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D90LE loud pop noise in pre-amp mode

Italian Job

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Hello, it's my first post on ASR!

I've had a D90 in my system for a while, always used in dac mode as my power amp (IOM 250) has a volume controller.
In anticipation of my new power amp with no volume controller, I decide to give the pre-amp mode a go.

With the d90 in pre-amp mode and the amp on full volume, I can hear a loud pop coming through the speakers whenever the dac changes sample rate, when pausing/play music and weirdly enough also when muting the dac via remote.
Initially I thought the problem was the sending device/usb cable but the fact the it pops also when muting the dac with no source connected, makes me think it might be something else?

The pop noise is loud and lessen as I turn the amp volume down, the dac volume doesn't affect the loudness of the pop whatsoever, I'm saying this because Topping support told me to raise the volume on the dac to cure the problem.

I don't know what to think, I wonder if the problem is related to the power amp having a volume controller? or maybe the dac is faulty? Any advice or suggestions would be gratefully received.

thanks!
 

asrUser

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Sell your chifi and buy a higher quality Schiit DAC or an RME ADI-2. :D
 

Sokel

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Do you have any other DAC to try to replicate it?
(anything will do,doesn't have to be fancy)

Also,can you measure the DAC's output at these conditions with a DMM? (both AC and DC)
 
OP
Italian Job

Italian Job

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chifi haha never heard that before
yeah will likely end up doing that, I wonder how much would a non chifi dac (that measure as good) set me back...
 
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OP
Italian Job

Italian Job

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Do you have any other DAC to try to replicate it?
(anything will do,doesn't have to be fancy)

Also,can you measure the DAC's output at these conditions with a DMM? (both AC and DC)
Unfortunaly I don't have any other dacs available atm, I might borrow an smsl from a friend and see what happens.

Topping insist the dac volume in preamp mode should always be at maximum, and use the volume on the amplifier, what if the power amp doesn't have a volume pot? why on earth would I use the dac in preamp mode if the volume cant be anything else other than -00.0dB?
I can't make any sense of it..
 

Sokel

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Unfortunaly I don't have any other dacs available atm, I might borrow an smsl from a friend and see what happens.

Topping insist the dac volume in preamp mode should always be at maximum, and use the volume on the amplifier, what if the power amp doesn't have a volume pot? why on earth would I use the dac in preamp mode if the volume cant be anything else other than -00.0dB?
I can't make any sense of it..
What kind of preamp mode is that,that requires the maximum?
It's funny and it defeats the purpose,even makes the term "pre-amp" sound funny.

What other purpose can a preamp have other than volume control and good impedance matching?
That's weird...
 

asrUser

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I read the review of the Schiit Bifrost and the measurements looked a bit schiit....
You better listen with your ears and not just measurements. Do you mean amirm's measurements? There are old ones Bitfrost 1 and Bitfrost 2. Latest one is Bitfrost 2/64. He probably measured Bitfrost 1.
 
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I have a Teac UD-501 Dac That is phenomenal and one in excellent condition will be around $400 US. They are no longer produced but will faithfully reproduce whatever you throw at it. Check some HiFi sites with resale.
 
OP
Italian Job

Italian Job

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You better listen with your ears and not just measurements. Do you mean amirm's measurements? There are old ones Bitfrost 1 and Bitfrost 2. Latest one is Bitfrost 2/64. He probably measured Bitfrost 1.
I see I thought it was the latest modem, the defrost 1 did terribly!
I'll check the 2 64 out, thanks!
 
OP
Italian Job

Italian Job

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I have a Teac UD-501 Dac That is phenomenal and one in excellent condition will be around $400 US. They are no longer produced but will faithfully reproduce whatever you throw at it. Check some HiFi sites with resale.
Sounds interesting. I'll check that out too! Cheers
 

Streamc

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I also own the LE, do you use it in preamp mode?
I used it in pre mode too. But here everything is banal. A specific analysis and service are needed for a specific breakdown. This requires services, knowledge, tools.
 
OP
Italian Job

Italian Job

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I used it in pre mode too. But here everything is banal. A specific analysis and service are needed for a specific breakdown. This requires services, knowledge, tools.
you're right!
but all I wanted to know is if the dac in preamp mode, makes any loud popping sound when muted from the remote, amplifier on full volume, no source needed for the test.
 

ComasSky

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Classic issue with class D amps .... There is generally no decoupling capacitor with Hypex / Purifi kits (and the assemblers don't add any).

As a result, even the smallest DC signal emitted by the preamp (relay for example = volume relay, source relay, sample rate change) is not filtered and becomes a small pop (even more detectable with high-output loudspeakers).

Class D amplifiers sold by assemblers generally have no filtering whatsoever, so even the slightest signal is amplified.

That's why I sold my Purifi 1ET400A stereo amp.
 
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OP
Italian Job

Italian Job

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Classic problem with class D amps .... There is generally no decoupling capacitor with Hypex / Purifi kits (and the assemblers don't add any).

As a result, even the smallest DC signal emitted by the preamp (relay for example) is not filtered and becomes a small pop (even more detectable with high-output loudspeakers).

That's why I sold my Purifi 1ET400A stereo amp.
So Topping might be right that's nothing wrong with the dac, I have an Hyperx based amp and just bought a purifi model
I guess I'll need to buy a passive preamp!
I guess that would also explain why the pops volume lessen as I turn the amp volume down
thanks @ComasSky
 
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Streamc

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Classic issue with class D amps .... There is generally no decoupling capacitor with Hypex / Purifi kits (and the assemblers don't add any).

As a result, even the smallest DC signal emitted by the preamp (relay for example = volume relay, source relay, sample rate change) is not filtered and becomes a small pop (even more detectable with high-output loudspeakers).

Class D amplifiers sold by assemblers generally have no filtering whatsoever, so even the slightest signal is amplified.

That's why I sold my Purifi 1ET400A stereo amp.
I have ET400 board but no such problem.
 
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