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iFi Audio Nano iDSD discussion + impression - Page 12

post #166 of 1712

Ok, got some updates:

 

The very soft clicking goes away when I choose WASAPI instead of ASIO.  However on foobar, there is no place to configure DSD playback for WASAP; the SACD plugin seems to be having only ASIO option.

 

I'm still testing the volume knob...

post #167 of 1712
Quote:
Originally Posted by iFi audio View Post
 

 

Hi,

 

We use a chip that combines differential input, volume control and an Amplifier all on one Chip. This volume control is similar to that in the Abbingdon Music Research AM-777.

 

The iDSD, at FULL volume, has NO resistors remaining in series with the volume control.

 

The volume works for both RCAs and Headphones. So it is a type of small pre-amp. Or turn to full volume and there will be no more resistors in the chain. Eat and cake!

 

How much voltage does the iDSD output through the RCA jacks when it is turned to full volume? I can't seem to find this spec. It really should have been designed with the option of outputting a fixed voltage through the RCA outputs so that the volume control would only affect the headphone output while providing a line-level out via RCA at the same time for speaker amps. The RCA output should have had a fixed option, so that folks would only have to use their speaker amplifier volume control to control the volume of their speakers.

 

Since the volume control seems to affect the RCA outputs, it creates a problem of not overdriving speaker amplifiers that are accepting an RCA input. When a person uses the volume control to turn up the volume in their headphones plugged into the iDSD, they apparently have also just changed the voltage being output through the RCA outputs to their speaker amplifier. Any changes made to the volume control for headphone listening apparently will also have an effect on the voltage being sent out of the RCA outputs to the speaker amplifier. This creates a problem of overdriving the speaker amplifier when one only wants to change headphone volume.

 

Since the volume control affects the RCA outputs, what is the range? What is the variable voltage output range of the RCA outputs? With the volume control at max, what is the RCA output voltage? I would really like to know that particular spec...

 

Let me try to describe the situation... Ideally, the iDSD is connected to my computer all the time. I'm using the RCA jacks to output from the iDSD to my speaker amplifier, and I'm also plugging my headphones directly into the iDSD. I should be able to use the volume control on the iDSD to change the volume in my headphones. However, when I turn on my speaker amplifier later to listen to my stereo, my speaker amplifier should not have been affected. The only thing that should be controlling my speaker volume is my speaker amplifier, not the changes I made to the iDSD volume control because I just wanted to change my headphone volume with the iDSD volume control, not the output voltage from the RCA outputs of the iDSD to my speaker amplifier.

 

There should be an option which lets the volume control of the iDSD change the volume of the headphone output without affecting the RCA output voltage to my speaker amplifier! The iDSD should be able to provide a constant voltage "line-out" signal through the RCA outputs that is not affected by the volume control.


Edited by StratocasterMan - 2/5/14 at 2:10am
post #168 of 1712
Quote:
Originally Posted by StratocasterMan View Post
 

 

How much voltage does the iDSD output through the RCA jacks when it is turned to full volume? I can't seem to find this spec. It really should have been designed with the option of outputting a fixed voltage through the RCA outputs so that the volume control would only affect the headphone output while providing a line-level out via RCA at the same time for speaker amps. The RCA output should have had a fixed option, so that folks would only have to use their speaker amplifier volume control to control the volume of their speakers.

 

Since the volume control seems to affect the RCA outputs, it creates a problem of not overdriving speaker amplifiers that are accepting an RCA input. When a person uses the volume control to turn up the volume in their headphones plugged into the iDSD, they apparently have also just changed the voltage being output through the RCA outputs to their speaker amplifier. Any changes made to the volume control for headphone listening apparently will also have an effect on the voltage being sent out of the RCA outputs to the speaker amplifier. This creates a problem of overdriving the speaker amplifier when one only wants to change headphone volume.

 

Since the volume control affects the RCA outputs, what is the range? What is the variable voltage output range of the RCA outputs? With the volume control at max, what is the RCA output voltage? I would really like to know that particular spec...

