[preproman]

.

 

[preproman]

  Keep in mind that while the roll-off may be -3dB or so at 20KHz, it'll be between -0.5-0.75dB at 10KHz and about -1.5dB at 15KHz. Given most music, the performance of most headphones, and the average hearing ability, this isn't much to worry about.
 
I spent a lot of time playing around with upsampling methods when I had my Metrum DACs on hand. HQPlayer is fun to mess with, because it lets you try a bunch of different upsampling filters. Some are linear phase, some are minimum phase, and they all have varying amounts of pre and/or post ringing. I think it has a couple filters that aren't supposed to have filter ringing. If you're using a Mac, I think there's a known good audio player with different upsampling filters available. Common upsamplers seem to use linear phase, IME. The more you play around and test various filters, the more you might be able to hear the sound they impart on the DAC (and the Metrums acted as a good "template" to test how these filters sound, in a sense). Yes, you'll likely get a better sense of clarity and detail with upsampling, but whether or not you'll prefer that is up to you. I decided I just preferred NOS on everything, even 16/44.1.
 
It's expensive and ugly as sin, but XXHighEnd supposedly has a good upsampler designed for NOS DACs (the Phasure DAC, in particular). I believe it avoids filter ringing.
 
Upsampling will bring some other measurable benefits to the table outside of the frequency response (much like playing higher bit-rate and sampling rate files will improve NOS performance to an extent), but, again, it really comes down to what your ears hear as most pleasing.

 
 
What other bit depth and sample rates did you do testing on besides 16 / 44?  I'm interested how 24 / 44 sounds.

 

[hans030390]

I had some 24/96 material on hand, but not much. On NOS DACs, you'll hear more of a difference with a higher sampling rate than a higher bit-rate, IMO (makes sense, as higher sampling rate = less stair-stepping look to waves due to sample and hold and lack of any upsampling or oversampling).

 

[zilch0md]

I don't want to stick my neck out too very far, as I've only had the Octave MkII for a few days, but...  while I agree it does a better job with 96/24 than with 44/16, I'm utterly convinced that the Octave MkII does a better job with 44/16 than any OS DAC I've ever owned (including several ESS9023 and one ESS9018 implementation (OPPO HA-1), as well as two CEntrance DACs (Dacmini CX and DACport LX).
 
I'm concluding that you have to spend a lot of money (> $2k ?) to get an OS DAC that can properly deal with 44.1 khz files.  As recently discussed here in this thread, Cees Ruijtenberg advised me not to upsample in advance of sending data to the Metrum Octave MkII because depending on the tool I use, it can cause pre- and post-ringing and other undesirable artifacts.  
 
Having left my Octave MkII turned on 24/7 (which I'll do for at least two weeks, as he has advised), I'm finding that the treble of 44.1 kHz files is getting all better than I've heard those same files on my HA-1's ESS9018 for example, balanced out to the HD800.   Tracks with nothing but solo guitar and maybe a vocal seem to be easy for the ESS9018 to decode, but really complex 44.1 kHz tracks, like most classical music or "wall of sound" rock and roll recordings, sound congested on the ESS9018 or ESS9023 DACs, compared to the Octave MkII (with no upsampling applied in advance).  Even music that has always demanded forgiving headphones, some of which are favorites of mine, like Jimi Hendrix' Purple Haze (just try and find a good recording of this), sound much cleaner, with excellent separation - sounding much more like a live performance on the HD800, than listening to two blocks of crispy styrofoam getting rubbed together.
 
