rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Jan 18, 2009 23:08:08 GMT
seems to me many of the type products have the basic designs already "swiped" from the work of others with the only addition the pcb layout which is pretty much both crap anyway from a tecnical standpoint (crosstlk etc.) AND having been done by the software the only real work putting up the "For Sale" page. The internet has brought forth a breed of hobbyist turned prfiteer that has access to miles and miles of both commercial and DIYer designs that wil be sold back to those very same hobyists even though the "seller" many times not only has NO CLUE how his own product works having been copied/cobbed together from various other similiar designs but if you even THINK about product support or a lucid answer to an operational/TS question is just so much pissing into the wind-wet leg and all. A bargain is only a bargain when there is a usable product as the result.Everything else is more often than not a point of frustration that once you get it to behave usually means by the time you do all the dirty work you pretty much end up with a new design but with a pcb as the starting point-not always a bad thing BTW.Something I do oftern is buy a pcb having the pinouts for what i want to build then use the other holes as a "kluge" area for a new design having little or nothing to do with the original. Not trying to pick on this design but more making a general observation as one who grew up with proven designs from magazine DIY articles that at worst would have a typo needing correction in the following issue of the mag (more of an issue for a total newb,not as much for the experienced who would see and correct the flaw beforehand).well designed and documented kits from Dyna,Eico,Hafler,Heat,SWTPC,Ace etc. and if an actual product one that came not only with a full warantee but an actual product manual that had detailed operational/TS instructions from common to things no human may ever see happen but being possible in some plane of existance included just in case ;D The "good old days" are sometimes more than just nostalgia and it is no surprise to some "older" hobyists that designs even from 50 years ago still work at spec because we would not buy a thing unless it was there to stay nd being such had to not only work but have reliability as well rather than disposable smi-annually. BTW-When I get the chance I will study the design to see what is going on (or not  ) if the issues have not been resolved.I do know this chip and to be honest it is not that hard to get it right unless the design is really "off" which this may well be.Problem is I am currently watching the NFL playoffs which I expect will end late tonight and the way my work schedule has been,two days in a row off not on the list,time is something I have little of so I try and squeeze way to much into a short span with the usual result being the "box" breaks and everything falls out  |
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Jan 18, 2009 23:13:01 GMT
BTW-A quick 'n dirty basic power bus for digital audio usualy begins at +12VDC "Raw" which is then regulated down to the various chip needs.If you are trying to get 8VDC regulated from a 9VDC RAW supply and your regulators are not LDO's then you have in effect NO regulation there not being enough voltage to compensate for the 1.6 VDC drop of the typical LMxx type V-Regs.If this is the case then your choices would be a higher voltage input feed to the regs or pull the regs and replace them with properly sized LDO replacements www.raleighaudio.com/lv_power_supply.htm |
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robertkd
Been here a while! 
Electronics Engineer from sunny Queensland
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Post by robertkd on Jan 19, 2009 1:56:46 GMT
 Did you forget to take your "happy pill" when you woke up? Miguel I tried too be too cryptic/smart with the answer. I thought that quoting the converted selling price would be a big hint. And yes, I am a little forgetful and sharp at the moment due to severe leg and back pain from RA. ((Rheumathoid Arthritis) I'm leaving cupboard doors open and other stupid things at the moment,including missing editing mistakes. Alex Alex sorry to hear that however think how I feel I suffer badly from arthritis as well and I'm only a youngster, some times I want my wife to take me to the knackery  Robert |
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Deleted
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Post by Deleted on Jan 19, 2009 4:08:04 GMT
Robert
Which do you have, Rheumathoid or Osteo ?