 

Let me try to describe the situation... Ideally, the iDSD is connected to my computer all the time. I'm using the RCA jacks to output from the iDSD to my speaker amplifier, and I'm also plugging my headphones directly into the iDSD. I should be able to use the volume control on the iDSD to change the volume in my headphones. However, when I turn on my speaker amplifier later to listen to my stereo, my speaker amplifier should not have been affected. The only thing that should be controlling my speaker volume is my speaker amplifier, not the changes I made to the iDSD volume control because I just wanted to change my headphone volume with the iDSD volume control, not the output voltage from the RCA outputs of the iDSD to my speaker amplifier.

 

There should be an option which lets the volume control of the iDSD change the volume of the headphone output without affecting the RCA output voltage to my speaker amplifier! The iDSD should be able to provide a constant voltage "line-out" signal through the RCA outputs that is not affected by the volume control.

maybe it's just me, but i find your use of bold and your repeating the same thing a dozen times to be in poor taste. the whole tone of this post is poor form. if you don't like the product, don't buy it. simple.

post #169 of 1712

I bought one, because I like cool toys, but I also feel obligated to point out the basic design flaws of the device.

post #170 of 1712
Quote:
Originally Posted by StratocasterMan View Post
 

 

How much voltage does the iDSD output through the RCA jacks when it is turned to full volume? I can't seem to find this spec. It really should have been designed with the option of outputting a fixed voltage through the RCA outputs so that the volume control would only affect the headphone output while providing a line-level out via RCA at the same time for speaker amps. The RCA output should have had a fixed option, so that folks would only have to use their speaker amplifier volume control to control the volume of their speakers.

 

Since the volume control seems to affect the RCA outputs, it creates a problem of not overdriving speaker amplifiers that are accepting an RCA input. When a person uses the volume control to turn up the volume in their headphones plugged into the iDSD, they apparently have also just changed the voltage being output through the RCA outputs to their speaker amplifier. Any changes made to the volume control for headphone listening apparently will also have an effect on the voltage being sent out of the RCA outputs to the speaker amplifier. This creates a problem of overdriving the speaker amplifier when one only wants to change headphone volume.

 

Since the volume control affects the RCA outputs, what is the range? What is the variable voltage output range of the RCA outputs? With the volume control at max, what is the RCA output voltage? I would really like to know that particular spec...

Hi,

 

Please see below reply from Thorsten Loesch, Head of R&D (AMR/iFi):

 

How much voltage does the iDSD output through the RCA jacks when it is turned to full volume?


1.8V. 

> It really should have been designed to output a fixed voltage through the RCA outputs so that the volume control 

> would only affect the headphone output while providing a line-level out via RCA at the same time for speaker amps. 

> The RCA output should have been fixed, not variable.


We have received quite a number of iDAC customers who complained that the line outputs (which was designed following indeed this concept) were fixed and the volume control worked only on the Headphones, which forced them to use adapters from the headphone outputs to get volume control on the line levels.

This was presumably due to the use with active speakers or in other kinds of systems lacking a volume control.

As a result we decided to offer on all future iFi Products with Volume control so that it operates on both line and headphone outputs, with minimal compromise to the sound quality of the line out. In the iDSD nano we use modern, highly-integrated circuits in the stage.

The actual Volume control Potentiometer is not part of the signal path, but instead varies a DC voltage applied to an AD converter which in turn sends the position of the pot, derived from DC voltage to a Microprocessor. The Microprocessor then controls a 64 Step attenuator which form an integral part of the output stage. 


The complete output stage combines a differential input and lowpass filter, a 64 step stepped attenuator and a Output Amplifier/Driver. It allows both inputs from the DAC and outputs to be direct coupled (no coupling capacitors).

Due to the high output current capacity designed into the output amplifier it can drive headphones directly with very low distortion. It can drive 700mV into 16 Ohm with 0.005% Distortion, at higher load impedances, especially at line output loads of a few KOhm or more, distortion is vanishingly low.

