iFi Audio Pro iDSD discussion thread
Feb 25, 2015 at 1:11 PM Post #421 of 2,785
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Understood and quite informative. So, in iFi's experience - and perhaps especially pertinent to the conversation since the release of the iDSD Pro and the iCAN Pro will roughly coincide with one another - running two Op-Amp components, inline, let's say a DAC and an HP Amp, does the compatibility of both device depend on how well the internals are implemented, individually, that dictates how synergistic the two components are?
 
That is to say, if I've had poor experience with running two device, one as a DAC/pre-amp, and one as an HP amp, could it be because the internal implementation of one device is skewed just enough that the audio comes out slightly "off," in turn? Or, is it the mix-and-match approach of trying gear from different manufacturers, and expecting them to synergize, that is the problem? 

 
Hi,
 
For sure it depends mostly on implementation.
 
Many designers when implementing Op-Amps  (or DAC Chips for that) never really look what is going on inside.
 
They just take a "datasheet" circuit, cookiecutter style and then swap Op-Amps around (or not) until it more or less sounds like they want (which may or may not be what others want or like).
 
Also, one thing that differs with AMR/iFi is that we have a team of lead designers - each with their own strengths and experience. If there is only one lead designer, that product tends to go down a certain path based upon the strengths/weaknesses of that one person.
 
More in the next part...
 
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Feb 25, 2015 at 8:03 PM Post #422 of 2,785

Emerpus

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Hi iFi,
 
Not sure how to read this ... does this mean the iDSD Pro will have XLR Pre-Out or XLR Headphone out too? Or is the HP Out limited to 6.3mm?
 
OutputXLR True Balanced Audio (Output adjustable 4/10V @ 0dBFS [+14dBu/+22dBu])  
 Audio RCA (2V/5V @ 0dBFS)   
 6.3mm Headphone 4V/10V maximum output   
 Headphone Output Power 4,000mW/16R max.
 
Feb 25, 2015 at 8:43 PM Post #423 of 2,785

earfonia

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To Filter or to not Filter: Part 3

....

Having Op-Amps or not is not a reliable indicator of quality.
 
Even the best Op-Amp's in the world can be implemented so ham-fisted that the result is poor, using Op-Amps that seem rather old and pedestrian correctly can give surprisingly good results in the real world.
 

 
+1
Thanks for the good short article! Very true indeed!
Waiting for part 4 
normal_smile .gif

 
When I did Op-Amp rolling on Sound Blaster X7 a while ago, I ended up leaving the stock op-amp, the old and inexpensive NE5532 variant, the NJM2114D in its place. I found that in SB X7 circuit, the NJM2114D sounds optimum, and to my ears better than some other more expensive op-amps I tried, that I have in inventory. It's all about the implementation.
 
Mar 4, 2015 at 12:52 PM Post #425 of 2,785

EVOLVIST

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Here's a valid question for the iDSD Pro, I believe:
 
Will the HP input for the iDSD Pro be the same as the one just implemented in the Retro 50? Or is it not applicable since we're not talking tubes?
 
Mar 4, 2015 at 1:57 PM Post #426 of 2,785
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  Here's a valid question for the iDSD Pro, I believe:
 
Will the HP input for the iDSD Pro be the same as the one just implemented in the Retro 50? Or is it not applicable since we're not talking tubes?

 
Hi,
 
You mean the HP outputs?
 
The iDSD Pro has more or less the same output as the iDSD micro, but with Class A Biasing added,better power supplies and better components in criticalplaces,however it is a very minimalist Headphone Amplifier (and takes too much space as is).
 
But Retro and Proline are really diametrically oposed. There is little sense to compare them. Like comparing an suv with a track car.
 
The Retro is Retro. It has design goals and approaches that are radically different from other iFi Products.
 
It is mostly Class A and Tubes handle the Amplification. We have addressed some shortcomings common to many Tube Amps, but the Retro is very much a traditional tube amp.
 
Like traditional coffee, no decaf, but full strength extra roast, double portion and then topped up with ton's of Full Fat Cream and sweeted with a lot of sugar. No modern "skinny latte" there.
 
In most ways, except the price and some small details the Retro is more an AMR Product than an iFi one. It just misses the final few bits for ultimate refinement.
 
Had it been made with silver wound permalloy output transformers and silver coupling cap's (which at volume purchasing cost would cost more than the retail of the Retro is now) and with a Philips TDA1541 Multibit DAC added to the current Burr Brown one, it would be an AMR 77 Class Product for all it is worth.
 
