Any chance of a diagram Leo.
just in case i get bored one evening.
Printable View
Any chance of a diagram Leo.
just in case i get bored one evening.
http://i374.photobucket.com/albums/o.../WithTants.jpg
Hi,
Legs a little shorter.
Considering the components have had very little burn-in time its sounding rather good. Its a little bit bright at the moment but I guess this will settle down with time. Bass is still a little shy.
Richard
Richard.
The surface mounts are the bypass caps, in most cases anyway.
Most of the electrolytics are already bypassed with an adjacent surface mount cap. Its these we are trying to improve, on as much as anything.
http://www.lampizator.eu/LAMPIZATOR/...RA/schemat.jpg
I 've bypassed the surface mounts with a variety of 0.1uf poly caps which are hopefully better quality. This now means the lytics have bypass caps of 0.22. I could have added some 0.01uf as well, but space is tight.
I can't remember much about the burn in except that it didn't seem to change much after a few hours constant use. It's quite some time since i first fired it up.
I have a few questions…
I intend to house the DAC pcb and transformer/power supply in separate aluminium enclosures. I have some 4 pole Speakon connectors and five core mains cable for the umbilical. Can I combine the analogue and digital grounds together?
http://i374.photobucket.com/albums/o...nconnector.jpg
http://i374.photobucket.com/albums/o...connector2.jpg
http://i374.photobucket.com/albums/o...owersupply.jpg
I also have some light weight coax for connecting a coax socket to the pcb. Will this be ok?
http://i374.photobucket.com/albums/o...photo/coax.jpg
Leo said the LM4562 needs a lot of tweaking for it to sound half decent. Will it sound better than the stock opamp without tweaks?
Thanks
Richard
p.s I am available for hand modelling if anyone is interested ;)
It was cobbled together from various circuits so I'll have to try and draw it outQuote:
Originally Posted by alb
Basically a centre tapped transformer, centre tap as ground, both the secondaries go to a MBR20200 double schottky, 2200uf- 1R resistor - 2200uf- cap multiplier-shunt
Cap multiplier is based on this http://www.pinkfishmedia.net/forum/s...ad.php?t=39990
Shunt uses a transistor as a current source
I might seperate the 3.3v supply on the dac board and feed it its own shunt, I don't like the layout of this dac, also the fact that the main 5v is too far away from the circuit
The LM4562 is a double edged sword, it offers good performance but only when used with care, its also crap at driving capactive loads, it needs a really good clean low impedance supply to work its best , ideally regulation needs to be close not run from lengths of cable which will likely result in a thin sterile sound.Quote:
Originally Posted by Tripmaster
Basically a slower lower spec op-amp may be better and easier to use
The dacs analogue and digital grounds are all on the same ground plane on the dacs pcb, normally best to keep the ground impedance as low as possisble , I'd personally run them all separate from the regulated PSU to the dac board, you can try running all together but it may sound worse
I don't have one of those supplies, do the ground wires from that supply have separate grounds or are they just fed from a ground plane same way as the dac board? if the regulated psu has a single ground plane for both supplies multiple/separate ground wires to the dac probably won't make any difference, if that makes sense:)
Nice pics BTW, pin sharp on my monitor!
Hi LeoQuote:
Originally Posted by leo
Thanks for your reply.
Here is a picture of the rough layout I am proposing. Please ignore the cables in the picture.
http://i374.photobucket.com/albums/o.../DACLayout.jpg
I plan to run all signal cables along the top and power along the bottom of the picture. In your previous reply you suggested keeping the power supply close to the DAC pcb. Am I going to suffer any RFI with this configuration? If this is OK I intend to mount the transformer in a separate enclosure with mains umbilical between the two.
Which opamp do you think works best for this project?
Picture not so good this time ;(
Thanks
Richard
It should be ok, try not to have the lead from the transformer too long either if possible, its normally a transformer when run too close to signal that causes noise pick up, toroidals radiate more crap
What I'd do if possible is before drilling holes etc in the case try to run it as you intend to lay it out first, obviously you have to be careful not to short anything etc, if it sounds ok then you can then start bolting things together.
Using shielded cables for the signals should also help prevent unwanted noise pick up, having unshielded signal cable running close to supply cable as you know can give hum
Regarding the best op-amp, I've honestly no idea, they tend to be a personal taste thing, I mainly use AD826 because of its good output drive, its also much harder to implement than the LM4562 though
OPA2111 sounds ok and usually behaves, some people like OPA2107, opa2132 AD8066 and AD8620, the last two are smd so need to be fitted on brown adaptors, they also have a max voltage of +/-12v
The fet input based ones sound smoother if thats what you want
I have now added leads to allow using optional valve output stage, something I'm still messing about with:)
Hi Tripmaster, just wondering what are those 2 black caps for? Could you explain your setup basically? I have done similar job, but still waiting to get Vishay for c9 . My board's analog part is intact, all I will be doing is remove those e-lytes after digital and steal signal for my lampizator tube stage.Quote:
Originally Posted by Tripmaster
Just interested in your approach...and those 2 black caps :)
Hi!
