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Sennheiser HDVD800 Headphone Amplifier - Page 69

post #1021 of 2308
Quote:
Originally Posted by palmfish View Post

Im not very familiar with USB, but it sounds like a software/driver problem to me. Is there an updated driver download available from Sennheiser perhaps?

 

This problem occurs on IMacs and Macbook Pros as well as Windows. The Apple products need no driver as they have the industry standard driver already in place. The CD that comes with the HDVD800 has drivers (or a driver) for the Windows applications. The issue is, if you are getting music of any kind coming out of the DAC then the USB is successfully getting the audio data to the DAC.

 

I believe that there are two main data transfer methods defined in the USB Audio class 2 standard. The first, which has been around for many years is a synchronous mode (called Adaptive mode). To transfer each 24 bit sample (actually 48 bits for both channels) of the 24/192 audio file, the PC must just spit out the stream of sample data chunks onto the USB at exactly 192 kHz and spaced at EXACTLY EQUAL spacing. The DAC simply sits and grabs each sample as it comes in and loads them into the converter. It also uses the timing of the incoming samples to reproduce the clock that they were send with. The clock is used when inserting the converted digital value into the analog output signal. Problem is that PCs (and other transports) have a problem spacing the data samples in EXACTLY EQUAL spacing. As a result the clock jumps around a not positioning the digital converted to analog value in the exact correct place in the output signal. This is jitter, and on highly resolving systems its effects can be heard (soundstage reduction, less clarity, and other artifacts)

 

Note that this is also very much the same way that the S/PDIF interfaces work (e.g., TOSLink, Coax) in that the device sending the data is using its own clock for sending and then the receiving item has to recreate the clock in order to to the conversions

 

The second transfer method is asynchronous and is (guess what?) called Asynchronous transfer mode. It is relatively new and hasn't been around a long time. Older DACs with USB interfaces may not even support this mode. There is going to be more overhead with this in that the DAC now using its own internal clock says to itself "it's about time to get some more samples" so it sends a message to the PC requesting the data. The PC puts a batch of samples together and sends it to the DAC. Since the DAC is using it's own high grade internal clock, it can sit there an easily do the conversion on each sample and put them into the exactly correct place in the output analog signal. No incoming jitter to worry about at all.

 

The problem is that it appears the appearance of this bug seems to be when worst case load conditions on the DAC's processor are occurring. E.g., 24/192 kHz tracks, software that bypasses all of the generic audio processing of the OS (i.e., is fast), and the additional USB overhead in the DAC associated with Asynchronous transfer mode.

 

If you have an older sound card or USB driver, you might not be able to even use Asynchronous transfer mode. If not, I don't think that you would even be able to trigger the bug. However, you also would not be able to talk to the DAC in a jitter free fashion as well. If you have the ability to run in Async mode, then you would normally want to do that.

 

All that is happening is that each sample on the digital data for the audio file is pulled from the file and sent out on the USB connection. If the data got lost or was modified somehow, you would get terrible noises, not hiss. 

 

And the last item is that USB Audio class 2 is defined by international standard so if you only get hiss when talking with an HDVD800 through a given USB driver but you DON'T get hiss on other DAC products using the same driver, it would make sense that the problem in the the DAC's processing.

 

Oh dear. It just occurred to me that this was probably all talked about in the forums' Wiki. Hope this clarified things a bit thoughnormal_smile%20.gif

 

- Jeff

post #1022 of 2308

Ok I have the high resolution files hooked up and I am hearing the same thing. There is hiss on all files  from 24hz-192 and less the same thing is happening to the  files on 24-176/.4 . This is totally unacceptable and will let them Know what I am hearing. The dacs are defective and not working properly.  I dont hear it on losseless files but it there on all high resolution files and is totally not right. It will be interesting to see how this all plays out and I am going to find out what needs to be done. My Oppo BDP 1045 played flawlessly. This is a major issue and Sennheiser needs to step up to the plate here.  It plays iTunes loss-less without issue.


Edited by Frank I - 6/20/13 at 7:51pm
post #1023 of 2308
Quote:
Originally Posted by TheManko View Post

Tried WASAPI push and it behaved the same as event.

 

Thanks for that. So it is capable of being triggered in PUSH mode as well.