Then there's the overall naturalness of the Octave MkII - with everything I send through it.  My ESSxxxx and CEntrance DACS (and perhaps all affordable OS DACS?) sound absolutely sterile in comparison.  But it's not as if the Octave MkII is thick and syrupy.  I'm talking about timbre, mostly - with instruments and voices just sounding a lot more realistic than with oversampling DACS.  The Octave MkII is perhaps only a little bit darker in the treble than the HA-1's ESS9018, but it's not at all darker than my CEntrance DACmini CX or DACport LX DACs - if that puts things into perspective.  The mids are emphasized with the Octave MkII, but more in their fullness or wetness than in terms of energy (it's a little bit warm, but not "colored" in the mids.  In fact, overall, it's just as beneficial with my admittedly "colored" LCD-2 as it is with the HD800.  And given that I'm on a personal quest to morph the HD800 with a signal that gives it more of the FR of my beloved LCD-2, I've only raised the bar by listening to the LCD-2 with the Octave MkII - making the the LCD-2 more attractive along with the HD800 - instead of closing the gap!
 
The HD800 is still a little too bright for my tastes, and using the HA-1 amp, I'm still hearing a little bit of edginess in the treble, but much less so than when using the ESS9018 DAC.  Cees Ruijtenberg has suggested that this residual edginess I'm hearing in the HD800 can be ameliorated with a low or zero-feedback amp, where feedback is not used to eliminate measurable distortion.  For the record (amazingly), he has not so much as mentioned that he happens to sell a zero-feedback headphone amp (the Metrum Aurix).
 
The quest continues...
 
Mike

 

[boatheelmusic]

Jimi would probably be disappointed to hear this:
 
Jimi Hendrix' Purple Haze (just try and find a good recording of this), sound much cleaner, with excellent separation -

 

[zilch0md]

  Jimi would probably be disappointed to hear this:
 
Jimi Hendrix' Purple Haze (just try and find a good recording of this), sound much cleaner, with excellent separation -

 
For real, that has occurred to me while listening to his Are You Experienced album, for example. In truth, I haven't made a thorough effort to look for remastered versions, but there might be a "clean" copy out there somewhere.  At least the Octave MkII makes it more palatable than it is with oversampling DACs.
 
Mike

 

[boatheelmusic]

I remember my friend and I listening to a first copy of that.......in 1968!

 

[zilch0md]

That's about the same time I was listening to Sgt. Pepper's Lonely Hearts Club Band and Magical Mystery Tour.  

 
 
I didn't get into the likes of Jimi until much later in life.  

 

 

[slim.a]

For those who are interested, I have just post a full review of the Metrum Octave MKII here: http://www.tweak-fi.com/apps/blog/show/42726063-building-a-reference-system-part-1-metrum-octave-mkii-nos-dac
 
When using the Octave MKII in combination with the Audiophilleo 2, Glenn's OTL amplifier (with a 6SN7 driver and six-6BL7s as output tubes) and the HD800s, the sound is absolutely fantastic.

 

[zilch0md]

 
Wow!  That was very enjoyable reading, Amine!
 
Quote:

  For those who are interested, I have just post a full review of the Metrum Octave MKII here: http://www.tweak-fi.com/apps/blog/show/42726063-building-a-reference-system-part-1-metrum-octave-mkii-nos-dac
 
When using the Octave MKII in combination with the Audiophilleo 2, Glenn's OTL amplifier (with a 6SN7 driver and six-6BL7s as output tubes) and the HD800s, the sound is absolutely fantastic.

 
I really felt some empathy for your statement regarding your experience with upgrading from the Audio-gd DAC19MK3 to the DAC19DSP:
 

 I felt, nonetheless, that after a (very) long term period of listening that something was lost in the subjective realm.

 
I hate it when observations like this sneak up on me long after upgrading. More often than not, I'm initially thrilled with a change in my system, then get a more mature perspective within a a day or two, but sometimes, it's not until I've had a new piece of gear through many hours of playing a lot of very familiar songs that the truth percolates to the top of my consciousness.  Going back to the older component after even a week of "adaptation" is a good technique, however, for ferreting out that which can otherwise go unnoticed.  
 
Sadly, it has taken me years to overcome that arrogance which foolishly assumes, "I can A/B two components and straight away decide which is better."
 

