USB Bridge

I admit I've never looked into the details of XMOS designs, but a more powerful processing engine/more memory can't be a bad thing as designers face fewer constraints when writing processing code and can deal with some situations that can arise without or making fewer compromises. That is probably where the improvements come from, if there are any.
 
for_p1 thanks for the info, it makes a lot of sense since development r&d is the major barrier to entry

the Chinese copy & pirate everything- until I read XMOS stereo was free I had assumed the supplied drivers were cracked versions of xmos commercial software

I don't believe XMOS is truly open source- the driver they supply is actually for "evaluation" and only supports stereo. multichannel is definitely proprietary.

some of the Chinese mfg gustard, breeze, etc actually send modified XMOS unsigned drivers with their products, possibly to circumvent some built in limitations, or to get around the blatant reselling of "evaluation" software commercially


as far as the sonic performance I can't tell you whether its the topology/component/PS change between the u8 and u208 based DDC or its the actual chip itself

I know that the u208 based DDCs sounded better.
 
FLAC is just like ZIP. You can actually take text file and compress it with FLAC. After you decompress it - it will be the same text file.

I don't think that statement is true. Flac's algorithm relies on being able to recognize PCM data in a binary stream such as the sampling rate and bit-depth to run the compression, just a text file won't do.
 
I don't think that statement is true. Flac's algorithm relies on being able to recognize PCM data in a binary stream such as the sampling rate and bit-depth to run the compression, just a text file won't do.

Just put text into WAV container with SOX or specify all parameters as command attributes.
 
Just put text into WAV container with SOX or specify all parameters as command attributes.

WAV container isn't a text file. If you are saying you can compress a WAV file containing noise sure, but it is not the same as compressing a text file.
 
I agree the U208 sounds even better than the U8. The U8 bridge I owned (Audio-gd DI-U8) sounded great but the Breeze U208 is even better. Basically more of the same.
 
WAV container isn't a text file. If you are saying you can compress a WAV file containing noise sure, but it is not the same as compressing a text file.

See below:

user@king2:~$ cat 6ac7-spice.txt
.SUBCKT 6SJ7 A G2 G1 K
BGG GG 0 V=V(G1,K)+0.40161932
BEP EP 0 V=URAMP(V(A,K))+1e-10
BEG EG 0 V=URAMP(V(G1,K))+1e-10
BEG2 EG2 0 V=URAMP(V(G2,K))+1e-10
BM1 M1 0 V=(0.02462593*(URAMP(V(EG2)-1e-10)+1e-10))**-0.84287662
BM2 M2 0 V=(0.64023858*(URAMP(V(GG)+V(EG2)/14.609049)+1e-10))**2.3428766
BP P 0 V=0.0011655656*(URAMP(V(GG)+V(EG2)/22.818133)+1e-10)**1.5
BIK IK 0 V=U(V(GG))*V(P)+(1-U(V(GG)))*0.00071703729*V(M1)*V(M2)
BIG IG 0 V=0.00068041382*V(EG)**1.5*(V(EG)/(V(EP)+V(EG))*1.2+0.4)
BIK2 IK2 0 V=V(IK,IG)*(1-0.4*(EXP(-V(EP)/V(EG2)*15)-EXP(-15)))
BIG2T IG2T 0 V=V(IK2)*(0.78466568*(1-V(EP)/(V(EP)+10))**1.5+0.21533432)
BIK3 IK3 0 V=V(IK2)*(V(EP)+12950)/(V(EG2)+12950)
BIK4 IK4 0 V=V(IK3)-URAMP(V(IK3)-(0.00044226898*(V(EP)+URAMP(V(EG2,EP)))**1.5))
BIP IP 0 V=URAMP(V(IK4,IG2T)-URAMP(V(IK4,IG2T)-(0.00044226898*V(EP)**1.5)))
BIAK A K I=V(IP)+1e-10*V(A,K)
BIG2 G2 K I=URAMP(V(IK4,IP))
BIGK G1 K I=V(IG)
* CAPS
CGA G1 A 0.005p
CGK G1 K 3.6p
C12 G1 G2 2.4p
CAK A K 7p
.ENDS

user@king2:~$ flac --endian big --sign signed --channels 1 --bps 8 --sample-rate 8000 6ac7-spice.txt

flac 1.3.1, Copyright (C) 2000-2009 Josh Coalson, 2011-2014 Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY. This is free software, and you are
welcome to redistribute it under certain conditions. Type `flac' for details.

6ac7-spice.txt: wrote 9107 bytes, ratio=N/A

user@king2:~$ ls -l 6ac7-spice.*
-rw-rw-r-- 1 user user 9107 Jun 8 2013 6ac7-spice.flac
-rw-rw-r-- 1 user user 969 Jun 8 2013 6ac7-spice.txt

user@king2:~$ file 6ac7-spice.flac
6ac7-spice.flac: FLAC audio bitstream data, 8 bit, mono, 8 kHz, 969 samples

user@king2:~$ flac -d --endian big --sign signed --force-raw-format 6ac7-spice.flac

flac 1.3.1, Copyright (C) 2000-2009 Josh Coalson, 2011-2014 Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY. This is free software, and you are
welcome to redistribute it under certain conditions. Type `flac' for details.

