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Post by Deleted on Feb 12, 2008 0:13:25 GMT
Rick Nobody is disagreeing with you. Leo is just tring to encourage a few members to try something simple that works O.K. , then after they have become more confident, try ideas like yours to further improve it. You have to crawl before you can walk ! The more experienced members would opt for a more upmarket DAC kit. BTW, for somebody who thinks they won't be around much longer (?) you sure are coming up with some pretty good info and suggestions ! SandyK
Alex .
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rickcr42
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Post by rickcr42 on Feb 12, 2008 1:21:57 GMT
not trying to argue bro just offer lucid counter to "same old" and maybe aim some of the more adventurous into a new/old direction and sometimes my strong opinions come off as if no one elses count which is not my intent. i'm just a stubborn old prick is what Anyway,this is an interesting tidbit on the internal antialiasing filter and maybe part of why the chip really doesn't sound too shabby................................................if you isolate the shit out of it and feed it properly that is www.stereophile.com/hirezplayers/474/index1.html
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Post by Deleted on Feb 12, 2008 1:39:57 GMT
And I'm not ? ;D
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Post by PinkFloyd on Feb 12, 2008 3:38:54 GMT
You've mentioned Rizzla's I now want a fag I'm back on the old liquorice papers You ok for Golden Virginia? I think I mentioned a good source but, if not, PM me.
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Post by PinkFloyd on Feb 12, 2008 3:51:33 GMT
sometimes my strong opinions come off as if no one elses count which is not my intent. Not at all Rick, those of us who think we know you are well aware you mean the best. I know of nobody else who has given so much to the audio "community" as you have.... you are numero uno, and a true gent as far as I'm concerned and will always remain so...... Mikesterooni
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rickcr42
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Post by rickcr42 on Feb 12, 2008 22:26:11 GMT
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XTRProf
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Pssst ! Got any spare capacitors ?
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Post by XTRProf on Feb 13, 2008 7:40:46 GMT
Excellent discussion here. Hope apprentice can decipher some pointers here to store in the limited AT computer above torso.
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leo
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Post by leo on Feb 13, 2008 9:09:45 GMT
Your really tempting me towards the output traffo's Rick, they are bloody expensive though for the El cheapo First thing I'm going to do is the 75R BNC and input traffo, may have one input as cheapo standard and the the other modified BNC/pulse traffo. Then will have a play with the PLL filter BTW this is being fed by the 5v modded super reg ain't too bad, its got a long way to go before it comes close to my diy AYA dac or PCM1794 dac so will prove fun
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leo
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Post by leo on Feb 13, 2008 9:10:29 GMT
Good links, the shoot out was quite interesting
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jonclancy
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Post by jonclancy on Feb 13, 2008 16:02:14 GMT
Hey, I've got one of those!!! OK Dudes, After a low-current abort, I've got mine up and running properly now. The 12v supples are sorted with a (temporary) Elliott P05 and the +5V is another ALWSR (first time I've fired it up and it's rock solid at 4.97V - that'll do it!!). Currently playing a bit of Dave Gilmore and sounding OK, with no crackles or pops. A burn in will hopefully open it up a bit as it's a little congested at the moment. Overall, cheap and not too bad out of the box AT ALL!! I've got a couple of pix, too, if I can work out how to attach them!! Cheers Jon
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Post by jonclancy on Feb 13, 2008 16:06:54 GMT
OK, here they are: Jon
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rickcr42
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Post by rickcr42 on Feb 14, 2008 3:06:03 GMT