I just want to thank for all the great help I found here.
Just for fun I did a measurement of my Lawrence DAC before I started modding.
This is the frequency measurement before doing anything.
http://img.skitch.com/20080924-pp4n2...nsg4npqr64.jpg
As you can see, the -3db point is at 13.000hz!
After changing out the resistors to the same value and then changing C32, C33, C34, C35 to 150pF it now looked like this!
http://img.skitch.com/20080924-kjb48...ftc4srp1et.jpg
And it sound great! My wife said that it sounded better than my extensivly modified Zero DAC. And I have to agree. Next step, better opamp and modify the power supply.
Thanks guys for the help!
A good result then.
You are fortunate to have a wife who has sufficient interest, to be able to hear differences.
My wife seldom comments on anything, unless i emerge from the garage with some ridiculously large home made speakers.:)
Im back!
Here are a few more photos of my project.
http://i374.photobucket.com/albums/o...hoto/rear1.jpg
http://i374.photobucket.com/albums/o...hoto/rear2.jpg
http://i374.photobucket.com/albums/o...hoto/rear3.jpg
http://i374.photobucket.com/albums/o...to/inside1.jpg
http://i374.photobucket.com/albums/o...to/inside2.jpg
http://i374.photobucket.com/albums/o...to/inside3.jpg
http://i374.photobucket.com/albums/o..._photo/psu.jpg
Here is a list of the components changed so far...
C3 Jamicon 220uf
C18 Jamicon 220uf
C11 3.3uf Tant
C10 Vishay 0.1uf ERO 1837
C7 Vishay 0.1uf ERO 1837
C9 Vishay 0.1uf ERO 1837
C16 Oscon 150uf
C8 3.3uf Tant
C12 3.3uf Tant
C25 Oscon 150uf
C26 Oscon 150uf
C13 3.3uf Tant
C41 Wima 0.1uf
C19 Panasonic FC 2200uf
C21 Panasonic FC 470uf
C17 Oscon 150uf
Bypass caps are SCR 8uf with R68 resistors
Using standard JRC opamp and have also tried LM4562
The output sounds a little bit veiled and lacking sparkle. The internal coax is a 50ohm cable from Maplin. I was after 75ohm to match the 75ohm socket but the chap at Maplins said it would not make any difference because the cable length was so short.
Leo recommended keeping the transformer close to the DAC. Do you think I have mine too far?
Can you recommend changing any of the parts to help improve the sound?
Thanks
Richard
Hi StifaQuote:
Originally Posted by STIFA
Sorry for taking so long to respond I have been up to my neck in solder!
The two black caps are SCR 8uf coupling caps for the output. These were pinched from a pair of speaker cross-overs.
How are you getting on with yours?
Richard
There is my project.
DAC is built in to the Cambridge Audio D500SE. Original output stage is unusable for me, so I decided to build tube stage. It's SRPP using E88CC. Sounds very good, far better than original opamp based circuit.
Photos and comments:
-purple frame original trafo moved to make room for additional trafo (for tubes)
-green frame additional trafo for tubes
-yellow frame filament supply
-red frame anode supply
-turquoise-coloured frame DAC board
-pink frame tube output stage
http://www.audiostereo.pl/zalaczniki/1167490_1.jpg
http://www.audiostereo.pl/zalaczniki/1167490_2.jpg
http://www.audiostereo.pl/zalaczniki/1167490_3.jpg
What are those great little tube PCBs and where can I get some. Nice job BTW.Quote:
Originally Posted by Makgajwer
Cheers
Rob
Thanks for the heads up on the FR. Did you change the resisters as discussed by Leo in this post?Quote:
Originally Posted by jackenhack
Where he suggests R8,R9,R14,R17 to 30k and C32,C33,C34,C35 to 150pf.
Has anyone tried to connect a clock to this board?
What are those great little tube PCBs and where can I get some. Nice job BTW.
Cheers
Rob
Thanks.
"Those great little tube PCBs" are custom made in Poland.
Do you sell them?Quote:
Originally Posted by Makgajwer
I don't sell them. I buy them ;-)
Yes, changed to 30k.Quote:
Originally Posted by fordgtlover
Jacken
Hi everyone ! Thank you for all the good infos provided here ! I've been reading about your mods with interest ! I'm not expert when it comes to electronics...I'm trying to get good results from this pretty dac too. Do you need to change the caps WITH the resistors, or can just the resistors be changed to 30k to get that amazing response curve jackenhack showed ? Thanks...Quote:
Originally Posted by jackenhack
I thought I might try the output stage that Leo previously posted here. So, I thought I would put my newly developed Eagle skills to work, and try a PCB layout.