Alex
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robertkd
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Post by robertkd on Jan 19, 2009 4:31:10 GMT
Osteoarthritis ya gotta love it hey I remember getting back from the doctors some years back after she informed me of the condition, thought I had ross river virus or dengue fever or something. I did a net search and the realization there is no cure, no relief, only snake oil and people who would take your money My mother suffers with it and she developed it at an early stage as well. Robert |
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robertkd
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Post by robertkd on Jan 19, 2009 12:53:37 GMT
Glad others are taking a pop at these cheap dacs, its normally me faffing about with the things  got to admit though guys both are cheap, imagine buying something like these a few years ago? Absolutely good spot Leo, thanks I'm sure there is a lot to bodger  |
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Post by PinkFloyd on Jan 19, 2009 23:04:55 GMT
Actually guys...... this little DAC is sounding pretty darned good today, maybe it just needed some time to cook who knows? I tried one of those variable linear PSU's on it and have tried it at 7.5V / 9V and 12V and do believe it sounds best with 12V feeding it..... of course, the differences in SQ between 7.5V / 9V and 12V are minimal but to my ears 12V sounds "right". The level thing seems to have improved  I have had a bit of a head cold of late and it could simply be I was rendered temporarily "deaf" (seriously).... I blew my nose earlier and my ears kinda "whooshed" and there was a crackling sound in my head..... everything's a lot clearer now thank god The erythromycin seems to be kicking in at last and is loosening all this shit in my head / lungs. I really shouldn't have commented in this condition but we all do it don't we? You're lulled into a false sense of security thinking your bunged up state is your "normal" state and it's only when you blow your head clear you realise just how much info you have been missing. Soooooo........ I can't possibly put this new found detail / volume down to the cap swaps and I'll never know if WIMA city is better than el cheapo china metropolis..... well, WIMA city certainly looks a lot nicer to my eyes anyway At the moment I've got the DAC strapped onto an old (and trusty) Marantz CD-52 MKll into a Graham Slee Novo powering (old and trusty) Senn HD-600....... the el cheapo DAC is most certainly an improvement over the internal CD-52 DAC, no doubt about it at all. The presentation is not as lush and full as it is with the integral CD-52 DAC, in fact it is TOTALLY different....... it is lighter, more agile with each musical component "dancing" before you in a more microscopic arena..... a very intimate, informative listen....... It is not a "grand scale" trumpet fanfare "high end" type listen with soundscapes as wide as the Cheddar Gorge but it is most certainly an intimate, realistic, "discover all those hidden sounds" listen....... Dare I say it, digital "purists" would love this one (vinyl junkies would hate it) ....... this is a "nosey bastards" DAC..... if you want to dissect the recording and follow each individual component with ease then this is a nice little tool to do so..... If you want to drink a few beers, let the music take you to a different plane and blow your mind in a 1970's stylee then something more "congealed" / "warmer" / "valve like" / "muddy" / "chocolaty" may be more appropriate. Hell...... it MUST be good! I've sat here typing all this shit listening to it........ long time since I have done that So........ it may be well worth buying this sort of thing to complement and old CD player that has a good transport / crap DAC (In my opinion / generalising / the older the transport the better the quality)..... a good old swinging arm with a modern DAC may be the perfect marriage? Certainly worth looking into these cheap Chinese offering though..... isn't it? You're right Leo, we couldn't have dreamed about obtaining these at such ridiculously low prices years ago could we? RICK..... get a fckin' life man..... I'd rather get 90% working for a fraction of the cost than 100% working for a ball busting charge...... Fck the fat chinned middlemen, they do not deserve to live... these bastards have ruled the audio roost for way too long, lining their pockets along the way, Clueless bastards the lot of them..... Damned BOX shifters, all of them! Do you know these fckers cream a good 70% profit per item and all they do is "stock" the item? Graham Slee Solo for example....... £500 to the customer........ Middleman gets each unit for £130 so £370 in the pocket of the middleman. Graham gets "£130" and some fat slag with storage gets £370........ we pay to keep Fat, talentless bastards alive..?? Not me mate...... fck 'em....... bring on the cheap Chinese 90% working gear...... I'm prepared to have a go at the other 10% |
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Deleted
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Post by Deleted on Jan 19, 2009 23:49:56 GMT
Mike
Seeing you are using a regulated 12V supply, did you short out D2 (1N4001) ?