at first glance yes but when you consider everything that goes into creating an active stage to do the same thing AND not have it add noise or degrade the SQ AND and overdesigned power supply for headroom the cost comes at damn near a wash with the difference being there is zero ground isolation with an active device unless it too has a coupling trafos somewhere.. I have been using this method for all things digital for over ten years after reading an article on computer audio SQ before there even WAS such a thing as HQ Computer audio (back when Winamp was uncrippled sharware and yes i actually payed the $10 even though I did not have to ) and the short of it is the computer feed sounded like shit until they hung an audio transformer on the output between It and the SYSTEM which they claimed transformed the entire experience from bearly listenable to not too bad for music so i decided to try it for myself. Well that being before ebay got everyone greedy (and when TV ads still had to spell out a web address for the knuckleheads to find the joint and the days of DOT COMS going for $100 a share even though they operated deep in the red ) so if you knew what you were looking for and knew where to look you could damn near STEAL vintage audio gear that was mostly in basements/attics/garages rusting away instead of on ebay for a kings ransom so finding an old mixer with transformer isolated line inputs was not too hard and for a mere $20-$50 i could get anywhere from six to ten of the fkers so i was making "digital isolation" boxes and handing them out as gifts to freinds that listened to music on the computer. four gold RCA jacks from radio shack,the radio shack aluminum with vented steel cover utility boz,some sheet rubber and sheet cork to line the bottom for trafos vibration damping (sheet cork dirt cheap,sheet rubber from bicycle tire inner tubes ),some "rainbow" wire from rat shack (four colors of wire like a ribbon for intercom use-solid copper in the #24 size 0 and total cost to build not counting my time (1/2 hour or so ) around $15 So anyway,i try it and never looked back but at that time ONLY on the computer line out because while we ALL know the sound card has the most godawful ground and stray RF it never dawned on me at the time that it was ALL digital that need isolating and as a side benefit the natural rolloff of a good audio transformer in the 40kHz range adds a nice -6dB per octave rolloff of the signal (hear that you NOS DAC/no analog output filter 'minimalist" DAC guys ? Built in tweeter protection ) anyway i eventually got around to trying it on the output of my CD player and then my DACs and then my SATV box,DVD player,Cable boxes and EVEN my portable players and EACH benefitted from the addition ! Now i need also say i use very sensitive headphones and very sensitive speakers so ANY noise is audible that would otherwise be masked in another system but even masked it is STILL THERE so while it may not be an major irritant once you remove you may not even notice.......until you remove the trafos and give another listen ! The "NO SHIT !" moment we all live for Limitations/downsides ? the output stage needs to be able to drive the trafos impedance AND the interconnects should be ultra-low capacitance/ultra-low resistance type,should be kept to 1/2 meter in length AND the next stage input impedance NEEDS to be 50K or better,preferably 100K. Can't meet the requirements ? Buffer the bitch and drive the shit out of the cable
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pagan
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Post by pagan on Feb 14, 2008 20:23:33 GMT
rickcr42 And a transformer is sonically perfect? And you can get two that match?
Any suggestions on grounding ideas ie separate digital and analogue grounds to a certain point?
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jonclancy
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Post by jonclancy on Feb 14, 2008 20:42:38 GMT
Hi Guys,
Just a few thoughts here on power supplies. Using ALWSR, one 3.3V directly into the output of that SMD reg, 5V for the other parts and +-15Vfor the discrete output stage (either ALWSR or JLH) could be a good (and cheapish) starter for 10. Aim is to keep the costs below, say, £100 and see how far up the SQ ladder we can get for the dosh.
There are some great suggestions coming from all quarters here - good work!
Jon
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Post by Deleted on Feb 14, 2008 22:06:16 GMT
Jon It should be possible to modify the JLH layout to take a 78/79xxx VREG in place of the current limiter.This could mean even better performance with no extra <300mV drop. I am presently using a +-15V LM317/337 supply directly into a JLH, instead of through it's current limiter, (shorted out the current limiter) in a Silicon Chip based headphone amplifier using an LM4562 instead of the original OPA2134, and 2SC5171/2SA1930 in the output stage. My Sony headphones have never sounded so good from my PC soundcard!! So far, there have been no complaints from the VREGs about that brief current inrush on switch on either. Alex
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jonclancy
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Post by jonclancy on Feb 14, 2008 22:20:10 GMT
Hi Alex,
Great idea!! 300mV might not sound a great deal, but it's as much as I'm feeding into the ALWSR at the moment!! (Possibly a bit less).
I picked up a few parts from Jaycar, but I think I'll need to get a few more in from Farnell over the next week or so. I'll have a look at a BOM after the weekend.
I also like the idea of the JLH being somewhat a soft starter - seems like a great circuit - just need to get one built!!
