[upstateguy]

Quote:

USG,
I did a little experiment at work yesterday comparing optical out on a macbook and imac to the modded hiface feeding a headroom ultra micro dac (it has undefeatable upsampling). I also compared the optical out to the modded hiface with a 15dB attenuator.  I was using my SE530's, an inexpensive coax cable from esoteric usa and an optical cable from lifatech.  The DAC has a manual switch that I can flip to optical or coax input.
The setup I used included two computers with one computer feeding optical and the other feeding the Hiface and both coax and optical inputs of the DAC were simultaneously being fed signal.  Lest I be accused of not being thorough, I switched computers and checked my results and they were similar.  I had to sync iTunes/Pure music between the 2 computers and then changed inputs on the DAC as the tracks were playing.  This was no means a blind test.  
 
First off, I did not hear any volume differences between inputs in this setup. The optical out of the Mac's and modded hiface were similar sounding; however it was clear that the presentation with the hiface was more organic and had a bit more dimensionality.  When I added the attenuator the sound improved a great deal.  The presentation became 3 dimensional and the tonality of the instruments was much better than without the att. or the optical input.  The reverberation within the recording venue was revealed more clearly.  In addition there was a better lower end presentation that grounded the music and provided a more solid and satisfying experience.  I was listening to a redbook recording of Carmignola Vivaldi late violin concertos. 
 
Even using this modest setup consisting of the ultra micro stack with SE530's, I was able to detect these differences.
 
What I took away from this is that the attenuator helps as John has suggested by reducing reflections.  I have now tried 2 upsampling DACs and I can hear differences with the modded hiface feeding the DAC's  compared at least with optical out. The sound improves greatly by including the attenuator in the HIface setup!!!!!  In my experience, the benefits of feeding good (presumably low jitter) digital signal to an upsampling DAC can be heard but it becomes extremely obvious and clear with the addition of  the attenuator. As has been stated by Regal in other posts, using the attenuator makes the battery modded hiface a phenomenal transport!!

That was a very neat little test you set up Bubu. 

 
Just to be clear, you're saying that the volume out of your macbook's optical connection and the volume USB of the modified HiFace from the same computer, when played through the headroom ultra micro dac were  exactly the same?
 
I think it was on DIYiIFi that an attenuator was first demonstrated to have an effect with the HiFace.  I don't recall, however, that the effect was anything more than a rounding out the edges.
 
Btw, were you using long cables or short cables?
 
USG

 

[upstateguy]

Quote:

I don't blame you guys for being doubtful.  I have no way to substantiate what I'm saying. I don't have the technical knowledge or equipment to test cables outputs etc.
John has explained elsewhere why he thinks using an attenuator works for the HiFace.  I just tried it and found that it improved the sound.  I don't think that this will work for all transports or digital cables as the Hiface has higher output voltage than spec'd for SPDIF coax and that's why the attenuator trick works.  I spent $40 to try this and I think it was worth it.

I meant to ask you why you're talking about the efficacy of using an attenuator?
 
JosephK posted about it in DIYHiFi.org back in June.
 
This is what he said:  regarding the high output level fromthe HiFace.  THREAD LOCATED HERE
 
"This same high level also permits the "Jocko" trick to be applied, that is padding the line. It permits to fit in a 75ohm 10dB attenuator, with still a lot of headroom left. And the 75ohm padding makes simply wonders, at least for me.. It restores the the proper termination at least at one side in the line, so the energy is absorbed much quicker.
I use it at the receiver end. In theory it would need a BNC input on the dac, ( I have it like that) but it works also if you fit a bnc/RCA converter AFTER it.
Like: SPDIF line with 75ohm BNC conn.-> 10dB att. -> BNC to RCA converter -> DAC with RCA socket."
 
USG

 

[Bubu1]

USG,
Thanks for the compliment!
 
I guess I'm talking about the attenuator because I'm surprised how well it worked for me.  Just thought I would share my experience and my enthusiasm for this little tweak.  I take my hat off to the guys who you credited with originally coming up with the idea. I asked John about my observation with the attenuator and he said that his experience was similar.
 
You are correct about the volume. That was my assessment based on my hearing and not on any measurements.  Take it for what it's worth. 

 
The cables I used were both 1 meter.
Quote:

I meant to ask you why you're talking about the efficacy of using an attenuator?
 
JosephK posted about it in DIYHiFi.org back in June.
 
This is what he said:  regarding the high output level fromthe HiFace.  THREAD LOCATED HERE
 
"This same high level also permits the "Jocko" trick to be applied, that is padding the line. It permits to fit in a 75ohm 10dB attenuator, with still a lot of headroom left. And the 75ohm padding makes simply wonders, at least for me.. It restores the the proper termination at least at one side in the line, so the energy is absorbed much quicker.
I use it at the receiver end. In theory it would need a BNC input on the dac, ( I have it like that) but it works also if you fit a bnc/RCA converter AFTER it.
Like: SPDIF line with 75ohm BNC conn.-> 10dB att. -> BNC to RCA converter -> DAC with RCA socket."
 