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Mar 5, 2015 at 7:22 AM Post #428 of 2,785

earfonia

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The iDSD Pro has more or less the same output as the iDSD micro, but with Class A Biasing added,better power supplies and better components in criticalplaces,however it is a very minimalist Headphone Amplifier (and takes too much space as is).

 
Hmmmm.... frankly speaking, I consider iDSD micro headphone output to be the weak point of ifi micro iDSD. Big power but lacking of refinement. It sounds dry and not pleasing for long period of listening. Simply put, the sound quality of the micro iDSD headphone output is not on par as the sound quality of the micro iDSD DAC section. And added to it, the severe volume imbalance below 9:30' am position.
 
I really hope ifi will revamp the headphone output of the iDSD Pro headphone output, to be much better than iDSD micro. It doesn't mean it has to be highly complex and large size amp, but a different approach with better, 'more refine' sound quality. For example, Op-Amp + Buffer Jung multiloop, or other approach that I believe ifi knows better. Btw, I really like the approach for volume control of my Mytek Stereo192-DSD DAC. It gives both 100 steps precision analog volume control (separate, one for line output, one for headphone output) as well as digital volume control, for us to choose. The separate volume control for line output and headphone is really useful for studio, where we can adjust independently the volume for speaker and headphone. That's really a feature for the Pros.
 
Mar 5, 2015 at 7:58 AM Post #429 of 2,785

ClieOS

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As long as iDSD Pro has an headphone amp section near that of iCAN micro, I'll be happy. The better the merrier.
 
From what I have read, the pot that is going into the iDSD Pro is going to be pretty high end (same can be said the the whole volume control scheme). So hopefully any imbalance issue should be minimum to none.
 
Mar 5, 2015 at 8:05 AM Post #430 of 2,785

rickyleelee

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Hmmmm.... frankly speaking, I consider iDSD micro headphone output to be the weak point of ifi micro iDSD. Big power but lacking of refinement. It sounds dry and not pleasing for long period of listening. Simply put, the sound quality of the micro iDSD headphone output is not on par as the sound quality of the micro iDSD DAC section. And added to it, the severe volume imbalance below 9:30' am position.

I really hope ifi will revamp the headphone output of the iDSD Pro headphone output, to be much better than iDSD micro. It doesn't mean it has to be highly complex and large size amp, but a different approach with better, 'more refine' sound quality. For example, Op-Amp + Buffer Jung multiloop, or other approach that I believe ifi knows better. Btw, I really like the approach for volume control of my Mytek Stereo192-DSD DAC. It gives both 100 steps precision analog volume control (separate, one for line output, one for headphone output) as well as digital volume control, for us to choose. The separate volume control for line output and headphone is really useful for studio, where we can adjust independently the volume for speaker and headphone. That's really a feature for the Pros.


I followed the crowd desgn thread from early on and if you read it too, you would say the 3.5mm is there for convenience, it is firstly a dac/headmp for desktop and portable use. In some ways I think iFi tried too hard to make the micro iDSD so feature-rich that people don't take into account this thing retails for 499 big ones. I too would be disappointed if the micro dsd headphone section was rolled into the dsd pro. The mytek at 1.5k is a direct competitor to the dsd pro. But if you are using at 9.30, something is wrong in your config and no wonder the sonics is not on song.
:blush:
 
Mar 5, 2015 at 8:18 AM Post #431 of 2,785

earfonia

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I followed the crowd desgn thread from early on and if you read it too, you would say the 3.5mm is there for convenience, it is firstly a dac/headmp for desktop and portable use. In some ways I think iFi tried too hard to make the micro iDSD so feature-rich that people don't take into account this thing retails for 499 big ones. I too would be disappointed if the micro dsd headphone section was rolled into the dsd pro. The mytek at 1.5k is a direct competitor to the dsd pro. But if you are using at 9.30, something is wrong in your config and no wonder the sonics is not on song.
:blush:

 
Well, I really wonder, if the headphone output (1/4" output, not 3.5mm) is just for convenience, what's the reason to make it so powerful that reach 4000 mW of maximum power?  Or for iDSD Pro case, 3000 mW?  In my understanding, if it is just for convenience, a few hundreds mW would be sufficient for most headphones.  I'm not asking for high end headphone amp to be included in iDSD Pro (which is actually make sense for the price). I just need something that sounds more refine, to make it a practical one box solution. I rather have 200 mW really good sounding headphone amp, than dry sounding 4000 mW headphone amp.  And leave the high power to be served by the iCAN.
 
