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So a bolt of DC burnt out my Zensor 5

Wharfedale Linton Heritage Speakers

sound_cycle

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I added a new DAC to my rig a while ago, there was DC in the output, which went through my pre- power amp and onto the speakers. As a consequence of that defect, both the woofers on one channel are burnt out. The tweeter output seems to be functional/ okay based on simple listening tests.

from the spec on the Dali website: The Zensor 5 has 2 x 5.25" LF units, the crossover is 2,400 Hz after which the tweeter is to take over. Both 5.25 inch woofers in the ZENSOR 5 feature 4-layer voice coils for maximum control of the wood fibre cone.

I have not been successful in getting a response from Dali India (I did not interact with them directly but through a dealer)

I see 4 possibilities

1) Replacement drivers from Dali - looks bleak, from what the dealer told me no spares are imported
2) Replacement with alternate drivers - Would there be something that is a candidate, these wood fibred cones were nice to listen to
3) Get them rewound - Would that be possible ? Would really appreciate tips on where to get it done in India
4) Look for Z5 used in the EU/UK and get only the drivers down through some one kind enough to take the trouble to find, pickup, strip and then bring the speakers over : Wishful thinking dept

Would be grateful for any pointers on getting these speakers fixed singing again, esp on pts 2 and 3

ciao
gr
 

MaSh

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Oh damn. That's really sad. Which dac was that? A diy one? Only one channel affected or both sides? If yes, then for the mean time you could move one good mid bass to the affected speaker. Disconnect the affected drivers on both cabinets.

You could contact dni home theatre too. They are dealers for Dali.

MaSh
 

hydrovac

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I added a new DAC to my rig a while ago, there was DC in the output, which went through my pre- power amp and onto the speakers. As a consequence of that defect, both the woofers on one channel are burnt out. The tweeter output seems to be functional/ okay based on simple listening tests.

from the spec on the Dali website: The Zensor 5 has 2 x 5.25" LF units, the crossover is 2,400 Hz after which the tweeter is to take over. Both 5.25 inch woofers in the ZENSOR 5 feature 4-layer voice coils for maximum control of the wood fibre cone.

I have not been successful in getting a response from Dali India (I did not interact with them directly but through a dealer)

I see 4 possibilities

1) Replacement drivers from Dali - looks bleak, from what the dealer told me no spares are imported
2) Replacement with alternate drivers - Would there be something that is a candidate, these wood fibred cones were nice to listen to
3) Get them rewound - Would that be possible ? Would really appreciate tips on where to get it done in India
4) Look for Z5 used in the EU/UK and get only the drivers down through some one kind enough to take the trouble to find, pickup, strip and then bring the speakers over : Wishful thinking dept

Would be grateful for any pointers on getting these speakers fixed singing again, esp on pts 2 and 3

ciao
gr



Have you dismounted the drivers... do they look anything like this?


1539940297139.png

1539940361677.png
 

hifitoaster

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) Look for Z5 used in the EU/UK and get only the drivers down through some one kind enough to take the trouble to find, pickup, strip and then bring the speakers over : Wishful thinking dept

The above would be my route patiently keeping this aside, meanwhile getting something else. Dont replace with anything else, since the orginals are DALI in house made specific to that cabinet. I am surprised how the woofer died and not the tweeters. Sure there is nothing wrong with the crossover? The tweeters normally are quite easier to kill than the woofers.

Keep an alert in Hifishark.com someone will have a pair which has some other problem.
 

sound_cycle

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Oh damn. That's really sad. Which dac was that?[snip]

You could contact dni home theatre too. They are dealers for Dali.

MaSh
Schiit Gungnir multibit. From the factory in its unopened original packaging !!

Schiit as they say happened.


Have you dismounted the drivers... do they look anything like this?
The part number I think was 350291, have to check. The size matches 5.25"
 
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jls001

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This whole affair is so unbecoming of a brand new equipment from a brand as reputed as Schiit:oops: But before you lodge a formal complaint, arm yourself with hard data. If you don't have one, buy yourself a multimeter (Rs 500-600), preferably something that has a DC voltage range starting at 200 mV.

Switch on the DAC without connecting any input or output and with the multimeter set at 2V DC range, measure the voltage across right RCA output. Red probe goes to +ve lead of RCA socket, black probe of multimeter goes to barrel of RCA. If the meter can't measure the voltage, change the range to the next higher range of 20V and measure again. Similarly, if the reading in 2V range is is lower than 0.2V, change the range to 200 mV to read the voltage more accurately. Measure left channel too.

This measures the DC Offset of the device that is self generated by the device (no input is given so the chance of sending some DC component from source to the DAC is ruled out). Ideally one should short the input but I don't know how USB input can be shorted outside of making an elaborate jig.