Cheers
Jon
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rickcr42
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Post by rickcr42 on Feb 16, 2008 4:47:50 GMT
I have yet to hear anything perfect and to be honest not sure if I would know it when I did having nothing else perfect to compare it to but if music is the standard then a good trafos is as good sound wise as it gets assuming you pay attention to proper layout and interconnecting techniquec.If there are errors they are errors of omission (rare) rather than errors of inclusion (common with active circuitry) If you are the type that needs to see a perfect square wave to SEE rather if a thing sounds good rather than LISTEN then no,not even close due to the typical 40khz F3 but then neither is digital being a "sample" of a thing and not the entire thing plus that "sample" torn to shreds then re-constructed in a stair step that needs a damn filter just to make it look like a coisine signal again so we have imperfections all over the place with iour job to minimize the damge to the musical event and NOT to showcase equipment. I can easily live with a natural 30Hz to 15kHz bandwidth rather than one that goes from DC to RF ruler flat but that imprints ALL that goes through it with a sonic signature that says "You may have played the instruments and sang the song bubba but i OWN the sond others will hear" ABSOLUTELY ! One thing about most of the the "iron mongers" is they are very hands on,practical application oriented and down to earth and will not only bend over to make sure you are happy but if you don't see what you need will be MORE than happy to do a custom winding for you Just use proper audio techniques for the analog stages,good RF design for the digital (remember man,at these speeds the fkn thing IS a radio ! ),keep both as far apart as practical then tie the grounds together at a single point which will be RIGHT AT the DAC chip because it will have both analog and digital grounds. I always do my layouts with paper and pencil and do each "block" as if it was a single system (it is ) then look at how i want to inbterconnect the "blocks" until i am happy with what i see at which time I more often than not go right to a vector board construction using adapters for the SMD parts (see Spark fun for the best in prices on the planet ). No three or four or five layer boards,no "optically isolated" grounds,no fancy "tricks" just paying attention and if it doesn't work the vector-board allows some slack for a RE-DO On thing that is REALLY REALLY REALLY important is to not only do proper bypassing/decoupling but isolation as well so the signal does not have an easy path to "talk" back to the other chips on the same power buss (LCR networks) Again if in doubt simplify because then there will be less that can go wrong.Techs get PAID to muck shit up and they do in order to justify their own existance many times and why a damn lot of folks pay out long green to have a mod service take shit OUT instead of put things in (well other than goofy ass prices for "upgrade" parts that many times just LOOK better than what was replaced but at a cost that a rational human would piss on ;D )
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Post by pagan on Feb 16, 2008 9:39:51 GMT
Rick ok sonically "perfect" is the wrong word, how about sonically correct, being it doesn't add it's own signature, or leave something out.
"no,not even close due to the typical 40khz F3" on a transformer 30 to 15K
What about other Hirez eg formats sacd 10 to 100k.
Really, how well are the matched transformers. even the best "iron Mungers" have there limits, and users have the price limits too...
"digital being a "sample" of a thing and not the entire thing plus that "sample" torn to shreds then re-constructed in a stair step that needs a damn filter just to make it look like a coisine signal again so we have imperfections all over the place with iour job to minimize the damge to the musical event and NOT to showcase equipment."
I gather you don't like digital, then you difinitely won't like the T amps!
" On thing that is REALLY REALLY REALLY important is to not only do proper bypassing/decoupling but isolation as well so the signal does not have an easy path to "talk" back to the other chips on the same power buss (LCR networks)" "grounds together at a single point which will be RIGHT AT the DAC chip because it will have both analog and digital grounds."
star ground at the Dac?
I don't like T-amps either
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Post by jonclancy on Mar 2, 2008 23:30:55 GMT
I was messing around with the DACs a day or so ago. I'm now using my Pedja Rogic 1.1b with my headphone amp. I tried comparing the cheapo with my stock Philips CD960 (CD94-a-like). Well, the cheapo sounds better! Much more open and detailed. Granted the 960 needs a service and could do with me bunging in the tent XO and PFM Flea psu that I've got, but the difference was more than I was expecting. I just love my old 90's CDP, but this DAC is a great bargain!!
Cheers
Jon
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leo
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Post by leo on Mar 3, 2008 2:52:16 GMT
Hey Jon, check out the PPL filter on the CS8416, they look the wrong values to me (C22,C23,R2) Also notice that surface mount HCF4053 chip on the bottom of the board? its on the output of the op-amps, I can' quite work out what its supposed to be doing yet The caps on the CMOUT pin are going to be worth playing about with too C25
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jonclancy
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Post by jonclancy on Mar 5, 2008 23:16:52 GMT
Hi Leo, I'll pull out the datasheet and have a look at the filter. Definitely worth making sure it's OK, as Wildmonkeysects et al have dicovered. I didn't notice that chip underneath - good question!! Anyone got any suggestions? I'll post a pic tomorrow. Cheers Jon
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leo
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Post by leo on Mar 6, 2008 0:24:33 GMT
Hi John, I reckon some minimelf resistors and smd PPS caps would be nice in this dac, the op-amp based output stage is also quite a bit different from whats on the datasheets value wse but it should be easy to convert
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leo
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Post by leo on Mar 6, 2008 0:27:58 GMT
For my PCM1794 dac the PPL values for the CS8416 is 3k/1NF and 22NF, in this dac its 1k 100N, not sure of the other cap
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leo
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Post by leo on Mar 7, 2008 10:53:25 GMT
Also check the onboard regulator for the 3.3v supplying the CS8416, its measuring 3.9v on mine thats too high so could do with replacing I can see why they used different PPL values, they worked off the older evaluation circuit which is wrong, it was corrected in a later version
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Post by rowuk on Mar 7, 2008 22:35:14 GMT
Neutrik makes a line of reasonably priced transformers (in mu-metal cases) that are of very high quality, without having the "boutique" price of a Lundahl. Would this work Rick? www.canford.co.uk/commerce/item_23-001_2002061.aspxCould help keep the price "cheapo"!
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