[Mad Lust Envy]

Okay, I know how taboo double amping is in general, so no need to tell me that it's bad, etc.

Thing is, lots of us video gamers NEED to double amp certain gaming headphone devices due to inadequate amp sections. We use these devices to impart their virtual surround features, which are a significant benefit to many of us (yes, DSPs that cause 5.1 signals to be downmixed and virtualized into 2 channel, very much like the Smyth Realizer and the Beyerdynamic Headzone (not the headtracking, but the emulated surround feature). Double amping is necessary, because virtual surround for these devices are limited ONLY to their headphone outs.

I'll make a good case for double amping the Beyerdynamic Headzone. The Headzone has a 100ohm output impedance, and thus using a better amp would allow a headphone to mitigate the effects of mismatched output impedance while retaining the surround properties of the Headzone.

My question(s) is/are, Once a line level source has hit an amp...does the line level's decibel level/loudness change to account for the amp, or does it stay as 'quiet' as before it hit the amp?

I.e., if I wanted the source fidelity to reach my second amp, would I need to keep my volume level on my first amp high, or is line level relatively low on the volume pot for the first amp? Another example: Say line level is 50% volume on the first amp, would I lose information if I went below 50% volume on the first amp and sent that to my second amp?

This question is odd and not something most of you will ever need answered, but for gamers (movie watchers with headphones) with very, very limited options, this is important.

 

[castleofargh]

bit=digital signal
amp = analog amplifier.
so I'm not sure I understand what you're talking about?

 

[Mad Lust Envy]

Ah, well... I assume, like when you lower software volume on PC on say a 16 bit source, you lose some fidelity. I assumed it's the same thing if you under line level when double amping... Unless the first amp retains all the data from the dac regardless of volume level.

I ask these questions because, well i obviously don't know all the scientific mumbo jumbo behind double amping.

Like say those who use portable amps attached to their cellphone's headphone jacks (if they don't have a LOD). I thought being close to max volume from a cellphone would be ideal for the next amp due to retaining all the data. Is it not necessary, and volume level from the first amping stage isn't a factor at all?


I'm obviously more of a subjective guy vs objective.

 

[Mad Lust Envy]

A simpler example of what I'm confused about: (This is seriously what i should've started the topic with. Sorry, it's really late at the moment)

Step 1: Fiio E17 dac only - line out to Schiit Vali - volume pot at about 40% to hit my sweet spot

vs

Step: 2 Fiio E17 - headphone jack out to Schiit Vali - certain volume setting on the E17 = same volume as step 1.

I assume: Would going LOWER in volume on the E17 for step 2 (meaning sending out a lower than line level signal volume from step 1) = losing source audio fidelity?

I'm well aware that bit data is digital, and my question is almost entirely analog related.

So... since the first amp stage already has all the data from the DAC... the second amp can retain it, regardless of the first amp's volume level? I always thought going too low in volume from the first amp would lose some data. Now that I think about it... I feel really stupid. I'm starting to believe that as long as the second amp can reach your desired volume level, you retain the same information regardless of whatever volume level is on the first amp. I mean, it is all analog. once it reaches the first amp.

 

[stv014]

It is recommended to set an output level on the first amplifier that works optimally as a line input for the second one. Setting a very low volume and then compensating for it by turning up the volume and/or gain on the second amplifier does tend to make the overall SNR worse, similarly to digital volume controls.
 
However, the output level obviously should not be increased so much that it leads to clipping (or, in extreme cases, damaging the input of the second amplifier). It is also best to avoid a very low volume setting on either device, to prevent channel balance issues.
 
In practice, with good amplifiers, there is likely a relatively wide "window" of volume settings that works well enough.

 

[Mad Lust Envy]

Thanks, stv. And I agree. From my experience, too low, or too high has been problematic to sound quality. I found something around 70-80% from my specific devices to be ideal, to keep from getting the high volume distortion, or low volume channel imbalances.

 

[ProtegeManiac]

Quote:

Thing is, lots of us video gamers NEED to double amp certain gaming headphone devices due to inadequate amp sections. We use these devices to impart their virtual surround features, which are a significant benefit to many of us (yes, DSPs that cause 5.1 signals to be downmixed and virtualized into 2 channel, very much like the Smyth Realizer and the Beyerdynamic Headzone (not the headtracking, but the emulated surround feature). Double amping is necessary, because virtual surround for these devices are limited ONLY to their headphone outs.

I'll make a good case for double amping the Beyerdynamic Headzone. The Headzone has a 100ohm output impedance, and thus using a better amp would allow a headphone to mitigate the effects of mismatched output impedance while retaining the surround properties of the Headzone.

 
Is ther anything about the Headzone that a(n external) gaming soundcard like the Xonar U3 can't do? (Beyer's site isn't loading on my browser right now, not sure why) I mean, for $39 just to get surround DSP (assuming you already have a DAC-HPamp or DAC and HPamp that can decode SPDIF and drive whatever headphones) that's not a bad price.
 
Quote:

My question(s) is/are, Once a line level source has hit an amp...does the line level's decibel level/loudness change to account for the amp, or does it stay as 'quiet' as before it hit the amp?

