[diamondears]

It is called the 'Pro' series now. No more 'mini' and certainly no 'regular'. If they start making anything bigger and more expensive, it might as well be part of AMR's line-up instead.

Does AMR have a DAC-amp unit?

 

[diamondears]

I wish iFi would put as many digital filters as possible on the iFi pro. All the popular filters as well as its proprietary filters. Also hope iFi would develop not only filters that transparently reproduces the intended recording with minimal noise, but also filters that colors the sound like what tube rolling does that creates "fun" sound signatures. With DSD capability, this would be a truly awesome endgame integrated DAC-amp.

 

[ClieOS]

Does AMR have a DAC-amp unit?

 
For loud speaker, yes. For headphone, no. Though it is sometime quite possible to plug a pair of very insufficient planar headphone directly into the power amp section.

 

[diamondears]

   
For loud speaker, yes. For headphone, no. Though it is sometime quite possible to plug a pair of very insufficient planar headphone directly into the power amp section.

Yes, thanks. So when again will iFi release the pro iDSD?

 

[iFi audio]

  Yes, thanks. So when again will iFi release the pro iDSD?

 
Hi,
 
The iCAN Pro and the iDSD Pro are being developed simultaneously.
 
At least one will make Munich in May (though we are aiming for both).
 
The iCAN Pro we may have a sneak peek for you guys soon on here in the not too distant future.
 
Cheers.

 

[Franatic]

   
Hi,
 
The iCAN Pro and the iDSD Pro are being developed simultaneously.
 
At least one will make Munich in May (though we are aiming for both).
 
The iCAN Pro we may have a sneak peek for you guys soon on here in the not too distant future.
 
Cheers.

I have asked this before and received no reply from ifi. Will you make a version of the pro without the headphone amplifier section? I will use it straight up as a dac and feel I will be paying for functionality I will never use. I am sure I am not alone in this. I currently use the micro idsd in this way.......and love it. I just use the RCA out direct and don't use the headphone amp.
 
Thanks, ifi! Keep up the great work and develpment. I love how you guys interact with the customers.

 

[Jimi Zine]

Ifi idsd Pro was originally going to make CES this year, then Bristol in the UK, then Munich in May, now looks like it won't even make this, c'mon Ifi please just give us a realistic release date for the idsd pro and stick to it

 

[iFi audio]

  I have asked this before and received no reply from ifi. Will you make a version of the pro without the headphone amplifier section? I will use it straight up as a dac and feel I will be paying for functionality I will never use. I am sure I am not alone in this. I currently use the micro idsd in this way.......and love it. I just use the RCA out direct and don't use the headphone amp.
 
Thanks, ifi! Keep up the great work and develpment. I love how you guys interact with the customers.

 
Hi,
 
The outline specs made it a few pages back. This is all we can give out at the moment as they may be subject to revisions.
 
Cheers.

 

[iFi audio]

  Ifi idsd Pro was originally going to make CES this year, then Bristol in the UK, then Munich in May, now looks like it won't even make this, c'mon Ifi please just give us a realistic release date for the idsd pro and stick to it

 
Hi,
 
We do understand and empathise with your comments.
 
But, and this is a big, but the iDSD Pro has morphed into another totally different beast.
 
At AMR/iFi we only bring out products we know we are going to be "white hot".
 
If it takes longer, then so be it. We ask for your trust on this.
 
Given the iDSD Pro will be the flagship, it is even more imperative that we make this thing the "helicarrier" in a sea of aircraft carriers.

 

 

[tf1216]

   
Hi,
 
We do understand and empathise with your comments.
 
But, and this is a big, but the iDSD Pro has morphed into another totally different beast.
 
At AMR/iFi we only bring out products we know we are going to be "white hot".
 
If it takes longer, then so be it. We ask for your trust on this.
 
Given the iDSD Pro will be the flagship, it is even more imperative that we make this thing the "helicarrier" in a sea of aircraft carriers.

 

 
I wonder what the General's listening room looks like on that thing. 

 

[EVOLVIST]

I have asked this before and received no reply from ifi. Will you make a version of the pro without the headphone amplifier section? I will use it straight up as a dac and feel I will be paying for functionality I will never use. I am sure I am not alone in this. I currently use the micro idsd in this way.......and love it. I just use the RCA out direct and don't use the headphone amp.

Thanks, ifi! Keep up the great work and develpment. I love how you guys interact with the customers.

Fran,

Just get yourself a headphone amp with XLR ins. Pro Audio is the way to go!

Or use the iDSD Pro as a preamp. If my understanding is correct and iFi is not using OP-Amps in the iDSD analog stage, you should be able to use this kit as a preamp without any overt colorization of the music, while lifting your gain to taste.

Tweak that system, bro!

 

[Franatic]

Fran,

Just get yourself a headphone amp with XLR ins. Pro Audio is the way to go!

Or use the iDSD Pro as a preamp. If my understanding is correct and iFi is not using OP-Amps in the iDSD analog stage, you should be able to use this kit as a preamp without any overt colorization of the music, while lifting your gain to taste.

Tweak that system, bro!

Nick,
I am using my Woo WA2 as my preamp and headphone amp! That is not going to change. I am open to upgrading the idsd micro as my dac if it comes at a reasonable cost. I've been doing nothing but tweaking, but at some point you have to make a decision on the neighborhood you're going to live in. If the idsd pro offers me an upgrade to my system at a price I'm willing to pay, I'm in. Too much invested in tubes and such on my WA2 to change that......and I love my WA2. With the tubes I have in there now this amp is awesome!

