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Volume Adjustment Thump Troubleshooting
Volume Adjustment Thump Troubleshooting
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Old 18th November 2019, 01:49 AM   #11
Hypnoglitz is offline Hypnoglitz
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Ubergeeknz- The higher capacitance was a recommendation from a vendor and I found supporting information on another site....so I figured I would go with the higher value, the space was there. I went with Jantzen as I read a handful of testimonies that seemed in par with what I was seeking and their price when on sale seemed okay.

Douglas Blake- I get your drift, completely.

A shot in the dark but I read a similar experience by another listener that found a fix by replacing a signal relay. My device has a NAIS TX2-5V ATX 209 low signal relay just before the rca jacks, might this be the culprit? Admittedly, I have no idea what this component actually does.
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Old 18th November 2019, 02:40 AM   #12
sgrossklass is offline sgrossklass  Germany
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Relay is probably for output muting.

Could you show a picture of the DAC PCB in original form? What model DAC is this anyway?

2 F seems like an odd value for an output coupling cap in a DAC. Usually I would expect dozens if not hundreds of F, electrolytic.

All of this smells quite esoteric to me. I don't like esoteric.
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Old 18th November 2019, 03:39 AM   #13
Hypnoglitz is offline Hypnoglitz
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The dac is a MHDT Stockholm 2. This link MHDT Labs Stockholm 2 : A Review | Headphone Reviews and Discussion - Head-Fi.org shows the internals well. The capacitors that I changed were the large yellow ones in the upper right section of the frame.
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Old 18th November 2019, 04:03 AM   #14
rayma is offline rayma  United States
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There must be enough DC leakage in the new capacitors that the volume control's wiper is affected.
The specific uF value has nothing to do with this, although larger uF capacitors of the same voltage
will have more leakage. The relay just shorts the output during warm up.

Last edited by rayma; 18th November 2019 at 04:12 AM.
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Old 19th November 2019, 12:44 AM   #15
Hypnoglitz is offline Hypnoglitz
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Swapped out the dac with an alternate. I could still hear the noise but it was much quieter. I also swapped out the preamplifier with an alternate passive preamplifier, no noise, and I really cranked it.

So maybe the trouble is with the preamplifier? My head is spinning from this.
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Old 19th November 2019, 01:04 AM   #16
ubergeeknz is offline ubergeeknz  New Zealand
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Did you check for DC at the DAC output? There should be none (after initial settling time)
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Old 19th November 2019, 01:34 AM   #17
Douglas Blake is offline Douglas Blake  Canada
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Quote:
Originally Posted by Hypnoglitz View Post
Ubergeeknz- The higher capacitance was a recommendation from a vendor and I found supporting information on another site....so I figured I would go with the higher value, the space was there. I went with Jantzen as I read a handful of testimonies that seemed in par with what I was seeking and their price when on sale seemed okay.
I can understand going up a standard value or two and maybe one step in the voltage ratings, with the same type of capacitor. Beyond that, I would quickly suspect my advisors were the same people who suggested charging iPhones in a microwave oven.
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Old 19th November 2019, 01:36 AM   #18
Hypnoglitz is offline Hypnoglitz
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Ubergeeknz- Forgive my ignorance but how exactly is the dc chceked? Ive checked the offset on my first watt clone but the rca jacks have binding posts. On my dac they're pcb jacks....just not sure how to measure them.
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Old 19th November 2019, 01:38 AM   #19
Hypnoglitz is offline Hypnoglitz
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Douglas- I get now that the vendor was perhaps out for more money. Lesson learned.
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Old 19th November 2019, 02:17 AM   #20
ubergeeknz is offline ubergeeknz  New Zealand
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Quote:
Originally Posted by Hypnoglitz View Post
Ubergeeknz- Forgive my ignorance but how exactly is the dc chceked? Ive checked the offset on my first watt clone but the rca jacks have binding posts. On my dac they're pcb jacks....just not sure how to measure them.
Measure between the inside contact of the RCA socket and the outside (ground)
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