 

I think the impedance of the second amp can affect the first amp's output just as much as different headphone impedance can, except this time it won't have to deal with for example impedance swings on a dynamic driver, but total loudness will be affected not simply by the end headphone's efficiency but also by each amp's gain. The Headzone kept constant, then it's the second amp's gain that is variable.
 
 
Quote:

I.e., if I wanted the source fidelity to reach my second amp, would I need to keep my volume level on my first amp high, or is line level relatively low on the volume pot for the first amp? Another example: Say line level is 50% volume on the first amp, would I lose information if I went below 50% volume on the first amp and sent that to my second amp?

 
You can't "lose information" that way in terms of bit depth because at that point the signal is already analog; in which case, since you already have two preamps in the same signal chain, might as well not use the software volume control to avoid that. When setting the analog volume controls your goal is to minimize THD and noise while driving the transducer at the end to adequate listening levels; bit depth is of no concern here.

 

[cdsa35000]

In general most headphone output can function as line-out, as long as you can't hear distortion/clipping when the headphone-out is "overdrived", means its good and compatible for further amping.
The input impedance of most (head) amps. are at least 10k Ohms, so no mismatching.
Line-out and line-in levels are standardized with dB references:
http://en.wikipedia.org/wiki/Line_level
http://www.google.com/search?q=0dB+line+input+reference

 

[Mad Lust Envy]

Is ther anything about the Headzone that a(n external) gaming soundcard like the Xonar U3 can't do? (Beyer's site isn't loading on my browser right now, not sure why) I mean, for $39 just to get surround DSP (assuming you already have a DAC-HPamp or DAC and HPamp that can decode SPDIF and drive whatever headphones) that's not a bad price.

Well, problem with something like the Xonar U3, is that it only works for PC. As a console gamer first and foremost, the U3 does not work. That is why we're limited to options like the Astro Mixamp and other such similar devices that only output their virtual surround DSPs through their headphone out, hence the double amping.

Believe me, I would be ecstatic if they sold an affordable device that output their virtual surround through their DAC (like the Xonar U3 can through it's spdif out). Apparently, the Creative X7 can, but that's already an all in one device, and a hefty $400.

 

[ProtegeManiac]

Well, problem with something like the Xonar U3, is that it only works for PC. As a console gamer first and foremost, the U3 does not work. That is why we're limited to options like the Astro Mixamp and other such similar devices that only output their virtual surround DSPs through their headphone out, hence the double amping.

Believe me, I would be ecstatic if they sold an affordable device that output their virtual surround through their DAC (like the Xonar U3 can through it's spdif out). Apparently, the Creative X7 can, but that's already an all in one device, and a hefty $400.

 
Oh, I didn;t know this was for consoles. Still, I'm more inclined to just use the Creative X7 - at least that one will just drive many headphones directly without any real issues.

 

[Mad Lust Envy]

Oh, same here. Once I'm able to afford it, the X7 is definitely the best setup. The question is for everyone else who can't, and already own devices like the Mixamp and their own audiophile amps.

 

[RRod]

Well, problem with something like the Xonar U3, is that it only works for PC. As a console gamer first and foremost, the U3 does not work. That is why we're limited to options like the Astro Mixamp and other such similar devices that only output their virtual surround DSPs through their headphone out, hence the double amping.

Believe me, I would be ecstatic if they sold an affordable device that output their virtual surround through their DAC (like the Xonar U3 can through it's spdif out). Apparently, the Creative X7 can, but that's already an all in one device, and a hefty $400.

 
I still have no idea why 3D sound libraries that do HRTF aren't standard yet, for consoles and PC. I guess hardware people want their $$ too.

 

[castleofargh]

it's what stv014 wrote then. if you could measure the output and have many specs for the amps and the console, it would help fine tune the system. but if all you have are your ears, then go for the first amp relatively loud but making sure you don't get any clipping. and then set your preferred loudness with the second one. and if the second one is subject to channel imbalance at that loudness then obviously lower the first amp a little to get out of that zone on the second amp. it doesn't look like very educated advice, but those stuff are usually built to work nicely on a pretty wide range of voltages so you don't need to concern yourself too much about the changes in performance. they should be small on most settings.
 
same with the sound quality loss from double amping, it's not ideal, but it's also not a drama. being plugged into an amp makes the job for the first one really easy(thank to a few thousand ohm load) so it may even in a few cases give a better signal than on it's own trying to drive something of lower impedance.

 

[cdsa35000]

Well, problem with something like the Xonar U3, is that it only works for PC. As a console gamer first and foremost, the U3 does not work. That is why we're limited to options like the Astro Mixamp and other such similar devices that only output their virtual surround DSPs through their headphone out, hence the double amping.

Believe me, I would be ecstatic if they sold an affordable device that output their virtual surround through their DAC (like the Xonar U3 can through it's spdif out). Apparently, the Creative X7 can, but that's already an all in one device, and a hefty $400.

Too bad you just miss the deal X7 for 279 at Amazon minutes ago, as reported from other thread.

 

[Mad Lust Envy]

Yeah, it hurts that I missed it, but I can't exactly afford even that price right now.