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Old 7th September 2011, 03:35 PM   #21
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am i going to see any benefit fitting better bypass caps if i'm to do op-amp bypass mod? if so what values are the blue ones after the dac chips? i want to replace all of them.
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Old 8th October 2013, 07:15 PM   #22
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Just wondering if this thread is still alive?

I just have 2 questions about replacing the caps C5,6,7,8,12,13,14,15 in the Lite Dac. I read somewhere that caps are being replaced with ".1uf 63V Polypropylene Film caps". But what does .1uf mean?

Does it mean the caps C5,6,7,8,12,13,14,15 are 0.1uf (100nf)? or 1uf (1000nf)? And the voltage is 63VDC?

And are the caps C38 and C39 different caps? Are they 0,001uf (1nf) and 630VDC. I'm just wondering about the voltage because the caps of C5 etc. are 63VDC.

By the way this is still a good thread! I found a lot of information about the mods and tweaks. Hopefully somebody will answer my question!! Because I want to take the DAC apart and tweak it.
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Old 8th January 2015, 01:28 PM   #23
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More about "taming" resistor on inverting input of cfb op amp here.
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Old 16th January 2015, 02:31 AM   #24
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Greetings to old thread.

A dac of many years. I am toying with it due to current dac spoilt. I bypass with a pair of 0.33 sound cap direct to rca and nothing else. Result is distortion. I try to see around but most of bypass done not more then 2 caps. did I miss out something? Many thanks.

Best regards,

Alfred.
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Old 16th January 2015, 03:21 AM   #25
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Quote:
Originally Posted by alfred wan View Post
Greetings to old thread.

A dac of many years. I am toying with it due to current dac spoilt. I bypass with a pair of 0.33 sound cap direct to rca and nothing else. Result is distortion. I try to see around but most of bypass done not more then 2 caps. did I miss out something? Many thanks.

Best regards,

Alfred.
try any electrolytic from 1 to 100 uF (preferably 2.2 uF poly cap) just to see if the distortion goes away. neg side to the RCAs.
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Old 16th January 2015, 06:17 AM   #26
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Hi Whaleman

Tq. I try up this weekend.

Best regards,

Alfred.
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Old 16th January 2015, 10:43 AM   #27
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Alfred,

be sure existing C35 and C36 output caps are disconnected from RCA jacks .

For DAC VDD = 6 Volts:
R35, R36 (I/V Resistor) should be 150 Ohm. To accomplish this, solder 150 Ohm parallel to the existing 270 Ohm. With digital input open, adjust VR1 trimpot for 3.3 Volts across I/V resistors.

For DAC VDD = 8 Volts:
R35, R36 (I/V Resistor) should be 270 Ohm, which is already built in. No changes needed. With digital input open, adjust VR1 trimpot for 4.3 Volts across I/V resistors.

Attention: allow DAC to warm up and voltage across I/V resistors to stabilize before adjusting VR1 as voltage may fluctuate as much as 700 mV during warmup.
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Old 17th January 2015, 02:04 AM   #28
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Quote:
Originally Posted by whaleman View Post
try any electrolytic from 1 to 100 uF (preferably 2.2 uF poly cap) just to see if the distortion goes away. neg side to the RCAs.

Hi Whaleman. Before I did anything, originally with active sounds fine. Comparing to my spoilt Shigaraki dac, I found this Lite had an add on buster.

My bad. I bought 4.7uf sound cap and resistors too to try up after I passive this dac. The distortion was very bad that hardly audible. I found out it caused by removing AC 18 0 18 power input which I plug it off, thinking the active side no longer in use. Now all are okie. Many thanks.
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Old 17th January 2015, 02:16 AM   #29
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Quote:
Originally Posted by Karstenpg View Post
Alfred,

be sure existing C35 and C36 output caps are disconnected from RCA jacks .

For DAC VDD = 6 Volts:
R35, R36 (I/V Resistor) should be 150 Ohm. To accomplish this, solder 150 Ohm parallel to the existing 270 Ohm. With digital input open, adjust VR1 trimpot for 3.3 Volts across I/V resistors.

For DAC VDD = 8 Volts:
R35, R36 (I/V Resistor) should be 270 Ohm, which is already built in. No changes needed. With digital input open, adjust VR1 trimpot for 4.3 Volts across I/V resistors.

Attention: allow DAC to warm up and voltage across I/V resistors to stabilize before adjusting VR1 as voltage may fluctuate as much as 700 mV during warmup.


Hi Karstenpg,

C35 and C36,

I removed the connection directly from the RCA, but left the negative intake. Therefore I didn't remove this 2 caps.

Dac Vdd 6, and Vdd 8,

Please enlighten me why I need to choose either both of this. I measure pin 5 and read 5.9v. I had replace R35 and R36 to 180 ohm. I do that because a quick read thru to old posting hoping to solve the bad distortion issue but after hook back 18 0 18 all are fine. Currently adjust to 3.3v for pin 8 and 6.

Dac warm up.

Yes, thank you. after warm up it drops to 3.1 so I adjust it back to 3.3v.
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Old 17th January 2015, 02:23 AM   #30
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1)Now, my itchy hand. How am I gona remove all active parts since without plug in AC 18 0 18, it distorted. I cant get it. Since not using active why the main ac disturb the sound. My reason of removing the active part because of tight area for mounting huge sound caps in future.

2)I think x8 is unnecessary. I want to remove at least half of it for other project since last year CAD had make a 1543 x 16 cost near 7000 pound. Is it 1543 reborn? I see thru the schematic, 2 psu feeds 4 each side. If I cut down, should I go for 2 psu left 2 dac each side, or 1 psu for x 4.



Really appreciate your help.


Best regards,

Alfred.
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