  Those who think that upsampling cannot have any positive impact on sound and can only degrade data should consider this: most, if not all, sigma-delta based DACs already have oversampling filters which are doing … integer upsampling (8x, 16x… ). So there is already upsampling (called oversampling) and digital filtering going on the DACs whether we like or not. Also, one has to keep in mind that the digital filters that are most difficult to construct are those made for the 44.1K (in comparison with 88.2K and 96K+ frequencies) CD/ Redbook format. Programmers have to arbitrate between frequency domain and time domain performance; that is why we see different types of filters: slow roll-off, fast roll-off, minimum phase, intermediate phase…
 
As a result, it is not straightforward and easy to construct very good sounding digital filters. Some companies, such as Ayre or Meridian to name a few, have developed some interesting sophisticated digital filters and their products are acclaimed by many audio critics. However, those DACs are relatively expensive and are still based on sigma-delta with built-in oversampling.

 
Yes!  I so believe this (bolded parts, above)!   The bulk of our libraries, like it or not, are comprised of 44.1kHz files, but you have to spend a lot of money on an oversampling DAC (i.e. sigma-delta) to get filters that can decode 44.1k files as well as a NOS DAC can (i.e. Octave MkII).  
 
Quoting the first paragraph of my earlier post (while patting you on the back):
 

  I don't want to stick my neck out too very far, as I've only had the Octave MkII for a few days, but...  while I agree it does a better job with 96/24 than with 44/16, I'm utterly convinced that the Octave MkII does a better job with 44/16 than any OS DAC I've ever owned (including several ESS9023 and one ESS9018 implementation (OPPO HA-1), as well as two CEntrance DACs (Dacmini CX and DACport LX).
 
I'm concluding that you have to spend a lot of money (> $2k ?) to get an OS DAC that can properly deal with 44.1 khz files.  
 
[snip]

 
Wow, you really dug deeply into upsampling:
 

Upsampling:
 
After a lot of experimentation, I ended up settling on SoX upsampling (on Foobar) with the following parameters:
 
Upsampling to: 176.4K (for 44.1K files only)
Quality: Best
Passband: 90%
Allow aliasing: checked
Phase: 25% (i.e. intermediate phase)
 

 
You've got me curious now, despite my having previously decided, on Cees Ruijtenberg's cautions, to avoid upsampling. Your obvious awareness and avoidance of pre- and post-ringing has me wanting to try SoX in Foobar.  Thanks for sharing your no doubt hard-won parameters.  

 

Given the right conditions (i.e. proper source upstream, as well as transparent amplifiers and headphones downstream), the Octave MKII’s depiction of timber of instruments and voices is absolutely stunning.

 
Again we concur:
 

  [snip]
 
Then there's the overall naturalness of the Octave MkII - with everything I send through it.  My ESSxxxx and CEntrance DACS (and perhaps all affordable OS DACS?) sound absolutely sterile in comparison.  But it's not as if the Octave MkII is thick and syrupy.  I'm talking about timbre, mostly - with instruments and voices just sounding a lot more realistic than with oversampling DACS.  
 
[snip]
 

 
It's like eating fresh vegetables vs. frozen!
 

However, what struck me when listening to the Octave MKII was not its ability to portray a big soundstage but, rather, its ability to transport me to the recording venue. On many recordings, you can get a pretty good idea of the size of the recording room not by trying to calculate the size of the room that is being painted in front of you but by measuring the size of the room that you are actually occupying.

 
Another amen - seriously.  The Octave MkII takes me to Realityville.   
 
With a good deal of variability, depending on the quality of the recordings, the Octave MkII leaves me feeling I'm no longer listening to recordings - it's more as if I am actually at the original performances.  And you certainly don't need binaural recordings or purely acoustic recordings to experience it.  That sense of being there can happen even with complex studio mixes, like Michael Jackson's Billie Jean, where the remarkable presence of the backup singers, violins, and trumpet accents have given me goose bumps on occasion.  I think this benefit is a byproduct of not processing the signal as much as so many other DACs do.
 

But on its own, and fed from the Aqvox powered Audiophilleo 2, the Octave MKII gratified me with the best soundstage I have heard from a digital source.

