DACs with PCM63 chips??

[Rug Doc]

Yes, you can, essentially, stuff SPDIF into one.

Worth noting that - yes the PCM 63 is a very fine ladder dac; it also was critically-reliant on correct / in-calibration adjustment of the two MSB trimpots.

Trimpots, even the tiny sealed multi-turn-types, are crap parts: they drift, they move, they have lousy tempcos.

Now in these days of really, really good ADC (18+bit) cards for free in everything - it is not difficult to feed-in a low-level sine (-90db, dithered, 16-bit data) and re-adjust for least IMD*. In fact - since these things are 20yrs old - that's exactly what I would do as a matter of course: finding a DAC based on 'PCM63' alone is not a guarantee otherwise of anything you might like. Finesse-ing one, could well be.




(*e.g. I did such a tweak to a friend's ancient Denon based on the pcm56, a slightly-downspecced version of very same dac architecture/chip innards - and the outcome, for stuff that shouldalready be in the noise-floor - was quite a revelation in terms of enjoyment.)

I have no idea what you are talking about Martin with regards IMD and there is no way that I’d personally be capable of pulling apart a DAC and replacing the trim-pots. But I appreciate your thoughts and I’ll send whatever comes my way in your direction if you like??!! Haha

 

[martin clark]

@Rug Doc - actually it's not difficult at all: but just to note that this family of dacs - while deserving their reputation - are not fit-and-forget; and it'd be sad if that rep went away simply because an essentially-simple /10-min service recal procedure got forgotten.

 

[mandryka]

It's too complicated, I need an introduction -- like DACs for Idiots, Teach Yourself DACs

 

[martin clark]

Well not really: you feed a dac a known signal, like a-90dB, 1khz sine wave: watch the dac output via a spectrum analyser (these days - via a good soundcard and software) and tweak/check the +/- MSB offset pot settings are the ones that give the smallest/most-minimal profile of harmonic spurs (esp best -suppression of anything 5th harmonic and above). It sounds more complex than it is to do - very, very much easier now, than when the dac was designed!

 

[mandryka]

No I didn’t mean that. I mean I know I’m not going to get a soldering iron, oscilloscope and screw driver out, but I may pay someone to do it.

It’s that the are of DACs is new and complex, I need to understand the implications of the different chips better, and understand all the other factors which effect sound better, to make an informed decision about what to buy. Otherwise it’s a bit too much of a leap of faith.

 

[Dave Smith]

I also have a preference for multibit DAC chips, although personally I prefer the sound of the AD1862 to both the Philips and Burr Brown chips.

 

[Stefano Papini]

Well not really: you feed a dac a known signal, like a-90dB, 1khz sine wave: watch the dac output via a spectrum analyser (these days - via a good soundcard and software) and tweak/check the +/- MSB offset pot settings are the ones that give the smallest/most-minimal profile of harmonic spurs (esp best -suppression of anything 5th harmonic and above). It sounds more complex than it is to do - very, very much easier now, than when the dac was designed!

Hi, I know I'm resurrecting an old thread, but @martin clark could you kindly suggest a couple of soundcards/related sw and steps for the dumb (myself) in order to perform the adjustment? I happen to have a pcm63 based dac and I see on the board no potentiometers, so I might add them and try squeezing the most of of them.

Thanks a lot,

Stefano

 

[LazyHammer]

Well since the thread was already resurrected I'll chime in to say I don't have a PCM63 based dac but I have a PCM-53JP DAC and it does indeed sound wonderful.

 

[Stefano Papini]

I just googled for it, JP-V or JP-I? The JP-I should be a Iout like the PMC-63. I'm also interested in a good discrete I-V project to get rid of the two op-amps now performing the conversion on my dac (a Monarchy M22B)

 

[Mike P]

Hi, I know I'm resurrecting an old thread, but @martin clark could you kindly suggest a couple of soundcards/related sw and steps for the dumb (myself) in order to perform the adjustment? I happen to have a pcm63 based dac and I see on the board no potentiometers, so I might add them and try squeezing the most of of them.

Thanks a lot,

Stefano

Hi Stefano,

See this thread here

After years of messing about with sound cards and distortion analysers I eventually found that by far the easiest way to do this is simply using a set of headphones.

 

[the caretaker]

Isn't it about implementation more than the dac? I am listening to my kingrex amp with built in dac ( burr brown 2702e ) it's sounds great only 48kHz..compared it against my newer higher res dacs and I think its better...

 

[Stefano Papini]

Hi Stefano,

See this thread here

After years of messing about with sound cards and distortion analysers I eventually found that by far the easiest way to do this is simply using a set of headphones.

Thank you Mike, I'm going to read the thread!

Stefano

 

[Stefano Papini]

So, I definitely have to solder a couple of potentiometers and 330KOhm resistors according to Burr-Brown schema, play a disc with that signal and listen! Thank you

 

[martin clark]

Hi, I know I'm resurrecting an old thread, but @martin clark could you kindly suggest a couple of soundcards/related sw and steps for the dumb (myself) in order to perform the adjustment? I happen to have a pcm63 based dac and I see on the board no potentiometers, so I might add them and try squeezing the most of of them.

Thanks a lot,

Stefano

Stefano,

You might find this recent thread helpful:
https://pinkfishmedia.net/forum/threads/pcm56-msb-adjustment.258120/

 

[Mike P]

I beat you to it Martin.

I've been playing with this subject over the last few days and have some interesting results to share. I'll post in my original thread when I have some spare time.

 

[Stefano Papini]

Thank you all,
subscribed to the thread and looking for decent 100K pots on mouser

 

[beammeup]

Yes, you can, essentially, just stuff 44-48Khz SPDIF into a Numerik, but bear in mind it will be totally reliant on how 'good' the source is - no reclocking etc.

Don't Audio Note choose not to put reclocking in even their modern DACs - reason being altering the signal? Therefore the need is there for an excellent transport when connecting to AN.

 

[jpk]

Another vote for the AD1862. There is a thread about the Cyrus Dacmaster on diyaudio with recap and mod info

 

[martin clark]

Don't Audio Note choose not to put reclocking in even their modern DACs - reason being altering the signal? Therefore the need is there for an excellent transport when connecting to AN.

Well, it's a bit more than that, an adherence to an ill-informed/discredited view of how 'digital audio' and the necessary reconstruction filter actually works to fulfill the Nyquist-Shannon theorems; but that doesn't stop it being popular.

 

[hairyderriere]

Well, it's a bit more than that, an adherence to an ill-informed/discredited view of how 'digital audio' and the necessary reconstruction filter actually works to fulfill the Nyquist-Shannon theorems; but that doesn't stop it being popular.

Well, they're not exactly alone in their approach, if that's what you mean. Unless you're referring to something specific to their design?