justin

Here are some of the testing results.... A note on the frequency response....currently waiting for a part, so the bass roll-off is about -2dB at 20Hz until I get it. The final version will not have this roll-off. Frequency Response Noise Level Dynamic Range THD+Noise (0.0007%!) Intermodulation Distortion (0.0058%!) Stereo Crosstalk IMD (Swept Tones)

I'm going to be previewing a new portable USB DAC/Amp -- no official name yet -- at the Maryland meet next weekend, in the form of a working prototype circuit board. I'll have it hooked up to a MacBook with lossless FLAC. There are several portable USB DAC/Amps available but all of them use the same DAC design -- one of the all-in-one chips from TI which has a USB receiver, 16-bit DAC, and analog/headphone output stage. This chip is really intended for use in things like cheap USB speakers, LCD monitors w/ built-in speakers, and the performance is not very good (my prototype has 10% the THD of this chip, and that's including my headphone amp stage set at a gain of 6 capable of driving all headphones). Some features of this new USB DAC/Amp, most of which have never been done before in a portable DAC/amp or even just a portable DAC: - Upsampling design! - Uses a flagship level 24-bit/192KHz digital-to-analog converter chip! - Extremely low distortion analog filter - Protects USB ports from over-current - Extreme care in keeping noise to a minimum, separate power supplies for each stage - 4-layer circuit board for optimum digital layout - Separate analog input to use as headphone amp only - Gain switch (toggle) on front panel - Alps volume control w/ built-in power switch - Lithium-polymer battery (estimated 35 hours, or 70 hours w/ extended battery option) - Built-in battery charger w/ charge status LED on front panel (2-4 hour charge time depending on battery option) - Back panel has the USB jack (Mini- and DC adapter jack Also, it is very, very small -- within 5% of the size of some amps designed for IEMs only. I'm very excited about this new design and have been spending a lot of time revisiting my FLAC library with my MacBook I got a few weeks ago. Nothing like this has ever been done before, except in home wall-powered DACs 10 to 100 times the size of this portable. I'm going to be having a beta test of 5 to 10 units after I complete the 2nd prototype, and there are probably about 2 spots still open for that. I may post some early distortion/noise/frequency response measurements this week before the meet. There will be 2 versions available (the DAC/Amp, or just the Amp), an option of the regular battery or extended battery, and several color choices.

What is it, a 2.5mm jack? I think that's standard on phones

Did you put the ZD on top of the FirstWatt?

Unless he bought it from grawk/tkam it sounds like sloppy fourths

If you're that concerned, spend $100 (just an estimate) on an SPL meter. Only 1% the cost of the rig you just bought. I think anything over 80dB for an extended period of time can cause permanent damage.

Peter, Are you going to have them at the July maryland meet?

Cases are expensive but they make or break a product. Most expensive cases I have had were for the Aristaeus which cost me $900 for the set, more if I had to pay someone to do the drawings.

I wonder if they had a fountain pen war on that forum It all started when someone posted pictures of the inside of a Conrad-Shiffler-Stewartsharp pen

The only reason the TDA chips became popular is because it is so easy to build a DAC with them, if you can build a cmoy you can almost build a TDA154X DAC.

old DACs are the new tubes!

It's good to know the quad Alps RK27 exists. It's not in the Alps datasheet

I know Tyll has always said 5% of his sales come from Head-Fi. But for the "Head-Fi manufacturers" like myself and many others, most of our sales come from Head-Fi. And it's extremely difficult to keep the spotlight on a product on Head-Fi for more than the first few months. From my experience, if my amps are being mentioned somewhere on Page 1 of the amp forum, they'll sell. If not, they won't sell. There doesn't seem to be much in the middle. Maybe this is just the nature of doing business on an internet forum. I think this is what is driving a lot of constant revisions and new models, not manufacturer greed.

It's been a while, but i finally got around to taking photos of the AE-2 and putting up a new page on it: http://www.headamp.com/portable_amps/ae2/index.htm I'm not much of a photographer and I wasn't able to get any photos that show the laser engraving on the silver amp -- it's easily visible under normal house lighting. I'm open to suggestions on how to improve that

I've had this happen a few times before, only with "new" tubes and somewhere in the first hour of their use, but after that no problems. You could possibly avoid this by extensively burning in all tubes with a dummy load on the amp. When I mentioned this to KG, he said Atmasphere had the same problem and just burned in all the tubes for 100 hours at full current before use

Polypropylene capacitors of that value are huge, and very expensive. Solen makes a 220uF 400V, it's $50 at partsconnexion...it's about the size of a coke can

You can also use it when making pasta

I haven't had a good opportunity yet to take photos of the AE-2, but here is the circuit board. I took these photos a while ago, when I was waiting for the enclosures.

There is about 2000 feet of wire inside each Aristaeus transformer, I would not want to wind that myself

Right now I'm shipping the backorders, and all of them will be sent out by next week. Then, I'll take some pictures and put out some more information.

Do you think I should make a Louis Vuitton edition?

More info to come this weekend...

I haven't, but I would definitely trust the Pass stuff.

Nah....make the Pass Labs Ono! http://www.passdiy.com/gallery/alephono-p5.htm Or start with the Pearl Phono http://www.passdiy.com/projects/pearlono1.htm

I'm going to be raffling off a Porsche 911