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Post by tripmaster on Sept 12, 2008 9:07:09 GMT
All of the tracks seem ok and I have tested them using a meter
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Post by tripmaster on Sept 12, 2008 17:26:33 GMT
Hi I have the C7 value now, thanks ALB. I am really keen to try bypassing the solder pads where this chip once was. [/img]
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Post by tripmaster on Sept 13, 2008 19:19:05 GMT
YES! I've just soldered the the link in the past five minutes. The sound is back albeit only the right channel, and its not distorted. It is however sadly lacking in the bass department. Progress! I have checked the connection between pin one of the opamp to the left output pin and its fine. I attached the meter to the right output pin but could not make a connection with any of the other opamp pins. I do have a connection between the blob on the base of the board and the right output. I have tested the leads to the rca sockets and they appear fine. Any suggestions? Richard
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Post by puffin on Sept 28, 2008 6:48:41 GMT
Has anyone tried to connect a clock to this board?
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Post by minivan on Oct 5, 2008 8:36:46 GMT
Q1 and Q6 inputs are 2SD786, the Emitter follower is a BC517 Darlington, I basically used what I had. I also tried J-fets for the input and output, also mixed them but didn't like the results leo, i am having trouble sourcing these transistors 2sd786 and bc517 any other equivalents i can use? thanks
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Post by canjunkie on Oct 5, 2008 8:48:19 GMT
Minivan,
For the 2SD type, try 2SC1627, they should be ok. I'll PM you about the darlington.
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leo
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Post by leo on Oct 5, 2008 13:03:41 GMT
Q1 and Q6 inputs are 2SD786, the Emitter follower is a BC517 Darlington, I basically used what I had. I also tried J-fets for the input and output, also mixed them but didn't like the results leo, i am having trouble sourcing these transistors 2sd786 and bc517 any other equivalents i can use? thanks You can try a range of transistors there, main reason I used 786 is because of their low noise, something like BC550C should also be ok there, if you can't find any Darlingtons its easy to make your own strapping a pair of BC550's together BTW you may actually prefer the J-fets so give those a try too , 2sk170BL's work, I liked the transistors better but it is worth comparing
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Post by fordgtlover on Oct 6, 2008 6:12:35 GMT
I have found some 2sd786 on ebay - for $25 each!!! www.bdent.com lists the 2SC2003 as a replacement part. Do those with much greater knowledge than I think is a reasonable replacement?
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Post by fordgtlover on Oct 7, 2008 12:46:27 GMT
I thought I might try the output stage that Leo previously posted here. So, I thought I would put my developing Eagle skills to work, and try a PCB layout. I have recreated the schematic here: And, here is my PCB layout: The board is 40mm x 60mm and will require two for the complete output stage. I have assumed BC550C for Q1, Q3, Q4 & Q6 & a BC517 for Q2. I have used the Murata 2200R inductors. You might note that for the output cap I have provided the option to use either a large(ish) film cap (c2) or an electrolytic bypassed by a small film cap (C9 & C10). Is this a sensible option and implementation? Does C2 need to be 10uF? Can it be a smaller value? I'd be interested in any feedback about the layout or the parts selections. This is my first board layout, so all comments welcome. Cheers Rob
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Post by minivan on Oct 8, 2008 11:37:52 GMT
awesome, when u make ur pcb, if it's ok, can u make me one as well? thanks
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Post by fordgtlover on Oct 8, 2008 13:57:12 GMT
awesome, when u make ur pcb, if it's ok, can u make me one as well? thanks If I can get this off the ground, I'd be happy to get a few extras done.
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Will
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Post by Will on Feb 20, 2009 20:23:45 GMT
I've ordered one of these as a stop-gap to go with my Shigaclone, until the new sabre chip is out in the wild.
Still able to get one for £40 delivered, including 78xx based PSU and traffo.
I think the more straightforward mods detailed here and over at AOS, will be the limit of what I do, with a JLH fed opamp I/V.
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Will
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Post by Will on Mar 1, 2009 18:13:17 GMT
The wee beast dropped through the letter box Thursday morning, but today was the first time I've had chance to bung her together.