 

I had discussed this with the folks at BitPerfect (I thought initially that it might have been the software since when I disable BitPerfect the problem always went away). Anyway, they felt that the transfer mode  might be a red herring since they felt that the bug was somewhere in the PCM to SDM conversion algorithms of the DAC. high speed loading of the DAC seems to trigger this and so Asynchronous mode can exacerbate it making it easier to reproduce, but may not strictly need to be present for the bug to occur.

 

- Jeff

post #1024 of 2308
Quote:
Originally Posted by wisemanja View Post

 

Thanks for that. So it is capable of being triggered in PUSH mode as well.

 

I had discussed this with the folks at BitPerfect (I thought initially that it might have been the software since when I disable BitPerfect the problem always went away). Anyway, they felt that the transfer mode  might be a red herring since they felt that the bug was somewhere in the PCM to SDM conversion algorithms of the DAC. high speed loading of the DAC seems to trigger this and so Asynchronous mode can exacerbate it making it easier to reproduce, but may not strictly need to be present for the bug to occur.

 

- Jeff

Jeff I got a call from Sennheiser USA today and there should be some insight by the end of this week. They need to address this  problem or they will have a huge issue with their dealers. I can see many people sending these back if they use high resolution files.  I hear no of it on concert videos or on itunes lossless but on the CC colletti and a USB DSD download of high resolution files converted to PCM its hissing to the point that the music  can't be listened to, and that is totally unacceptable in a product priced in reference territory. I believe these all need to be recalled and sent in for a fix.  They should  do the right thing with it I believe.

 

The major question I have is how can they release a product with this flaw.  I use the Oppo for sacd and cd playback and was using this for only itunes lossless and for concert videos which work well. I just got the Collettii from a fellow member and also my brother sent me a USB drive of all high resolution files and they are unplayable on this sac.  Right now I am listening to Botti on the dac using itunes and it sounds fantastic. I hope they do not drag there tails addressing this.


Edited by Frank I - 6/20/13 at 8:33pm
post #1025 of 2308
Quote:
Originally Posted by Frank I View Post

Ok I have the high resolution files hooked up and I am hearing the same thing. There is hiss on all files  from 24hz-192 and less the same thing is happening to the  files on 24-176/.4 . This is totally unacceptable and will let them Know what I am hearing. The dacs are defective and not working properly.  I dont hear it on losseless files but it there on all high resolution files and is totally not right. It will be interesting to see how this all plays out and I am going to find out what needs to be done. My Oppo BDP 1045 played flawlessly. This is a major issue and Sennheiser needs to step up to the plate here.  It plays iTunes loss-less without issue.

 

Thanks for the info Frank,

 

So it can occur at 24/176.4 as well as 24/192.

 

So now the so called 24/192 kHz on all digital interfaces feature might just really be a 24/96 kHz on all digital interfaces (except of course the optical which is only 24/88.2).

 

Dang it! What DOES play on it can sound just so good!

 

And by the way, I finished my balanced to single-ended adapter so I could listen in both modes. Even a quick check shows that the balanced does really sound better than the unbalanced on the HDVD800 with Beyer T1. The balanced is quicker and a bit clearer. The sound seems to be more coherent. The unbalanced seems to be more indistinct especially in the bottom end and a little bit bloated. You can notice this a lot with electronic bass (I was using the latest Daft Punk). The tightness and speed of the electronic bass is just better controlled in balanced mode in my humble opinion.

 

- Jeff

post #1026 of 2308

I am listening to 24 96 and it sounds terrific. i think they will get this squared away.

post #1027 of 2308
Quote:
Originally Posted by Frank I View Post

Jeff I got a call from Sennheiser USA today and there should be some insight by the end of this week. They need to address this  problem or they will have a huge issue with their dealers. I can see many people sending these back if they use high resolution files.  I hear no of it on concert videos or on itunes lossless but on the CC colletti and a USB DSD download of high resolution files converted to PCM its hissing to the point that the music  can't be listened to, and that is totally unacceptable in a product priced in reference territory. I believe these all need to be recalled and sent in for a fix.  They should  do the right thing with it I believe.

 

The major question I have is how can they release a product with this flaw.  I use the Oppo for sacd and cd playback and was using this for only itunes lossless and for concert videos which work well. I just got the Collettii from a fellow member and also my brother sent me a USB drive of all high resolution files and they are unplayable on this sac.  Right now I am listening to Botti on the dac using itunes and it sounds fantastic. I hope they do not drag there tails addressing this.