Mar 5, 2015 at 9:46 AM Post #433 of 2,785

rickyleelee

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+1 
I agree.


I have both and would say the micro iCAN is noticeably better but it is mains powered and lives inside the same footprint (And I can't take it out with me) It is like have a pro SLR and then saying the auto function is ok and is the weak link. I would think that is quite normal. First and foremost run it as a dac headamp or dac direct. The headamp is not that bad but again with running it at 9 o'clock and or just using the headamp isnt really the optimal system deployment. I see so many people buying pro dslrs with expensive lense and then using in auto mode most of the time and saying they get average photos. But ymmv. :blush:
 
Mar 5, 2015 at 10:41 AM Post #434 of 2,785
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To Filter or Not Filter (Part 4)


 

Go Discrete

Often the use of discrete circuits is touted as the ultimate expression of the audio design craft. Certainly, going discrete does free us from the shackles of the Op-Amp data-sheet and from the limitations of the manufacturers catalogs, which despite offering 100's of parts usually seem to lack the one with the precise combination of spec's we want. Whatever we want, we design it in.

BUT often discrete designs are not as good as the best modern Op-Amps. With discrete circuitry we can never be as complex modern integrated circuits and this complexity can be used to improve performance.
 
If we try to imitate integrated circuit Op-Amps in discrete form – we are often ending up with something performing worse, bigger and more expensive than a good and inexpensive Op-Amp chip used right.

Additionally, we can always add discrete parts to extend a good Op-Amp chip that lacks some specific feature we want. Be it an ultra-low noise input stage or a big class A output stage, we can often add these to an otherwise suitable chip and in the process make a hybrid that keeps all the good stuff of the integrated Op-Amp and adds our own desired features with much less complexity and of course cost than a fully discrete design.
 
At iFi you can find an example of this in the iPhono and its added super low noise MC stage and the added Class A Buffer, that deliver a performance that no single Op-Amp chip could and that would be, if at all possible in purely discrete circuitry, neither small nor particularly affordable.
 
The iPHONO

 
(Incidentally, one of the few "objective audio tests" when auditioning a phono stage is to 1) play music as loud as you normally listen at. 2) Then lift the needle. 3) Then listen for the "noise" from the phono section. A good phono stage amplifies only the signal so you should not hear "it" from the normal listening position. A normal phono stage amplifiers the signal AND the noise).
 
So, realistically, there is just one reason to go fully discrete. To get something that does away completely with the fundamental Op-Amp circuit structure and instead does things radically different, something that allows us to step outside the triangle with its + & - sign and it's fundamental set of unavoidable design compromises.

And this is precisely what we are doing for the Pro line. But, just because it is discrete and not Op-Amp it is not automatically good either.
 
We do truly think what we are putting in is something rather different in a good way though.
 
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Mar 5, 2015 at 6:54 PM Post #435 of 2,785

earfonia

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I have both and would say the micro iCAN is noticeably better but it is mains powered and lives inside the same footprint (And I can't take it out with me) It is like have a pro SLR and then saying the auto function is ok and is the weak link. I would think that is quite normal. First and foremost run it as a dac headamp or dac direct. The headamp is not that bad but again with running it at 9 o'clock and or just using the headamp isnt really the optimal system deployment. I see so many people buying pro dslrs with expensive lense and then using in auto mode most of the time and saying they get average photos. But ymmv. :blush:

 
I mentioned volume imbalanced below 9:30 am, it doesn't mean that I'm using it below 9:30 am. I mentioned it as something to be improved by ifi. Some amps and DACs don't have problem around 9 am with their volume pot. Why you keep mentioning that and what make you think that I'm using my iDSD micro at below 9:30 am?
 
I also have both micro iDSD and micro iCAN. I & @ClieOS wish that the quality of the Pro iDSD headphone output to be similar to micro iCAN, doesn't mean that the whole same footprint has to be put inside the Pro iDSD case, but to achieve similar quality. For example, I have Fiio E12DIY, much smaller than iCAN, now I use OPA827 + LME49600, and also battery powered, and the sound quality is much better than the iDSD micro headphone output. Remove the battery, and the whole circuit is small enough to be put inside the Pro iDSD.
 

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