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lingDAC - cost effective RBCD multibit DAC design
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Old 14th July 2018, 01:41 PM   #21
abraxalito is offline abraxalito  United Kingdom
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In my estimation TDA1387 is more true to the source than TDA1543. The bipolar chip is very pleasant indeed to listen to with the lingDAC I/V and buffer stage after it, but somehow its just a bit romanticized when compared to the 1387 - a little softer and subtly coloured.
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Old 14th July 2018, 01:54 PM   #22
schillg11 is offline schillg11  Germany
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hi abraxalito,


where to source the TDA1387T? Are there any trustworthy sources to buy this part?


BR
GŁnni


PS: Group buy or Gerbers available?
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Old 14th July 2018, 02:05 PM   #23
abraxalito is offline abraxalito  United Kingdom
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I sourced all my TDA1387 on Taobao, I have no documented chain of custody for them but I believe them to be 'pulls' from old 'Soundblaster' PC audio cards. They're obviously not new chips. Seeing they're so cheap (nowadays around 35 to the USD) I've never worried about whether they're 'legitimate' or not. Having used a few hundred of these parts during my prototyping years I've not found one yet which has sounded bad though I do note the DS shows the worst-case SNR can be just 86dB.

Gerbers I will make available after I've made the schematics more presentable (and corrected any errors) but I am not interested in organizing a group buy myself. Should anyone else wish to get involved in that (which seems to me to be rather a thankless task) I'll support them to the extent I am able. If anyone is interested in acquiring a finished DAC you're free to PM me.

I've attached a picture of one of the early incarnations of lingDAC - its a USB-fed DAC-AMP driving low impedance headphones direct up to 100mW or so. Three of the PCBs (DAC, I/V-filter, SE buffer) are in the plexiglass tower. In the wooden base are a USB-I2S interface (not my design, sourced from Taobao) and a power supply.
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Last edited by abraxalito; 14th July 2018 at 02:17 PM.
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Old 14th July 2018, 03:16 PM   #24
schillg11 is offline schillg11  Germany
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thanks abraxalito,

i have also an 8xTDA1387 as replacement for a TDA1541aA in my Marantz CD583 in use. Worked without any modifications. These chips were also pulled and i got them for €6 (8Pieces).

Thnx for publishing the gerbers, when all debugging is done.

BR
GŁnni
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Old 14th July 2018, 04:13 PM   #25
Bartb is offline Bartb  Slovenia
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lingDAC - cost effective RBCD multibit DAC design
Quote:
Originally Posted by abraxalito View Post
I sourced all my TDA1387 on Taobao, I have no documented chain of custody for them but I believe them to be 'pulls' from old 'Soundblaster' PC audio cards. They're obviously not new chips. Seeing they're so cheap (nowadays around 35 to the USD) I've never worried about whether they're 'legitimate' or not. Having used a few hundred of these parts during my prototyping years I've not found one yet which has sounded bad though I do note the DS shows the worst-case SNR can be just 86dB.

Gerbers I will make available after I've made the schematics more presentable (and corrected any errors) but I am not interested in organizing a group buy myself. Should anyone else wish to get involved in that (which seems to me to be rather a thankless task) I'll support them to the extent I am able. If anyone is interested in acquiring a finished DAC you're free to PM me.

I've attached a picture of one of the early incarnations of lingDAC - its a USB-fed DAC-AMP driving low impedance headphones direct up to 100mW or so. Three of the PCBs (DAC, I/V-filter, SE buffer) are in the plexiglass tower. In the wooden base are a USB-I2S interface (not my design, sourced from Taobao) and a power supply.
Hello Abraxalito,
the lingDAC project you are presenting here is for driving headphones if I understand correctly? How much modification (if any) would be required for interfacing with a preamplifier/amplifier ?
Thanks B.
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Old 15th July 2018, 01:36 AM   #26
abraxalito is offline abraxalito  United Kingdom
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Hi Bart

In reality there's no need to modify anything to drive a preamp or poweramp but in practice there may be a small improvement in SQ by replacing the electrolytic output capacitors for some film/foil ones of smaller value (say 6.8-10uF) and increasing the output cap biassing resistors by a factor of 20 (to 100k).
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Old 15th July 2018, 11:03 AM   #27
Bartb is offline Bartb  Slovenia
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lingDAC - cost effective RBCD multibit DAC design
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Originally Posted by abraxalito View Post
Hi Bart

In reality there's no need to modify anything to drive a preamp or poweramp but in practice there may be a small improvement in SQ by replacing the electrolytic output capacitors for some film/foil ones of smaller value (say 6.8-10uF) and increasing the output cap biassing resistors by a factor of 20 (to 100k).

Ok! thank you for the explanation
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Old 15th July 2018, 12:50 PM   #28
kokoriantz is offline kokoriantz  Lebanon
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Tda1387 has only 30db ripple rejection ratio vs 50db for tda1543 . The Vref being 1/6th of Vcc , did you try to impose externally a fixed low impedance potential on Vref ?
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Old 15th July 2018, 01:14 PM   #29
abraxalito is offline abraxalito  United Kingdom
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No - I have thought about that but not gone on to implement any ideas I had, I'd always assumed that any active driving of pin7 would potentially increase output noise. A few years ago I was advocating a few thousand uF to be put on pin7, these days I use nothing at all as I hear no improvement when I do add some amount of capacitance.
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Old 17th July 2018, 06:54 AM   #30
kokoriantz is offline kokoriantz  Lebanon
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In 2014 you were in love affair with tda1545A . What happened that you switched to tda1387 ? And why not 1311?
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