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Old 28th August 2011, 12:53 PM   #581
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Well, Johnm, I'm not sure I agree with all the things you are considering doing.

1) Over the top Capping. Picking the right size and the right quality capacitors is sometimes better, audio quality wise, than simply over-sizing the caps. I don't know what Naim equipment you are thinking of, but if it was digital certainly there were regulators. Try the go the schematics and look at what they did, what regulators they used and how they bypassed the legs.

2) Tantalum caps. Be careful there: I had tantalum caps getting on fire before my eyes. If you are willing to use them, get solid types. If possible find out exactly what type they used.

3) Optical and USB outputs. They are not the best type for top quality audio. Coaxial S/PDIF and I2S are the best outputs to use for high quality audio. Isn't there a way for you to get them?
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Old 28th August 2011, 01:12 PM   #582
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Hi Calmart - thanks for your post.

1) Yep I'm aware of these considerations - believe me I won't just dive in there without giving it any thought I've owned a Naim CDI CD player in the past, as well as the NAP140, and I've built a NAP180 clone so familiar with what parts they use. I believe Erin back at the beginnings of this thread successfully used 20,000uF worth of capacitance too and claimed it bought quite a benefit to the sound over just the onboard caps. I'll try both. Regs - they seem to use LM317s a lot. I'll have to refresh my memory as to what they used in their CDPs.

2) I've heard this many times, but thus far (touch wood) it's never happened to me. I believe Naim use them as output caps in their CD players (the older ones at any rate) as well as decoupling around the op-amps and DAC chips. The Naim CDI is one of the most analogue sounding CD players I've ever heard (regret selling mine) so I'll try and emulate some of their design considerations as far as possible. I do have some solid types too, so I'll keep your points in mind. Thanks.

3) I think the benefits of I2S are over-rated in the real world to be honest. I think a well implemented toslink or SPDIF can be just as good. In fact I've heard toslink sound better than SPDIF, and I'm not alone here. Toslink also has advantages when using a computer as a source of course. At the end of the day I think it all depends on the implementation, rather than stating one is without question better than the other. For the time being, I have to use toslink though - for better or worse - so I don't have much choice. As I said though, once I get the Kingrex USB-SPDIF converter I'll then be able to get back to SPDIF.

Cheers,

- John

Last edited by johnm; 28th August 2011 at 01:16 PM.
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Old 28th August 2011, 02:03 PM   #583
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Hi John,

First of all, and to explicit what values we are leading here with, we are talking subjective opinions here. And talking about other people's opinions too. They are not really facts.

But if you didn't, you should read Jung/Marsh article on Capacitors, and see what they say there about tantalum caps. AFAIK they are talking facts there, not opinion. Obligatory reading for DIYers.

I don't think the analog sound of Naim CD players had to do with the output caps, but with the whole implementation of their analog stage.

On my DAC I will be using an external board for the filter and pre-regulation of the DAC, and also with a dedicated supply for the analog stage, detaching it from also feeding other chips. On my pre-regulators I will be using 3X7 chips, which is quite likely what Naim used on theirs.

Soon I will also be trying a Sulzer/Jung regulator for the analog stage too.

Now about the digital interface. We are talking errors here. In a scale from very few or none of them, I2S benefits are far from being over-rated. They are the best way to interface digital. AFAIK it's the way BD players interface internally.

Next come S/PDIF, which are a bit more error prone than I2S, but are still quite good.

Toslinks have a serious problem: they have to go through two conversions, one on transmitter and another on receiver. Those are sources for more errors. This is not opinion either: in an error prone scale, they do go from better to worst.

I'm not alone on this either: magazines like Hi Fi News and RR or Stereophile have many times said this.

Now, whether or not you hear them as better or not, that might be very much like preferring tubes over solid state. So I would not like to take this discussion much further. It will take us nowhere.

The problem I see with USB sources is that they are sample limited by definition, but there might be an implementation that makes them work very well or superb. And I would really like to know it too.


Carlos
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Old 28th August 2011, 02:27 PM   #584
johnm is offline johnm  United Kingdom
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Well if we're talking facts, it is a fact that I like the 'sound' of tantalum caps, having used them in other projects as output caps and been pleasantly surprised. It's a fact that Naim have also used them for over 30 years so there must be a good reason for them doing so. They seem to be doing alright as a company Of course it all depends when/where they are used.

I've read that paper on capacitors and it is very good indeed, but one needs to supplement that with one's own personal real life experiences with various parts. Sometimes the theory and the practice do not mesh.

