Power spike? Speaker wire loose?

 

[NiagaraPete]

Huh? It’s a power amp. It amplifies whatever you feed in.

My point is, don’t blame the DAC. It could be a number of issues.

 

[restorer-john]

My point is, don’t blame the DAC. It could be a number of issues.

I absolutely 100% blame a DAC that defaults to 0dB after previously being set at a much lower level.

That is what the OP is describing.

 

[NiagaraPete]

I absolutely 100% blame a DAC that defaults to 0dB after previously being set at a much lower level.

That is what the OP is describing.

But a default as a DAC is 0db.

 

[sarumbear]

Then we should be looking at that, and not blaming the DAC as the absolute problem.

Really? A power amplifier is blamed for amplifying the input signal is at fault?

But a default as a DAC is 0db.

He was obviously using it in pre-amp mode. Duh!

 

[sq225917]

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.

 

[Cars-N-Cans]

But a default as a DAC is 0db.

Considering some of these DACs can go beyond 2Vrms single-ended or 4Vrms balanced that is going to be A LOT of voltage swing for an amp with a gain of 20 dB, which is a gain of 10. With RCA out that is going to be >20Vrms into speakers that have a sensitivity of 88.5 dB/1m with a 2.83Vrms input. Modern speakers with their low impedances don't like large voltage swings for obvious reasons. Things go up in smoke in a hurry due to the dissipation.

 

[maverickronin]

This is an unhappy reminder for me to add a limiter to my DSP chain.

 

[gvl]

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.

Yup, this rule goes back half a century at least.

 

[raif71]

A more general protocol is to not run powerful amps into wimpy speakers.

 

[Rottmannash]

... never thought of the F208s as "entry level".

 

[amirm]

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.

I am very sorry for the OP loss. But above is what I follow religiously given the fact that I have 1000 watt amplifiers. I even have an analog pre-amp and still do this. Shut down is then the reverse procedure. This is both for protection of speakers/ears and the amps themselves. Using a DAC with volume control is perfectly safe using this protocol.

I don't know why @restorer-john is saying this is brand specific. Throughout my audiophile life I have had countless times where a system has powered on at full volume. At work we also had an American made multi-thousand dollar DAC short out and blow out the drivers in a loaned speaker. On my desktop system, I have routinely have had to pull off the headphones from my head with lightning fast action because the volume was at max (or very high).

This is just one of the hazards of audio systems.

 

[amirm]

As another example, we had a $120K Wisdom audio system in our theater at work. During Room EQ, if you didn't take one specific step, it would feedback from the mic into the system and play at full volume! It was incredibly scary the first time I experienced it! From then on, my fingers would shake every time I hit the go button on EQ process!