DGX-670 versus PSR-SX920 USB Audio Interface.

[Tully]

Hi, I started out asking questions on this forum some 10 years back having purchased a PSR-S950. Recently it was damaged so time to move on. I used it with a UR44 Steinberg audio interface and ran a USB line from the UR44 to the computer and or IPAD PRO.Ran speaker lines to 2 external  studio monitors from the UR44.

That all worked great. Today however I am confused .The DGX-670 has an"Audio Interface" built in to allow direct connection to host-computer or IPAD. The SX920 evidently does not the same built in chip/hardware and so some say to run from the SX920 through an audio interface then to the computer.

The Yamaha SX920 manual suggests connection directly to the host/computer/IPAD.No mention of through an audio interface. What is the difference between the DGX-670 and SX920 regarding audio interface ? What data is actually transferred in both cases. Just digital   Just midi. Any clarification greatly appreciated.Thank you.Tully

[BogdanH]

hi Tully,

..The DGX-670 has an"Audio Interface" built in to allow direct connection to host-computer or IPAD. The SX920 evidently does not the same built in chip/hardware...
...
What is the difference between the DGX-670 and SX920 regarding audio interface ?

You answered the question by yourself: The difference is, SX920 doesn't have audio interface built-in.

What data is actually transferred in both cases. Just digital  Just midi.

Any data sent over USB can only be digital. That is, analog signal can not be transmitted over USB. For analog audio, analog connections are used (Line in/out, Aux, phones).

Files, midi data, audio data.. all that is digital data. The difference is, each of these three uses different transmission protocol. That is, both sides (sender and transmitter) need to understand the protocol. For example, sender has "I am transmitting MIDI data" state, but receiver must be able to understand what that means and how to deal with that data.
SX920 doesn't have audio interface built-in and so it can not covert analog signal (that exist on Line-Out) into digital signal that's needed for USB.
That is, USB (Host) connector on SX920 can only have "I'm sending file data" or "I'm sending midi data" state -it can not have "I'm sending audio data" state.

I hope all that makes sense to you 

Bogdan

[Tully]

Hello Bogdan,  very much appreciate your help with my understanding of this issue. It leaves  me with unresolved questions for which there may be no answers.

1- Why would Yamaha design the DGX 670 with an audio interface and specify in the manual for the 670 that the interface "gives you clear sound in which the sound quality has less noise and deterioration than that from the AUX IN jack" and therefore not provide the same improvement to their higher cost models ie the sx920?

2- Again why would Yamaha not specify in the 920 manual to connect the instrument to an audio interface for the reasons cited above in 1. and state in the manual to simply  connect using the USB from keyboard to computer ?

Same thing occurred with my PSR 950, no mention of improved signals going in and sound out using an audio  interface.

If anyone has the answers direct from Yamaha already I would love to hear them.Otherwise I will continue to do as I have done for 10 years with a new instrument sx 920. Hopefully others love this instrument as much as my old 950.

Tully

[LaHawk]

Why? We've been asking that question for years. Why would upper tier Yamaha arranger keyboards not have a built in Audio Interface while lower tier (Yamaha DGX-670 for example) does? Yamaha's answer is to use the built in audio recorder, or use an external Audio Interface. Bad answers. Anyway it is what it is, and all we can do is keep complaining to Yamaha.

I believe the direct connection you may be referring to (from the SX920 to a PC) is midi data only. That should be noted in the user manual.

[BogdanH]

@Tully
Technically, if both interfaces (internal and external) have equal parameters, then there's no difference in audio quality. However, most external audio interfaces allow higher sampling rates and bit-depths. Keyboards are usually fixed to 44100Hz/16bit and so external interfaces are considered as higher quality.

The reason why built-in audio interface is usually preferred is the convenience: plug keyboard directly to PC and we can start recording.
But that has also downsides. One of the downsides is, it has only two channels (stereo). That is, if we connect a microphone and/or a guitar on keyboard, then everything will be down-mixed to stereo: sound will contain keyboard audio (what we play) and microphone/guitar audio. Means, we cannot later separately adjust microphone/guitar loudness.

With external audio interface that's not a problem. We can connect keyboard (=stereo), microphone and guitar, and we can record four separate synchronized tracks on PC.
Obviously, for that to be possible, external audio interface must have multi-channel capability. I say that because (for example), Yamaha AG03 & AG06 mixer only has two channel audio interface.

About noise when external audio interface is used...
Nowadays audio interface circuits are of such high quality, that we shouldn't worry about that (by assuming we have a decent brand). The only place where noise/distortion can occur, is audio cable(s). And again, if cables are of decent quality and are not too long, then there's nothing to worry about.

I agree, it's nice to have built-in audio interface... if nothing else, we need less cables to quickly record something. But then, if two channels are enough, then we can also record without cables: by using USB stick 

Bogdan

[Tully]

thank you again Bogdan. You have been very helpful.We do not yet have the 920 available throughout Canada. Supply issues.More later.
Tully

[Amwilburn]

thank you again Bogdan. You have been very helpful.We do not yet have the 920 available throughout Canada. Supply issues.More later.
Tully

I mean yeah, we sold out in the month of December, but we received a bunch of stock last week...?

So should the rest of Canada,

Mark

[Gudvi]

Models such as SX700, SX900, SX920, and Genos use the SWP70 chip, which does not support USB audio. Genos2 has added a new chip to support USB audio.

[kriom]

Hello Bogdan,  very much appreciate your help with my understanding of this issue. It leaves  me with unresolved questions for which there may be no answers.

1- Why would Yamaha design the DGX 670 with an audio interface and specify in the manual for the 670 that the interface "gives you clear sound in which the sound quality has less noise and deterioration than that from the AUX IN jack" and therefore not provide the same improvement to their higher cost models ie the sx920?

2- Again why would Yamaha not specify in the 920 manual to connect the instrument to an audio interface for the reasons cited above in 1. and state in the manual to simply  connect using the USB from keyboard to computer ?

Same thing occurred with my PSR 950, no mention of improved signals going in and sound out using an audio  interface.

If anyone has the answers direct from Yamaha already I would love to hear them.Otherwise I will continue to do as I have done for 10 years with a new instrument sx 920. Hopefully others love this instrument as much as my old 950.

Tully

I think that sx920 is based on the same hardware platform as sx900, while DGX 670 is somehow similar to SX600, that was developed after SX900/700 and has some advantages, like USB audio interface.
Unfortunately, Yamaha didn't make any efforts to make SX920 better and it's outdated from the start.
Nevertheless, I bought sx920 as a SX600 replacement.

[BogdanH]

I think that sx920 is based on the same hardware platform as sx900, while DGX 670 is somehow similar to SX600, that was developed after SX900/700 and has some advantages, like USB audio interface.

I think you're right on this.

Unfortunately, Yamaha didn't make any efforts to make SX920 better and it's outdated from the start.

Here I disagree about "outdated". I would say it's well featured midrange arranger and so I can only congrats you for buying it. 

Bogdan