Is Dorati a new version of Kubelik?
Sound record of static type noise
The static noise could be one of the DACs gone bad, investigate that by shorting pin7 to pin4 on each DAC chip in turn (I use a pair of tweezers for this) to see if the static noise goes away. If no success with that then you can eliminate stages one by one by taking the output signal from TP7 rather than TP10. To do this you'd need to connect R46 to Q9 instead of Q16 - this bypasses the NOS droop filter. If the static goes away from doing that then you know its the droop filter making the noise. If its still there, then it must be DACs or I/V stage.
Dorati isn't a replacement for Kubelik, it is inspired by Kubelik though. Kubelik's successor is Toscanini in the progression of opamp-based DACs.
Dorati isn't a replacement for Kubelik, it is inspired by Kubelik though. Kubelik's successor is Toscanini in the progression of opamp-based DACs.
Dorati has a more dynamic sound than Kubelik, a lower noise floor. My wife says though that Kubelik has a 'coherence' quality that Dorati lacks but I don't notice that. I haven't listened to Toscanini vs Kubelik but my guess is it would be a little more dynamic than Kubelik as the DACs are running at higher bias.
If you're after a significant step up in SQ maybe build a Stack DAC which will be coming along in a few weeks.
If you're after a significant step up in SQ maybe build a Stack DAC which will be coming along in a few weeks.
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I took output signal from TP7. Short pin4 and 7 of dac. The static noise persisted. BY implication the culprit is in iv section.
How do l proceed from here?
All of the DACs, one by one?
Not necessarily as that was a quick check which catches many DAC problems but not all.
I suggest next step is disconnect one pin of L6 and listen again. If the DACs are the source of static, it will disappear with L6 out of circuit.
l connect output from TP10 to an amp and then ground pin 7 of the TDA1387 , one by one for testing. The Kubeik is powered during testing.
Do l have to take output from TP7 and then repeat the test of shorting Pin7 of TDA 1387 , one by one ?
BTW is pin7 is the Iref pin and is floating in this circuit ?
L6 is the big inductor with 4 pins soldered. Can l substitute by removing R40, 2k resistor ?
Yes, correct. By setting it to 0V a DAC is effectively disconnected from the circuit. But some damage to DAC chips disables this function.
Only one pin needs desoldering - one with a wire connected to the coil. Removing R40 is almost as good as disconnecting the inductor, but you may damage R40 in the process.
That indicates that one or more of the DAC chips have gone bad. The way to find out which is to lift pin6 (L output) on them, one by one.
If you have an oscilloscope, it would be worth checking that the digital inputs to the DAC chips look correct (pins 1,2 and 3). There is always the slim possibility that the input buffer is damaged but seems rather unlikely as you're only getting static on one channel. Normally a problem with the inputs affects both channels.
If you have an oscilloscope, it would be worth checking that the digital inputs to the DAC chips look correct (pins 1,2 and 3). There is always the slim possibility that the input buffer is damaged but seems rather unlikely as you're only getting static on one channel. Normally a problem with the inputs affects both channels.
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I haven't tried that so I don't know what the result would be.
For lifting pins I've used sharp-pointed tweezers which have curved ends (not the straight type). Get the sharp point behind the pin, right next to the package. Apply the iron to the pad and move the pointed end away from the package. This flicks up the pin from the pad, leaving a gap between it and the pad.
For lifting pins I've used sharp-pointed tweezers which have curved ends (not the straight type). Get the sharp point behind the pin, right next to the package. Apply the iron to the pad and move the pointed end away from the package. This flicks up the pin from the pad, leaving a gap between it and the pad.
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