To illustrate:

DAC Chip  -> DC coupled to ->  Filter -> Stepped Attenuator -> Amplifier DC coupled to Headphone Jack or RCA Jack

If the Volume control is turned to the maximum this is switched to:

DAC Chip  -> DC coupled to ->  Filter -> Amplifier DC coupled to Headphone Jack or RCA Jack

This is about as minimal a circuit as possible and has as little impact on the sound quality from the DAC as possible and when the stepped attenuator is advanced to maximum the signal path no longer includes it.

 

To add a fixed output would have meant to add a lot more circuitry in the audio-path which could at best not have improved the line out over what is in place and made the headphone one worse.

Or we could have "faked" a fixed output by detecting the switch-over between line and headphone and then setting the output automatically to maximum and depriving anyone who actually wants a variable line out of that feature.

So we feel our choice offers the best compromise between features and sound quality, at the cost of the user having to turn the volume control to the maximum if requiring a "fixed" line output.

 

post #171 of 1712

To add to the above, it also seems logical to me to have a pot on the line out as well as the headphone out due to the nature of not being able to use a digital volume control with DSD 1bit data stream. Currently I use JRiver's 64bit digital volume control for PCM, but it is my understanding that I will not have the option of using it when playing DSD native.

post #172 of 1712
Quote:
Originally Posted by StratocasterMan View Post

How much voltage does the iDSD output through the RCA jacks when it is turned to full volume? I can't seem to find this spec. It really should have been designed with the option of outputting a fixed voltage through the RCA outputs so that the volume control would only affect the headphone output while providing a line-level out via RCA at the same time for speaker amps. The RCA output should have had a fixed option, so that folks would only have to use their speaker amplifier volume control to control the volume of their speakers.

Since the volume control seems to affect the RCA outputs, it creates a problem of not overdriving speaker amplifiers that are accepting an RCA input. When a person uses the volume control to turn up the volume in their headphones plugged into the iDSD, they apparently have also just changed the voltage being output through the RCA outputs to their speaker amplifier. Any changes made to the volume control for headphone listening apparently will also have an effect on the voltage being sent out of the RCA outputs to the speaker amplifier. This creates a problem of overdriving the speaker amplifier when one only wants to change headphone volume.

Since the volume control affects the RCA outputs, what is the range? What is the variable voltage output range of the RCA outputs? With the volume control at max, what is the RCA output voltage? I would really like to know that particular spec...

Let me try to describe the situation... Ideally, the iDSD is connected to my computer all the time. I'm using the RCA jacks to output from the iDSD to my speaker amplifier, and I'm also plugging my headphones directly into the iDSD. I should be able to use the volume control on the iDSD to change the volume in my headphones. However, when I turn on my speaker amplifier later to listen to my stereo, my speaker amplifier should not have been affected. The only thing that should be controlling my speaker volume is my speaker amplifier, not the changes I made to the iDSD volume control because I just wanted to change my headphone volume with the iDSD volume control, not the output voltage from the RCA outputs of the iDSD to my speaker amplifier.

There should be an option which lets the volume control of the iDSD change the volume of the headphone output without affecting the RCA output voltage to my speaker amplifier! The iDSD should be able to provide a constant voltage "line-out" signal through the RCA outputs that is not affected by the volume control.

I'm sorry but I don't quite understand your concern here. Why would adjusting the volume with the volume knob cause an overdriving of the speaker amplifier? I have tested the iDSD out and I believe that a quick listen would reveal that at maximum volumes, the line out amplitude is really not that large that it would blow out a speaker amplifier.