 

Sounds great!

 

Standard engineering testing usually needs to assume that there will be failures at boundary points because that is where they usually occur. Obviously the advertised and implemented top speed of the units should have been thoroughly tested, but when you do it with standard iTunes on an Apple product and it works, I'm not sure that is "good enough" for a reference grade product. There's a lot of stuff that got missed, and now I wonder about the other digital interfaces that I don't have any way to test at present but might want to use later.

 

Also, please don't forget to remind them and point out the 24/192 S/PDIF advertised speed that can't make it over 24/88.2 on the optical. I was really wanting that option...


Edited by wisemanja - 6/20/13 at 11:21pm
post #1028 of 2308
Quote:
Originally Posted by Frank I View Post

Jeff I got a call from Sennheiser USA today and there should be some insight by the end of this week. They need to address this  problem or they will have a huge issue with their dealers. I can see many people sending these back if they use high resolution files.  I hear no of it on concert videos or on itunes lossless but on the CC colletti and a USB DSD download of high resolution files converted to PCM its hissing to the point that the music  can't be listened to, and that is totally unacceptable in a product priced in reference territory. I believe these all need to be recalled and sent in for a fix.  They should  do the right thing with it I believe.

The major question I have is how can they release a product with this flaw.  I use the Oppo for sacd and cd playback and was using this for only itunes lossless and for concert videos which work well. I just got the Collettii from a fellow member and also my brother sent me a USB drive of all high resolution files and they are unplayable on this sac.  Right now I am listening to Botti on the dac using itunes and it sounds fantastic. I hope they do not drag there tails addressing this.
looks like u guys r having some real problems with the usb on this amp.l don't use the usb but I think it's a shame that a great sounding amp like this has been released with this problem.come on senn get ur act together and sort this mess out,ur letting ur selfs down.
post #1029 of 2308

Hi everyone,

 

I just met with Axel Grell in our headquarters and he has provided the following explanation.

 

"Some customers found some 24Bit 192kHz files create noise when played via USB on the HDVD 800. We have analyzed the files and found they contain information above half of the sampling frequency. This leads to interference and noise when not pre-filtered before digital/analog conversion according to the Nyquist theorem. There is a failure in the files that must have been done in the mastering process. Other DACs do not give the full resolution and avoid this problems. In the meantime we are looking for a solution that allows the full bandwidth as well as a limited bandwidth for non-standard conform files."

 
Frank, I believe you'll get a similar response from Sennheiser USA very shortly. I'll try to get as much information while I'm here in Germany and keep everyone posted.
post #1030 of 2308

Glad to hear sennheiser is searching for a solution for the problems mentioned in this thread. Even though I am very happy with my Hdvd800 and using the V800 as a dac, a 1800 euro amp shouldn't come with any issues.
 

post #1031 of 2308
I am also getting the hiss on the c.c coletti tracks using pure music for mac. I have a feeling it could be the HD track files. I've read several times before that its pot luck when it comes to quality from HD tracks and some high res files are actually upsampled. Now as to why this noise doesn't effect other dacs is more complicated but could it not be that the other dacs are not 'bit perfect' dacs and are filtering the noise somehow? Maybe sennheiser have actually implemented that dac to spit out exactly what is put in but others play it safer? Just a thought .
post #1032 of 2308
I've just gone through all my 192/24 tracks from Linn records and highresaudio and no problems with them. Has anyone got hiss from anything other than HD tracks high res?
post #1033 of 2308
Good to get a resolution of sorts, sounds like it must be HD Tracks.
post #1034 of 2308
Quote:
Originally Posted by James-uk View Post

I am also getting the hiss on the c.c coletti tracks using pure music for mac. I have a feeling it could be the HD track files. I've read several times before that its pot luck when it comes to quality from HD tracks and some high res files are actually upsampled. Now as to why this noise doesn't effect other dacs is more complicated but could it not be that the other dacs are not 'bit perfect' dacs and are filtering the noise somehow? Maybe sennheiser have actually implemented that dac to spit out exactly what is put in but others play it safer? Just a thought .

That's more or less what Rosmadi has just said above.
post #1035 of 2308
I know I went to bed last night annoyed with the hdvd800 after reading about the hiss and then downloading the album to confirm it. I had these thoughts before I fell sleep and immediately posted them when I woke . Just read the remaining posts, sorry for repeating a post.
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