One immediate problem I noticed when looking at the main board was that pin 2 of the DAC had been bent, and was soldered to pin 3. Looking here and at other resources on the web, this is not normal, so in with the SMD tip and pin 2 was returned to normal.
Got everything fired up and it sounds fine, using spdif. Only really had chance to have a listen for about 5 minutes, but look forward to further listening.
DC offset was 2 mV on the left channel, 0 on the right.
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Post by jeffc on Mar 2, 2009 3:25:59 GMT
Wilbur,
Might have been useful to leave the DAC chip ground pin2 lifted in your surgery and then connect it to pin 16 of the CS8416 receiver via a small gauge wire. From memory of the AOS thread, this will allow the DAC to operate at bit rates higher than CD std. Maybe the reason it was bent up in the first place but just caught a little solder from its neighboring pin during manufacture. Of course this mod will only useful if you're interested in using it at higher bit rates. ;D
cheers.. jeffc
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Will
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Post by Will on Mar 2, 2009 17:38:49 GMT
Thanks jeffc, now that you mention it, I remember reading that on the AOS thread.
Higher bit rates feature in the future, soon as I get SPDIF on the computer sorted (number 43 on the list of DIY things to do....)
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Post by jeffc on Mar 24, 2009 7:51:10 GMT
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XTRProf
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Post by XTRProf on Mar 24, 2009 23:44:01 GMT
Thanks for bringing that up. So far I only saw solutions which must have a Pacific Motion PMD 100 or 200 to do that. If that chip is inbuild that will be very good indeed. I wanted to know as well.
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Will
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Post by Will on Mar 25, 2009 15:10:19 GMT
Modified this board as per the changes discussed earlier, but found at this link in a condensed form. theartofsound.net/forum/showpost.php?p=14693&postcount=96 There's a bloke over there called Leo, who is ever so helpful! As it stands it's much better than the standard DAC in an Arcam Alpha+, and ahead of a DacMagic 1 that I borrowed. Quite listen-able, and well up to the job of feeding me music 'till the Buffalo32S is in my hands. Decent sound for £50, inc mods and a cheapo maplin box is pretty good!
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Will
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Post by Will on Mar 25, 2009 19:01:49 GMT
The original is a JRC 5532, but most swap out for what ever they please. I've re-homed the LM4562 that was supplanted by the metal jacket 4562 in my SCHA into this DAC for now.
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Post by jeffc on Mar 26, 2009 0:34:32 GMT
Will, The LM4562HA sounds f***ing exceptional in mine , although I have JLHs feeding both the digital and opamp sections. Only using +/-12V for the opamp section at this point. Using the PSU and 18VA transformer that came with the DAC so there might be scope for some further improvements here. Couple of pics of my DAC over in the SCHA zone opamp group buy thread. You change the SMD resistors and caps to correct the HF cut? XTRProf, On the HDCD ?, some homework indicates that the CS receiver and DAC are capable of passing this through, but from what I can gather, only when sent a signal already decoded back to 16 bits. As decoding is done on-board the BB PCM1732 DAC chip (only one that does this apparently) in my NAD C542, rather than separately, I can only guess that the digital s/pdif out won't carry the decoded signal. Need to double check the C542 Service Manual when I get a sec to make sure this is correct. cheers.. jeffc
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XTRProf
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Post by XTRProf on Mar 26, 2009 1:20:15 GMT
On the HDCD ?, some homework indicates that the CS receiver and DAC are capable of passing this through, but from what I can gather, only when sent a signal already decoded back to 16 bits. As decoding is done on-board the BB PCM1732 DAC chip (only one that does this apparently) in my NAD C542, rather than separately, I can only guess that the digital s/pdif out won't carry the decoded signal. Need to double check the C542 Service Manual when I get a sec to make sure this is correct. cheers.. jeffc Hi there, AFAIK, the 20 bits HDCD codes are still in those 16 bits codes. Oh dear, how to put that across as it seems contradicting . It is only unlock, by whatever method I have yet to find out, thru the Pacific Motion chip. Hence, when we rip a HDCD track and when we play it, the HDCD decoding light will come on eventhough the ripping is done at 16 bits.
