DAC Kit - what else do I need?
- Thread starter Suffolk Tony
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Your easy mods are...
Remove or bypass signal path caps - you need to check some things out first so dont rush in.
Remove buffer amp,
Remove output relay,
Change op-amp to dual mono giga offering of dual mono (OPA627?) or better LT1024 on adapter but a little small for soldering.
Decouple which ever op-amp rigt on the chip.
Maybe disable usb power supply section if not used.
I had better stop now as it gets a little more tricky.
We could talk you through any steps if you ask but you need a dac first.
big-bur welcome to our little world of bodging this little dac.
Btw be sure to post up your schematic when your dac comes, be good to see if its any more acurate.
Remove or bypass signal path caps - you need to check some things out first so dont rush in.
Remove buffer amp,
Remove output relay,
Change op-amp to dual mono giga offering of dual mono (OPA627?) or better LT1024 on adapter but a little small for soldering.
Decouple which ever op-amp rigt on the chip.
Maybe disable usb power supply section if not used.
I had better stop now as it gets a little more tricky.
We could talk you through any steps if you ask but you need a dac first.
big-bur welcome to our little world of bodging this little dac.
Btw be sure to post up your schematic when your dac comes, be good to see if its any more acurate.
Oleg - Hello and welcome. Yes, get the gigaworks DAC and get stuck in. If you are sticking with the op-amp output stage then follow the steps Bemused mentioned. Then later have a play with regulators and power supply mods.
Just to clarify: it's 2 x LT1028 op-amps that are recommended. They are available as samples.
Tony - Package received thanks. email sent.
Possibly make a reg booster for the sampler reg and use a flea for the DAC chip supply. Would it be too much for the flea to supply both 3.3V rails? Certainly worth an experiment to see which one yields the best results. Then make a booster for the other.
Don't forget that the 3.3V regs share their supply with their respective 5V regs. So maybe remove the ferrite links that bridge the tracks and take the rectified DC from there and output from the flea to the output pin of the removed 3.3V reg (the tab pad is also output)
Oh and swap those big green output caps by the regs for some nice nichicon KZ's
Just to clarify: it's 2 x LT1028 op-amps that are recommended. They are available as samples.
Tony - Package received thanks. email sent.
Possibly make a reg booster for the sampler reg and use a flea for the DAC chip supply. Would it be too much for the flea to supply both 3.3V rails? Certainly worth an experiment to see which one yields the best results. Then make a booster for the other.
Don't forget that the 3.3V regs share their supply with their respective 5V regs. So maybe remove the ferrite links that bridge the tracks and take the rectified DC from there and output from the flea to the output pin of the removed 3.3V reg (the tab pad is also output)
Oh and swap those big green output caps by the regs for some nice nichicon KZ's
Sam cat, Bemused and Lobo, thanks!
So, I'm going to buy dac kit and Lt1028 op-amp from gigaworks, then the recommend case. Do I need to buy smth extra to start with? What's about PS? Should I change the regs or whatever?
Btw, what's about sound quality? Have anybody tried this dac with sb touch as a transport and naim amps? Have anybody compare this dac with some others (Teddy, Lavry, benchmark)? Probably it's another class of dacs, but who knows...
So, I'm going to buy dac kit and Lt1028 op-amp from gigaworks, then the recommend case. Do I need to buy smth extra to start with? What's about PS? Should I change the regs or whatever?
Btw, what's about sound quality? Have anybody tried this dac with sb touch as a transport and naim amps? Have anybody compare this dac with some others (Teddy, Lavry, benchmark)? Probably it's another class of dacs, but who knows...
Easy Oleg, one step at a time. Doing all the mods at once may be a risk at first, your de-soldering skills need to be bang on as the tracks on the board are very fragile. A mistake would be hard to pin point. Best to do the changes in steps.
The DAC can be ordered with optional upgrades DIR9001 and PCM1798 chips. Ask the seller about these.
I suggest you read as much of the thread as you can and digest the info. All of our ideas are here as well as our mistakes so it's an opportunity to learn from the fruits of our efforts.
The power supply is built in to the board and a suitable transformer is available from the seller, so this is taken care of.
As for comparison to DAC's costing £1500 or more it's asking a lot. But to be honest with careful attention to certain areas and upgrading accordingly this little DAC can hold it's own. The only way to know is to take it to some HiFi dealers and do some demos.
The DAC can be ordered with optional upgrades DIR9001 and PCM1798 chips. Ask the seller about these.
I suggest you read as much of the thread as you can and digest the info. All of our ideas are here as well as our mistakes so it's an opportunity to learn from the fruits of our efforts.
The power supply is built in to the board and a suitable transformer is available from the seller, so this is taken care of.
As for comparison to DAC's costing £1500 or more it's asking a lot. But to be honest with careful attention to certain areas and upgrading accordingly this little DAC can hold it's own. The only way to know is to take it to some HiFi dealers and do some demos.
My dac has arrived from far across the sea, incredible. thanks whoever you are!
I have a couple or three questions/queries/comments.
1. The large caps are made from ally that is so scarred it looks like the moon under a hand lens. Are these caps any flippin' good?
2. Looking carefully there were a few blobs of solder around and one of these could easily short one of the surface mounted components! Are there any areas that need particular care with shorts?
