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AliExpress AD1865 R2R DAC
AliExpress AD1865 R2R DAC
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Old 6th November 2018, 02:13 PM   #131
Hugh Jazz is offline Hugh Jazz  Taiwan
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It will be hassle to return and I will lose money but I'm not going to waste time fixing badly made gear from China. So, SF Express it is - thanks ;-)
Heads up about that seller - the goods are returned by SF Express but he's refusing to sign for them so he can avoid giving a refund. Seems a bit of dirtbag.
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Old 19th November 2018, 04:51 PM   #132
PJN is offline PJN  United States
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I finally got around to hooking up this board this weekend. I agree with Hugh, it sounds pretty good, better than the "little giant" TDA 1387 board from the same maker. Ran it for about 2 hrs nice vocals but can't hear into the music background much. Like you can't really hear the recording venue well in the background of recordings. I'll bypass the output caps next to see what improvement it brings. so far it hasn't burnt up yet so I'll keep my fingers crossed.
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Old 19th November 2018, 05:56 PM   #133
jean-paul is offline jean-paul  Netherlands
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Hi I am encasing the single TDA1387 board from that seller. Replaced the 22 µF 16V bipolar electrolytic caps for Wima 22 µF 16V MKS2-XL film caps which I happen to stock. These are the largest value film capacitor in 5 mm pitch.

There lack stop resistors in the output of the output stage. From L and R a 47 Ohm resistor should be used to the L and R output RCA to prevent the opamps from oscillation with capacitive loads i.e. cables.

Not listened yet but board design and choice of regulators both seem fine.
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Old 19th November 2018, 09:29 PM   #134
erin is offline erin  Australia
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I Ran it for about 2 hrs
Thanks for your report.
I find a new DAC will sound best after 20 hours of power up time. That is when the depth will happen. Every DAC I ever heard was two dimensional during the first few hours.
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Old 20th November 2018, 12:26 AM   #135
Hugh Jazz is offline Hugh Jazz  Taiwan
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Quote:
Originally Posted by PJN View Post
I finally got around to hooking up this board this weekend. I agree with Hugh, it sounds pretty good, better than the "little giant" TDA 1387 board from the same maker. Ran it for about 2 hrs nice vocals but can't hear into the music background much. Like you can't really hear the recording venue well in the background of recordings. I'll bypass the output caps next to see what improvement it brings. so far it hasn't burnt up yet so I'll keep my fingers crossed.
Most likely I was unlucky and got one with a damaged/used/fake dac ic but I would run yours for more than 2 hours (mine died after 4 iirc) continuously and check temperatures to be sure. Besides, this breaks in the caps and gets the DAC ready for evaluation. I hope it's good!

I decided to go with AD1862 but I have yet to get round to making it. I found a seller with an AK4137 ASRC that uses low frequency clocks (under 17MHz), another seller with a logic shifter/buffer to split left/right, truncate to 20 bits etc, and then another seller who sells allegedly paired and genuine AD1862NJ chips. I shall hack them together at some point. I am curious about using TPA6120 current feedback amp as I/V followed by a 3rd order passive filter. The TPA can easily drive a 32 ohm load making a passive filter with a low impedance possible. I hope. ;-)
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Old 20th November 2018, 01:11 AM   #136
abraxalito is online now abraxalito  United Kingdom
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Originally Posted by PJN View Post
Ran it for about 2 hrs nice vocals but can't hear into the music background much. Like you can't really hear the recording venue well in the background of recordings.

One circuit aspect responsible for flat sound IME is opamps. They do this by virtue of their classAB output stage creating noise on their power supply. It can be reduced by classA biassing the opamp's output (use a 2 or 3mA current source to the -ve rail) and decreasing the supply impedance (use polymer capacitors on the rails as these have very low ESR).
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Old 20th November 2018, 01:17 AM   #137
abraxalito is online now abraxalito  United Kingdom
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Quote:
Originally Posted by Hugh Jazz View Post
I am curious about using TPA6120 current feedback amp as I/V followed by a 3rd order passive filter. The TPA can easily drive a 32 ohm load making a passive filter with a low impedance possible.
I've not tried TPA6120 but I do plan on trying the nearest ADI equivalent to it, the AD815. Its super-cheap here, even on Aliexpress its about $1. So far the clear winner on I/V is the AD811, streets ahead of AD8017. The clear difference between these two though almost disappears with a CLC filter before the I/V.

If using TPA6120 to drive a low impedance load, be sure to classA bias it.
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Old 20th November 2018, 01:55 AM   #138
Hugh Jazz is offline Hugh Jazz  Taiwan
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TPA6120 is hard to hear - it's really very good at reproduction in every bit of gear I've listened to. I just bough a cheap kit to try for US$3 :-) TPA6120 ???HIFI TPA6120A2????????????????-???
It costs only slightly more than the headphone protector kit ?ZEROZONE?E12-I??????????????????--??-???

Here's the link for the AK4137
AK4137 I2S/DSD?????? ??PCM/DSD?? ??DOP??-???
And the R2R I2S converter
NOS DAC/I2S?? NOS????????I2S?????????-???
And the AD1862 (no idea if this seller is reliable tho)
AD1862N-J ??{???}??(??100?)-???
Click the image to open in full size.
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Old 21st November 2018, 10:27 PM   #139
PJN is offline PJN  United States
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bypassed the two electrolytic output caps, sounds better, more detail. I like this DAC sounds nice. I need to run it in for a few more hours but so far so good, board runs nice and cool. I have this in a test box that I can easily swap out this board for the tda1387 "little giant" to compare the two. I'll try some of Jean Paul's suggested mods to the 1387 and compare.
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Old 21st November 2018, 11:20 PM   #140
phase is offline phase  United States
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Originally Posted by Hugh Jazz View Post
Hello all,

What do you think of this DAC?

AD1865 decoding finished board r2r decoding nos mode DAC hifi audio good-in Digital-to-Analog Converter from Consumer Electronics on Aliexpress.com | Alibaba Group

EDIT. The thread almost immediately digressed into one about TDA1387 (from post 8 on) and then later into op amp in the I/V for TDA1387. Sorry.

And then when my DAC eventually arrived, it was faulty, and was returned. See post 96.

And the saga went on... the seller refused to sign for the faulty goods so he could "negotiate" a partial refund.
No need to apologize for the topic sway, many dac threads taper off rapidly after the diyer has determined that bypassing the I/V stage is “best”. Then there are no more posts, as things have gone, well, quiet, so to speak.

I haven’t attempted any returns, sorry about the bad experience with that...
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