[Midweek Crisis] Different amps = different sounds?

[creatip123]

It's midweek (Tuesday actually), and I already got bored out of my ears. Between sitting at my desk, daydreaming, and reading forums, I thought of this one.

 

So it seems the 'hot' topic is how an amp, beside of its main function, to amplify signals, can make 'things sound oh-so-much-better'. I figured I might do a little experiment, if only to kill my boredom.

 

The correct way to do the experiment/test is to use various amps, a headphone, and a dummy head with high-quality mics embedded in the ears.

 

 

Put the headphone on the dummy head, play a song through various amps, record and compare the sounds the mics are picking. Too bad, I'm not that hardcore as to deliberately shop for that audio dummy head, just to do this experiment. So I just have to make do with what I already got.

 

 

Those are the things that I used. The idea was to play a song(s) through various amps, plug the audio signal out to my mobo's line-in, and record the results (with Audacity), to be compared.

 

1. iPad3 as the song playing device

2. DMM to measure and keep the signal voltage as constant as possible

3. Fiio E6

4. Small (not very powerful, but enough) CMOY amp

5. Ipad's interfaces, the Camera Connection Kit, and the Line out Dock adapter

6. Interconnect cables, m2m as well as RCA-to-stereo 3.5mm (plugged at the back of the Aune T1)

7. Aune T1

8. Extension stereo cable that's plugged to the back line-in jack of the onboard audio. 

 

The constants:

 

- The song played between various amps

- The song playing device and app, iPad3, Onkyo HF player

- The voltage of the signal going into the line in (explained below)

- The ADC, which was VIA VT1708S 8-Channel High Definition Audio CODEC

- The recording volume and application used, Audacity

 

The variables:

- Amps used, which will be the test subjects

 

An amp's main function is to amplify audio signal, so needless to say, an additional amp will add more loudness. That's not what the test was about though. The test was about, 'aside from making the signal stronger/louder, does different amps give different sounds?'. So to avoid the result comparisons being biased by different loudness, I tried to keep all the loudness at the same level.

 

To keep the loudness level recorded as close as possible, every time I switched between amps, I do a calibration of the signal voltage. So I played a 1kHz sine tone, and measured the signal voltage, and adjust the volume knobs to get pretty much the same voltage between all amps. The voltage was 0.355 (what was read in the DMM anyway), with little deviations of 0.352-0.355. The point of contact which I measured the voltage was the point that went into the extension stereo cable (#8 in the picture), as that was the entry point to the ADC of the onboard audio.

 

I played 2 songs with those amps, and recorded each of the results. To keep the size down, I only recorded the songs below 2 minutes from the start (about 1:30 or something)

 

Now I don't know how accurate the results are, or even if it's an acceptable method. So just treat it as it is. 

 

I exported all of them into FLAC format, which is frankly just to eliminate the possibility of someone protesting 'it's not valid, because it's in a very very bad lossy MP3 format' (read this with a thick Pakistani accent for extra points)

 

You can download the recording results here: http://www.filedropper.com/amptest It's 117MB

 

There are 2 folders, sorted according to the 2 songs I tested. 1 song was a Daughtry's song, the other was an EDM or trance music (to compare the kicks/basses)

 

 

The file names should be pretty much self-explanatory

 

- Audio out = iPad's headphone out => PC's line in

- LOD = iPad's line out dock adapter => PC's line in

- Fiio E6 = iPad's headphone out => Fiio E6 => PC's line in

- CMOY = iPad's headphone out => CMOY => PC's line in

- AuneT1 line in = iPad headphone out=> Aune T1's RCA line in => headphone out => PC's line in

- AuneT1 tube dac = iPad digital/USB out (using the camera connection kit) => Aune T1's DAC => headphone out => PC's line in (extract the digital audio data from iPad)

 

Download it if you're curious, or even only just for kicks. See if you can hear any differences between the recordings. 

 

I'm not making any claims here, you might hear differences, then again you might not. So again, treat it as what they are, test recordings of various amps, recorded with mediocre onboard ADC. 

 

If you can hear differences, then good for you. You got sharp ears that are sensitive to minuscule sound details

If you can't hear any differences, then good for you too. This means you won't be confused by all the debates about 'this amp make the music oh so heavenly', or 'that amp turns my $100 headphone to a $1000 one', etc

 

Oh, another note. Say you can hear some differences, the next step for you is to judge for yourself, do the differences justify the extra money or not. The end decision is in your brain, and your wallet, of course....

[BoredErica]

How are you keeping the loudness at the same level if not by checking the voltage? 

I don't see the point of this test. Efforts should be put towards running tests to level-match two amps and then double-blind testing it.

[creatip123]

How are you keeping the loudness at the same level if not by checking the voltage? 