USG

 

[upstateguy]

Quote:

USG,
Thanks for the compliment!
 
I guess I'm talking about the attenuator because I'm surprised how well it worked for me.  Just thought I would share my experience and my enthusiasm for this little tweak.  I take my hat off to the guys who you credited with originally coming up with the idea. I asked John about my observation with the attenuator and he said that his experience was similar.
 
You are correct about the volume. That was my assessment based on my hearing and not on any measurements.  Take it for what it's worth. 

 
The cables I used were both 1 meter.

 

 
I wonder if you'd come over to the HiFace, sensitive information thread where I'm discussing the exact same macbook volume issue with aimlink.  http://www.head-fi.org/forum/thread/503323/hiface-sensitive-information/300
 
USG

 

[sleepy dan]

It depends on the quality of the implementation of the upsampling.  The ideal upsampler would a) eliminate incoming jitter, b) not add any jitter of it's own and c) not add artifacts from the sample rate conversion.  However no upsampler is perfect in any of these regards.
 
So, and ideal with an ideal upsampler, fitting the best or worst transport in the world would make no difference.  A poorer upsampler will let through significant amounts of jitter, making differences more audible.  But it may also mask differences by adding jitter/artifacts of its own.
 
Clearly it's not a simple issue, and there is no easy way to determine the amount of benefit that will be obtained short of testing for oneself.  My personal experience has been that even very good upsamplers can benefit from a lower jitter source.  Hope this sheds some light on the matter.
 
 
Quote:

... and I understand that 'upsampling' forms a bottle neck to improvements that can be gained from a low jitter device.
 

 

[sleepy dan]

Do you have any measurements for this 3dB treble tilt, or is it  just a guess?
 
Quote:

 
In any event, that has certainly been my experience in trying to use a stock HiFace with an upsampling DAC, and it certainly is no reflection on you or your modifications, that m2tech did not alert users to this serious limitation and instead produced a treble tilted, louder playing device designed to trick those with upsampling DACs into believing that the pseudo-details they heard from the 3db treble tilt was the sonic benefit of low jitter.
 

 

[upstateguy]

Quote:

It depends on the quality of the implementation of the upsampling.  The ideal upsampler would a) eliminate incoming jitter, b) not add any jitter of it's own and c) not add artifacts from the sample rate conversion.  However no upsampler is perfect in any of these regards.
 
So, and ideal with an ideal upsampler, fitting the best or worst transport in the world would make no difference.  A poorer upsampler will let through significant amounts of jitter, making differences more audible.  But it may also mask differences by adding jitter/artifacts of its own.
 
Clearly it's not a simple issue, and there is no easy way to determine the amount of benefit that will be obtained short of testing for oneself.  My personal experience has been that even very good upsamplers can benefit from a lower jitter source.  Hope this sheds some light on the matter.
 
 

 
Hummm,  what you say makes sense, but PS Audio seems to think that with a low jitter source (or no jitter as they 'claim' their transport can produce), the upsampled data stream is sonically inferior to one that is bypassed..... (and this with their top of the line DAC.)


 
Quote:

Do you have any measurements for this 3dB treble tilt, or is it  just a guess?
 

IIRC it came from a CA Legato review that I linked to a few pages back.  Let me know if you can't find it.
 
There was also a short discussion of the HF "playing louder", either in this thread or the "sensitive information" thread.
 
To be accurate,  the treble tilt is the observation of many people I've talk to about the (stock) HiFace (including myself), playing  3dbs louder comes from the Legato review.... (also the stock HF.)
 
I've done some pretty extensive comparisons with the Blue Circle Thingee which I had before the HiFace and I've done similar comparisons with forum members at some of the meets.  The upshot is that the USB Thingee pretty much sounds exactly like optical or coaxial into the Stello and Benchmark I DACs as well as  the North Star, Constantine and Stello on my home rigs.  By sounds pretty much the same I mean that there is no tonal shift (bass or treble accentuation) to the sound as compared to previously mentioned DACs other inputs.  This is not the case with the HiFace, which is immediately noticed to be treble tilted and bass light,  when compared via quick switching,  to the  neutral rendition of the  Thingee.
 
The HF treble tilt is a bitter pill to swallow  for those who have perceived extra detail a the top,  but when you combine a treble tilt with a volume boost, the result is the same kind of perceived "pseudo details" that can reproduced by boosting the volume and EQing the treble of a neutral transport like the BCT.
 
USG

 

[mmerrill99]

USG,
Can you show this by playing a frequency sweep through the Hiface & through the Thingee & recording the outputs from both. This can be analysed for differences. This should show the frequency lift that you claim. At the moment it's anecdotal. Again, I'm not saying that you are wrong but perceptions aren't always accurately translated into a technical description such as yours "3db HF lift"  

 

[aimlink]

Quote:

I find very strange that adding an attenuator can improve the sound so much. Logic suggest than any digital coaxial connection should benefit from adding one of those. How comes no company came up with a cable with a built-in attenuator?
I probably shouldn't have said that as few cable companies will start selling those for few hundreds...If they happen to work..or not 

Will an attenuator as this one from Harrison Labs work?