What should be an ideal measurement? Zero. But in real life it is often a few millivolts in single digits. Assuming you measure 50 mV (a very high voltage taken for example), this DC gets passed on to the preamp. Let us say the preamp has a gain of 6x. The preamp will output 300 mV. Further down, let us say the power amp has a gain of 24x. If you do the math, what gets passed to the speakers is a lot of DC, enough to fry the speaker.

I assume the Schiit DAC is DC coupled, meaning it doesn't have any DC blocking capacitor in the signal path.

Your pre and power too must be DC coupled if they let the DC reach the speakers.

And while you're at it, check the DC offsets of your pre and power too.
 

sound_cycle

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)Sure there is nothing wrong with the crossover? The tweeters normally are quite easier to kill than the woofers.

Keep an alert in Hifishark.com someone will have a pair which has some other problem.

Thanks. That's what surprised me too..The tweeters still make music. Not the best of diagnostics but that was how I came to this conclusion.

The LF drivers were checked with multimeter for continuity and failed.

This whole affair is so unbecoming of a brand new equipment from a brand as reputed as Schiit:oops:

The warranty claim was honoured. It however does not cover damage to equipment. This DAC was from the India D&D (HPZ) so there was no shipping to the US and wondering about getting hit by customs etc.

Remote diagnosis by Schiit was very quick. Curiously they suggested repair and not replacement (which is the warranty terms on the HPZ website). The main and analog boards were replaced (with my agreement).

I had requested that HPZ carry out the fix and then check with multimeter and oscilloscope and the said they could not look at the wave form but would test it thoroughly, with HP and spkrs. It was with some trepidation that I hooked it back up and connected it up again, but Vidar (which was heating up like a toaster with the faulty unit and going to thermal shut down failure mode stayed as cool as the proverbial cucumber).

Then my greed, obsession, impatience, lack of impulse control AND I said YOLO and got the door size planars, with their boat sized sound stage.
 
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hifitoaster

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The warranty claim was honoured. It however does not cover damage to equipment. This DAC was from the India D&D (HPZ) so there was no shipping to the US and wondering about getting hit by customs etc.

Remote diagnosis by Schiit was very quick. Curiously they suggested repair and not replacement (which is the warranty terms on the HPZ website). The main and analog boards were replaced (with my agreement).

I had requested that HPZ carry out the fix and then check with multimeter and oscilloscope and the said they could not look at the wave form but would test it thoroughly, with HP and spkrs. It was with some trepidation that I hooked it back up and connected it up again, but Vidar (which was heating up like a toaster with the faulty unit and going to thermal shut down failure mode stayed as cool as the proverbial cucumber).

Then my greed, obsession, impatience, lack of impulse control AND I said YOLO and got the door size planars, with their boat sized sound stage.

ciao
gr
I have toasted the tweeters of my speakers before along with one inductor with JDS labs C5D's headphone out directly connected to a power amp. It sounded super clear and sound stage was really 3D. Then I thought, ok now let me try how it sounds with a bass boost. It clipped some how, I guess my amp, few seconds later 1 am down with two blown tweeters and 2 months time with the crossover to find out what really failed.(Surprisingly 2 inductors screwed up, which was parallel to the tweeters). In your case, you are sure about the drivers. I guess the entire zensor range has the same woofers. You may find the smaller speakers and take the drivers out of them.

what puzzled me was why it didnt screw up my amp?

Edit:
If you have someone to pick it up from EU, this shop sells single piece for 249€. https://www.stassen-hifi.com/speakers/speaker/dali-zensor-5. You may get fresh woofers and a spare crossover and tweeter for future. ;) (Abandon the box)The average asking price for a used pair in EU is about 300-450€. Then again we dont know if those are abused or not.
 
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spirovious

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Schiit Gungnir multibit. From the factory in its unopened original packaging !!

Schiit as they say happened

Thanks.

Ciao
GR
I guess problem could be power amp.
Usually power amp do have coupling caps at preamp input stage.So l guess its hard to pass dc even if dac sends it.Just check nothing short within poweramp or coupling caps are blown.
 

sound_cycle

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I guess problem could be power amp.
Usually power amp do have coupling caps at preamp input stage.So l guess its hard to pass dc even if dac sends it.Just check nothing short within poweramp or coupling caps are blown.

Vidar has some fancy microprocessor based fault detection. Vidar was driven into thermal mode protection fault by the Gungnir. The manual listed three conditions for that failure case to present, overheating, shorting of speaker cables and DC in the input. I was not in country when this was hooked up and tried out by my son (Gumby was delivered and had to be tested). He did hear a hum, he observed that Vidar protection faulted and that the heating was one side but read the manual and concluded that since connections were okay it was an amp issue.

The power- and pre- are functioning normally since the DAC was fixed.

If you have someone to pick it up from EU, this shop sells single piece for 249€. https://www.stassen-hifi.com/speakers/speaker/dali-zensor-5. You may get fresh woofers and a spare crossover and tweeter for future. ;) (Abandon the box)The average asking price for a used pair in EU is about 300-450€. Then again we dont know if those are abused or not.
Thanks much.
 
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