Topic: R-09 - Does Opitcal out bypass circuitry?? (YES IT DOES!!)

[uncledrax]

Hi Guys,

I have been using the R-09 for a few months to great effect. I have now started using my H120 as a backup using the optical out on the R-09. My question is, if i record with the R-09 using mp3 320kbps, is that 'mp3 sound' sent through the optical out or is it clean??

I'm sorry if this has already been discussed but my search came up with nothing.

Cheers,

Travis

[leshlush]

My question is, if i record with the R-09 using mp3 320kbps, is that 'mp3 sound' sent through the optical out or is it clean??

I may not be the best person to answer this for you but I'll give it a shot...

First of all, by that 'mp3 sound', I'm going to assume you mean the lossy compressed audio sound...

From the way I see it... You're looking to save a lossy copy on the R09 while passing a wave file onto your H120... Unfortunately, I don't think that it is a possibility... Here's why... When you feed the signal into your R09, you're feeding it an analog signal... That signal is then passed through the front-end(or pre) and then onto the ADC (analog to digital converter)... The ADC does just that, it changes the analog signal into a digital signal... Both MP3s and Waves are different typed of digital files... Although an MP3 is just a compressed wave(lossy at that), it is essential a different type of digital format... Whatever type of file you choose to record is the type of conversion that your ADC does... The ADC in the R-09 has the ability to convert your analog signal into all sorts of different mp3 bit-rates or has the ability to convert that analog signal into a few different types of wave bit-depths and frequencies... That being sd, for your unit to be able to produce 2 different digital sources, it would need to have 2 independant ADCs that both fed independantly off of the analog source...

Sorry to say, but I don't think that you'll be able to do it...

Why do you want to record in MP3 on the R09 for anyway?

Is it a size constraint due to your SD card?

If that's the case, I'd say you should try and save for a bigger card... You may even want a big enough card so that you have the space to run 24 bit... Just a thought...

I see that by your post count, you're pretty new around here... This place is great... I'm still fairly new to the game and have been able to learn so much and there's still so much more to learn... Look around, there's so much information to be had and if you gfet in a pinch, everyone around here is great at helping out as best as they can...

And here's a +T for ya...

[Brian Skalinder]

The R-09 has an optical out?

[dorrcoq]

The R-09 has an optical out?

You know, I was going to ask that but thought maybe I was missing something.

[leshlush]

The R-09 has an optical out?

Yeah, it's kinda ridiculous, it has an optical out but not an optical in... You'd think they would have done the opposite for those who would have used it as a bit bucket... I guess that you can use it to patch out, but as far as using to dump your data, it also has a usb 2 so I don't really see the point... but that's just me...

It's digi-out is a mini/mini-optical out, so you can go digi or analog out... I'm not really sure if the analog out is a passthrough or whether it hits the coverters twice... I assume the latter...

[uncledrax]

Thanks for the replies.

I just did a recording last night and the optical out does passthrough any converters. I used tau-analyser and audiochecker to verify the wave file captured by the H120 and it is 99-100% positive it is a CDDA.

But you guys are right, i need to definitely get some bigger sd cards especially now that it supports SDHC.

Thanks.

[leshlush]

I just did a recording last night and the optical out does passthrough any converters. I used tau-analyser and audiochecker to verify the wave file captured by the H120 and it is 99-100% positive it is a CDDA

I'm not that familiar w/ CDDA files, but I'm still pretty positive that the digi-out is not doing what you think it is doing... Is it possible that you're passing the H120 the compressed file and then the H120's onboard ADC is changing it's format to CDDA upon your request... But if that's the case, are you only feeding the H120 the lossy-compressed signal an then the H120 is accounting for the missing information when changing the format to CDDA...

Maybe I'm missing something here, but first let's make sure we're on the same page... The signal that you're feeding the R09 is analog(not digital, the R09 doesn't have any digital inputs) and for that signal to be output through digital, it has to have hit the converters (that's what the ADC does is converts the analog signal into digital)...  So when you say that it passes-through the converters, that's not the case... It has to have gone through the converters for it to be in digital...

Now as for compressed formats like MP3s, maybe it does hit a second stage (a saving stage) where the data is actually compressed to MP3.. To be honest, I don't know the answer to that but it's my understanding that it in fact does the MP3 compression at the same stage that it digitizes the analog signal... I could very well be wrong about that, cause as I told you, I'm not a hundred percent how the MP3 compression takes place or at what stage... To be honest, I don't know alot about MP3s, other than when they first came out, I've actually tried to  stay away from MP3s...

If it in fact does have a second compression stage, what type of bit-depth and frequency wave is the ADC first converting the signal to? I couldn't tell you... And why is it going through 2 stages? And why would the optical-out bypasses the second stage?

As for the file that you're left w/ in the end, I'm not sure what type of analasis that you've performed, but I don't question that you ended up w/ an alt format other than MP3, in fact, I'm sure you did, I'm just not sure what format you fed the H120 to get your final format...

[Roving Sign]

Try setting the R9 to the most compressed mp3 setting - (so you can really hear the mp3-ness) and repeat your experiment...320 sounds too "good" for this experiment...

