I'm also looking for somewhere to draw power for some LEDs to indicate which input is being used. I'm using a rotary switch to select between coax and optical, and could do with an external LED indicator.
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I'm also looking for somewhere to draw power for some LEDs to indicate which input is being used. I'm using a rotary switch to select between coax and optical, and could do with an external LED indicator.
A schematic can be found here (scroll down to near bottom of page) : http://lampizator.eu/LAMPIZATOR/LAMP...ampizator.htmlQuote:
Originally Posted by paradox
As Leo said, the part numbers are different from those on the board.
I tested the dac before fitting parts and it worked fine.
The story so far...
Stage 1
Changed LM4562 OPAMP Sound: ok
---------
Stage 2
Removed and bypassed PS caps (C30, C31, C28, C27 & C54, C6) with thin wire. connected coupling caps and R68 resistors on RCA output, soldered two blobs to bypass chip on the base of board.
Sound: Treble is OK but bass really muffled and distorted - Sounds really bad.
----------
Stage 3
Change all other caps. Sound: Still sounds the same, but it still works!
I have not removed any of the smd caps, just bypassed with vishay
I have not changed any resistors.
Do you have any clues?
Aaaaaarrrrgh! CAPACITOR OVERKILL!!!!!
I think you may have made things difficult for yourself, with the choice of caps. Not easy to see whats what.
Probably best to retrace your steps and find out where it went pear-shaped.
Even put it back to std board and use it for a few days, till its all nicely run in. Then you'll know better what to expect.
I don't use opamps in mine so difficult to comment.
It should when upgraded(and before), sound very clear and dynamic.
Good luck.
A few problems I can see
WAY too many Oscons there I'm afraid, the ESR will be too low, you need to check for possible instability on a scope, Oscons also have a tendency to kill bass if you use too many of these which will give very soft signature
Those film caps are too big physically, their inductance will be too high
A mistake I've seen a lot is people tend to think low ESR capacitors are the best for all apps, infact it can cause a lot of problems with regulation regarding stability
If you have to use this many Oscons and after say a few days it still sounds bad try adding a low value resistor in series with those caps to add some impedance and help cure any possible ringing
Also I noticed you used Sonicaps, these are reported to need some burning in , also the LM4562 tends to be poor at driving capacitive loads, I tried this chip but removed it, it needs care before it sounds half decent IMO
Hi
I think I may have got little carried away! ;)
The bass is in fact very heavy. It sounds like strumming a loose bass guitar string
I started by just changing the opamp and it didn't sound any worse than the stock card.
I then proceeded to remove only C30, C31, C28, C27, C54, C6 and added two SCR coupling caps and 68R resistors. It was at this point the sound took a turn for the worse. I changed to the Sonicaps because I thought the SCRs may have dried up as they are quite old (18years)
In my parts bin I have the following items
10x 47uf 16v Tant beads
5x WIMA 150pf
10x Panasonic FC 470uf
Would I be better off replacing some of the components with these items, And if so at which points?
Thanks for your help
Richard
The oscons are 150uf SA
Grey Vishay MKP 0.22uf
Blue Vishay MKP 0.1uf
The Vishays are bypassing the SMDs
Richard.
Sorry for the poor photo but this will show you how mine looks with the upgraded caps.
http://i27.photobucket.com/albums/c1.../Baffles-1.jpg
C19 is 1000uf Pana FC.
C21 is 150uf Pana FC.
You can use your 470uf at C19. C21 should be smaller.
C9 is Vishay mkp1837 0.1uf. This was the best i found after trying twelve different caps here. Big ones don't work properly and generally mess up the sound, sometimes in a big way.
C9 is in my opinion one of the most important caps on the board. This also the only surface mount that i removed.
C16,17,20 and 25 are Oscon 150uf 16v. Probably enough Oscons.
C3,C18 are 220uf Samwha caps(gold), but any decent quality cap suitable for purpose would perhaps do.
C8,11,12,13 are 3.3uf Tants.
All lytics are bypassed by 0.1uf film caps.
I think blue Vishays are preferable to Wima, anywhere on this pcb.
This DAC works very well. Hope this is helpful.
Whilst listening to the DAC last night one of the solder connections attaching the right channel lead to the coupling cap broke away.
I re-soldered the lead and at the same time decided to remove the two blobs of solder from the chip on the base of the board (These blobs bypass the chip). I fired it up it up again and only the left channel works. All of the connections seem fine and both channels operate via the DACMAGIC.
I re-soldered the two blobs to the chip and now the output is very quite and distorted.
This is not a good way to finish the evening!
HELP!!!!
Quote:
Originally Posted by alb
Thanks, I will give that a go if the board returns to a stable state ;)
HiQuote:
Originally Posted by Tripmaster
Late on Tuesday night...
Whilst listening to the DAC last night one of the temporary solder connections attaching the right channel lead to the coupling cap broke away.
I re-soldered the lead and at the same time decided to remove the two blobs of solder from the chip on the base of the board. I fired it up again and only the left channel works. All of the connections seem fine and both channels from my amp operate ok via a DAC MAGIC2 box.
