Peter:

Today I use PC > Fireface400 > spdif coax cable > DAC. [which is superior SQ compared to USB adaptive mode, BTW].

But you are using PC > DIY modification > I2S cable > DAC. (Is that correct?)

I don't know if you have mentioned it in the past, but do you consider your DIY 12S solution superior to SPDIF?
Eventually, what have you done to get the I2S output from your PC?

(Probably you DAC will accept several digital inputs, but the whole point about your DAC is to get the best sound quality. Right?)

All the best.

I mix formats all the time. Never had problem till now.  Never had a problem so far.

Peter is about to announce that if Holland win the WC finale in football, then old XX customers and members (>100 postings) of this forum will receive a €1000 discount on the new DAC!

Everybody in here wants YOUR dac, but with the price of the other...
(But you knew that, of course  )

Congratulations Peter, reaching this conclusion makes you a Mythbuster! The very first generations of opamps didn’t sound good. That is a fact. And many manufactures still use the cheapest ones they can find. (Image the hundreds of cheap Philips opamps inside most mixing consoles in recording studioes, degrading the sound quality of our beloved music, recorded during the 70s and 80s).  Because of this, many audiophiles keeps the myth alive about opamps not sounding good in year 2010.  But the very best opamps of today, for instance the new top of the line from National Semiconductor, measures better and probably sound BETTER than any passive circuit. (The cost and space saved can be used to power supply and other important matters).

My old Dynamic Precision DAC had removable opamps, so I was able to upgrade 2 times. Each time the sound become less grey, more full bodied and with blacker background. This happened a few years ago.

Last year I upgraded the opamps inside my power and preamp, to the very best ones from National Semiconductor (I don’t remember the name. I think there are several ones of same quality, but suitable for different purposes). Holy smoke! They sound more “tubey” than tubes. Extremely detailed in a natural way, with so much bloom and nuances in the treble. Never heard cymbals sounding so good before.

Opamps applied in a DAC can sometimes be a disaster, if it is fed the raw unfiltered signal from the DAC chip. All the HF (noise) will stress the opamp making it sound a little coarse. According to an insider I know, this error has been done with quite a many DACs… But within the right environment, like Peter says, opamps are the best and certainly the most convenient solution.

In case of even better opamps in the future: If the opamp is not soldered to the circuit board, but attached mechanically to a universal adapter, then it can be easily upgraded by the owner without need for shipping back to the manufacturer. (hint, hint). 

Thanks for your interesting reply.

-Actually it came to my mind while using my new software Adobe Audition 3, doing a spectrum analyze of several hi-rez files. Then I realised there is not much(!) HF content above, lets say, 25kHz. Close to the half of the samplingfrequency (48, 88 or 96) there is practically speaking only noisefloor.
[Even if the digital recording technology can capture signals >50kHz, the mics does not. If we are speaking about music recorded in the haydays of analog, then most multitrack mastertape machines rolled of above 20kHz, too].
 
Conclusion: *Nothing* left to filter at sf/2 when the music file has 88k2Hz or higher sampling frequency. The less lowpass filtering, the better. I look forward to hear you DAC!

Thanks for the link, IVO. It looks interesting. Lampizator doesn't mention anything about oversampling or (absens of) lowpass filter, though...

PETER: While we are on the subject:
Is your analog section based on tubes, opamps or discrete?
Does it offer XLR balanced outputs?

All the best,

Lately, my main music source are hi-rez files from various disks and downloads. Sampling frequencies are mainly 96k, but also 88k2, 176k4 and 192kHz. It strikes me that a filterless DAC is perfect for hi-rez files, because they have a natural roll-of with very little(!) amplitude left above, let's say, 40kHz. So no *need* for low pass filtering, because the aliasing distortion will be very low anyway.

I cried too, on Sunday. Well at least my eyes got wet. I was playing the ELP Brain Salad Surgery DVD-A, bonus track "Luck Man" at +100dB with the latest XX version and 1024 latency. Oh my god. The realisme could make an old prog rock fan cry anytime. (I am really into hi-rez now. Bought all the titles I could find on eBay and Amazone + downloads from HDTracks. When you get used to music mastered in 24/96 or 24/192, then you easily forget about compressed CD).

WISHLIST: upsampling and ARC with hi-rez formats, not only 16/44.


PS: Maybe you should make a new section in the forum called "The last time I cried", as the ultimate listening experience? (You can rename the "Measurements" section. It has never been used). It can also be used for hardware accidents, like "yesterday I cries beacuse my amps blew up", or "my harddisk crashed without backup".
 