3. Are there any particular settings of the board that may result in disaster.
4. I am not familiar with the power transformer, again is this item any good?
5. I have a slight worry as the mains iec is wired wrongly. The live and neutral are reversed. Not a big issue I know, but why not wire it up correctly???
Cheers,
Mike.
I have a couple or three questions/queries/comments.
1. The large caps are made from ally that is so scarred it looks like the moon under a hand lens. Are these caps any flippin' good?
2. Looking carefully there were a few blobs of solder around and one of these could easily short one of the surface mounted components! Are there any areas that need particular care with shorts?
3. Are there any particular settings of the board that may result in disaster.
4. I am not familiar with the power transformer, again is this item any good?
5. I have a slight worry as the mains iec is wired wrongly. The live and neutral are reversed. Not a big issue I know, but why not wire it up correctly???
Cheers,
Mike.
Hi Mike
Have you got the same DAC as us?
There are no surface mount components on the Gigaworks big DAC apart from 3.3V LDO regs.
If the transformer you have is an R-core, then it is very good.
IEC inlet?... there is no IEC inlet with our DAC. Have you bought one ready cased?
Please post a pic or link to the DAC you have bought. I have a feeling you have bought the little DAC?
Have you got the same DAC as us?
There are no surface mount components on the Gigaworks big DAC apart from 3.3V LDO regs.
If the transformer you have is an R-core, then it is very good.
IEC inlet?... there is no IEC inlet with our DAC. Have you bought one ready cased?
Please post a pic or link to the DAC you have bought. I have a feeling you have bought the little DAC?
sam_cat
C'est Crounchifique!
Ditto here.
Inlet is not worth braging about, real crappy. I fitted Neutric powercon which is now my prefered connector.
Anyway I ignored you advice Rich and went and fitted the 3v3 flea to the position to feed the converter in place of the B117 3v3 D-pak.
Current is 35mA in this position and maybe a little high for the AD797 so a BC547C is probably going in as pass transtistor current dumping duty. This flea is a double red diode with no setting resistors or feed back capacitor. The whole implementation is some what naughty with four fleas ballanced on edge and is going to need some real tlc to tidy the job but there is still lots of surgery inprogress.
More on SQ latter when its all warmed up.
Anyway I ignored you advice Rich
and went and fitted the 3v3 flea to the position to feed the converter in place of the B117 3v3 D-pak.Current is 35mA in this position and maybe a little high for the AD797 so a BC547C is probably going in as pass transtistor current dumping duty. This flea is a double red diode with no setting resistors or feed back capacitor. The whole implementation is some what naughty with four fleas ballanced on edge and is going to need some real tlc to tidy the job but there is still lots of surgery inprogress.
More on SQ latter when its all warmed up.
More or less plug n play.
You need to set the jumpers in the corner of the board for our chosen input for example optical, coaxial or usb. Just wont work if wrong. Connect the transformer secondarys to the board if not already connected. Will damage if wrong. Set the dac chip dip switches fr your chosen data stream. Just wont work if wrong or may squark a little. Usually up / down / down / up or up / down / down / down from memory. Have you got yhe up-sampling module?
Picture of caps would be good, caution is needed if caps are suspect, they can explode.
You need to set the jumpers in the corner of the board for our chosen input for example optical, coaxial or usb. Just wont work if wrong. Connect the transformer secondarys to the board if not already connected. Will damage if wrong. Set the dac chip dip switches fr your chosen data stream. Just wont work if wrong or may squark a little. Usually up / down / down / up or up / down / down / down from memory. Have you got yhe up-sampling module?
Picture of caps would be good, caution is needed if caps are suspect, they can explode.
Mine seemed to take a week or so to settle down were upon it was maybe a little better than my DacMajic and a far bit better than an old Digilog.
Inlet is not worth braging about, real crappy. I fitted Neutric powercon which is now my prefered connector.
Anyway I ignored you advice Rich
Current is 35mA in this position and maybe a little high for the AD797 so a BC547C is probably going in as pass transtistor current dumping duty. This flea is a double red diode with no setting resistors or feed back capacitor. The whole implementation is some what naughty with four fleas ballanced on edge and is going to need some real tlc to tidy the job but there is still lots of surgery inprogress.
More on SQ latter when its all warmed up.
jeepers creepers, I've just tried to swap the terminals on the iec socket over. In trying to de-solder the inlet plug the terminals have melted the plastic and fallen out!!!! This piece of crap is alarming and in no way complies with the Uk safety standards. This is the only piece of electrical gear that I have ever destroyed using a bit of heat.
mikesnowdon
resU deretsigeR
Ok a blury picture of how not to build a dac. My excuse is development
Wow 2 STR's and 4 Fleas!
I'm thinking about using Fleas to power the DAC chips in my CD player.
Hi Mike, I am getting to like the fleas very much indeed however there are at least four differing boms that I am aware of, Rays boards differ from the original slightly and there are a few vias from top to bottom ground planes that can be a suprise if you stuff the board in a way that was not intended. All four fleas in my dac are different the 3v3's being the nicest as there is no voltage feed back divider or capacitor which was a nice Martin touch.
The STR is doing traditional analogue duty on the output stage.
When your ready to do your fleas I can do you some close up pics though I doubt you would need them.
The STR is doing traditional analogue duty on the output stage.
When your ready to do your fleas I can do you some close up pics though I doubt you would need them.
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