robertkd
Been here a while!
Electronics Engineer from sunny Queensland
Posts: 111
|
Post by robertkd on Mar 29, 2009 10:34:40 GMT
As for the SC HA, well my earth connection goes to the chassis, then to is at the 0V point on my PSU isn't yours My earth does indeed go to the chassis (or at least, the alum baseplate, since I have a plastic case). What do you mean by 'then to is at the 0V point on my PSU'? Do you mean that I should connect my PSU's 0V to the chassis too? Is that a safety thing, or a SQ thing? Jeremy you have a number of options and this is where the world of hurt begins earthing to the metal work is indeed a safety feature, your insulating tape is not ;D your choices are to not reference the PSU to earth, has some benefits and disadvantages. for me I would disconnect the earth wire to the SC HA and optionally connect to the 0V on the PSU for such a trivial PSU it would be your choice as to which 0V pint you choose, likely the one at the DC output.
|
|
XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
Posts: 5,689
|
Post by XTRProf on Mar 29, 2009 14:44:12 GMT
Jeremy, Perhaps, my 0 cent worth to clarify matter from my point of understanding to your confusion now. All things being equal, the Earth should be just earthing the casing from electrical shock and to trip MCB if there is a serious leak. That's it. On the other, the O V should be just the neutral side of the power supply. However, the complication comes when circuits use the chassis (or what is technically called the ground) as a return path to return current. In other words, the chassis becomes part of the circuit. Then the 0 V becomes automatically connected to the Earth point. All in all, the best practice is still to isolate or float the Earth from the circuit power rails to reduce noise coming from the Earth as well. If the circuit is not using the chassis as ground type, connect it this way. As we all know, we have differential noise as well as common mode noise. Part of the differential noise is from the Earth to the PS. Common mode noise refers to those affecting both + and - ve rails equally at the same time. Hopes this amatuerish knowledge is of any help to you to realise your understanding.
|
|
|
Post by jeffc on Mar 29, 2009 22:25:11 GMT
Hi XTRProf,
Good moral and a 'been there done that' lesson learned by me too that just because this balanced isolation transformer trick can work great in one application using the right type of transformers, it can't be taken for granted any transformer system designed to kill common ground mode noise will reap the same rewards will all equipment, irrespective of whether a mega-KVA transformer is used. As mentioned, what is gained in noise floor drop and added musical nuances can be seriously out-weighted by the music being strangled in various ways.
That said, however, with this low-power cheapo external DAC that must be quite sensitive to power noise, my isolation transformer setup will be staying put, at least until I've tested other options. ;D
cheers.. jeffc
|
|
|
Post by jphoward on Mar 30, 2009 0:42:30 GMT
Thanks for the explanation, Xtrprof. When you say it's best practice to isolate the earth, I'm afraid that's a bit too technical for me... does that mean I should, or shouldn't connect the earth to the PSU input?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 30, 2009 1:51:37 GMT
Jeremy All of our electrical and electronic equipment is required to meet Australian standards. I would advice against altering existing earthing arrangements. Normally, if the device uses a 3 pin power plug, the earth wire will be connected to the chassis if it uses a metal chassis. Earthing the chassis on certain items like transformerless TVs will blow up their power supply. Even attempting to hook up a normal C.R.O. to one of these will damage it also. Alex
P.S. I will leave the final word to Robert.
|
|
XTRProf
Fully Modded
Pssst ! Got any spare capacitors ?
Posts: 5,689
|
Post by XTRProf on Mar 30, 2009 2:29:51 GMT
Thanks for the explanation, Xtrprof. When you say it's best practice to isolate the earth, I'm afraid that's a bit too technical for me... does that mean I should, or shouldn't connect the earth to the PSU input? Yes, that's the idea at least. Separate the earth from the circuit if your equipment can use that. However, some when separated will not function as the chassis is part of the return path for the circuit. When I say the circuit, I mean the circuit doing the audio thingy (as in your HA) and not the PS side primary. Like I had said, the primary function of the Earth is to protect us poor soul from electrical shock. If your equipment can use it, the chassis should be Earthed. I repeat, If Your Equipment Can Use It Safely, as some cannot do that. But for your HA, it should generally be ok if the audio circuit doesn't use the chassis (ground) as part of the circuit. That should technically improve your HA performance at least when talking about noise factor. But try the 2 versions to see what you like, by all means, as the sound that you prefer may be better in one form. However, this Earth separation from the audio circuit is always in congruent with better sound. Yeah, technical and subjective shake hands.
