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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
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Old 27th November 2018, 12:09 PM   #7761
nano35 is offline nano35  Hong Kong
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Quote:
Originally Posted by TNT View Post
It is a correct observation - at 352k, the "major" filter is not engaged anymore.

//
Thank you TNT for the quick reply.
I will go ahead.
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Old 27th November 2018, 02:35 PM   #7762
living sounds is offline living sounds  Germany
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Quote:
Originally Posted by spikestabber View Post
If you end up feeding separate +/-15V to the opamps then there is very little reason to not go straight +/-5V for the dam, then bypass bridge rectifier and both onboard 7x05 regulators. A general observations over the years is that there is more bass to be had the more you tank up the vref rails be it with caps and/or super regulator. The super reg was a time before the current production vref with low output impedance however it is known to improve things so long as you dump the 7x05 regulators upstream.

On my own setup I can still see the vref dip at higher volumes on the uV scale even with the super regulator and straight 5V so to see more caps improving the response on a stock dam1021 v4/5 isn't so surprising.

Also note the onboard mute circuit is locked muted at 5V inputs and there isn't a known way to make it work other than by using a muting relay which I better prefer anyway as it's not an active device the signal chain.
Thanks! I'm going to build a multichannel unit (16-32) for studio mixing purposes soon. In this scenario local regulation is probably preferable to one high performance PSU feeding all the boards (through isolating resistors). I might end up powering all the buffer op amps from a separate PSU though.

I don't need the mute circuit and the output volume circuit and currently haven't connected anything there.
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Old 29th November 2018, 01:33 PM   #7763
deanoUK is offline deanoUK  United Kingdom
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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Default DAM1021 for sale.

I seem to remember someone was looking for a DAM1021 ?
I have a DAM1021-01 Serial Number 2004 for sale.
Available with PSU and input switiching board if required.
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Old 29th November 2018, 04:11 PM   #7764
avr300 is offline avr300  Denmark
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What's the value of each capacitor in position c166-c177?

In post #4700 I think I can read 100uF each. Is that correct?
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Old 3rd December 2018, 07:52 AM   #7765
nano35 is offline nano35  Hong Kong
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Default modding and distortion

After the successful modding of adding 12 polymer caps, I continued with the extra 4 caps of 2200uF by attaching them to the 4 SMD caps; and also swapped the 2 filtering caps with blue color caps (560uF). I believe the polarity is correct.

It failed. There was a horrible distortion/some popping coming out of the speakers. I tried both SE and buffered balanced output-same problem.

Now I reversed back to the previous state by removing all 4 caps and putting the 2 original filtering caps back in near the clock.
I know I ripped one of the 4 SMD caps so I desoldered it and turned it to other side when re-soldered it. The dac worked as normal with fantastic SQ for a couple of seconds and then severe distortion came back again.


How do I troubleshoot this? Is the board dead forever?
Can I just replace the 4 SMD capacitors? what value are they?
or should I replace the whole Vref section there?

Thank you for your help! Sad weekend.
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Old 3rd December 2018, 12:37 PM   #7766
soekris is online now soekris  Denmark
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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Quote:
Originally Posted by avr300 View Post
What's the value of each capacitor in position c166-c177?

In post #4700 I think I can read 100uF each. Is that correct?
All the large 1206 ceramics are 100u 6V3 X5R.
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Old 3rd December 2018, 12:43 PM   #7767
avr300 is offline avr300  Denmark
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Quote:
Originally Posted by soekris View Post
All the large 1206 ceramics are 100u 6V3 X5R.
Thanks (Tak) Søren.
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Old 3rd December 2018, 10:11 PM   #7768
bmxmen is offline bmxmen
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Measure that You have an +-4v on 4 added polimers.
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Old 7th December 2018, 03:07 PM   #7769
spikestabber is offline spikestabber  Canada
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@nano35, indeed you have a short on vref somewheres, keep in mind the large 1206 ceramics seem to be rather sensitive to excessive heat, you may have shorted one out, shouldn't be difficult to figure out.
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Old 7th December 2018, 07:17 PM   #7770
rhythmsandy is offline rhythmsandy
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I have found a strange noise coming from the DAC like white noise. Im using Bib 1.1 regs for regulation. I thought its coming from the regulators but when I have used two 12V batteries i still get this noise. Im thinking that the firmware might have got corrupted. The signal is getting locked and synchronized but im getting this additional noise from the new boards. I have used ver1 and 2 but I never got any issue with them but now Im getting this strange noise i have tried all version from unbuffered to buffered outputs as well. Do i need to use new firmware for this? or just install new firmware?
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