Besides, no offense but why is it so important that the headphone out volume be independant of that of the RCA line out? Forgive me if I am wrong, but I definitely cannot see myself listening to music through both the headphones and the speakers at the same time, and I am sure most others do not too! As such, you simply have to spend 5 seconds to adjust the volume knob before you listen each time (something you have to do anyways considering that the volume knob is also the on/off switch).
post #173 of 1712
Quote:
Originally Posted by Watcherq View Post

Yep, I understand that and honestly they are not really noticeable unless you pay attention.  However, I think it may be possible to reduce or eliminate the 3-4 clicks when starting up/jumping in the track via software/firmware since it seems that the system is the one that seem to be resetting the internals.  As for the clicks when you turn the dial, that is unfortunate but not a major issue.

As for the sensitivity, I hope that in the v2 of iDSD, there is a gain switch.  Right now on the Shure, between nice to uncomfortable loud to painfully loud is about 15-20 degrees turn of the knob to reach the next level.  On my Fiio X3, I would need to go, on low gain, from 15-17 to 23-25 to over 30.  On such a small knob, it is quite tricky.  Furthermore, the iDSD is using the 3.5mm plug which is meant for portable use thus IEMs with the sensitivity like Shure is expected to be used together with the iDSD.

Don't get me wrong, I'm quite happy with the iDSD, but these issues should be looked into and refined in the next version of the device.

Sonically how does the iDSD compare to the X3?

Just got 846s myself so very interested in your impressions.
post #174 of 1712
And that 1.8V max output is below the very common 2V output of most CD players and DACs. iFi see to have made excellent design choices in my opinion. I am more and more impressed by this device.
post #175 of 1712
Quote:
Originally Posted by iFi audio View Post
 

 

Due to the high output current capacity designed into the output amplifier it can drive headphones directly with very low distortion. It can drive 700mV into 16 Ohm with 0.005% Distortion, at higher load impedances, especially at line output loads of a few KOhm or more, distortion is vanishingly low.
 

 

 

 

Any more detailed info about headphone output power in different loads?

 

I think it's 130mW - 16 Ohm

       

                   80mW - 32 Ohm

 

Is this correct?

 

Any info with other loads ? 50 -120 -300 Ohm.

 

Thanks for all your replies you are giving!

post #176 of 1712
Quote:
Originally Posted by WCDchee View Post


I'm sorry but I don't quite understand your concern here. Why would adjusting the volume with the volume knob cause an overdriving of the speaker amplifier? I have tested the iDSD out and I believe that a quick listen would reveal that at maximum volumes, the line out amplitude is really not that large that it would blow out a speaker amplifier.

Besides, no offense but why is it so important that the headphone out volume be independant of that of the RCA line out? Forgive me if I am wrong, but I definitely cannot see myself listening to music through both the headphones and the speakers at the same time, and I am sure most others do not too! As such, you simply have to spend 5 seconds to adjust the volume knob before you listen each time (something you have to do anyways considering that the volume knob is also the on/off switch).

 

I'm not concerned about listening to headphones and speakers at the same time. That isn't the concern. From the response above, it does sound like iFi has put quite a bit of thought into the issue.

 

If I am understanding things correctly, it is necessary to set the volume control of the iDSD on maximum to get the proper output from the RCA outs. Apparently, this is 1.8V. That is a little less than what seems to be the accepted standard of 2.0V, although in reality, I don't think a standard really exists. That means that the user must have a more powerful speaker amplifier to obtain the same results than if the output was 2.0V, because the speaker amplifier is receiving a slightly weaker signal than what I would call normal.

 

It also means the user must constantly remember to unplug their headphones from the the iDSD when switching from headphones to speakers and vice versa. If one wishes to use their speakers, it will be necessary to turn the volume control on the iDSD to max to obtain 1.8V output through the RCA jacks, which is probably at best on the low side. Doing this without unplugging headphones (or while wearing headphones) means that the iDSD headphone amplifier will now be outputting the maximum headphone volume it can output.

