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Post by bpgoa on Jan 10, 2010 23:51:32 GMT
Adrian Replacing the 2n2 caps with 2.2pf caps will do almost nothing.You can get that much capacitance from stray capacitance, or the internal capacitance of the actual RCA output socket ! You can try leaving them out, which may make the unit quite sensitive to the type and length of output lead, or you could try fitting 47pf or preferably 100 pf at that location. Alex P.S. I took the liberty of editing your previous post for clarity reasons. alex, no worries... feel free..... what magic answer did you have for these? 2 x 27nf MKT Metalized Polyester 4 x 8.2nf MKT Metalized Polyester 4 x 2.7nf MKT Metalized Polyester they are not on the farnell site? also... have you read the December issue of Silicon Chip? the article on setting this up for balanced outputs was supposed to be in there. Adrian |
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Post by Deleted on Jan 11, 2010 0:16:25 GMT
Adrian
I do not have a magic answer for the other capacitors at this time.
Many of mine came from Rockby surplus clearances.
The article was in the January 2010 issue.
Alex
P.S.
At the moment I am a little preoccupied with trying to make and fit a simple outboard oscillator module. Unfortunately, I do not recommend this addition for anybody who hasn't had a fair amount of experience in this area, due to fine tracks and the risk of damage.
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Post by Deleted on Jan 11, 2010 10:55:58 GMT
IMPROVED XTAL OSCILLATOR FOR S.C. DAC. O.K. It's likely not as good as a PFM Flea, but it costs a fraction of the price and can be even built on veroboard or perfboard. Besides, PFM Fleas are not currently available (not even the PCB) and require 18V supply rails. The Xtal Oscillator module used MUST be designed for 3.3V working. The small DIL version Oscillator module that I used came from HyQ in Melbourne,(QXO-8BCA -24M576) although numerous other suppliers sell equivalent modules at very good prices. Most importantly, it did improve dynamics and overall SQ in comparison with the original simple Xtal design. However, I would not recommend that this be used unless you are fairly experienced, as PCB damage could result. Alex P.S. FB1 and FB2 are ferrite beads slipped over a piece of copper wire. e.g. cut off resistor lead etc. The 100nF capacitors used were 0.1uF 50V Blue Chip Monolithic Capacitor
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Will
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Post by Will on Jan 11, 2010 20:42:36 GMT
I cannot find any 2.7nf, 8.2nf or 27nf polyprop, 5mm pitch caps in the UK stores. 10mm pitch y or x class, yes, but we get into funky mountings then, and as we have yet to see the pcb over here, I don't know how they could mounted.
That oscillator is nice, Alex, especially as it's doable on a stripboard. Needs a name, though.
AK Cricket?
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Post by Deleted on Jan 12, 2010 2:07:15 GMT
Will A photo of the actual oscillator module installation. It was a quick and dirty PCB using a Dalo pen this time.On the Input PCB, I removed the existing Xtal and 33pf capacitors, as well as putting a link in place of the 100 ohm resistor. I then fitted a couple of PCB pins. It uses the +5V supply from the PSU PCB. The Xtal Oscillator module used was from HyQ in Melbourne (QXO-8BCA -24M576) Alex  |
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Post by bpgoa on Jan 12, 2010 17:01:52 GMT
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Post by Deleted on Jan 12, 2010 17:24:09 GMT
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Post by bpgoa on Jan 12, 2010 17:36:19 GMT
you bad man  They are polyester. |
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Post by Deleted on Jan 12, 2010 18:28:22 GMT
you bad man They are polyester. I'm certainly no fountain of knowledge on these matters BUT as I understand it... If I'm wrong please explain  |
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Will
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Post by Will on Jan 12, 2010 19:30:10 GMT
I think the confusion is that Adrian (and me!) wants to replace the:
27nf MKT Metalized Polyester
8.2nf MKT Metalized Polyester
2.7nf MKT Metalized Polyester
in the SC Dac with polyprop versions, MKP.
I'm looking for 27nF polyprop as well, so if anyone does know a source...
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Post by Deleted on Jan 12, 2010 20:50:31 GMT
There is a source for all 3, as well as the 4n7 for the DIR9001.
In the next day or 2 , I will post sufficient of each to Will, for him to pass on to Chris and Adrian. You will still need to source the 68nF polyropylene caps.