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Post by jeffc on Mar 26, 2009 3:32:09 GMT
Hi XTRprof,
Yer agree, need to read how HDCD works 3 times and then read it again before being tested, bit tricky. Just checked the NAD C542 block diagram in the service manual and the digital out is not HDCD decoded, which occurs in the DAC chip itself. So, unless the CS4397 DAC can do the decoding, which from my homework it can't, I'd have to find another source/way of exporting adecoded digital signal, which I gather must be possible from chips dedicated to HDCD decoding.
cheers..jeffc
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Will
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Post by Will on Mar 26, 2009 9:12:35 GMT
Jeff, is the HF cut mod the replacement of R8,9,14,17 and C32,33,34,35 with 30k resistors and 150pF caps?
From what I read that modification has two very beneficial benefits. The first is that it balances the lop-sided implementation of the op-amp, which led to poor DC offset, and also it prevents the HF from rolling off a badly as it did, extending well into bat territory.
Did you replace the SPDIF PPL components as well?
I had a further listen to this last night, and it is really opening up know. At the start of wish you were here, the movement and the sounds of handling the guitar before it is played were much easier to hear, even at low levels. A real bargain, and now you have me thinking of asking Robert if he has anymore LM4562HA, and building up some JLHs, when the money should be going on the Buffalo..
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Post by jeffc on Mar 26, 2009 21:43:04 GMT
Hi Will,
Detail retrieval with the HA can opamp installed is spectacular. Can wrapped in 3M damping foil that I have access to through a friend, must get some more, good stuff. I'm using the DAC in a minilalist system, DAC to DIYFidelity 10K stepped attenuator to DIYparadise Charlize T-amp to essentially crossover-less open baffle speakers. So benificial mods very easy to spot.
Yep modded the SPDIF PPL to correct values and replaced R8,9,14,17 and C32,33,34,35 with the 30k SMD resistors and 150pF SMD caps recommended? Canjunkie and I were playing with this DAC at the same time and thus were sharing part purchases. And the other reason I was able to get extra JLHs, before his back decided to give him mysery. BTW I've got a stack of these SMD parts left over if you want some sent. Can't see me using them for anything else. PM me.
I'd push it a little further, the CS4397 DAC is very good and even though V out that some will snear at, the internal output stage was apparently designed with assistance from the Philips guys involved in the TDA1541 DAC design, which might add some cred to its design and why its reported by some to sound nicer 'more analog like' than the updated CS4398 DAC.
cheers.. jeffc
PS Yes, if you consider >16kHz bat territory, with the R and C changes HF roll off is pushed to >20kHz, not as though my aging ears can hear antything up there. One thing I keep wondering though, with all the forum sites dedicated to this DAC, and maybe feedback to the sellers, why haven't the guys making it taken this advice and altered the parts values, wouldn't cost them anything, and saved late comers like you the hassle???
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Post by jeffc on Mar 27, 2009 0:35:22 GMT
Will, One more thing, the SQ of this DAC, and my guess any DAC with low power needs, is likely to be improved startlingly when placed downstream of a balanced isolation transformer to negate the nasties of common ground mode noise. Hooking up mine was one of those OMG what have I been missing moments. Not just me on this one, guys at DIYparadise found that beyond the use of medium to massive 12V batteries, the use of a balanced isolation transformer delivered profound improvements in SQ to the Monica NOS TDA1545A DAC that I've also been toying with. I made one using 2 x 12-0-12 30VA encapsulated transformers I had at hand that seems to work quite OK but DIYparadise sells one specifically designed for the job. Not too expensive either. No affiliation with Yeo except that I think he's a very decent guy and has quite a bit of my hard earned. diyparadise.com/shop/index.php?main_page=index&cPath=9diyparadise.com/web/index.php?option=com_content&task=view&id=77&Itemid=26cheers.. jeffc
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