[uncledrax]

damn, why didnt i think of that!!!

well i the test you suggested. I had the R-09 set to record at 64kbps and had the optical out connected to the H120 (Rockbox-fitted) recording wave files.

I can confirm that the optical out does indeed bypass internal compression/conversion circuitry. If people would like my test files, just speak up and ill post them.

Thanks everyone,

Travis

[Brian Skalinder]

I had the R-09 set to record at 64kbps and had the optical out connected to the H120 (Rockbox-fitted) recording wave files.

I can confirm that the optical out does indeed bypass internal compression/conversion circuitry. If people would like my test files, just speak up and ill post them.

Did you confirm this by ear, or test the resolution of the actual data within the WAV files from the H120?  (I think by ear, if I'm following the thread properly.)  Even if the R-09 outputs 64 kbps data, the H120 will still generate a 16-bit / 44.1 kHz (or whatever) WAV file.  The question is whether the data it contains utilizes the full resolution, or is restricted to 64 kbps.  Post the files?  I'm sure there's some way of testing the data itself, rather than listening by ear.

[beefstew]

I had the R-09 set to record at 64kbps and had the optical out connected to the H120 (Rockbox-fitted) recording wave files.

I can confirm that the optical out does indeed bypass internal compression/conversion circuitry. If people would like my test files, just speak up and ill post them.

Did you confirm this by ear, or test the resolution of the actual data within the WAV files from the H120?  (I think by ear, if I'm following the thread properly.)  Even if the R-09 outputs 64 kbps data, the H120 will still generate a 16-bit / 44.1 kHz (or whatever) WAV file.  The question is whether the data it contains utilizes the full resolution, or is restricted to 64 kbps.  Post the files?  I'm sure there's some way of testing the data itself, rather than listening by ear.

yeah spectral analysis should determine it

[uncledrax]

Here are the files. I dont think a spectral analysis will be needed, trust me. 

http://users.on.net/~uncledrax/r_09.mp3
http://users.on.net/~uncledrax/h120_from_r09.flac

[M]

The mp3 dl isin't working......I got the flac one fine.

[Nick's Picks]

cool.
i've used the optical output of the r9.  nice feature for playback.

[uncledrax]

Yes but what im trying to show is that the optical output acts as a bypass when monitoring recording on the R-09.

[Brian Skalinder]

FWIW, the MP3 link is still bad.

[leshlush]

Yes but what im trying to show is that the optical output acts as a bypass when monitoring recording on the R-09.

Sorry to repeat myself but...

Maybe I'm missing something here, but first let's make sure we're on the same page... The signal that you're feeding the R09 is analog(not digital, the R09 doesn't have any digital inputs) and for that signal to be output through digital(optical out), it has to have hit the converters (that's what the ADC does, it converts the analog signal into digital)...  So when you say that it passes-through or by-passes the converters, that can't be the case... It has to have gone through the converters for it to be in a digital format...

I'd have to agree w/ Moke

color me skeptical, but, wouldn't it take two adc's to produce two different file format types at once?

Maybe I'm completely off here, but I have a feeling we're all missing something...

[guysonic]

Yes but what im trying to show is that the optical output acts as a bypass when monitoring recording on the R-09.

Sorry to repeat myself but...

Maybe I'm missing something here, but first let's make sure we're on the same page... The signal that you're feeding the R09 is analog(not digital, the R09 doesn't have any digital inputs) and for that signal to be output through digital, it has to have hit the converters (that's what the ADC does is converts the analog signal into digital)...  So when you say that it passes-through the converters, that's not the case... It has to have gone through the converters for it to be in digital...

I'd have to agree w/ Moke

color me skeptical, but, wouldn't it take two adc's to produce two different file format types at once?

Maybe I'm completely off here, but I have a feeling we're all missing something...

Block diagram for the R-09, shows ALL A/D and D/A functions are done with a single CODEC IC that also functions as mic/line preamp.  Digital output of the CODEC IC is passed to a digital processing IC that does the MP3 and other digital audio processes.  Apparently there is a path where non-processed digital audio is input to the CODEC AND optical driver IC for monitoring/optical output purposes.

[leshlush]

+T guysonic for the schematic and answer...

As I mentioned before, I don't know alot about MP3s and wasn''t sure if it was done at a different stage or if the ADC did the compression...
Your post will definitely clear up a few questions... Or it at least clears up some of mine...

But I guess it still leaves me w/ one... When setting the R09 to an MP3 setting, what bit-depth and frequency are being passed to the digi-out? Does it default 16/44.1? or to highest quality 24?

If you're not sure, don't worry, I was just curious...

[leshlush]

But I guess it still leaves me w/ one... When setting the R09 to an MP3 setting, what bit-depth and frequency are being passed to the digi-out? Does it default 16/44.1? or to highest quality 24?

I guess I should have just checked out the R09 in MP3 mode before asking... I just realized that when choosing to record in MP3 mode, you still have to select a frequency(44.1 or 48), so I guess I have half of the answer to my question...

but...

I still don't know what bit-depth that it would default to for the pass-through, when recording in MP3... I would assume 16-bit but I have nothing to back my assumption...  Does anyone know for sure?