Regarding toslink: yes it has to go through two lots of conversions. But it also has bonuses with its lack of any earthing related problems or the 'sound' of different metals to transmit the signal, cables, or the impendence matching sagas. The publications you have mentioned have also had reviews were the reviewer preferred toslink. As usual, there is no right and wrong in this crazy hobby, and it really is the end result that ultimately counts, as one has to live/listen with that.

As stated, at the moment I have to use toslink anyway. There is no way around this at the moment as I do not have the money to buy a fancy USB-to-SPDIF converter. This AK4396 DAC kit only has SPDIF input so I need to use that and not end up rebuilding it with too many mods

In short, I have to make the best of what I have at the moment. And that's unfortunately optical.

Last edited by johnm; 28th August 2011 at 02:29 PM.
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Old 28th August 2011, 03:03 PM   #585
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Quote:
Originally Posted by carlmart View Post
How do you do that? Just input the files regularly?

I have some 24/96 files that I wish to put through it.

What 24/192 files are those you are using? Where can I get them?
Yeah, just send the files from a digital source that is capable of playing them. The DAC will automatically detect the format and switch to the desired 96kHz or 192 kHz mode. If you are using a computer as a source, make sure that you access the sound card directly, for example with ASIO4ALL and set the software volume to maximum (0 dB) to ensure bit-perfect playback.

My 24/192 files are vinyl rips, but I've got some HQ 24/96 DVDs too. Although, if you don't have access to any of these, here's a link to some pretty good samples for testing: Index of /samplerdownload. I hope it is legal to use them.

Last edited by jeffzen; 28th August 2011 at 03:08 PM.
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Old 28th August 2011, 03:23 PM   #586
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One of the reasons for me to go into DACs was to be able to listen to higher definition discs in a proper way. That is with good chips and regulation involved.

Very few (and expensive) BD or DVD players can offer that, and even so with some restrictions on some cases. Only the Oppo players offer a BD player with better quality DAC option and a not so expensive price.

My idea is to convert all my vinyl LPs to HD audio, and then discs. But something I can play with any player, not specific ones.

Not considering playing from computer yet, but who knows, maybe in the future. In any case I want something I can stored on discs, not in HD.
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Old 28th August 2011, 03:25 PM   #587
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Hello, I see the ever returning subject of tantalum caps catching fire came up again. I have to admit I hate those stinkers too as they were very unreliable in the past. When I started with this hobby it was common that tantalum caps exploded (especially the "water drop" or dipped type) when used directly on rails. When you wanted to repair an electronic device you would start to check if tantalum caps were used...

However, production methods have changed etc. and they now can be very reliable.Fact is that when they fail they fail mostly with a short circuit and a thermite like reaction (this is due to the way they are made). They are very sensitive to spikes and overvoltage and will fail when not used right. So when you use them you will have to take more care in protection against these things:

http://en.wikipedia.org/wiki/Tantalum_capacitor

Cell phones are full of tantalum caps as they can be made small in size with a large value and low weight. Features that are not always needed in audio devices except maybe for portable stuff.


Still, there are some relevant issues against the use of tantalum caps:

First: they are expensive. More expensive than other good electrolytic caps.

Second: the "coltan" issue: tantalum is made from coltan that is only found cheap in Congo. There sticks blood to coltan for sure as weapons are bought with coltan. Also gorillas can become extinct because of the illegal mining.

Coltan - Wikipedia, the free encyclopedia

Third: dry tantalum caps may measure fine but standard low ESR industrial caps sound better and don't have the drawbacks as described.

Manufacturers of tantalum caps try to convince us from the opposite:

http://www.digikey.com/Web%20Export/...f?redirected=1

I have to admit that wet tantalum caps are quite special but given the described drawbacks I don't use those anymore too.
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Last edited by jean-paul; 28th August 2011 at 03:49 PM.
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Old 28th August 2011, 03:32 PM   #588
Alexium is offline Alexium  Ukraine
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Guys, what DAC kit are you discussing here? Can't find any link.
P.S. As for tantalum caps: I'm not a big specialist, but I can say my amplifier uses lots, I mean LOTS of those (pretty much every polar cap except for main PSU cans), they are all ancient (manufactured between 1975 to 1980), and not a single one has died in almost 30 years the amp worked.
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Old 28th August 2011, 03:56 PM   #589
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Maybe your amp has wet tantalum caps ? And if they are the dry tantalum type: there is always an exception to the rule
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Old 28th August 2011, 04:12 PM   #590
Alexium is offline Alexium  Ukraine
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Seems like you're right, they are wet, and also they are military-grade. Didn't know there are different tantalum cap technologies.
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