6ac7-spice.flac: done

user@king2:~$ ls -l 6ac7-spice.*
-rw-rw-r-- 1 user user 9107 Jun 8 2013 6ac7-spice.flac
-rw-rw-r-- 1 user user 969 Jun 8 2013 6ac7-spice.raw
-rw-rw-r-- 1 user user 969 Jun 8 2013 6ac7-spice.txt

user@king2:~$ cat 6ac7-spice.raw
.SUBCKT 6SJ7 A G2 G1 K
BGG GG 0 V=V(G1,K)+0.40161932
BEP EP 0 V=URAMP(V(A,K))+1e-10
BEG EG 0 V=URAMP(V(G1,K))+1e-10
BEG2 EG2 0 V=URAMP(V(G2,K))+1e-10
BM1 M1 0 V=(0.02462593*(URAMP(V(EG2)-1e-10)+1e-10))**-0.84287662
BM2 M2 0 V=(0.64023858*(URAMP(V(GG)+V(EG2)/14.609049)+1e-10))**2.3428766
BP P 0 V=0.0011655656*(URAMP(V(GG)+V(EG2)/22.818133)+1e-10)**1.5
BIK IK 0 V=U(V(GG))*V(P)+(1-U(V(GG)))*0.00071703729*V(M1)*V(M2)
BIG IG 0 V=0.00068041382*V(EG)**1.5*(V(EG)/(V(EP)+V(EG))*1.2+0.4)
BIK2 IK2 0 V=V(IK,IG)*(1-0.4*(EXP(-V(EP)/V(EG2)*15)-EXP(-15)))
BIG2T IG2T 0 V=V(IK2)*(0.78466568*(1-V(EP)/(V(EP)+10))**1.5+0.21533432)
BIK3 IK3 0 V=V(IK2)*(V(EP)+12950)/(V(EG2)+12950)
BIK4 IK4 0 V=V(IK3)-URAMP(V(IK3)-(0.00044226898*(V(EP)+URAMP(V(EG2,EP)))**1.5))
BIP IP 0 V=URAMP(V(IK4,IG2T)-URAMP(V(IK4,IG2T)-(0.00044226898*V(EP)**1.5)))
BIAK A K I=V(IP)+1e-10*V(A,K)
BIG2 G2 K I=URAMP(V(IK4,IP))
BIGK G1 K I=V(IG)
* CAPS
CGA G1 A 0.005p
CGK G1 K 3.6p
C12 G1 G2 2.4p
CAK A K 7p
.ENDS
 
Fair enough, although close to 10x flac file size as compared to the original txt doesn't quite strike me as compression.
 
Fair enough, although close to 10x flac file size as compared to the original txt doesn't quite strike me as compression.

Metadata + headers. You need a much bigger file than 969 bytes to see some compression.
 
So being that I am a semi old crusty tech and follow most of these threads trying to learn some digital audio stuff I have noticed 2 sides to these discussions. 1) A digital signal is a digital signal. 2) The digital audio signal is from heaven there for special. Now this is just the opinion of someone with over 30 years chasing ones and zeros through Sonar equipment and I am probably wrong, I hear and understand all the examples but I tend to be a believer in #1 so far. If I am way off I apologize.

:beerchug:


Gates.gif
 
Last edited:
:lurk: Wow, I am an old fart who never really understood how a transistor does its thing. I am in the process of upgrading from behringer 202's and hope to be able to hear some difference after installing a Topping D30. I compare this to back in the day moving up from cheap BSR and Garrard changers to a Dual with a nice shure cartridge. I love being able to store all of my music on a digital format so there is no way to avoid the digital to analog interface. But I never really upgraded very far above the Dual TT and I don't plan on spending big dollars ($200 for any one piece really slows me down) for digital audio
 
Yeah that’s right, it is just 1s and 0s, and vinyl is just a grove pressed in plastic....
 
After all I decided not to take my chances with the Breeze Audio unit mainly because of the missing drivers for W7 and bought a pre-owned Matrix Audio X-SPDIF 2: http://matrix-digi-usa.com/x-series/x-spdif_2 . About 2x the price of the top-level Breeze but solid build, can run off USB or external power, official drivers. Won't comment on how it compares to the previous gen of XMOS or other USB interfaces but it is a definite improvement over Toslink out of a laptop Creative Sound Blaster card which I thought sounded kind of lean and on the bright side, and indeed the gains in the low-end and low mid-range are huge. So much for the "bit-accurate" playback mode on the sound card. The DAC itself doesn't have a USB input, so this purchase was "justified" :)
 
I had hopes for the CCA I got during the most recent sale to be used as a Spotify Client through Toslink to an external DAC but it didn't live up to my expectations. I didn't expect much from its onboard DAC but given many positive reviews here I thought using its optical digital output should be pretty good. To my surprise it wasn't, it is not bad but it sounds somewhat compressed and congested. Using the same optical cable and input on my DAC the sound is much more open and airy when playing Spotify from my laptop, so it is a CCA issue. I suspect its mp3 decoder or the Toslink interface are not up to snuff. Oh well, it's more then adequate for my patio speakers connected to Zone 2 of a Denon receiver and that's where it will be now used.

Well, turned out I was barking up the wrong tree. The CCA and the newly acquired DDC sound much closer so it was the SPDIF out of my sound card messing with my brain. The CCA is fine and "compressed and congested" is how it was supposed to sound. My apologies for the noise.
 
One issue I'm finding annoying is that I can't force the DDC to operate in 16 bit/44.1kHz, or advertise itself as such a device on Windows. Basically it gives an option for apps to pick a mode that is not compatible with the downstream DAC. Generally not an issue with powerful players like JRiver where you can fully control the output mode, but say Tidal Masters MQA->PCM transcoder appears to pick a mode that's incompatible with my vintage DAC (48kHz/16bit max) resulting in weirdness. While it is probably not a very good idea to use a vintage redbook DAC with Tidal masters, for Tidal HiFi I can only hope than the app doesn't dither 16 bits to 24 bits as the DAC just drops LSBs on the floor. Sigh.
 
Damn, I came to this thread because I thought it would be about USB Bridge's.

Instead, we get sidelined with talk about CCA, MQA, FLAC, ZIP & BS.

Sad.
 
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