Help please using an external audio interface

The onboard sound card is bypassed. You would select the native ASIO driver of your new sound card as the audio driver in a drop down menu in the preferences of Pianoteq. The digital data would go from your CPU to the new card, where it would then be converted to analog using its higher quality DACs and amps. With a good sound card/driver, you would experience quite an increase in quality.

I disagree. USB introduced latency is negligible compared to the one introduced by many internal sound cards drivers. A friend of mine just tested a very cheap Tascam US-144 MKII interface on his Macbook and saw a considerable improvement both in the sound and in the perfomance: he had "cracks" when playing many notes together (he's quite good at it!) and now he may just play as he wants. Try it for yourself if possible, you' ll see. The difference is even bigger on most PC's.

The external interface is basically just another soundcard, but with better components and a native ASIO driver.  So you connect this to an amplifier or headphones just like your built-in sound card.  Amplifiers usually have several inputs, so you can run both cards into it and switch between them.

Most interfaces will also work for normal system sounds, so you can completely replace the in-built card if you like (sometimes this can actually be completely disabled in the computer's BIOS).

Or you can dedicate the built-in one to system sounds (eg. through cheap multimedia speakers when you're just doing non-PT things), and the external one for ASIO use.  That's how I use it, my 'pro audio' goes through a better amp and studio monitors, my inbuilt is just going through cheap PC speakers.

I can personally vouch for the Asus Xonar Essence series as matching the sound fidelity of the most expensive cards. I have the internal ST, which takes up a standard pci slot. There is also the STX which uses one pci express slot internally. Both require molex for clean power direct from the power supply.

You will probably want the STU, which plugs in externally, and features the same circuitry with better op amps than the ST/STX (you've got to change those manually for the internal cards if you want the better ones). If you've a PC and you go with an internal version of the card, you can use the 'Unixonar drivers', which are improved third party drivers for the cards.

I've done some audio latency measurements, and I'd like to illustrate the sound card (audio interface) situation with some figures. The latencies are the delay of the sound with respect to the internal sound of my Kawai MP6. The latencies are not the latencies between a key press and a sound, and they are also not the values reported by Pianoteq in the Options. I use a mixer and send the Kawai sound in the right channel and the Pianoteq sound in the left, record the output from the mixer, and analyze the audio file in Sonic Visualiser. I recorded the C3 key sound played at the fortissimo velocity.

The integrated sound card in my 2 years old Asus laptop has a latency of 8 ms. The integrated card in my desktop PC produces a latency of 7 ms. The buffer size of 128 samples was in both measurements. A USB sound card (Sound Blaster X-fi - I know, it is a cheap one) run with the same buffer size has a latency of 13 ms. On the other hand, the Sound Blaster is capable of running with a 64 sample buffer and in this case the latency drops back to 8 ms.

To summarize, if you bought a USB sound card, the latency might actually stay the same, and the sound quality would be better. I suspect that a good PCI express or PCI card would be improve both latency and quality (assuming you have a desktop computer).

I think this thread is about "how to implement an audio interface", which basically boils down to being able to choose a suitable one in terms of audio latency and quality. Sound cards are connected in three different ways: by USB, Firewire (I have no such hardware, cannot test it) or PCI express (or PCI). A point was raised that an external USB interface introduces extra latency.

I've shown that latency is indeed introduced (about 5 ms, it will depend on the operating system, I use Linux), but this effect can be counteracted by smaller buffer size (ASIO buffer size under Windows). So, in effect, the total latency might stay about the same. But I don't think that an external USB sound card would actually significantly decrease latency. Well, at least not under Linux.

In the Linux world, there is no ASIO. We use a sound server called "jack", which is not a sound card driver (a driver is a different thing). Such a solution is actually more flexible, because we even can use our crappy motherboard-integrated sound cards with buffer sizes of 128 or 256 samples (64 sample buffers are too small and the jack server doesn't run with them). Whereas under Windows, a sound card without ASIO support in the driver (or using ASIO4ALL) would probably use a buffer of 1024 samples (I've no idea), which results in noticeable latency. Any attempts to reach buffer sizes of 256 or lower would probably fail. I think this has also been mentioned in this thread:

The numbers I shared are "relative" latencies. I've just made this term up. I basically measure the change of delay relative to the Kawai piano sound, and the delay changes when a different sound card or/and different buffer size is used. My Kawai has 4 zones. I let zone 1 play an internal mono piano sound, and connect the instrument into the mixer (balance set to right). Zone 2 sends MIDI signals into the computer, where Pianoteq computes the sound, and again the output of the sound card is connected into the mixer (balance set to left). Then I record the output from the mixer.

So I don't see why the numbers would not be relevant for the choice of a suitable audio interface. I just wanted to show which type of audio interfaces has the lowest latencies (I mean from my personal experience using concrete examples). The round-trip latency is not needed for that purpose. It seems that the ideal choice for someone with a desktop computer is a PCI express card which able to use a 64 sample buffer. Firewire might be the same case as USB, adds some extra latency. Whereas the PCI express interface is used for graphic cards (have you ever seen a graphic card connected by a USB bus? :-) ), so its throughput must be higher, and I guess its latency is also low. I've read some article about increased PCI latency in the case when multiple devices are connected, but PCI express is designed differently.  If I knew this a year ago, I would buy a PCI express card instead of a USB sound card.

Sorry for the long reply. The article on digital audio latency is a good read, BTW.

FWIW, I can go down to the mimum setting (64 samples) using ASIO4ALL on my old Dell E6500 laptop, running Win8.1-64.  This laptop uses an IDT chip. Having said that, using 128 samples (the mimimum for this device) with my USB audio interface does feel like it has better (less) latency - not by a lot though.

Greg.

To elaborate even further, if your integrated sound card can run with a 128 sample buffer (Pianoteq reports latency of 2.7 ms), there is no need for an extra audio interface to improve latency. I cannot comment on sound quality. The equipment I own is cheap, but still, I do like what I hear.

Thank you all for your responses. Bottom line, I set the system to run 128 samples with 2.7 ms latency, and no perceptible latency. It now feels and responds like an acoustic instrument. Simple solutions are the best.