It's only there in case someone is stupid enough to connect the 12V supply the wrong way around, so there may be a further improvement , if a regulated supply is used. If not a regulated supply, leave it in for a small amount of ripple reduction.
Alex
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Jan 20, 2009 4:34:00 GMT
RICK..... get a fckin' life man..... I'd rather get 90% working for a fraction of the cost than 100% working for a ball busting charge
Really ?
so you would rather line the pockets of some little theif bastard without a clue than pay the guy who actually sweated a design ?
and you and others wonder why I NEVER post any of my own goods ?
Everyone wants a bargain but the truth is you get what you pay for in not just product but customer satisfaction.I personally WANT someone on the other end of the telephone answering my questions and I WANT a company backing a product that if/when there are updates the chance to do it and in fact would pay for a Ray Samuals or HeadRoom amp over just about any other "product" or "kit" or "project" headphone amp on the planet if I were not dedicated to tube drive at home and ampless on the go but you folks are more than welcome to buy "mystery" products from no name designers at will-your loot,your choice but in the end I personally consider MY TIME the same as loot since I either work or do contract electonics work and then there is my time so if I need to spend time to make a thing be what it should have from the box and if I add in my normal contract work "hourly" then that bargain gets to the same monetary figure as would the legit company Plug 'N Play version plus I don't have to sweat casing the bitch up which to be honest is usually for DIYers the part where even an idiot can tell it was a home made cob job unless you spend AGAIN big bucks for a properly deigned and labelled product.
No free rides and those who think there are are just kidding themselves and worse,encouraging even more pirated products/designs made with suspect parts for a fraction of the cost which not only cut out the middle man but THE MAN who did all the damn work to begin with.
'Nuff on this topic by me or I will REALLY say what I think on the general subject of cheap bastards paying plagarists and/or deceptive/suspect vendors for products that are hardly worth even the piddling amounts asked when the "tear down" is done and you realise just how bd the implementation is until you ro;; in good parts and re-work the design making that "cheap" whatever no longer cheap
rick out
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Jan 20, 2009 4:41:15 GMT
And BTW-I not only HAVE a life but an extremely full one rich in both freinds and family that could give a shit about "expensive hobbies" preferring real life as the topic of conversation not "guess what I did on the computer today" which if a life than yes,I need to get one because my online time is severly lacking in comparison to my "out in the world human interaction" time |
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Jan 20, 2009 4:43:45 GMT
or better yet,as more than one "significant other" has said when their partner is nose deep in the books/bench/computer :  rick out |
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Post by PinkFloyd on Jan 20, 2009 11:17:36 GMT
;D hehe......... I love pulling your plonker Ricky I thought the "get a life" bit would get you going and it did Remember mate, there has to be a devil's advocate to promote healthy, heated debate..... not all of what I say is meant and some of it tongue in cheek...... Glad you have a life my friend |
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insomniac
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Team Zopiclone
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Post by insomniac on Jan 20, 2009 18:45:07 GMT
Glad to hear the DAC is proving listen-able Mike! on the old glove HD600's too....nice  The el cheapo certainly seems like an nice affordable way to add an alternative sonic flavour to a CD player....or maybe add digital input to an amp project I doubt the individual components, pcb and alu case could be sourced here for such an attractive price....great value indeed. |
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Post by PinkFloyd on Jan 20, 2009 21:04:29 GMT
Glad to hear the DAC is proving listen-able Mike! on the old glove HD600's too....nice The el cheapo certainly seems like an nice affordable way to add an alternative sonic flavour to a CD player....or maybe add digital input to an amp project I doubt the individual components, pcb and alu case could be sourced here for such an attractive price....great value indeed. Yes, £29 is pretty good value and, no, you couldn't source such a thing here for that kind of money. I no longer look at it as "here" and "there" though as it is supposed to be a GLOBAL market..... I just call it "good value" and don't look at the country of origin, ebay to me is just a global market place. I no longer look at "made as China" as an inferior thing either.... the UK boutiques all source their bits and bobs from the cheapest source (China) and add some bullshit and a large mark up.... I no longer (never have) consider the stuff the boutiques sell as "ultra special from a secret magical audio source" cause it isn't.... it's all cheap shit with added bullshit (or as the business gurus would say.... "added value") Even these guys that Rick loves have to buy parts from China.... very few electronic parts are manufactured in the UK / USA these days...... so, at the end of the day, everybody is feeding out of the cheap Chinese trough from the fat cats to the bottom feeders.... everybody's at it. I love Rick's vision of everybody playing on a level playing field and doing things by the rules but, this is the real world, and people will grab you by the balls, kick the shit out of you and flout the "rules" to score a goal. It isn't "cricket" it's called the "modern world" where respect and honour mean little and lining pockets with large green mean everything..... wasn't it the Americans who taught us this way? |