I have recreated the schematic here:
http://img291.imageshack.us/img291/5071/os13schub6.jpg
And, here is my PCB layout:
http://img508.imageshack.us/img508/182/os13un3.jpg
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 1800R inductors, but I might swap them for the small Murata 2200R from Farnell.
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
I would go for both changes, but to alter the filter, change the caps. Here's a comparison with both res and cap change (MOD5) and just the resistors.Quote:
Originally Posted by madigwann
http://img.skitch.com/20081006-1y41x...af.preview.jpg
Click for full size - Uploaded with plasq's Skitch
Very nice longtailed pair cct. No feedback in the O/P stage:scratch:?
This circuits proven to work well with the CS4397 Stan which is already high enough output, its also dead simple and cheap.
Its just a differential input to line out using a simple emitter follower.
Normally the emitter follower is a Darlington
I wasn't very happy with the middle part of my board layout so I've redone it, I've also changed the indiuctor to the smaller version.
Any comments before I go ahead and get a couple of test boards made?
http://img80.imageshack.us/img80/81/os151xh5.jpg
Hello ! Thank you very much ! I'll make both changes as I like to see that white curve so much ! How good was the sound after you did that change (MOD5) ?Quote:
Originally Posted by jackenhack
Just noticed , Q1 emitter should go to R3
You can alter the gain by adjusting the emitter resistors on the differential pair
This circuit is based on this http://home.quicknet.nl/qn/prive/ra....ancer_evo3.pdf
Another version here including pdf with layout http://home.quicknet.nl/qn/prive/ra..../index_en.html
Hello !
That's what I 've done :
http://img206.imageshack.us/img206/3...cfecc86rt8.png
I redrawn an original schematic published by JR Broskie in Tubecad.com
This is a buffer with no gain, and filtered input, with low voltage tube ECC86/6GM8
The B+ is 24v, simple LM317, with a slow turn-on , about 30s
The heater,6.3v, 600mA, is also a simple lm317, with a slow turn-on , about 10s
Works perfectly for a symetrical voltage DAC...
R.C.
Your link not works
Hello !
Works better now!
Sorry
Hello againQuote:
Originally Posted by Tripmaster
I have been running this for a while and the bass is still poor. I don't like a really pronounced bass but after listening to a variety of music it is obviously lacking.
Can anyone provide a suggestion?
Thanks
Richard
Hi Richard,
I still think the bass issue maybe the choice of caps fitted, ideally you need to look at the datasheet for the dac etc to see what each of the pins are for.
The cap on the dacs CMOUT has an influence, a tant will be different to say an Oscon.
I currently use a 5mm spaced 10uf MKT cap there, I wouldn't fit much higher than 10-22uf there
Seriously though I'd remove most of those tants,Oscons and FC's and fit some cheap normal ESR types to start with, see how it sounds and then do changes to lower ESR parts in stages
Also it seems you still use the original values for the differential output stage, changing the values to whats posted earlier does improve the sound , it also measures much flatter on the output
THE CS4397 bass is reported to be light , mine sounds pretty deep and tight
So....without any warning my DAC started buzzing a whole ton through the outputs...the little crappy transformer that came with the DAC got VERY hot and started to melt my case.
Any idea what could have caused this? it was working fine for over a month. Just a cheapo transformer? What kind would you recommend for a cheapish but good replacement?
Also this morning I desoldered some bits from the PSU board to check out the components and see if I wanted to replace anything. The little green caps look very cheap and I don't know what sort of brand they are. According to the writing on the front I assume they are rated at 100V and .0035uF?
What caps would be good replacements for these? I was looking at Wima MKP10 .022 or .033uF? Anything cheaper?
And the big electrolytic caps are Rubycon YK for the 4700uF, and Elna RJB for the 1000uF.
Would I benefit in changing these to something else? What would you recommend?
http://img371.imageshack.us/img371/7447/img3663ys2.jpg
http://img49.imageshack.us/img49/9602/img3664mu3.jpg
Hi LeoQuote:
Originally Posted by leo
What would you recommend I remove/replace to start with?
Do you have a list of the components/brands you have used on your board and their location?
I really appreciate your time
Richard
I'm not using that standard regulated psu (I just brought the dac module only) so the caps I use may not work so well with that supply you use, problem is your using a lot of low ESR caps like Oscon and Panny FC/FM which are good caps but can cause stability problems if a standard reg like LM317/337 is used, the output pin on those regs can ring with too low ESR.
Apart from measuring worse ringing can make the sound bad too
I mainly started the thread as it was a fun and a cheap project, the dac as standard has obvious flaws like having all its 5v and 3.3v supplies shared from a single source, the PLL filter values are wrong and so is the Differential output filter, most things can be improved though and most is covered in the thread.