Alex
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Post by Will on Jan 12, 2010 21:13:58 GMT
Alex, thanks mate, you're a top man  And the osc board looks good, nice and straight forward. Do you have any next steps planned? I'm thinking supplies to the dac myself. Anybody else out there been playing around with this dac? We can't be letting these Aussies doing all the running now, can we  |
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Will
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Post by Will on Jan 12, 2010 21:17:05 GMT
Nice list of shops there, Adrian, I hadn't heard of half of them! |
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Post by Deleted on Jan 12, 2010 22:26:50 GMT
Will JeffC (another Aussie!) also has one up and running, but work precludes further playing for a little while yet. I was thinking of having a look at a couple of the "Ultra mini" Experimenter's boards from Jaycar. cat.HP9556 www.jaycar.com.au/productView.asp?ID=HP9556&keywords=hp9556&form=KEYWORDIt should be easy to fit a DIP8 opamp and a few other components on them,. with the possibility of giving as simple reference supply to areas like the 5V DAC supply. See fig.4 of the attached, but imagine the reference supply coming from the main opamp supply rail via a 2K2 resistor to a 3.3V or 5.1V 400mV Zener , then via the existing R and C to the opamp input. Apparently Alfred has now tried that suggestion with good results for the 5V DAC supply. Alex www.esstech.com/PDF/Application_Note_Component_Selection_and_PCB_Layout.pdf |
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Post by alchemy on Jan 12, 2010 22:54:06 GMT
Allan They don't appear to be using SMD devices,but we will need to see the layout and other photos next month.. Farnell has the DIR9001 and DSD1796,as well as the DIL OPA134, but the others are both SM .Farnell also has the xtal for under $2. A SPDIF Input transformer would be easily retrofitted. You are a digital "snob" !  There is very little available software available at higher than 24/96, except for a couple of DVD-As which can be ripped. SACD can not be ripped to .wav files AFAIK. This makes the DIR9001 a valid choice. I believe this project should be capable of coming close in performance to my X-DAC V3. I would use the existing analogue board , but reduce the voltage to +-12V, and everything fed via a dual JLH. This would permit the use still of the OPA134, but allow the use of SM AD8065 on adaptor PCBs. I would remove the added filter stage,and use the much simplified circuitry of the X-DAC V3 with it's much gentler filtering. Many resistors would simply be replaced by links. Alex  Just a quick note to say that the filter diagram used above adds a lot more to the SQ, and the little buffer/regulators Alex posted above are little miracle workers, I have made 4 of them three x 3.3 v and one x 5.0v, one 5.0v for the DAC one 3.3V for the DAC and two 3.3v for the DIR9001, one for the Anlogue pin 25 and one for the Digital pin 6, these have increased detail, separation, brilliant image and tightened up the base like you wouldn't believe. I am sorry you guys in UK are having problems with the supplies of pp caps in the antipodes, have you tried a stock transfer with RS for the caps we have in Aust., Farnell did a stock transfer from Newark for me, no extra charge. Alfred |
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Post by Deleted on Jan 12, 2010 23:02:10 GMT
Alfred Great to see you joining in. Will, Chris, Adrian and others, if you really want to get adventurous with this DAC, then Alfred is the guy to ask. While I am just thinking about it (old age ! ) , Alfred is doing it. Alex P.S. Alfred, are you using the existing 3.3V or 5V as a reference, or adding a zener diode to obtain the reference ? |
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Post by alchemy on Jan 12, 2010 23:29:57 GMT
Hello to the Poms
I have just spoken to technical services Aust RS Components, they are unsure of where these Panasonic components come from, they suggest Singapore, they also suggest to contact Product Management at RS UK and ask for the Part Nos and it should only take a few days for delivery. I am not sure if you must be in the privaledged position of an account holder or you can be a retail cust., I know if you don't have an account you must pay up front with a crdit card to secure a backorder.
