Overall I quite like my Audiophile USB. There is one almost unbeatable advantage that this particular unit can potentially be used for in a high end setting. The TUSB3200 supports Isochronous in Asynchronous mode USB audio protocol. If you set the controls to accept S/PDIF input on the unit...

Both of the above are correct explanations, but there is a deeper truth. If you consider the audio signal as a bandwidth limited channel with a defined signal to noise ratio (which any such signal is) we can define the data bandwidth needed to code it. This is a straightforward application of...

Also, never use a plug design that can be accidentally plugged into something that is not intended for that piece of equipment. For instance a USB or Firewire connector would be a terrible idea - since both connectors have power available in a computer host. It is only a matter of time before...

There are many mixtures of materials that can be used successfully. I would tend to say that the common element in any really good finish is sanding. You simply can't get away without careful sanding between coats. That and a fanatical devotion to cleanliness. Keeping the area really clean and...

I'm curious to know why you have specified the output impedance so low. It seems very stringent. Since it forms a system with the mechanical properties: frictional losses, platter rotational mass, drive belt spring constant, motor mass, and then into the electrical world, all coupled...

Actually they do use steel a great deal on component leads. A good reason for copper is better malleability. It bends easier and is resistant to fatigue. In highly critical applications where reliability matters steel would be bad. At very high frequencies the magnetic properties of steel may...

Quote: Good silver is always better than good copper though, right? Why? It has a very slightly lower resistivity. For audio purposes that is it. Your amp is a very nice neat build. However if you were to rewire it so that all those nice right angle wire dressings were replaced by...

You really need to ask yourself why you think there is any reason that changing the wire will make any difference. What physics is involved? If you want a better conductor, why not use thicker copper? If the silver wire is even one wire gauge thinner than the copper it replaces it will have...

Bah! Double post....

A common cause of noisy pots is DC on the pots. This sounds suspiciously possible given the symptoms you describe. I would check the ground potentials and PS layout. Something sounds very odd here, not just the pot noise. There is a hint of somthing amiss in the wiring or layout that is leading...

The speaker is essentially the same as a Magneplanar speaker - as invented by Winey. The voice coil is what you see - an etched spiral on the membrane. The magnet is a rare-earth type with its pole facing out. It isn't what purists would regard as a true ribbon. Intrinsically there is no...

OK, I think we are much on the same page. The "no feedback" is a bit of a red rag on occasion. I do rather suspect that the negative impedance amp will be difficult. I would really want to see some sort of stability analysis. Since you have the headphones in the loop I do worry about...

Looks a lot like Omnigraffle to me. www.omnigroup.com of course if you are stuck in the dark ages and don't have a Mac....

A couple of thoughts. I guess the DC adjust might be a source of noise injection depending upon how you drive it. But a more philosophical criticism. With all the distain of feedback, and desire to avoid it, it seems rather strange to see a negative impedance output amplifer - which is...

Well if you really do demand simply the best - yup, go browse the Amphenol or AMP catalogues. They will have exactly what you need. But getting one easily might be a bit harder. I just drove down to Jaycar and bought what I needed. If I were assembling an order to Digikey I might look to a more...

Absolutely. Never for a moment think of passing power in a 3 pin XLR, 3.5mm phono, 6mm phono, RCA, etc. I figure the microphone connectors are reasonably safe as their real use (microphones for tranceivers) is likey to be quite distinct from audio use. An evil trick you can pull is to use a...

I always use screw in microphone type connectors. They are about the best commonly available connector for this purpose. Available in at least 2,4, or 5 pins. I use a two pin for a STEPS/PPA and four pin for +/-/gnd, and one can also use the many pinned variants so that you can set your system...

There do exist optical to coax S/PDIF converters - they are pretty popular due to the needs of home theatre. It is just that you can only expect the (poor)performance inherent optical, at best. But it would probably beat the AX's internal DAC. Using an optical input with a S/PDIF coax based kit...

Sadly the Chimera Labs (why are these places always "labs"?) tutorial doesn't actually create a real Litz braid. But then again most audio places don't either. Although the tutorial does touch on the history, it does fail to understand what is going on, and has the usual slab of pseudo-science...

The problem with optical to coax, is that you get all the jitter inherent in the awful TOTX TORX interface (which is quite dreadful) plus the problems in your coax transmitter, the cable, and the quality of the receiver. It will work, but the DAC will have a rotten time of getting back a clean...

The Airport Express only provides optical S/PDIF. You can of course get an after market optical to coax converter. The jitter charateristics of this may be, um, not the greatest. But it will work. The Airpport Express does of course also have a PCM2704 DAC inside. The quality is, well...

This has the danger of getting into cable wars. Both capacitance and inductance are not intrinsic properties of materials. So you will never find such data. They are properties of a geometrical arrangement of conductors. Where the conductors need to be very close together we may employ an...

Quote: Two ground planes connected at a single point. Should it be disregarded? If not, how these grounds should be connected to the DAC ground? No, don't disregard this. We are no longer in DAC land. We are back in audio land. The charge pump runs at 320kHz, which is not RF (not...

Be careful when you worry about the grounds. The idea of somehow improving things by separating the DAC proper analog grounds from the digital ground with a resistor is widely discredited, and if you read back to my initial commentary on the layout you can see the reasons why. "Fixing the...

OK, I tend to agree on visceral side of things. But in the interests of furthering the technical side, a few thoughts. The headphone output of an iPod or clone, is low impedance, designed to power headphones. In order to mix in the microphone output you will need to do a few things...