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Post by Deleted on Jan 21, 2009 1:06:10 GMT
Miguel I noticed that your new president referred to U.S.A. as America . Had he been reading too many Superman comics when he was a kid ? ;D Alex |
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Post by PinkFloyd on Jan 21, 2009 11:49:51 GMT
... wasn't it the Americans who taught us this way? Are you using "Americans" referring to people from the USA or in the collective for those "Americans" of the "New World" which extends from "Tierra del Fuego" all the way to Alaska? If the first we learned it from the good old Brits that came over back in the 1600's. If the second there are a whole lot of europeans to blame. ;D Well.... I am certainly NOT referring to the "native" American Indians as they were a very civilised bunch..... I am referring to all the cowboys and crooks who raped and pillaged the place and built burger joints all over the hillside..... the same types who are ruining the rest of the world with coca cola, Macdonalds, burger king, KFC etc. etc...... you know, the REAL crooks |
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rickcr42
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Rest in peace my good friend.
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Post by rickcr42 on Jan 21, 2009 17:49:35 GMT
My "buttons" are easily accesable to those who know where to push which comes with time spent (and no,didn't miss the "Ricky" either bub ) and something I once worked on correcting before I decide to take an FTW attitude towards life (for the "I don't get out much and when I do prefer to keep to my own "FTW" translates to "F_ck The World  ). now I usually either ignore the "push" or if I am tired or sick which means I am "bitchy" and I was/am both just slap someone either actual or virtual,both being self satisfying in the extreme As Popeys always says "I yam what I yam and that's ALL that I yam..........toot toot"  |
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insomniac
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Team Zopiclone
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Post by insomniac on Jan 22, 2009 3:59:48 GMT
Are you using "Americans" referring to people from the USA or in the collective for those "Americans" of the "New World" which extends from "Tierra del Fuego" all the way to Alaska? If the first we learned it from the good old Brits that came over back in the 1600's. If the second there are a whole lot of europeans to blame. ;D Well.... I am certainly NOT referring to the "native" American Indians as they were a very civilised bunch..... I am referring to all the cowboys and crooks who raped and pillaged the place and built burger joints all over the hillside..... the same types who are ruining the rest of the world with coca cola, Macdonalds, burger king, KFC etc. etc...... you know, the REAL crooks These crooks don't happen to trade in Sugar and Diabetes medicines too by any chance? |
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robertkd
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Electronics Engineer from sunny Queensland
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Post by robertkd on Jan 25, 2009 11:19:30 GMT
Ok yeah I'm thinking same shyt here  as for the transformers it would seem they are suitable, I am waiting for data sheet from manufracture but hey it's Chinese New Year See no reason why not, I was just looking for a way to isolate the coax i/p  Robert Alex further yes the artificial ground goes think we only need 8VDC for the 5V and 3.3V regulators hence full wave rectifier from the two 7.5V taps less heat generated on board. As best I can tell the opamps are the only things feed direct so could well run +/- 15V. It will be interesting to see how the ground and supplies are done, the circuit is a little sparse in detail but seems analogue and digital share both supply and ground so depending on the layout might have some track cutting and reworking to do If you haven't already, download the Bur-Brown Spec Sheet, here focus.ti.com/lit/ds/symlink/pcm1793.pdfI think we are on a winner here |
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Post by Deleted on Jan 27, 2009 4:49:48 GMT
Robert,Leo,Allan
I received the PCM1793 DAC today, and have had a quick listen. It sounds O.K. Not as good as analogue out from my X-FI card , and of course not in the same league as my modded X-DAC V3. BUT, it is at the moment being powered by a cheap 12V SMPS plugpack, and SPDIF input from the soundcard. I expect that there could be quite a bit of improvement wrung out of it with better regulated power supplies, and removal of the "rail splitter" I.C. This would be just for starters.
