Allo USBridge Signature

[Tim Curtis]

The port power specs for the SIG are at this link
https://allo.com/sparky/usbridge-signature-pcb.html

MQA is not Open Source so not possible to support in moOde.

[Manni]

Hello,

Prioir to ordering USBridge Sig want to clarify couple of questions:
1. Will USBridge Sig is able to power DAC via clean USB port, as my DAC unfortunatelly doesn`t have separate power input except USB?
2. Is there any possiblity to play MQA via moOde? or its possible only when working as Roon endpoint ?

Not sure that this forum is proper place to find those out, pls re-direct me to more appropriate one if required.
Thanks in advance fore replies.

To your 2nd question:

Yes you can stream MQA files from Tidal, but it will be not in original MQA format. I use 2 ways to stream to my Allo USBridge Signature which is running moOde OS.
I do not use the moOde control directly, instead I either run “mconnect” on my iPhone or using Audirvana on my MacBookPro and the Allo USB only as renderer.
With mconnect you can play the MQA files and all will be shown as normal 16/44 flac files.
With Audirvana the software will do the first MQA unfold and than it will be streamed as 24/88 or 24/96 dependent on MQA source material.

I do not care about MQA files, as I do not hear a real difference in sound quality. Be careful, most MQA file are louder than the normal flac files and this suggests better quality, which is not true when you level match the files.
BTW difference in loudness level applies as well to Tidal vs Qubuz. Tidal seems to stream 1-2 dB louder.
.... and then consumer thinks Tidal “ sounds” better but it is the opposite.

[Manni]

@ Tim 

I do have a general question regarding the input vs output bit rate.
When I play a “regular” flac file from Tidal in moOde and look to the audio information I do get following :

Decoded to : 16 bit, 44,1 kHz, Stereo, 550 Kbps 

Output rate : 32 bit, 44,1 kHz, Stereo, 2.822 Mbps

I totally do not understand what is going on in the MPD of moOde??

Is there a kind of upsampling??? It is switched of for sure!!



When I stream a MQA file from “mconnect” app it shows as following:

In the mconnect app it says : Flac, 24bit, 44,1kHz, 1456kbps, MQA Original 44,1kHz

In moOde Audio information I read for that file:

Decoded to : 24bit, 44,1kHz, Stereo, 1.677mbps

Output rate : 32bit, 44,1kHz, Stereo, 2.822Mbps

Tim, please let me understand the difference between Kbps and mbps and Mbps.
Yes, it is not a typing error, these are what is shown on audio information and concerns me.

Sorry, I do habe screen shots but don’t know how to attach them here.

Thanks.

[Tim Curtis]

Ask the maintainers of the mconnect application about what's being reported by their app. I have no idea what they are doing.

moOde reports the rate and bit depth that is being sent to the audio device by ALSA. If the audio device reports to Linux that it only accepts 32 bit then ALSA will zero pad.

[Tim Curtis]

Here's an explanation of the abbreviations.
https://en.wikipedia.org/wiki/Data-rate_units

Scanning the moOde sources for case sensitive 'mbps' showed two occurrences :-0

Bug fixed :-)

[Manni]

Here's an explanation of the abbreviations.
https://en.wikipedia.org/wiki/Data-rate_units

Scanning the moOde sources for case sensitive 'mbps' showed two occurrences :-0

Bug fixed :-)

Thx Tim,

I do know what the abbreviations are and this is why I was concerned.

When input is kbps and output is in mbps there is a kind of multiplication.
As well I was not sure how to read the output rate of 2.822 mbps= Is it 2822 kbps or 2822 mbps.

A standard CD red book format in wav or AIFF would be input 16bit/44,1kHz/Stereo/ 1411kbps.

My DAC can accept 32bit/786kHz. The Allo USBridge Signature seems to handle 24bit/192 kHz as UPNP player.

I wonder why the output bit rate of 2822 Kbps seems to be twice (2x) the standard red book CD 1411 Kbps input bit rate.

I think it has nothing to do with mconnect as the same applies when I run Audirvana on my MBP and stream to Allo USBridge with moOde. In the moOde Audio Info I see same differences between input and output.

Sorry, do not understand your last comment regarding bug fix??

[Tim Curtis]

Output stream rate = bit depth X sample rate X number channels

For 16/44.1 Stereo
16 * 44100 * 2 = 1411200 bps = 1411.2 kbps = 1.4112 Mbps

When bit depth is 32
32 * 44100 * 2 = 2822400 bps = 2822.4 kbps = 2.8224 Mbps

[TheOldPresbyope]

Perhaps there's an ambiguity because of the difference in formatting of numbers in US/UK English and, for example, German. The usage of the comma and the period/full stop is reversed (or at least they were when I was still active in international standards groups).

In US/UK English this period means decimal point

2.822 Mbps = 2 822 000 bps

While in German this period means 3-digit (eg, thousands) separator

2.822 Mbps = 2 822 Mbps


where on the right-hand side of each I have used the standards-preferred space to separate 3-digit groups. (In type setting this would be a "thin" space.)

Meanwhile, 1.5 in English usage = 1,5 in German usage

Any other regional usages?

Regards,
Kent

[Manni]

Output stream rate = bit depth X sample rate X number channels

For 16/44.1 Stereo
16 * 44100 * 2 = 1411200 bps = 1411.2 kbps = 1.4112 Mbps

When bit depth is 32
32 * 44100 * 2 = 2822400 bps = 2822.4 kbps = 2.8224 Mbps

Thx for the quick reply, yes I thought it’s got to be like this.

It works out only for the WAV files, where input is 1411kbps.

Why is then flac input, which is dependent on file lower than 1411 as well output at 2822kbps??? ( see above sample in my initial post)

And for all different kind of hirez files like 24/88, 24/96, 24/176, 24/192 kHz in Audio info the “decoded to” shows always 32bit, XX kHz, Stereo, Y.YYY mbps.
Hereby the Bitrate Y.YYY mbps is always the multiple from 24bit x XXkHz x 2.

And output is shown as 32bit, XX kHz, Stereo, Y.YYY Mbps, hereby the Bitrate Y.YYY is the multiple of 32bits x XX kHx x 2 


But ...

the moOde software shows 32 bit and is set to it,  but the Allo USBridge seems to only accept max 24bit as statet above. In Audirvana it shows up as UPNP player with 24 bit. When I change the settings to 32 bit, it does not work properly.
So I wonder what the real Bitrate is, and more of, is it still bit perfect or modified??

It is just for interest, as it nevertheless sound good to my ears

[Tim Curtis]

FLAC is a compressed format and like other compressed formats will be decoded into the original PCM source at a given variable bitrate. For example 16/44.1 CD material encoded to FLAC typically decodes at around 700 to 900 kbps. I would imagine that 24/44.1 material encoded to FLAC will decode to PCM at around 1500 kbps.

The Audio info screen shows a snapshot of the decode bitrate reported by MPD. Each time you open Audio info the bitrate will most likely be different.

As I explained earlier the output rate represents the final PCM stream thats being sent to your audio device. If your audio device reports to Linux that it requires 32 bit word length ALSA will zero-pad to 32.

There were two misspellings of "Mbps" I found in the code and so these bugs have been fixed. Otherwise the information from Audio info that you posted looks perfect.