 

[Musicans2]

I am proud new owner of an ifi dsd micro!!! Addictive sound. Was going to buy a headphone amp from "senny" but now i am waiting for the PRO to come out! Question...will that have 512 special serial numbers and t-shirts and all that??? I missed the first one with the micro.

 

[iFi audio]

To Filter or to not Filter: Part 3

 
 

 
 
An Op-Amp digression
 
In our previous part 2 article, we mentioned the “O-Word” already, so let's digress a little.
 
The Op-Amp is represented by the Triangle with the + and – sign inside in the triangle in the active filter above.

When you read some advertising copy in high-end audio you may believe that Op-Amps are the latest and best thing since sliced bread and one might even believe some of the fellas using them invented them. But Op-Amp's are really old.

The first functional design is normally attributed to Karl D. Swartzel Jr. of Bell Labs in 1941 and was used in a Radar assisted Artillery director during World War 2.

The word “Operational Amplifier” for the type of amplifier circuit it embodies is documented in 1947 and the first “integrated op-amp”  using tubes was introduced in 1953
 
 

Historical timeline

1941: A vacuum tube op-amp. An op-amp, defined as a general-purpose, DC-coupled, high gain, inverting feedback amplifier, is first found in U.S. Patent 2,401,779 "Summing Amplifier" filed by Karl D. Swartzel Jr. of Bell Labs in 1941. This design used three vacuum tubes to achieve a gain of 90 dB and operated on voltage rails of ±350 V. It had a single inverting input rather than differential inverting and non-inverting inputs, as are common in today's op-amps. Throughout World War II, Swartzel's design proved its value by being liberally used in the M9 artillery director designed at Bell Labs. This artillery director worked with the SCR584 radar system to achieve extraordinary hit rates (near 90%) that would not have been possible otherwise.^[14]
 
All the way through to:
 
1972: Single sided supply op-amps being produced. A single sided supply op-amp is one where the input and output voltages can be as low as the negative power supply voltage instead of needing to be at least two volts above it. The result is that it can operate in many applications with the negative supply pin on the op-amp being connected to the signal ground, thus eliminating the need for a separate negative power supply.
 
The LM324 (released in 1972) was one such op-amp that came in a quad package (four separate op-amps in one package) and became an industry standard. In addition to packaging multiple op-amps in a single package, the 1970s also saw the birth of op-amps in hybrid packages. These op-amps were generally improved versions of existing monolithic op-amps. As the properties of monolithic op-amps improved, the more complex hybrid ICs were quickly relegated to systems that are required to have extremely long service lives or other specialty systems.
 
Recent trends. Recently supply voltages in analog circuits have decreased (as they have in digital logic) and low-voltage op-amps have been introduced reflecting this. Supplies of ±5 V and increasingly 3.3 V (sometimes as low as 1.8 V) are common. To maximize the signal range modern op-amps commonly have rail-to-rail output (the output signal can range from the lowest supply voltage to the highest) and sometimes rail-to-rail inputs.
 
(source wikipedia: http://en.wikipedia.org/wiki/Operational_amplifier#Historical_timeline).

 
 
Over the years the Op-Amp has slowly become the default building block for Amplifiers, both discrete and integrated and for the last few decades Op-Amps have been the dominant choice when it comes to “general purpose” Audio amplifiers (and outside audio).

They are manufactured in a huge variety at all price levels and with a massive array of different specifications and optimisations for specific jobs. Some are even sold as being optimal for audio. 
 
Unfortunately, this ubiquity has also led to a lack of understanding of what happens inside these Op-Amp's. There are circuit structures that are common to almost all Op-Amps, there are inherent limitations that are too.

These days we pick up the Datasheet for an Op-Amp and we read:
 
“The XXX Op-Amp is a JFET-input, ultralow distortion, low-noise operational amplifier fully specified for audio applications. Features include 5.1nV/√Hz noise and low THD+N (0.00005%).”
 
Surely it ticks all boxes?
 
Come on, zero point how many zeros THD?
 
Noise in Nanovolts?
 
It even says “J-Fet” there and “J-Fets” are in fashion this year we hear.
 
It's even a special audio grade part. So let's just use that one, okay?

Actually, at iFi WE DO USE THAT ONE.
 
But not because of these numbers. Or the J-Fets. Or the “Soundplus” moniker.
 
Sorry to disappoint but our reason is more prosaic. Correctly implemented it sounds as good as anything we have tried and much better than most.

There are some other numbers for that chip that are not headlined. They have more to do with what happens in the real world.
 
For example, the bandwidth is only 11MHz at no gain and gets substantially less wide as gain is increased. And while the distortion is low at 1kHz and under ideal conditions, there are many things that make it worse, not the least raising the frequency so at 20kHz we have wipe off one zero of that very low distortion figure and at several MHz three to four of the zeros.

It also is not so great with low impedance loads, without adding buffers distortion goes up, so strike another zero if we drive 600 ohm. Actually, the gain is very load dependent!
 
Now it is not such a low distortion device anymore, is it?
 
One thing we do not really want to do is to make this Op-Amp filter signals in the region of several MHz or have it driving headphones. We have to take that over by different means if we want to use this Op-Amp for it's undeniable qualities.

If we understand the limitations and possible problems we can design our circuits accordingly and avoid the pitfalls of the limitations and take best advantage of the exceptional audio performance.
 
If we are simply members of the “Op-Amp of the month” club, we may get all sorts of results, maybe good, maybe bad, maybe indifferent.

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.
 

 

[EVOLVIST]

If we understand the limitations and possible problems we can design our circuits accordingly and avoid the pitfalls of the limitations and take best advantage of the exceptional audio performance.
 
If we are simply members of the “Op-Amp of the month” club, we may get all sorts of results, maybe good, maybe bad, maybe indifferent.

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.
 

 
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?