|
|
|
Post by jphoward on Mar 30, 2009 3:39:26 GMT
I would advice against altering existing earthing arrangements. Normally, if the device uses a 3 pin power plug, the earth wire will be connected to the chassis if it uses a metal chassis. I'm not thinking about altering any of my retail equipment - just trying to work out how to configure my SCHA.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Mar 30, 2009 4:15:01 GMT
I would advice against altering existing earthing arrangements. Normally, if the device uses a 3 pin power plug, the earth wire will be connected to the chassis if it uses a metal chassis. I'm not thinking about altering any of my retail equipment - just trying to work out how to configure my SCHA. Jeremy From what I see in your photo , the earthing arrangemets are satisfactory already. You could try running an earth from your earthing plate back to 0Volts from your PSU's 3 terminal output block, but are unlikely to gain any improvement. I already tried that in mine. Alex
|
|
|
Post by jphoward on Mar 30, 2009 4:16:17 GMT
Many thanks Alex - that's exactly what I needed to know.
|
|
rickcr42
Fully Modded
Rest in peace my good friend.
Posts: 4,514
|
Post by rickcr42 on Apr 27, 2009 14:02:59 GMT
"Actually, this balanced isolation transformer thingy, I'm not too impressed, at least for first impression. My peer invited me to hear the "improvement" after seeing all the positive vibes about them and built one using a 2KVA trans to "kill" all doubts about load being a limiting factor. It was used driving his SET (300B I think as that was sometime ago of about 1.5 years) amp.
I still remembered him jive talking about all the good things about the sound but according to my ears were all about shitty sound, being undynamic, shrill and the muzak was just "For whatever reason anything between a POWER AMP and the mains outlet on the wall has a very large impact on the end sound of the amp with any line filters being mostly dynamics killers and with line cords being very high on the list of "audible change" while lne level devices less sensitive to line cord changes and totally design dependent on line filter better/worse (meaning you need to make the call in YOUR system) and didgital audio devices almost TOTALLY line cord nuetral but very much improved by locking down mains line garbage they being mostly in the ultrasonics range,right smack in the middle of where digital lives. At least in my personal experience this is so,YMMV (your mileage may vary ) and probably will ;D
|
|
Will
Been here a while!
Ribena abuser!
Member since 2008
Posts: 2,164
|
Post by Will on May 13, 2009 20:25:18 GMT
I've been re-reading this thread, and I've seen mention of 'the CMOUT mod'
Can any one explain what this is, and the benefits it may give?
Ta.
|
|
jonclancy
Been here a while!
Mr. Ripple Eater
Amateur EAGLEist
Posts: 1,131
|
Post by jonclancy on Aug 19, 2009 4:06:03 GMT
Apparantly, there is a mod to get this dac back to 196Khz. It's early, and i haven't looked into it, but does this ring any bells, chaps?
Cheers
Jon
|
|
Will
Been here a while!
Ribena abuser!
Member since 2008
Posts: 2,164
|
Post by Will on Aug 20, 2009 13:00:43 GMT
IIRC, lift pin 2 of CS4397, and connect to pin 16 of CS8416.
pin 2 was linked to pin 3 in some DACs that were supplied later.
|
|
|
Post by hifijunkie on Aug 24, 2009 6:21:59 GMT
Anyone tried installing it inside a CD player as a replacement to stock DAC chip ? I was interested in installing it in my MHZS CD33 .
|
|
jonclancy
Been here a while!
Mr. Ripple Eater
Amateur EAGLEist
Posts: 1,131
|
Post by jonclancy on Aug 26, 2009 12:26:14 GMT
IIRC, lift pin 2 of CS4397, and connect to pin 16 of CS8416. pin 2 was linked to pin 3 in some DACs that were supplied later. Thanks Will, I'll check my board. Jon
|
|
jonclancy
Been here a while!
Mr. Ripple Eater
Amateur EAGLEist
Posts: 1,131
|
Post by jonclancy on Aug 26, 2009 12:30:19 GMT
I've not tried it in another CDP. I assume the easiest way would be to tap off the power supplies from the original DAC and install the Cheapo "piggy-back" - using SPDIF, I would have thought. I haven't looked at the 4397 datasheet for a long time. Depending on the output stage of the MHz player, you could either plumb back into that, or use some other output stage like the one Leo mentioned earlier in the thread.
Cheers
Jon
|
|