TBH I'd have changed each cap in stages and evaluated the differences, its easy to go changing a lot of parts at once but this can make things hard trying to isolate which parts are ruinning the sound
Only thing I can recommend is taking out the Oscons,tants and replace with a decent quality general purpose type, give it a few days to run in and see how it sounds. I'd then try changing the caps in stages, this also ensures you don't go too far in the wrong direction.
Modding this stuff to your own personal preference can be tedious but with a bit of patience usually pays off
BTW don't always trust what you read regarding low ESR caps, their not always better in every application;)
Hi, I am planning to get this DAC and mod it according to the lampucera website AND the mods Leo showed. Will this have any conflicts?
Thank you
Quote:
Originally Posted by leo
I was foolish to change so many components at once. Having read the http://www.lampizator.eu/ website and and also heard a friends modded DAC I decided to go for it!
I normally like to take things slowly and evaluate each change. I have recently built Peter Daniels Shigaclone transport with great results and wish I had taken the same approach with this project.
http://i374.photobucket.com/albums/o...Use1edit-1.jpg
Should I stick with 150uf for the Oscon replacements and 220uf for the C3 and C18? And what about the tants, should I choose a larger value than 3.3uf?
Thanks Leo
Richard
Do you guys think i should ignore the Lampucera site mods and do these ones instead? How about bypassing the opamp? Is that better or should i keep the opamp? I plan to replace the opamp to the HDAM sun ones from here http://www.audio-gd.com/enweb/pro/diy/OPA.htm
Not foolish, just a little too eager;)Quote:
Originally Posted by Tripmaster
The original values for most of the decoupling caps was 100uf, the value isn't really critical so anything around 100-220uf should be ok
BTW, first easy thing to try is swapping C25 to a 10uf or 22uf cap, it looks like you have a big Oscon there, 150uf is too big for the CMOUT pin in my opinion, thats for the dacs internal bias
If that don't help much try changing just the other oscons and tants to general purpose 100-220uf, its worth leaving those two panasonic FM/FC caps until last and see what its like without the oscons and tants, we need to find a point where you start to hear improvements and then work from there
Very nice job on the Shigaclone :smoking:
No, the caps don't seem as critical if using a valve output stage, one lot of caps may sound awful when the op-amp is used but tends to be far less awful when using the valvesQuote:
Originally Posted by JDMz
Also with the Lampizator circuit your only using half of the differential outputs of the dac so don't take full advantage of the noise cancelling that this type of chip has
Only mod I'd consider on the Lampizator site is the valve output stage, the use of lots of oscons as shown on there probably won't mate too well if using the op-amp, the lead length of those caps is way too long IMHO anywayQuote:
Originally Posted by JDMz
The valve stage sounds quite nice in a coloured way, some people will love it, others won't
I find it pleasant with this dac, it also covers a lot of the flaws, the op-amp stage makes things much harder to get to sound right
My advice is try both, see which you prefer:)
I've never tried that discrete HDAM Sun so no idea how it performs
I plan to do your mods, and then get a HDAM opamp which was on the link of my last post. I am kind of new to electronics and need some elaboration on your instructions. What type of resistors are those 30k ones? (like wattage and tolerance) And the 68-75R.
Finally for the 150pf capacitors, would these work? http://cgi.ebay.com/Silver-Mica-Amp-...3A1|240%3A1318
Thank you
The resistors are just phoenix MRS25 metal film 1% which I matched, nothing special, just what I had spare in my parts box, the 150pf caps are just cog ceramic, again its what I had so nothing special.
Mica is usually technically better but also physically larger, theres not a lot of room on this dac pcb, if you think the mica's will fit then they should be ok
The resistors on the output are not critical, they are just to help with op-amps that don't drive capacitive loads very well, 22R to 100R should be fine
Should the input capacitor be a good brand? like Mundorf or something?
What tolerance and wattage were your 30k resistors? Sorry for so many questions.. I am ordering now that's why
It was 1:21am here so I'd gone to bed just after my last post:)
Any resistors I used was MRS25 0.6w 1% tol metal films, use the smallest you can find if it makes fitting easier, wattage is not really an issue here, obviously you don't need anything large over 1w, if the ones you buy come in packs I'd try matching them in pairs with your meter
SPDIF input cap is .1uf (100nf) Vishay MKP1837
My dac does not use output coupling caps, since doing the output stage mod in the differential (30k +150pf) output DC offset is near 0v
I'd only advise using no caps on the output if your pre-amp or amp has input caps just as a precaution
If your going to use output caps use any decent quality film type, I'm not sure what particular brand to recommend, everybody seems to have their own preferences for those
How do you go about sizing output caps?