Incidentally, the reason I was thinking of a +-6V dual regulated PSU via a JLH, in the beginning, is that I have such a supply for my X-DAC V3. It has trimpots for adjusting output voltages, and could easily be altered from +-15V to +-6V without much messing around.
Alex
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robertkd
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Electronics Engineer from sunny Queensland
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Post by robertkd on Jan 27, 2009 6:21:11 GMT
gee Alex I think I have another piece of tag board and some capacitors so I'll be right for a power supply for the DAC Might have to scrounge another piece of aluminum sheet, suppose I could actually pay for it and get the sheet cut to the exact size I need Seriously though that is good news mine shouldn't be to far away |
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leo
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Post by leo on Jan 27, 2009 11:25:42 GMT
I wouldn't be surprised if the dac sounds average as stock, its probably compromised in a few area's to keep costs down, the dac chip should be fairly capable.
It should be ok after some fettling , of course its worth giving it some time to run in first
As already noted the supply for the op-amp stage isn't that great, also ditch the switcher
I personally can't stand those green and blue Wima FKP caps, I've used those before in filtering and found them to have issues in the high frequencies, low inductive film types are better.
I'd use non inductive for receivers PLL filter, those 3 components making up the filter can have a surprising effect on the sound
Use a low impedance low leakage cap on the dacs VCOM pin, be cautious of ceramic, microphonic parts in this high value used on the VCOM is not a good idea imo, its part of the dacs internal analogue bias
Can't you base the differential to single ended output around the stage in the modded X-can V3? you don't need the I/V part because this dac in the Chinese one is voltage output
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robertkd
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Electronics Engineer from sunny Queensland
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Post by robertkd on Jan 27, 2009 13:08:46 GMT
Hi Leo,
whats the concern with the i/p selector jitter/clock recovery?
looking at the diagram the power supply is a little cheap and cheerful no seperation between digital and analogue likely worth a look at.
Robert
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Post by ramdog2004 on Jan 27, 2009 14:24:28 GMT
I was thinking of getting one of these and connecting it directly to a cdrom drive but assume I'd need a ttl / spdif converter. Has anyone made one???
Cheers
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robertkd
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Electronics Engineer from sunny Queensland
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Post by robertkd on Jan 27, 2009 14:30:10 GMT
I'm not sure why you would need a "ttl converter" as your CD player needs to have either SPDIF (RF) or TOSLink (optical) to use the DAC.
Robert
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) if the issues have not been resolved.I do know this chip and to be honest it is not that hard to get it right unless the design is really "off" which this may well be.Problem is I am currently watching the NFL playoffs which I expect will end late tonight and the way my work schedule has been,two days in a row off not on the list,time is something I have little of so I try and squeeze way to much into a short span with the usual result being the "box" breaks and everything falls out 
Did you forget to take your "happy pill" when you woke up? 
got to admit though guys both are cheap, imagine buying something like these a few years ago?
I have had a bit of a head cold of late and it could simply be I was rendered temporarily "deaf" (seriously).... I blew my nose earlier and my ears kinda "whooshed" and there was a crackling sound in my head..... everything's a lot clearer now thank god 
).