TDA1387 x8 DAC: let's check its design, mod it -or not-, play music -or not! :(-

Simplest mods - I'd suggest as much capacitance across the supplies (pins4 & 5) as will fit in the case and 1000uF on each pin7 to pin4 (GND) (only for the TDA1387). For the TDA1543 disable the internal CCS (leave pin7 to float) and provide an external filtered voltage reference (TL431 is suitable) to return the I/V resistors to.
 
Simplest mods - I'd suggest as much capacitance across the supplies (pins4 & 5) as will fit in the case and 1000uF on each pin7 to pin4 (GND) (only for the TDA1387). For the TDA1543 disable the internal CCS (leave pin7 to float) and provide an external filtered voltage reference (TL431 is suitable) to return the I/V resistors to.


Thanks for the info !
Much appreciated.

Case size is limited, so that will be a challenge.
 

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I have bought both, 4x tda1387 and 4x tda1543.
(Same ebay seller, link in previous post)
Both are very cheap, and sound great.
Very pure, no false detail, a joy to listen to, also for longer periods.

But I have to admit, USB power is coming from a good linear PSU.

Any simple mods to these dac's ?
(output capacitor’s or clock)

Is the world going narrower now and countries closing borders?

"Unfortunately, access to this particular item has been blocked due to legal restrictions in some countries. We are blocking your viewing in an effort to prevent restricted items from being displayed. Regrettably, in some cases, we may prevent users from accessing items that are not within the scope of said restrictions because of limitations of existing technology. Please accept our apologies for any inconvenience this may cause, and we hope you may find other items of interest on eBay."
 
Is the world going narrower now and countries closing borders?

"Unfortunately, access to this particular item has been blocked due to legal restrictions in some countries. We are blocking your viewing in an effort to prevent restricted items from being displayed. Regrettably, in some cases, we may prevent users from accessing items that are not within the scope of said restrictions because of limitations of existing technology. Please accept our apologies for any inconvenience this may cause, and we hope you may find other items of interest on eBay."

Amazing, never had this before on ebay !

You can try browsing the ebay store of the seller.
Shuguang tubes, Completed in case items in doukmall store on eBay!

Or maybe trying a different ebay site, like ebay.com.au or ebay.ca
 
Any change to write out a complete output schematic regarding this dac ?

I've reflected on that schematic on my blog some more and figured it can be improved by simplifying to a 2nd order LC filter. I've chosen a commercially available TDK inductor and Nichicon capacitor to make it easier. Here's the schematic (only for the TDA1543) - its using LT's LT1431 as they don't have the TL431 :
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I've reflected on that schematic on my blog some more and figured it can be improved by simplifying to a 2nd order LC filter. I've chosen a commercially available TDK inductor and Nichicon capacitor to make it easier. Here's the schematic (only for the TDA1543) - its using LT's LT1431 as they don't have the TL431​


Thanks for the schematic, very clear now.
If I would like to get 2V or more at the output when using your schematic, what would my I/V resistor value then be ?​
 
When you say '2V or more' do you mean 2VRMS? Or just 2V peak, or 2V peak-peak?

For a 5V-supplied TDA1543 the max output voltage is limited by the allowable output compliance, which is from 1.8V to 3.8V. That's just 2V peak-to-peak. If you want more you'll need to run the DAC from a higher voltage. The suggested I/V resistor value in my schematic of 870ohms gives the 2V maximum swing.
 
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They come from this manufacturer - 5VA power transformer PE3518D-I - Dechang Electronics that shows the physical dimensions. The digital trafo is 7.5+7.5VAC (two separate windings) and the analog one is 15+15VAC. Both are 5VA.

Update on my xformer search:

One of my Chinese colleagues did me a huge favor and contacted the seller regarding 110v xformers. The reply wasn't precise, but he suggested that the manufacturer of the stock transformers can make them in custom primary voltages (including 110v), even though the web page doesn't say anything about that.

But that was enough of a lead for me to type "PE3518D-I 110v" into google, which lead me to this AliExpress listing. Just like the manufacturer's website, the picture and table data shows only 220v, but there's this additional note at the bottom:

Attension: Kindly advise detail specifications you require when place order. Input voltage we can produce from 110v-380v, for this kind, also advise clearly. Thanks for your kind cooperation!

I also asked the ebay seller of this DAC about a 110v option, he said they can do it. But he didn't reply when I asked for the part number. But, that makes me think they use the exact same part, just with 110v windings.

On AliExpress, it's less than $3 (yay!) but shipping is over $30 (boo!). So now the search is on to find a reasonably priced shipper, or maybe a USA distributor...
 
hello. the static noise still there. only in right channel, though. and the static increase decrease along with music. much like some method of oscillation. where can oscillation cause this noise? 1387? ad744 i/v? i think 1387 because noise always right channel, even when i/v channel swapped.

hello, abraxalito, could you please input your thought? :)

http://www.diyaudio.com/forums/audio-sector/187748-pushing-limits-tda1543-nos-dac.html

i modify circuit, use this in place. breadboard on top of this dac pcb. passive i.v 2k2 then to transformers, just like the peter's circuit, but with 1387

the static noise there with 4 chips on each phase. but when 3 chips desolder with only one chip each phase, no static noise. so noise i think parallel chip oscillation. how? why?

board almost dead. desoldering gun melt pcb almost, hehe :(

please i would like parallel chip balanced dac before pcb die, hehe.
 
The link you posted above links to the whole thread - is the circuit the one in post no.6? If you want me to help you'll have to post up your circuit - Peter's circuit is for TDA1543 which is a different chip. The devil is in the details.

I've been paralleling TDA1387s for a few years now and have never encountered any problems simply from soldering them in parallel. When paralleling, I stack them vertically - heat's no concern.
 
Next-gen mods to this DAC...

My second of these DAC boards is currently undergoing a more radical mod - using some Coilcraft inductors I'm implementing a more substantial filter than the one I put into my first set of mods. Pic attached.

The anti-imaging filter is made up of two elements - a fifth order quasi-elliptic LC filter (made from 10mH coils) and then a 2nd order under-damped low-pass (using 5.6mHs) where the ringing compensates for the NOS droop. In between these two filters are a balanced pair of discrete classA buffers. Transformers at the output do bal-SE conversion and no voltage gain stages are needed as the I/V resistance is just large enough to create a swing between 1 and 2VRMS, balanced. I'm running the full 8 of the TDA1387s from 6V. No listening reports so far as its not running yet.
 

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Surprisingly this worked first time. Initial impressions - very positive. Its giving less LF colouration than the last set of mods (done on the first instance of this DAC) even without optimization of the power supply (i.e. no outrageous numbers of caps so far).

One other thing I changed on this build is to go for active (single transistor) I/V rather than using the opamps. Its a much simpler solution and not so demanding on the power supply. If there's interest I'll put up some schematics. This sounds like the best DAC I've ever built so far....
 
Thanks !

Here are the filters you can see in the photo using the Coilcraft MSS1210 inductors (available from Mouser). Since they're balanced, stereo there are four complete circuits of the filter on the right. The left one is for NOS droop correction of which two are required. In between go the buffers which I'll draw up later. Inputs are on the right btw.
 

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