 

Anyone who left their headphones plugged into the iDSD on their last listening session must not forget to unplug them before setting the iDSD volume to maximum in order to use their speakers.

post #177 of 1712
Quote:
Originally Posted by StratocasterMan View Post
 

It also means the user must constantly remember to unplug their headphones from the the iDSD when switching from headphones to speakers and vice versa. If one wishes to use their speakers, it will be necessary to turn the volume control on the iDSD to max to obtain 1.8V output through the RCA jacks, which is probably at best on the low side. Doing this without unplugging headphones (or while wearing headphones) means that the iDSD headphone amplifier will now be outputting the maximum headphone volume it can output.

 

Anyone who left their headphones plugged into the iDSD on their last listening session must not forget to unplug them before setting the iDSD volume to maximum in order to use their speakers.

 

This is a classic case of you cannot please all the people all the time.  The explanation by the AMR tech clearly shows they have thought about this from a technical / sound quality perspective.  Given that the headphone socket is next to the volume / on switch it shouldn't really be difficult to realise you still have your phones hooked up :) Just like when you want to run it off battery power, you need to remember to unplug the usb cable before you turn it on.  After a while it will become second nature and for a product as versatile/tiny and inexpensive as this I think they made some smart choices.

post #178 of 1712
Quote:
Originally Posted by StratocasterMan View Post

I'm not concerned about listening to headphones and speakers at the same time. That isn't the concern. From the response above, it does sound like iFi has put quite a bit of thought into the issue.

If I am understanding things correctly, it is necessary to set the volume control of the iDSD on maximum to get the proper output from the RCA outs. Apparently, this is 1.8V. That is a little less than what seems to be the accepted standard of 2.0V, although in reality, I don't think a standard really exists. That means that the user must have a more powerful speaker amplifier to obtain the same results than if the output was 2.0V, because the speaker amplifier is receiving a slightly weaker signal than what I would call normal.

It also means the user must constantly remember to unplug their headphones from the the iDSD when switching from headphones to speakers and vice versa. If one wishes to use their speakers, it will be necessary to turn the volume control on the iDSD to max to obtain 1.8V output through the RCA jacks, which is probably at best on the low side. Doing this without unplugging headphones (or while wearing headphones) means that the iDSD headphone amplifier will now be outputting the maximum headphone volume it can output.

Anyone who left their headphones plugged into the iDSD on their last listening session must not forget to unplug them before setting the iDSD volume to maximum in order to use their speakers.

I wouldn't worry about 1.8V being too low. But it should as your "overloading my speakers" concern to rest. Actually in most speaker setups by far having too much gain is more of an issue than not having enough. Often the only case that a preamp is adding gain is when it is getting a low voltage signal from a phono stage. For the types of outputs from CD players and DAC (incl the iDSD 1.8V) a preamp is attenuating a signal.

However, if the hassle of unplugging a headphone and adjusting the volume control is such a big concern to you, I have a solution that I know would be willing to accommodate:

Buy another iDSD.
post #179 of 1712
Quote:
Originally Posted by StratocasterMan View Post
 

 

I already bought the product. I'm trying to get people to understand the possible weaknesses in the product. I have purchased this product, and I am suggesting improvements.

 

Perhaps you should learn to capitalize your sentences. In that way, you may be judged as less of a moron.

have the iDSD and like it for what it is. understand its strengths and its weaknesses...and pose questions here if i'm uncertain of something. but i don't presume to tell the manufacturer how they should develop their products and tell them what the device SHOULD have or what it SHOULD be. and i certainly don't try to get my point across by bolding everything, which, IMO, is poor form. 

post #180 of 1712

Interesting with all the back and forth banter here about the HO vs LO and how its controlled...    Just yesterday I looked up the Texas Instrument data sheet (BurrBrown) because I wanted to see how the device handle's DSD and the other formats and to look at the output power specs....     It takes a while to read but everything that is in the IDSD is covered in the spec sheet...  there isn't much more for the designers to add besides a good power supply and the interface to control this chip...and a housing...   

The DAC chip does it all....  including the output volume settings...     in other words... as nice as the iDSD is, its still just an implementation of an advanced off the shelf DAC...   

Now just enjoy what ifi has brought to us all..  :-)

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