Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 14, 2009 23:38:52 GMT
Robert A little common sense goes a long way ?  Alex |
|
robertkd
Been here a while! 
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 15, 2009 15:06:16 GMT
So if I place a thoroidal transformer in the same case as the rest of the electronics and it is properly oriented I do not need to place a piece of metal to shield the electronics from the field generated by the transformer. Did I understand correctly? Thanks. well I would still consider some shielding, check out rbrook's maybe best of breed  point is how far do we take the numbers and what credence do we give the results. you need to apply a little physics and some practical know how then maybe you get some magic  Robert |
|
|
|
Post by jphoward on Mar 17, 2009 11:50:57 GMT
Alex is correct and and what I have achieved using the aluminum angle is to orientate the transformer so I have "about" the minimum magnetic field towards the signal area in this case the DAC PCB. Can you provide some information about what orientation to select in order to achieve this? |
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 17, 2009 12:00:42 GMT
Pretty much anything that doesn't face the face the aperture where the windings are, the cores are wrapped with Hi Silica steel (allegedly !)
|
|
|
|
Post by rbrook on Mar 18, 2009 13:06:36 GMT
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 18, 2009 13:29:07 GMT
|
|
|
|
Post by rbrook on Mar 18, 2009 15:50:40 GMT
Ordered the go faster red one Now to work out what I'm going to do to it |
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 19, 2009 11:06:16 GMT
|
|
|
|
Post by ticktockman on Mar 19, 2009 22:29:31 GMT
I have been following this thread for a while with some interest. May I suggest that stacking multiples of the 1543 dac chip might bring major benefits. From my own experience I have to say using multiple 1543 dac chips in an NOS configuration does produce excellent results. A good friend of mine has been experimenting with variations of this dac configuration with at the moment some limited commercial success. There would seem to be an optimum number of 8 chips but do bare in mind the heating consequences of all these chips. He has told me that he has found the dacs based on this configuration to be very sensitive to jitter. His design has his own proprietary jitter reduction solution (which he is keeping under wraps..) however for those with the ability to take such steps there might be some milage in going down this route in a quest for ultimate fidelity. I will look forward to the coming developments.
|
|
|
|
Post by rbrook on Mar 19, 2009 23:18:58 GMT
I went for the Mini SPDIF+OPTICAL DAC Board --PCM1793+DIR9001+OPA2134. Now to play the waiting game until it arrives  Probably a good time to sort out and order the parts i want to change on it. |
|
XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
Posts: 5,689
|
Post by XTRProf on Mar 20, 2009 10:25:28 GMT
I have been following this thread for a while with some interest. May I suggest that stacking multiples of the 1543 dac chip might bring major benefits. From my own experience I have to say using multiple 1543 dac chips in an NOS configuration does produce excellent results. A good friend of mine has been experimenting with variations of this dac configuration with at the moment some limited commercial success. There would seem to be an optimum number of 8 chips but do bare in mind the heating consequences of all these chips. He has told me that he has found the dacs based on this configuration to be very sensitive to jitter. His design has his own proprietary jitter reduction solution (which he is keeping under wraps..) however for those with the ability to take such steps there might be some milage in going down this route in a quest for ultimate fidelity. I will look forward to the coming developments. Hmm, your friend's dac sounds like a ring dac not taken to the limit like DCS. Am I right to say that? |
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 20, 2009 12:13:21 GMT
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 21, 2009 12:35:58 GMT
Alex,
have you tried the LM4562HA in the PCm1793 DAC?
Robert
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 21, 2009 20:30:12 GMT
Alex, have you tried the LM4562HA in the PCm1793 DAC? Robert Robert No, All that is on the backburner for the moment, as I have been preoccupied with drilling and making a JLH, assisting a local member etc. BTW, where do you get decent, reasonably priced PCB drills/multitool that take .8mm drill bits ? The smallest collets wear out in the el cheapos, which are now also damn hard to get locally. (some websites not updated either !) This always has been low priority for me because I already have a very good DAC in use, that this won't come close to, no matter how far it is tweaked. Another problem is it's a voltage type as well. Alex |
|
|
|
Post by ticktockman on Mar 21, 2009 23:17:25 GMT
That could make an excellent start point and so might the Lite Audio dac that one of our members uses but the point I was trying to make was my friend had spent a LOT of time trying different configurations and has come to the conclusion that some form of additional jitter reduction is required to get the best from this particular dac in any configuration that he tried. Especially if you want to add a USB input!!! On the issue of the Ring dac I dont believe his dac has anything in common with this piece of hardware which I understood to have elements of both multi bit and bitstream contained within the design. My personal (limited)experiences of the dcs(ring dac based) kit is that until you get quite high up the ladder £10k+ there is no great magic to them and the Chord dac's offer better(well more detailed) sound for less money. IMO obviously The other thing he told me was that although using a passive output stage when correctly designed produced excellent results in his opinion it could be bettered by an active one. He noted that the bass performance of the passive output always lagged behind that of his active ones, however, getting the rest of the frequency band to match the performance of the passive design was problematical and took him a considerable amount of time. The only alternative option he hasn't tried yet is the sabre dac/buffalo dac which has received much praise. I may have to get one of these for him to try( its ability to deal with DSD intrigues me but harnessing this seems to be a major nightmare in the realm of DIY. One thing to note is that as the number of dac chips goes up especially if you stack them the heat generated becomes more problematic and can influence their performance dramatically. Leave some holes for ventilation if you go down this route. |
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 21, 2009 23:28:17 GMT
