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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 13th March 2019, 02:50 AM   #8361
Peterma is offline Peterma  Australia
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Yeah just wondering if you can hear a difference between the 2 dams, would love to know.

If I were made of it I would spend more bucks and get another one
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Old 13th March 2019, 05:08 AM   #8362
ynmichael is offline ynmichael
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Quote:
Originally Posted by Peterma View Post
If I were made of it I would spend more bucks and get another one
We really don't know how good one is compared to the other. Theoretically, 1121 should be at least as good. Main advantages that I know of: 1. better power circuitry - lower noise and impedance to the 4v op amps if you feed it with a good shunt supply directly. The 5v ldo on 1021 is maybe 20mR, and the bridge rectifier more (though we don't know how much current fluctuation there is at the rectifier). 2. good for multichannel syncing, but maybe the improvement is probably more theoretical than practical in dual-mono. 3. reclocking. 4. no op-amp buffer noise.

BUT: 1. we don't know how much ripple we can hear. plus 1121 is harder to put vref caps on, and that's probably just as important ripple wise. 2. shift registers and flip-flops are not perfect switches. propagation delays have tolerances in the ns. We can't fix that. 3. can we really hear the op-amp noise?

Benefits of 1021: isolated I2S onboard (really non-trivial to implement separately with 1121 with off-the-shelf components, but a must if you want x8 sampling rates), op-amp buffers to drive headphones probably as good as any headamp for high impedance cans theoretically, harder to damage, wider voltage input, cheaper, easier to stack.

Until we get ABX tests between these boards and different advanced power mods on dam1021, we really don't know. But it's fine since both are quite capable. If you want perfection within current technical constraints, you probably have to do quite a bit of engineering development yourself. 1941 would be closer to perfection I guess. The wiring from the clocks to the ladders is more balanced, but still you need to test vref caps and then you'll start thinking about correcting resistors. And idk if I want to power USB interface with USB 5V, don't get a choice with dam1941. All the while shift registers probably causing ns level delays between some bits, less only if we're lucky.

Don't want to get too involved but maybe this can help clarify things.

Last edited by ynmichael; 13th March 2019 at 05:16 AM.
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Old 14th March 2019, 02:14 PM   #8363
living sounds is offline living sounds  Germany
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Great this thread is back. The DAM1021 with vref caps added and TNT's v2 linear filter sounds great.
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Old 14th March 2019, 02:44 PM   #8364
Spartacus is offline Spartacus  United Kingdom
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Location: Gloucestershire
Have just looked more closely at the DAM1121 images, and it does seem opamp regulators are no long used. I take it they are now low noise LDOs .... anyone know what type?
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Old 14th March 2019, 02:53 PM   #8365
soekris is offline soekris  Denmark
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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Quote:
Originally Posted by Spartacus View Post
Have just looked more closely at the DAM1121 images, and it does seem opamp regulators are no long used. I take it they are now low noise LDOs .... anyone know what type?
The dam1121 use the same opa365 as the dam1021....
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Old 14th March 2019, 07:58 PM   #8366
Spartacus is offline Spartacus  United Kingdom
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Quote:
Originally Posted by soekris View Post
The dam1121 use the same opa365 as the dam1021....
Ah Ok, thanks. I've had another look at a photo, and it makes sense to me now.
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Old 15th March 2019, 05:34 PM   #8367
gapson is offline gapson  Hong Kong
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Hi Søren,

I have done a DIY piece of LT3045 LDO with 12v 2a and 5v 2a for the DAC 1541.

It was measuring at 12v and 5v without any load. When I connected them to the 1541 board it turns out to be 10.8v.

Would you think it was too low for the board? Thanks.

Click the image to open in full size.
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Old 15th March 2019, 05:54 PM   #8368
androa76 is offline androa76  Slovenia
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Some voltage drop on inductors and diodes that are between wires and cap test points. Connect dc on capacitor positions after diodes.
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Old 15th March 2019, 07:39 PM   #8369
lwr is offline lwr  United States
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Default Audible benefits of replacing 1541 SMPS with DIY LT3025 LDO

Quote:
Originally Posted by gapson View Post
Hi Søren,

I have done a DIY piece of LT3045 LDO with 12v 2a and 5v 2a for the DAC 1541.

It was measuring at 12v and 5v without any load. When I connected them to the 1541 board it turns out to be 10.8v.

Would you think it was too low for the board? Thanks.
Please report the SQ differences you’re hearing after replacing the 1541 SMPS with DIY LT3045.

Have you also replaced the output low pass ceramic filter caps with equivalent value polystyrenes?
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Old 15th March 2019, 08:33 PM   #8370
soekris is offline soekris  Denmark
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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
+-10.8V would probably be fine, will just reduce the headphones output power a little....

But you should check your power supplies and the wires, there shouldn't really be that much loss....
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