I re-soldered the two blobs next to the chip and now the output is very quiet and extremely distorted.
This is not a good way to finish the evening!
Wednesday
Well...I have removed quite a number of the components previously added but am no further forward with regards to sound, still very distorted.
When I desoldered the small blobs from the base of the board next to the chip I think I may have damaged the solder pads (Solder is not sticking any more and they are barely visible).
Do you think I may have damaged this chip due to excessive heat? Or do you think the board is a right off?
Thanks in advance
Richard
Just send it to me ;)
hey everyone I am trying to bypass the onboard output stage to go directly to my headphone amplifier.
I removed the 4 capacitors in the middle of the board and connected the RCA outputs to where -R and -L caps were.
Now I am reading 2.5V on both outputs :/
What have I done wrong?
http://img386.imageshack.us/img386/9568/img3601di7.jpg
This is normal. You should add a 2,2uF capacitors (polypropylene or so) in series to outputs.Quote:
Originally Posted by gurusan
ok thanks. I have some 2.2uF MMK EVOX caps and some 3.3uF Philips MKC caps.
Which would be better? sorry I'm new at this....
You should use this one which sounds better.Quote:
Originally Posted by gurusan
gotcha. thanks :)
I have been playing around with some of the recommend cap values (I know the caps are a bit large)
I have tested the output from the psu and I am getting 12v & 5v
How do I check when connected to the board?
Hi
I have checked all of he solder joints and I cant see bridging. I also checked the Digital voltage from the CS8416 and I am getting a reading of 3.33v on pin 23 and 21. I also have a reading of 13.24v from pins 4 and 8 on the opamp.
I have not yet checked all of the tracks for continuity.
After some considering my options I decided to remove the chip from the base of the board.
Can anyone advise which pads I need to short for bypass?
I have check there is a connection along each track between all of the changed or removed capacitors.
Does anyone know the value of C7?
as far as I understand it you already soldered the 2 little pads on the bottom of the board next to the chip which effectively bypasses it. Physically removing the chip doesn't do anything extra.
I had problems soldering these pads at first because there may have been some lacquer/dirt over the contact point. I think the excessive heat trying to get a good contact may have damaged the chip. There was very little left of the solder pads prior to removing the chip.Quote:
Originally Posted by gurusan
A useful link to identify surface mount caps.
http://library.solarbotics.net/piece...p_code.html#sm
C7 is labelled 104 according to the schematic.
The first two digits are the base numbers ie 10.
The third digit is the multiplier, in this case 4.
So C7 is 100000pf = 100nf = 0.1uf.
Thanks for the info, very helpful!Quote:
Originally Posted by alb
Do you happen to know which chip solder pads need to be connected to enable a bypass?
Answer is lurking here:Quote:
Originally Posted by Tripmaster
http://theartofsound.net/forum/showt...?t=315&page=11
Iain
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
http://i374.photobucket.com/albums/o...o/SL272591.jpg
http://i374.photobucket.com/albums/o...o/SL272593.jpg
http://i374.photobucket.com/albums/o...o/SL272595.jpg
http://i374.photobucket.com/albums/o...o/SL272596.jpg
http://i374.photobucket.com/albums/o...o/SL272597.jpg
well done, at least you have some progress!
Don't suppose you have a scope? it would make finding whats causing the missing channel much easier
Regarding the bass, see the bottom pic with the three oscons? try changing the middle oscon to say a standard 10uf electrolytic, let it run for an hour and see if it makes any difference, that cap is for the dacs internal analogue bias, low ESR is good here but I personally didn't like a oscon in that position
also the large pair of caps in the middle of the board seem to be non polar, these are not really suited for supply decoupling, try a couple of polarised caps there instead
I know its hard but also try to keep the legs of the caps as short as you can, your adding inductance with the long legs, the caps should have as short lead length as possible to the chips, it makes them more effective
I'll be starting another dac thread soon:eyebrows:
Quote:
Originally Posted by leo
Hi Leo
Thanks for your reply
I meant the left channel is working, not right. I intend to cut the legs much shorter when this bloody thing works! ;)
I have put a meter between pin 1 of opamp and L-OUT and its fine. But I don't get a reading between pin 7 on the opamp and R-OUT. If I turn up the volume on the amp and turn the balance control right around I can hear I faint sound (Probably cross-talk)
Completely stumped
Is it definitely pads 3+4 to short for the chip on the base of the board?
Hi to all
This is my first post on this forum.
A brief intro first. My name is Rob, and while I don't really know a great deal about electronics, I do enjoy building DIY audio gear.
I'm posting here as it seems to be the most active site for mods to this neat little DAC.
I've had mine for a few weeks now, and have done a bit of tinkering. Now that I have a configuration that I think sounds pretty good, I thought I'd post it.