 

[mmerrill99]

Quote:

Will an attenuator as this one from Harrison Labs work?

No! This is not an RF attenuator!
Why not buy one of the minicircuit ones I recommended over on the DIY thread - it's $12 ?

 

[aimlink]

Quote:

No! This is not an RF attenuator!
 

  It's OK, I didn't post after buying one.  

 
Why not buy one of the minicircuit ones I recommended over on the DIY thread - it's $12 ?

After some sleuthing and fortune, I happened across your post here  which took me here .  I'll get me one of those.  May as well go that extra since it's relatively inexpensive.  Not to mention I've never tried an attenuator and your explanation was well written.  Even an ignoramus as myself understood it!!  

 
Edit: BTW, I'll need a couple adaptors for this thing to work with my RCA Modded HiFace.  Looks like I'll need a male RCA to female BNC to connect the attenuator to the HiFace and then a male BNC to female RCA to use with my coaxial cable.  Should these adaptors be the same 75 ohms.  I see that they have a resistance rating.

 

[upstateguy]

Quote:

USG,
Can you show this by playing a frequency sweep through the Hiface & through the Thingee & recording the outputs from both. This can be analysed for differences. This should show the frequency lift that you claim. At the moment it's anecdotal. Again, I'm not saying that you are wrong but perceptions aren't always accurately translated into a technical description such as yours "3db HF lift"  

 
When you use the letters HF do you mean HiFace or do you mean high frequency?
 
[[  Btw, glad to have you back on board !

looks like you got over the,  "I'm un-subscribing... " and  "In future all my posts will be of a marketing nature." 

   ]]

 

[mmerrill99]

I keep forgetting yours is a Mac. On the PC there is a Kernel Streaming audio stream (KS) & a Direct Sound audio stream (DS). The Hiface can use either stream - the KS is far superior to DS sound! I don't know if there is equivalent on the Mac?
 
Quote:

- An iMac connected to a vDAC is different from an iMac connected to an Ultra Desktop.

Yes but it is showing that optical out is clearly inferior to USB Hiface out in this configuration.
 
It boils down to this:
Either your sound is fantastic from the optical out & the Hiface is no improvement on this
OR
Your sound is not fantastic BUT the Hiface still sounds the same
 
If it's the first option above then we are wasting our time trying to improve anything but I believe it's the later & am trying to investigate it & show you that something is wrong in your system. Try the attenuators (get a 6 & 10dB one) & this will show you if it's your SPDIF cable. But if it is then your cable must be really terrible to make it sound as bad as optical out.

 

[aimlink]

Quote:

I keep forgetting yours is a Mac. On the PC there is a Kernel Streaming audio stream (KS) & a Direct Sound audio stream (DS). The Hiface can use either stream - the KS is far superior to DS sound! I don't know if there is equivalent on the Mac?
 
Yes but it is showing that optical out is clearly inferior to USB Hiface out in this configuration.
 
It boils down to this:
Either your sound is fantastic from the optical out & the Hiface is no improvement on this
OR
Your sound is not fantastic BUT the Hiface still sounds the same
 
If it's the first option above then we are wasting our time trying to improve anything but I believe it's the later & am trying to investigate it & show you that something is wrong in your system. Try the attenuators (get a 6 & 10dB one) & this will show you if it's your SPDIF cable. But if it is then your cable must be really terrible to make it sound as bad as optical out.

 
In your boils down to possibilities, you left out one possibility:
 
The UltraDesktop's Upsampling is making the Optical out sound great and the HiFace also sounds great, but not audibly better. 

 
We aren't sure about the contribution of the UltraDesktop DAC's upsampling to the Optical output's overall performance.  You seem inclined to think that the DAC's upsampling and jitter handling routine isn't that good and that it's also stifling the HiFace.  While I agree that this is a possibility, in the interest of futile spending, I have to seriously entertain the possibility that the UltraDesktop's DAC's upsampling and dejitter routine are doing great with the optical out and bringing its performance up to an audible equivalent to the HiFace my ears.  We have a conflict here and I like that.  Good often comes out of conflicts.
 
I've decided to go with the attenuator since it's a curious option that I have an interest in and don't mind fiddling with for my own edification considering the reasonable cost.
 

 

[mmerrill99]

 
 
Quote:

In your boils down to possibilities, you left out one possibility:

 

The UltraDesktop's Upsampling is making the Optical out sound great and the HiFace also sounds great, but not audibly better. 

That's exactly what my first possibility is! So are you saying that the optical out sounds fantastic or just OK  (& therefore the modified HIface)? 
 
What you are always coming back to is this - that the Ultradesktop's upsampling is making all your inputs equal sounding - now the question is - is this equally fantastic or equally mediocre (or somewhere in-between).
 
You see what I'm getting at:
Either you are hearing the best sound possible because your upsampler is doing a fabulous job on all inputs
OR
You are hearing all inputs the same but it's not the best sound possible