 
Whoa!  I've not been around the block as much as you have, so I'm thrilled to read this, especially given how much I agree with your other observations.
 

Actually, the imaging specificity is better than what you get in real life. Or to put it in other words, I have never been in a live event that approached the 3D performance and image specificity of the Octave MKII. There are maybe a few possible explanations. Either we do not listen the same way at home and at various concerts. Another explanation is that using multiple microphones has an impact on the 3D perception, but it has the same surprising and counterintuitive result.

 
You are so perceptive!  I wish I could write about what I hear, as well as you do.  Your thoughts, quoted above, have never crossed my mind, but on reading this, I think you're spot on.
 

However the Octave MKII is the most transparent DAC I have listened to in my system (or elsewhere). 

 
Again, I'm thrilled to read this, given your (obviously) greater experience.  I can add that the transparency of the Octave MkII improves greatly across the first week of leaving it turned on, 24/7.  Cees Ruijtenberg advised me to leave it on for a solid two weeks (with no need to run data through it.)  I'm currently two days away from completing that two-week burn in, but the most dramatic changes happened in the first week - nowhere near as big a change as how a 40-year old tube can rapidly improve, but it has been perhaps the most satisfying burn-in I've ever experienced with solid state gear.
 

On a Chesky classical music recording, I was able to hear the traffic noise outside the recording venue.

 
For the life of me, I can't remember which track that is, but I think I know exactly what you're referencing.  The one I'm thinking of is the sound of a truck downshifting, coming toward the studio as it moves from far right, behind the performers, to pass by the studio on the right (outside the studio walls, of course), and then continue on its way (to a vanishing point behind your right shoulder).  

 
Thanks again for reinforcing so much of what I'd already concluded on my own, with such a well-written piece.
 
I'm looking forward to your follow-up articles.  I hope I don't miss them...
 
Mike

 

[TokenGesture]

Agreed, a really excellent review, as a Mark 1 owner I agree with pretty much all of it.

 

[slim.a]

   
I really felt some empathy for your statement regarding your experience with upgrading from the Audio-gd DAC19MK3 to the DAC19DSP:
 
 
I hate it when observations like this sneak up on me long after upgrading. More often than not, I'm initially thrilled with a change in my system, then get a more mature perspective within a a day or two, but sometimes, it's not until I've had a new piece of gear through many hours of playing a lot of very familiar songs that the truth percolates to the top of my consciousness.  Going back to the older component after even a week of "adaptation" is a good technique, however, for ferreting out that which can otherwise go unnoticed.  
 
Sadly, it has taken me years to overcome that arrogance which foolishly assumes, "I can A/B two components and straight away decide which is better."
 
 
Yes!  I so believe this (bolded parts, above)!   The bulk of our libraries, like it or not, are comprised of 44.1kHz files, but you have to spend a lot of money on an oversampling DAC (i.e. sigma-delta) to get filters that can decode 44.1k files as well as a NOS DAC can (i.e. Octave MkII).  
 
 
Wow, you really dug deeply into upsampling:
 
 
You've got me curious now, despite my having previously decided, on Cees Ruijtenberg's cautions, to avoid upsampling. Your obvious awareness and avoidance of pre- and post-ringing has me wanting to try SoX in Foobar.  Thanks for sharing your no doubt hard-won parameters.  

 
 
Again we concur:
 
 
It's like eating fresh vegetables vs. frozen!
 
 
Another amen - seriously.  The Octave MkII takes me to Realityville.   
 
With a good deal of variability, depending on the quality of the recordings, the Octave MkII leaves me feeling I'm no longer listening to recordings - it's more as if I am actually at the original performances.  And you certainly don't need binaural recordings or purely acoustic recordings to experience it.  That sense of being there can happen even with complex studio mixes, like Michael Jackson's Billie Jean, where the remarkable presence of the backup singers, violins, and trumpet accents have given me goose bumps on occasion.  I think this benefit is a byproduct of not processing the signal as much as so many other DACs do.
 