 

 

 

To keep the loudness level recorded as close as possible, every time I switched between amps, I do a calibration of the signal voltage. So I played a 1kHz sine tone, and measured the signal voltage, and adjust the volume knobs to get pretty much the same voltage between all amps. The voltage was 0.355 (what was read in the DMM anyway), with little deviations of 0.352-0.355. The point of contact which I measured the voltage was the point that went into the extension stereo cable (#8 in the picture), as that was the entry point to the ADC of the onboard audio.

 

 

 

 

I don't see the point of this test. Efforts should be put towards running tests to level-match two amps and then double-blind testing it.

 

I provided the materials for the blind, double blind, triple blind, quadruple blind tests. Just load all the files to foobar and use ABX plugin, all should be good. 

[SSL]

Playing head-fi advocate, but couldn't you argue that the process of recording and then reproducing the sound of an amp will completely obscure any "quality" improvement? All that leaves is whether or not that the amps sound different, but I don't think anyone around here seriously argues against that.

[Lutkeveld]

It's more like judging the sound quality of a speaker by watching a video

[BoredErica]

I provided the materials for the blind, double blind, triple blind, quadruple blind tests. Just load all the files to foobar and use ABX plugin, all should be good. 

You have, I was just confused why you went through all that trouble and didn't do it yourself.

[creatip123]

Playing head-fi advocate, but couldn't you argue that the process of recording and then reproducing the sound of an amp will completely obscure any "quality" improvement? All that leaves is whether or not that the amps sound different, but I don't think anyone around here seriously argues against that.

 

Yes, this also crossed my mind. Instead of a passive device (headphone), in its place was the active ADC of the onboard, which could pick up EMI, and all stuffs of electrical garbage from inside the PC.

 

But the idea started out simple. It's not to show, 'Fiio E6 sounds like this, CMOY sounds like that', but rather, 'do different amps give different sound results, and if so, by how much? and can I really hear it or not?', so I tried to keep every other factors, besides the amps, as constant as possible

 

Got this idea from posts like, 'you can run a headphone straight from your phone, but you'll need an amp to make it really sounds good', so I provided the recordings from straight of iPad (representing smartphones) vs iPad ran through various amps. This way, hopefully, people will have more solid idea about the sound differences, as opposed to a vague line like 'you'll need an amp to unleash the headphone's full potential'

 

It's more like judging the sound quality of a speaker by watching a video

 

Not sure I'm following

 

You have, I was just confused why you went through all that trouble and didn't do it yourself.

 

No points of doing that, because from the beginning, it's not intended for me/myself. Even if I did the ABX testing, and succeed, or failed, the result is just for me alone. Meaning, if I succeeded, no guarantee others will have the same results, and if failed, same thing applies. 

 

From the beginning, my intention was to give people who don't have any idea of 'can an amp make my headphone sounds oh-so-much better, aside from louder?'. So this is not a project for me, but for people asking that kind of question. This way, hopefully they can test for themselves, and get a general idea of how much an amp affects the sound (not loudness), or even more basic, can they hear the differences or not? Eventually comes down to the ultimate question, 'is it worth the extra money to get these kind of differences?'

 

On the other note, after doing all those recordings, of course at some points I tried comparing them myself, although not in a blindtest. The most difference for me was between the Daughtry's song LOD vs Aune T1 line in or tube dac. That's for me, and naturally I can't speak for the others. 

 

Edit: seems like somehow I messed up with the LOD one, making it unsuitable for ABX testing, too distinguishable

 

[ShearMe]

Did you move the headphones/microphone at all between amplifiers?

Something to add to your constants and variables list.

[creatip123]

Did you move the headphones/microphone at all between amplifiers?

Something to add to your constants and variables list.

 

Ummm, I'm not using any headphones/mics. The dummy picture above is just a picture I found on the net about what I think is the 'proper way' to do it. The way I did it, it's audio player => amps => onboard audio's line in => recorded by audacity.

[ShearMe]

Ummm, I'm not using any headphones/mics. The dummy picture above is just a picture I found on the net about what I think is the 'proper way' to do it. The way I did it, it's audio player => amps => onboard audio's line in => recorded by audacity.

 

Either I misunderstood or skimmed over that bit. TLDR dood

[creatip123]

Either I misunderstood or skimmed over that bit. TLDR dood

 

Yeah, well, hopefully this project can answer the people asking something like 'I got enough loudness out of my headphone plugged straight to my phone, but I heard that an amp will make my headphone sounds so much better. Just how much differences are we talking about? Worth the extra money or not? Should I get it or no?'. 

 

Hopefully with those files, they can get a general idea of what to expect from using an amp vs straight of phones.