Here is my current configuration:
R2 - 3K (SMD)
C3 - 330uF 6.3V os-con
C8 - .22uf MKT EPCOS
C9 - .1uF MKP416 BC Components
C10 - .22uf MKT EPCOS
C11 - .22uf MKT EPCOS
C12 - .22uf MKT EPCOS
C13 - .22uf MKT EPCOS
C16 - 10uF 16V Tantalum
C17 - 330uF 6.3V os-con
C18 - 10uF 16V Tantalum
C19 - Rubycon MBZ 1500uF
C20 - 330uF 6.3V os-con
C21 - 470uF Panasonic FM
C22 - 22nF (SMD)
C23 - 1nF (SMD)
C25 - 10uF 16V Tantalum
Opamp - opa2107
Leo's bypass mod
C27,C28,C30,C31,C6,C54 - Bypassed
L & R out C - 2uF Obbligato PIO
L & R out R - 51 Ohm Kiwame
I am running this from my PC via a HAGUSB USB->S/PDIF convertor, which sound stacks better than the S/PDIF straight from my motherboard, into my DIY AMB labs M³ amp and finally out to my AKG K701 headphones.
This little DAC sounds better inplace of either of my CD players, a NAD 5320 and a Rotel RCD-855.
Thanks to all here (and other sites) for the ongoing tinkering and information - particularly Leo.
Cheers
Rob
Sorry to be post-whore on my first day.
I just wanted to relay one of my experiences with this DAC.
One of the first mods I made was to replace C19 & C21 with a Rubycon MBZ 1500uF and an os-con 330uF respectively. I found that the bass rolled off dramatically.
Noting that Leo mentions in one of his posts that the os-cons can kill the bass, and that he used 10uF tantalums in these positions, I swapped the caps for the tants but found that the DAC sounded rather dull and un-dynamic (sorry Leo). I then swapped the tants for the Rubycon MBZ 1500uF at C19 & this time a Panasonc 470uF FM, rather than the os-con, at C21. The dynamics returned, as did the bass.:)
Cheers
Rob
Reason I use a tant for C19/21 is because I use a far superior external psu , these two caps are for the input and output of the 3.3v regulator coming straight from the main 5v, if the main 5v isn't up to scratch you need to add some good low esr there, with my supply large values destroy this fairly neutral sound I currently have
C25 is the only place I'd recommend a 10uf tant as that cap is quite critical, it needs to be low leakage, of course some electrolytics may be better but tend to be more leaky , its something you just have to experiment with
I tend not to post fit this type of cap here and this type there mainly because my external regulated psu is nothing like the supplied unit so results would vary, what sounds good with mine may be crap with the standard one
Quote:
Originally Posted by Tripmaster
Don't get too excited but I may have spotted the problem (unless its the pic you posted playing tricks on my eyes)
Look at the two pads next to that chip which we short out for the right channel, look closely, is the metal pad missing on both?
The third chip pin on the left must have continuity to the top pad to be shorted out and go to the tiny VIA on the left, if you can post a larger pic I can edit I'll try to explain what I mean and what needs measuring
Yes, i think it's very much a case of suck it and see, with this dac.
I posted details of mine because it works nicely and doesn't have any obvious weakness. A good starting point.
There are of course an unlimited number of ways that this can be achieved.
Another thing that i think is worth trying.
Remove the crappy pcb mounted phono socket and fit a BNC socket to the dac case and source. Connect with some proper 75 ohm cable and you should notice an improvement.
One advantage of doing this early on, is that it creates more space on the pcb, and makes life easier, especially when experimenting with input caps.
Good point Al, those supplied sockets are really quite poor anyway, I had some problems with mine , intermittent SPDIF lock caused clicking/ticking noises
Thanks LeoQuote:
Originally Posted by leo
I have revealed the copper track and if I put a meter between here and pin 7 on the opamp I get a connection. I didnt get a connection between the blob and the copper. I desoldered the blob and tried to solder a link between the copper and the blob but I ended up removing the solder pad ARGHHHH!!!
I also pulled away the pad from the C19 negitive side, double ARGHHHH!!!
This is one project thats definatly not gone to plan :(
Can you recommend any other hidden tracks?
http://i374.photobucket.com/albums/o...oto/lifted.jpg
http://i374.photobucket.com/albums/o...padremoved.jpg
I have sorted C19. I scraped away some of the screen I now have a good connection to the cap
I think (going from memory, will have to check to be sure) you can wire from that solder blob (next to the R) to the first VIA (hole) between the chip pad on the left in that pic, it will need some scraping to expose the copper
Stick your meter on that first hole (inside that white rectangle between pin3 and 4) to see if it measures continuity to the Rout socket pin
Hold on, let me edit the pic
Yippee! STEREO
http://i374.photobucket.com/albums/o...moveScreen.jpg
I decided to scrape off the screen around the pins and it became obvious where everything should go.
Leo you are a life saver! :)
Well done!
You just have to tune it up to your taste now;)
I love a happy ending:).
Which PSU are you using, if you don't mind me asking?Quote:
Originally Posted by leo
Quote:
Originally Posted by alb
Me too!
I haven't finished soldering yet ;)
I too had problems with lifting tracks. Ended up with a piece of wire from input cap to chip pin.
It's the first time i've had to work with surface mounts, so i'm not exactly an expert.
All good fun though.
Schotty bridge, C-R-C + Cap multiplier feeding a shunt to lower the impedance, its knocked up on veroQuote:
Originally Posted by fordgtlover