The good news is that you need less components if you follow Alex's XDAC dwg for the SC DAC as I can vouch for and you only need the following,
401-4722 2.7nf DAC filter
401-4766 4.7nf Dir filter
401-4918 68nf Dir filter
401-4716 2.2nf DAC filter
lots of luck
Alfred
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Post by alchemy on Jan 12, 2010 23:37:44 GMT
Alfred Great to see you joining in. Will, Chris, Adrian and others, if you really want to get adventurous with this DAC, then Alfred is the guy to ask. While I am just thinking about it (old age ! ) , Alfred is doing it. Alex P.S. Alfred, are you using the existing 3.3V or 5V as a reference, or adding a zener diode to obtain the reference ? Hello Alex I am using the referance voltage from the chip I deduced that a zener "may" be too noisy, the 5v one come from the ripple eater with a LM317 set to 5v and the 3.3 is the LM3940T 3.3, I used 10uf tants for the filtering, referance and the output, plus a .1 across each chip Alfred |
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Post by bpgoa on Jan 12, 2010 23:42:11 GMT
Alex, thanks mate, you're a top man And the osc board looks good, nice and straight forward. i'll second that... and if there's anything i can send from Blighty... just let me know. Adrian |
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Post by bpgoa on Jan 12, 2010 23:47:39 GMT
you bad man They are polyester. I'm certainly no fountain of knowledge on these matters BUT as I understand it... If I'm wrong please explain oops ... sorry... ;D Will was correct in his post... they were the capacitors we are trying to replace with polypropylene... |
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Post by bpgoa on Jan 12, 2010 23:50:58 GMT
Nice list of shops there, Adrian, I hadn't heard of half of them! lol... neither had I... i got on a mission to find those capacitors... and failed (5hrs searching using google) p.s. one of those sites has a fantastic transformer range,,, |
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Post by Deleted on Jan 13, 2010 0:24:38 GMT
Alfred Great to see you joining in. Will, Chris, Adrian and others, if you really want to get adventurous with this DAC, then Alfred is the guy to ask. While I am just thinking about it (old age ! ) , Alfred is doing it. Alex P.S. Alfred, are you using the existing 3.3V or 5V as a reference, or adding a zener diode to obtain the reference ? Hello Alex I am using the referance voltage from the chip I deduced that a zener "may" be too noisy, the 5v one come from the ripple eater with a LM317 set to 5v and the 3.3 is the LM3940T 3.3, I used 10uf tants for the filtering, referance and the output, plus a .1 across each chip Alfred Hi Alfred What I had in mind is an altered version of the original from the attachment. A 3.3V Zener is actually slightly less noisy than a blue or green LED of that voltage. The parallel 1uF should get rid of the majority of HF Zener noise, and the CR network after it will further clean up what's left. To put this issue further into context, the PFM Flea uses a Green LED ,then filters it it with a single 10K 3.3uF network. The PFM Flea then amplifies this typical 1.95V reference voltage reference by almost 2 times. It would be interesting to compare versions. Alex P.S. The original came from www.esstech.com/PDF/Application_Note_Component_Selection_and_PCB_Layout.pdf |
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Post by alchemy on Jan 13, 2010 2:02:24 GMT
Hello again from the antipodes I forgot to mention if you are looking for clock modules, try this man he is an gingerbeer at Philips and got a business that helps the DIYs www.tentlabs.com/This is escpecially interesting www.tentlabs.com/InfoSupport/page35/files/Supply_decoupling.pdfAlex, I have run out of beads and my daughters don't work, I have left the 0.1uf bypass on the board, there seems to be plenty to go around this construction, RS confirmed that 0.1uf pp caps are no longer available from UK, I am highly suspicious they were never available from UK and some Asian purchase in lieu of UK supplier with area restrictions, and supplied via Singapore to us lucky Aussies who are suffering the heat whilst you guys are suffering the snow, if we suffer any longer we will all go to heaven! Alfred |
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Post by Deleted on Jan 13, 2010 2:34:11 GMT
Alfred
Do we really need the 100nF polyprop capacitors anyway ? Typical SPDIF input capacitor values range from 10nF to 100nF. The 68nF capacitors are already fairly big as can be seen in my photo, and the 5mm lead spacing is a joke. It is what they shaped the leads to in the factory. Jaycar sells packs of 6 ferrite beads for $2.95
Alex
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Post by bpgoa on Jan 13, 2010 15:08:38 GMT
Alfred Do we really need the 100nF polyprop capacitors anyway ? Typical SPDIF input capacitor values range from 10nF to 100nF. The 68nF capacitors are already fairly big as can be seen in my photo, and the 5mm lead spacing is a joke. It is what they shaped the leads to in the factory. Jaycar sells packs of 6 ferrite beads for $2.95 Alex ferrite beads in the uk.. here... www.modecomponents.co.uk/ |
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They are polyester.