Whoa!  I've not been around the block as much as you have, so I'm thrilled to read this, especially given how much I agree with your other observations.
 
 
You are so perceptive!  I wish I could write about what I hear, as well as you do.  Your thoughts, quoted above, have never crossed my mind, but on reading this, I think you're spot on.
 
 
Again, I'm thrilled to read this, given your (obviously) greater experience.  I can add that the transparency of the Octave MkII improves greatly across the first week of leaving it turned on, 24/7.  Cees Ruijtenberg advised me to leave it on for a solid two weeks (with no need to run data through it.)  I'm currently two days away from completing that two-week burn in, but the most dramatic changes happened in the first week - nowhere near as big a change as how a 40-year old tube can rapidly improve, but it has been perhaps the most satisfying burn-in I've ever experienced with solid state gear.
 
 
For the life of me, I can't remember which track that is, but I think I know exactly what you're referencing.  The one I'm thinking of is the sound of a truck downshifting, coming toward the studio as it moves from far right, behind the performers, to pass by the studio on the right (outside the studio walls, of course), and then continue on its way (to a vanishing point behind your right shoulder).  

 
Thanks again for reinforcing so much of what I'd already concluded on my own, with such a well-written piece.
 
I'm looking forward to your follow-up articles.  I hope I don't miss them...
 
Mike

 
Hi Mike,
 
I am glad you enjoyed reading the review. It also seems that we share a pretty similar view on how the Octave MKII sounds
 
What I have learned these past few years that it can take a very long time to get a complete understanding of how a component sound as you have experienced yourself. That is why I waited for a few months before writing my review.
Nonetheless, in the case of the Octave MKII, it sounded amazing from the start, and it has continued to amaze me ever since.
 
As for upsampling, I try to let my ears decide. In theory, according to my personal analysis, upsampling should help more OS DACs than NOS DACs (since upsampling would only deteriorate the perfect impulse response of NOS DACs). In practice, I have found that assumption to hold true in my listening sessions. While the best upsampling (i.e. SoX with the parameters mentioned in the article) improved everything with OS DACs, it had debatable results with the Octave MKII. On some heavily processed music, the upsampling might sound as superior as straight 44.1 kHz, but on very well material, I prefer straight 44.1 kHz. However, since everyone has different preferences, it does not cost a thing to try it
 
Happy listening everyone!

 

[zilch0md]

Thanks again, Amine.  
 
For the record, I should make it clear that Cees Ruijtenberg (via an email reply) did not condemn the use of upsampling, altogether - he just warned me of the possibility of undesirable artifacts (that I should listen carefully as I experiment with upsampling.) But yes, OS DACs can more readily benefit from upsampling- especially when starting with 44.1kHz files.
 
I think one of the greatest benefits of DSD, with sampling rates of 2.8 MHz and higher, is that it might actually be easier (I'm conjecturing, here) to design a DA converter to handle those rates - certainly easier than doing so for 44.1kHz - and perhaps that's why we are seeing a proliferation of inexpensive DSD-capable DACs that sound better than the same or similarly priced DACs sound when decoding 44.1kHz files.  DSD could actually transform the industry by bringing "clean" DA conversion to the masses, training their ears to find fault with the inferior 44.1k DA conversion we've come to accept.
 
Will any DSD DAC ever be as good as what I'm hearing with the Octave MkII?  I don't know - I'm just trying to emphasize the possibility that the higher the sampling rate of the recording, the easier it is to design a DAC to handle it.
 
Mike

 

[TokenGesture]

OK - got to say - Octave (Mk1) plus Aurix plus T1 = sonic nirvana.  Full, present, musical, detailed, deep/wide stage , analogue (as opposed to digital), dynamic - wow this combo has it all!  It is the best head fi I have ever heard.

 

[Clemmaster]

  OK - got to say - Octave (Mk1) plus Aurix plus T1 = sonic nirvana.  Full, present, musical, detailed, deep/wide stage , analogue (as opposed to digital), dynamic - wow this combo has it all!  It is the best head fi I have ever heard.

Better than Hugo?