Wow. All this reports are wetting my appetite. Peter, you have become a real…… dacteaser!

The first generation ICE power amplifiers from B&O are seriously flawed. They mute the micro dynamics and rob the sparkle and life out of the music. You get a lot of watt, but no soul. Kind of a “stupid blond”. They are not to consider as high end.

If you want to do something serious with Class D, then the first thing is to get rid of the integrated cheap switching power supply. They really suck.  Building a huge oversized linear PSU “by the book” is mandatory. (Because Class D is so efficient, the PSU still can be smaller/cheaper than with an A/AB/Tube amplifier). I have also heard that the Hypex modules are better sounding than ICE.

I believe in Manisandher observations. Class D has potential if done right. But remember that all Class D is like an open loop circuit. Noise can enter from anywhere and will be included in the music signal. The chassis, the interconnect cables, the mains cable, the loudspeaker cables, –all these works like an antenna for unwanted noise. So Class D will always be troublesome. And that’s why there must be a coil on the output loudspeaker terminal. The coil acts like a low pass filter preventing noise being picked up by the speaker cables and entered into the circuit. But a coil is a coil. It decreases bandwidth and it reduces the amplifiers performance with high frequency square tones. Especially with high-rez music, like SACD/Blu-Ray/DVD-A @ 24/192, I think you will hear the shortcomings of the limited bandwidth. In this regard, you might say that Class D is reducing what XX HighEnd software and (future) filter less DAC is trying to improve…

Also, there is so much global feedback in Class D. With traditional amplifier design, we have learn that the less feedback, the better sound. But with Class D it's "all feedback" as far as I have understood. I would guess this also puts its signature on the sound. But, I have not heard the Hypex modules, so it's only a speculation by me. But I have heard the B&O ICE modules in my system, and they are cr*p sounding in a highend perspective. (But OK for mid-fi/consumer sound systems).

About PeakTech:

I googled a little and it seems like it's a German company. Here is their website: http://www.peaktech.de/products/kategorie/dc-netzgeraete.html

They are specialized in "hospital grade equipment". Seems they have DC PSU in 2 categories: Linear and Switching Mode. (Maybe they sell linear to hospital enviroments which are sensitive to RF radiation?)
Judging from their product range, there are several options. To replace a ATX psu I have to buy 4 pcs PeakTech 6080? Is that so? Or maybe another model?

Anyone with some experience here?

This is very interesting. If they do it "right" I think they can sell hundreds, as PC-audio is catching on.

Mass-production, universal technology and the "China-effect" has brought down the price and lifted the performance on all kinds of stereo equipment. That's a fact, and that's very fortunate for all of us. Today you can purchase a "highend" system at unbelivable low price. But, there are still some factors which cannot be bought cheap. One of them is oversized clean power supplies. Here, I belive there are big improvements to be made.

A couple of years ago, Stereophile published jitter measurements from a Mac laptop running on its battery vs. the standard external switchmode powersupply. The jitter increased 10-fold with the switchmode in use...

This is really a no-brainer. Practically all PC powersupplies are rubbish switchmode or semi-rubbish switchmode quality, both letting through and generating new distorition into the audio signal, digital and analoge.

Upgrading to external powersupply is probably one of the best upgrades you can do to a media-PC. Unfortunately there is not so many to choose from. My dream is to find (or build) an overkill linear powersupply meeting the ATX standard with the 3 voltages:
+5V     for motherboard electronics, disk drives and cards
+12V   for disk drives and some cards
+3.3V  for the majority of modern logic electronics in motherboard
-12V   for some accessory cards

(Heat/silent cooling is also an issue. May it should feature big passive cooling wings?)


If anybody can find such a thing, please inform me!


EDIT: Here is a link to DIY Audio about the same thing: http://www.diyaudio.com/forums/power-supplies/100095-linear-pc-power-supply.html

Yes, I have made som reflections about the same. My experience and taste, say that also classical and acoustic music can be played with higher volume "than normal", BECAUSE most instruments are recorded with mic's very close to the instrument.

Through our hi-fi systems we are listening to the recording from the perspective of the microphones (and how they are mixed). A few record companies use single stereo mics placed quite far away from the instruments. Then the "correct" playback volume is quite low.
But most of the time the mic's are very close to the instruments, and then I prefer to turn up the volume. I mean, if I was sitting on a chair 50cm away from Anne-Sophie Mutter, then the live volume would be high too.

Same goes for acoustic guitar. The pick-up/mic is very close. In my system I can play such recordings at +100dB without boom. It just sounds "big", like it would if I had the instrument just in front of my nose.