Hi I looked up data sheet of both op amps and managed to work it out.
I have got resistors back in circuit and it sounds much better (no distortion)
I still like the tube outputs best bigger soundstage and everything comes together better.
The extra detail from the op amps are nice.
I think my op amp are real they are from a company called Farnell.
Thank you again NinoSimona.
even if I said I won't touch it until it's fixed temptation was stronger than me so here we go temporary until new ELNAs and new front panel arrive, spent 2 days on it, but I can imagine someone has it built together within few hours, I'm bit stickler it seems 
...
and how does it sounds??? I'll leave it for chapter 2 as it needs to burn in for few days but so far I can say my old (Horst) sounds better (to me), even my wife recognized it
, stay tuned 
...and how does it sounds??? I'll leave it for chapter 2 as it needs to burn in for few days but so far I can say my old (Horst) sounds better (to me), even my wife recognized it
, stay tuned
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Can't compare them, I only have got the dual AK4399. But, to be honest, I think it's quite obvious it would sound better. It has not only one DAC per channel (mono mode = better S/N ratio ), also analog power supply of the ICs is separate, which improves left/right channel separation (regulator has to deal with just one channel).
If you want to compare, I think you must compare two single DAC boards with this dual one. Linuxworks has choosen for two single boards (running hardware mode).
His post: http://www.diyaudio.com/forums/digi...ang-dual-x2-ak4399-dac-lcd-6.html#post3906210
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its not at all 'obvious', sorry.
on paper, if things are executed perfectly, it MAY be better. to the ear, its going to be a hard thing to double blind tell the diff between. again, assuming the board is well laid out, etc etc.
now, this is an ebay board by people who are not great at board layouts (we all admit this about the ebay sellers, don't we?). and so, a dual mono COULD be actually worse if its done poorly.
I had pretty bad luck with the so-called 'great' dac7 that is a dual mono chip. I built a board and I bought one pre-built and they both sucked and tested badly.
honestly guys, I would not fall for the dual-mono lure. its more complex and there is more room to screw up. if they can screw up the board, they will, and so I would have less confidence in things that are too fancy.
when it comes to junk ebay boards, simple is more reliable. I firmly believe that.
on paper, if things are executed perfectly, it MAY be better. to the ear, its going to be a hard thing to double blind tell the diff between. again, assuming the board is well laid out, etc etc.
now, this is an ebay board by people who are not great at board layouts (we all admit this about the ebay sellers, don't we?). and so, a dual mono COULD be actually worse if its done poorly.
I had pretty bad luck with the so-called 'great' dac7 that is a dual mono chip. I built a board and I bought one pre-built and they both sucked and tested badly.
honestly guys, I would not fall for the dual-mono lure. its more complex and there is more room to screw up. if they can screw up the board, they will, and so I would have less confidence in things that are too fancy.
when it comes to junk ebay boards, simple is more reliable. I firmly believe that.
Most here do not realize that the analog output far above all other responsible for the quality playback of DA converter..
All devices that are here compared have almost identical analog section..
Sellers who are unable or unwilling to provide basic information and drivers, fussing with the nonsense that are not essential..
A few days ago I compared these two devices, the output section is identical in both.. neither I, nor even a couple of people who listened to them, could not hear any difference.. so much for that..
Prize question, which device most here decided to buy?!
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Well, ok. I must agree with you that the output stage implementation is identical in both boards, and not that sophisticated, which could hold back improvements made with dual convertor ics. So from that point of view, maybe the single board is just as good 'out of the box'.
But since we are diy-ers, I bought the dual version to hook it up with my discrete output stage I had already (optimized as well as I could), with it's own regulators.
What's the fun of buying a DAC and doing nothing to improve it? So for me, the dual version could have more potential. I know that there's a risk one board has a bad lay-out, nothing to correct that.
The dual version is software controlled, it is more complex because it uses software to control the ICs. There is not much to control for the user: only digital audio source and two digital filter modes for the dacs. But it's working fine. Maybe later I can experiment with another micro controller as well, exciting!
Our own experiences play always a big role in giving advise to someone else, nothing wrong with that. linuxworks having bad experiences with the dac7 and vulejov with bad support for his usb dac. That's indeed the other side of experimenting with the ready-made boards from Chinese sellers at Ebay.
Advise could be: don't buy from Ebay. But there are lots of guys (me too) having fun with these DACs, and good results as well, also here on the board...
But since we are diy-ers, I bought the dual version to hook it up with my discrete output stage I had already (optimized as well as I could), with it's own regulators.
What's the fun of buying a DAC and doing nothing to improve it? So for me, the dual version could have more potential. I know that there's a risk one board has a bad lay-out, nothing to correct that.
The dual version is software controlled, it is more complex because it uses software to control the ICs. There is not much to control for the user: only digital audio source and two digital filter modes for the dacs. But it's working fine. Maybe later I can experiment with another micro controller as well, exciting!
Our own experiences play always a big role in giving advise to someone else, nothing wrong with that. linuxworks having bad experiences with the dac7 and vulejov with bad support for his usb dac. That's indeed the other side of experimenting with the ready-made boards from Chinese sellers at Ebay.
Advise could be: don't buy from Ebay. But there are lots of guys (me too) having fun with these DACs, and good results as well, also here on the board...
designing a truly competitive dac is not just an exercise in using eagle and the autorouter, but that's what it usually ends up being, for cheap ebay boards. I used to try using PGA vol control boards from china and the routing was so bad, they had digital and analog crossing each other, parallel to each other, even key lines being routed under the chip core on the board, which is a big no-no. I always ended up getting some impulse or shot noise from the PGA boards I built from ebay kits. tried 3 different ones and they all had routing and psu problems.
this is why I don't believe in just swapping out caps to 'fix' bad designs. either you start with a complete understanding of how the wires should be routed or you don't. stuff this major can't be band-aided.
I understand that people WANT their $100 dac boards to be $1000 quality but it will never happen guys, sorry. unless you entirely redo things, you can't make a silk purse from a sow's ear, as they say.
I am ok with mid-level or entry-level perfomance for my $100 ebay purchases. but I won't fool myself thinking this is a high-end dac product. it isn't and won't ever be, software driven or not (just a marketing item really; does not help the sound in any way and just gives more 'knobs for nerds', and for some, that makes them happy, too)
this is why I don't believe in just swapping out caps to 'fix' bad designs. either you start with a complete understanding of how the wires should be routed or you don't. stuff this major can't be band-aided.
I understand that people WANT their $100 dac boards to be $1000 quality but it will never happen guys, sorry. unless you entirely redo things, you can't make a silk purse from a sow's ear, as they say.
I am ok with mid-level or entry-level perfomance for my $100 ebay purchases. but I won't fool myself thinking this is a high-end dac product. it isn't and won't ever be, software driven or not (just a marketing item really; does not help the sound in any way and just gives more 'knobs for nerds', and for some, that makes them happy, too)
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