Alex, have you tried the LM4562HA in the PCm1793 DAC? Robert Robert No, All that is on the backburner for the moment, as I have been preoccupied with drilling and making a JLH, assisting a local member etc. BTW, where do you get decent, reasonably priced PCB drills/multitool that take .8mm drill bits ? The smallest collets wear out in the el cheapos, which are now also damn hard to get locally. (some websites not updated either !) This always has been low priority for me because I already have a very good DAC in use, that this won't come close to, no matter how far it is tweaked. Another problem is it's a voltage type as well. Alex Not sure where you would get a quality pin vice chuck from, I got some cheapo $10 thing from DSE but it's just a stright hand held pin vice affair thought I might need to drill some holes,... Hows Nick's rig going As for the DAC sure it's just a "reference" build from the manufacturers spec sheets. I'm not sure on your reference to "current out" since you ultimately going to use a voltage buffer, in the PCM1793 the have done i internally. Shame as it would be good to get your impressions after a few simple hacks and cap swap outs the DAC is at least impressive with an LM4562HA in the output stage, Richard has one of PCM1793 based DAC's on order be good to compare notes I'm waiting on a TDA1543 based DAC just to see what all this fuss is about with non over sampling vs over sampling. From what little I know, ATM I can certainly live with over sampling  Robert |
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 21, 2009 23:41:35 GMT
That could make an excellent start point and so might the Lite Audio dac that one of our members uses but the point I was trying to make was my friend had spent a LOT of time trying different configurations and has come to the conclusion that some form of additional jitter reduction is required to get the best from this particular dac in any configuration that he tried. Especially if you want to add a USB input!!! On the issue of the Ring dac I dont believe his dac has anything in common with this piece of hardware which I understood to have elements of both multi bit and bitstream contained within the design. My personal (limited)experiences of the dcs(ring dac based) kit is that until you get quite high up the ladder £10k+ there is no great magic to them and the Chord dac's offer better(well more detailed) sound for less money. IMO obviously The other thing he told me was that although using a passive output stage when correctly designed produced excellent results in his opinion it could be bettered by an active one. He noted that the bass performance of the passive output always lagged behind that of his active ones, however, getting the rest of the frequency band to match the performance of the passive design was problematical and took him a considerable amount of time. The only alternative option he hasn't tried yet is the sabre dac/buffalo dac which has received much praise. I may have to get one of these for him to try( its ability to deal with DSD intrigues me but harnessing this seems to be a major nightmare in the realm of DIY. One thing to note is that as the number of dac chips goes up especially if you stack them the heat generated becomes more problematic and can influence their performance dramatically. Leave some holes for ventilation if you go down this route. Are the example uses the 1543s and they parallel up a whole bunch wind the supply up hence the heatsinking apparently somewhere short of turning the silicon back into sand they sound very sweet  As for jitter and yes especially in the USB bit stream well there are a number of re-clocking schemes. sampling at multiples of the base data rate AKA exactly how serial is decoded. FIFO with dual port RAM clock data in with jitter through the write port clock data out through the read port locked to some nice stable derived clock, just be prepared to do some fancy leg work if the buffer runs out Robert |
|
|
|
Post by rbrook on Mar 23, 2009 14:18:38 GMT
Any update with your PCM1793 Robert, also if it isn't to much trouble could you explain why you have done some of the changes you have, i'm working on the theory that they must use nasty cheap caps so they must be replaced and you have changed the power supply for a cleaner one, am i along the right lines here?
Richard.
|
|
|
|
Post by jelosno on Mar 26, 2009 12:19:22 GMT
sorry for jumping back in the thread logic but... ;D what is a better material for shielding PSs Aluminium or Ferrous Metal in some articles I've read Alu is superiour others like copper and then some use simple mild steel dunno |
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 26, 2009 12:20:21 GMT
Any update with your PCM1793 Robert, also if it isn't to much trouble could you explain why you have done some of the changes you have, i'm working on the theory that they must use nasty cheap caps so they must be replaced and you have changed the power supply for a cleaner one, am i along the right lines here? Richard. I missed this, Ok first up I got rid of the rail splitter, this allows you to reference ground to system ground. The capacitors used are marked sanyo oscon so likely ok, my choice was simply to increase uF to provide low supply impedance, I probably should have put the regulators off board and maybe will do that anyway. Hopefully when I get time to complete this I'll do a more in depth explanation but for now compared to the original format this thing sings  Robert |
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 26, 2009 12:29:04 GMT
sorry for jumping back in the thread logic but... ;D what is a better material for shielding PSs Aluminium or Ferrous Metal in some articles I've read Alu is superiour others like copper and then some use simple mild steel dunno well that depends on what you want to shield against. honestly aluminum is not that good for electrostatic shielding copper is much better! for electromagnetic shielding it needs to be ferrous bassed, to provide any magnetic shielding, worth talking about. what did you have in mind? Robert |
|
|
|
Post by jelosno on Mar 26, 2009 12:49:14 GMT
I want to shield transformers (non toroidal) and maybe the PS filter caps if it makes sense.
The PS section will be inside a tube based headphone amp.
|
|
robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 26, 2009 13:09:08 GMT
I want to shield transformers (non toroidal) and maybe the PS filter caps if it makes sense. The PS section will be inside a tube based headphone amp. well I would go the sheet steel type "triditional" chassis maybe a sheet of copper as a ground plane laminated to the chassis in the tube stage Robert |
|
|
|
Post by jelosno on Mar 26, 2009 13:28:36 GMT
steel it is then
THANK YOU
|
|
XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
Posts: 5,689
|
Post by XTRProf on Mar 26, 2009 15:57:23 GMT
I want to shield transformers (non toroidal) and maybe the PS filter caps if it makes sense. The PS section will be inside a tube based headphone amp. Ha, ha, I will go the extra mile and put the PS in another steel box. |
|
