I'm not much here anymore either. I've got too little time to browse many forums and I've simply drifted to diyaudio.com because it suited me better. More technical minded, more diverse, more alive. And my all time favorite poster here is more active there (jcx).   My opinion is that head-fi's...

Here's a little amp. It's very simple: external 30vdc wallwart, regulated down to 24vdc. Opa134 in unity gain with a class A buffer in the loop followed by transformers set for a voltage gain of 2. All cased up in an old NAS box (I still have to find a nice frontplate, so no external pictures)...

It's been a while I didn't post something.   Here's a small amp inspired by the Van Waarde/Crack kind of things. Tubes are Mullard ecc82 and Syvlania 6080wc Quite tubey without surprise but still fun into hd650.       For the guys with good eyes: the red standoffs were to mount small...

Last time I checked (two minutes ago), the pcm2704C doesn't offer I2S out, only spdif... Only the pcm2706-pcm2707 offer I2S out.

There isn't anything magical about the speedball upgrade. Those are simple CCS, which could very easily be wired on perfboard. Schematics for similar ccs can be found here:   http://www.pastisch.se/faktiskt/diyAudio-CCS-beta3.pdf

Well, I did my own: http://www.head-fi.org/t/733177/usb-powered-dac-amp-musings/30   Works really well :-)

http://headwize.com/?page_id=427   This is very, very close in topology to the Crack. The Crack is one of the most basic designs around. 

      A good reason to wait a bit :-) I'm curious to see what you came up with, considering the use of the same output transformers. 

  Tomb and/or Dsavitsk will confirm/infirm... from memory, Edcor's rating are for DC draw with a capacitor input supply. Most other manufacturers specify their transformers for AC current (which means you have to derate them by a factor of almost 2).       as an aside: if you guys aren't...

  The Dragonfly uses the ES9023 actually. The wm8740 is used by Amb in his gamma 1.5 for example.    Those opamps are good audio opamps. The opa1612 swings closer to the rails at first sight, that might be a factor for a portable design.

  In the context of a I/V, the CMRR is pretty much irrelevant to crosstalk (have a look at the numbers achieved by the pcm1794 datasheet circuit). The only benefit you gain is wrt lower noise as you cancel the noise coming from the DAC analog supply (and some H2 cancellation). In the case of...

Out of curiosity... why do you want to sim the heaters of indirectly heated tubes ? I mean, you can pretty much simulate them with a resistor and a bit of common sense.   This thread is a goldmine too: http://www.diyaudio.com/forums/tubes-valves/243950-vacuum-tube-spice-models.html

  disclaimer: answering from a technical point of view.   There is little point in going for a instrumentation amplifier at this point. The output impedance of the I/V stages are usually well matched and quite low on one hand and, on the other hand, the extra load the differential amplifier...

  Not really. It would include considering what capacitors you put in //, their respective esr, capacitance, etc. It could include using tantalum mostly for RC filters and avoid places which could confront the caps to extremely fast charge-discharge.   To back up the tantalum's audiophile...

http://www.cordellaudio.com/papers/another_view_of_tim.pdf http://www.cordellaudio.com/papers/another_view_of_tim_II.pdf

  I'd rather say that tantalums aren't usually recommended for audio by audiophiles with too little electronics knowledge to implement them properly. They're perfectly fine if you know how to use them. Actually, as long as you don't do anything stupid such as forgetting to derate their voltage...

  There are four functions that possibly need to be adressed after a DAC.   -1- Current to voltage conversion: some (not all) ICs do not produce a voltage output but a current output. Typical example: the pcm1792-4-8 serie from TI.  -2- Filtering: a typical DA process require a...

Some people have had success writing code for the TAS1020B too. But I think it only does 24/96 (which is already more than waht is necessary imo).   Or, if you don't want to reinvent the wheel, I've had good results with this...

- No. - With the 22uF electrolytic oriented the wrong way, like it is, it will go boom and could send 9V into your line in device. - They don't make any sense. R1 limits the AC current going through the caps (and the current required from the line in device) but, in fact, this current will...

@customcoco: on your parafeed amp, the high gain position has a +/- 58r output impedance and the low gain position about 10r. Time to test ;-)

I cannot resist posting a pic of an amp in progress. It's kind of the opposite of my most recent project (a small usb dac-amp). It's a rebuild of this amp in order to use some parts I had stashed around.    Ridiculously big caps ? Check. Ridiculously big stepped attenuator ? Check...

And the final result, DAC+amp:    Frequency response (from 40 Hz to 15 kHz), dB +0.50, +0.45 Excellent Noise level, dB (A) -94.1 Very good Dynamic range, dB (A) 94.1 Very good THD, % 0.0018 Excellent THD + Noise, dB (A) -85.7 Good IMD + Noise, % 0.0063 Excellent Stereo...

Allright, I built the amp part and cased the whole thing. I had no time for stability testing nor noise or thd measurement yet. But offset is at 3-4mV and the amp is silent into average headphones (I've got no sensitive IEM).   Building the amp was actually more difficult than the DAC. A first...

The DAC is alive  :-)   No drama, everything works as planned.    Here's a RMAA summary at 16bits/44.1KHz, with a PCM5101 rather than a PCM5102. The setup is pretty awful, there is some 50hz hash as the board sits near the computer and long unshielded cables go to the soundcard. The DAC is...

How could you not love Mouser fast shipping ?  I received the parts.  It's nice to see how compact that Hammond case is in real life.   The good news is that my eagle home made libraries seem ok (especially for the headphones jack and that kind of things).   Let's heat the soldering iron !