That's a simulated response with resistive load. Peufeu has actually answered your question. But here is a simple clue: display the equalizer's spectrum visualizer. For every frequency point, the dB level can be drastically different. One of your clip has 20kHz response. This is probably because of a wide bandwidth bipolar output stage, if not any kind of 'mishandling'.
Many of these amps (especially the two transistor ones) have intrinsic bandwidths up to several MHz so hitting 20kHz or the 48kHz Nyquist limit of 96kHz sample rate is not surprising. Are you saying that there is a peak at 20kHz when looking at FFT of sound clip?
After normalizing the tracks properly (ie, using RMS not peak), spectra in the treble are all identical (and also identical to the original). No problems here, except the varying recording levels as previously mentioned.
In the bass, all amps are identical, except two :
one -1.6dB at 20Hz, the other -4dB at 20Hz.
They probably have smaller input coupling caps.
So, yeah, some amps have more bass than others!
Can't comment on distortion without lossless files...
In the bass, all amps are identical, except two :
one -1.6dB at 20Hz, the other -4dB at 20Hz.
They probably have smaller input coupling caps.
So, yeah, some amps have more bass than others!
Can't comment on distortion without lossless files...
Oops sorry, I meant that you can see the response level at 20kHz for certain musical note and you can see differences. Let me take an example:
I display the spectrum visualization (see attachment) for clip B, then when there is 20kHz note appear on the screen (above -60dB) after the lyrics "September (in Montreal)" I printscreen the image. Most of the clip doesn't have this 20kHz note, not above -60dB. Clip B shows 1.6dB above -60dB, so at least there is 1.6dB difference between clip B and most of the other clips at this frequency. This is what gets into the ears, not the +/-0.2dB.
For that 20kHz note as an example, you will see that clip B is the loudest, then clip F. I believe that this applies to the majority of notes. And you can see that clip B has the highest vote, then clip F. This is not coincident. Many people can perceive small loudness difference. Trust me, if this loudness is flat/same across all clips then almost everyone cannot hear differences.
I didn't say that clip B is chosen 100% because of the perceived loudness, but it is the major factor. After this factor is of course the bass quality that unfortunately comes with a price: accuracy. But this inaccuracy and the low distortion, who can perceive it by the way??
Attachments
The 20kHz is just an example (to make it easy to show differences) to explain my point that our ears do not hear +/-0.2dB from 20Hz to 20kHz. Certain musical notes can be drastically different between clips. It is up to the listener to choose which note (hence frequency) he wants to listen to when comparing. (I was just giving the clue. If I have time may be I will try to capture other notes.)
Loudness is the first thing most ears can perceive. I believe it is the first determinant factor (Many believe that it is the ONLY determinant). Second is bass 'quality', but loudness will reinforce bass perception too, right?
So I tried to check other notes. The highest note in the music, 1kHz, which is after the lyrics "That's where..." at 0:40. One clip has outstanding SPL here. This correlates with highest distortion. I believe this is the pocket class-A headamp which uses poor ZVN mosfet at the output.
They take too much room as limit is 1.8MB. I would have to repeat experiment as I did not save the lossless files. So no sorry can't do it.
So far only 1 person has submitted to me their guess of amp assignments to sound clips. There is one week left to do so if you want to win the pocket Class A amp as a prize. Minimum 4 correct matches.
I really like this! Are you conncerned about asking 2 different, but not independent questions (which one sounds best and which one maps to which amp), the results of which may be influenced by the other. I think this can skew the results. But I'm not a statistician
Last edited:
The latter question is to only be answered by sending me a PM so as to not skew the result of others. Or are you asking if people are asked to guess which one is which, then their own "knowledge", however accurate or inaccurate skews their voting? I suppose it could but then we all wonder what the amps are. I am just asking for it to be committed to writing so we can see how close people are.
I was thinking about people influencing themselves, if that makes sense. Again I'm by no means educated in this stuff... it just jumped at me when i read about the contest.
Poll closes tomorrow folks. If you haven't voted yet and want to do so please get it in. Also, if you want a shot at the free Pocket amp please send me via PM your predictions.
Big Reveal
Here are the identities of the sound clips and their respective amps. Thank you to all that participated.
Although the sample size is very limited, so don't flame me - one thing I see is that two simple transistor amps is all that is needed for good sound with headphones. Ultralow distortion opamps aren't always the best sounding. Overall preference was for the BF862/2SA1837 CFP amp designed by AKSA. The fact that the amp uses the now discontinued, but legendary Toshiba 2SA1837 is no mistake. That is a good sounding transistor!
The Little Pocket Class A amp was not too shabby here either.
Headamp Comparison Key
A = BF862 Pre & DAO
B = CFP BF862-2SA1837
C = CFP BF862-BD140
D = DCG3
E = Fiio A5
F = Pocket Class A
G = SRPP 4 pair BF862
H = Super CMOY 1688
Here is the summary of the test data from the amps on the day the test was made:
Note that the pocket class A has since been made into a real PCB with larger output caps and bigger rail caps so performance is even more improved (dynamic range is 94.2dB, stereo crosstalk is -72dB, noise floor is -126dB, freq response is +/-0.5dB 15Hz to 40kHz).
I do want to say that all these amps sound just great and I would be happy with them as daily listeners. However, given a choice, I will take my portable pocket class A amp any day. For sitting down and desktop amp listening, like many of you, I prefer the 2SA1837 CFP amp - it is my reference headphone amp. Now, if only one could squeeze the performance of the big 2SA1837 CFP onto a pocket amp to take with me... 🙂
Here are the identities of the sound clips and their respective amps. Thank you to all that participated.
Although the sample size is very limited, so don't flame me - one thing I see is that two simple transistor amps is all that is needed for good sound with headphones. Ultralow distortion opamps aren't always the best sounding. Overall preference was for the BF862/2SA1837 CFP amp designed by AKSA. The fact that the amp uses the now discontinued, but legendary Toshiba 2SA1837 is no mistake. That is a good sounding transistor!
The Little Pocket Class A amp was not too shabby here either.
Headamp Comparison Key
A = BF862 Pre & DAO
B = CFP BF862-2SA1837
C = CFP BF862-BD140
D = DCG3
E = Fiio A5
F = Pocket Class A
G = SRPP 4 pair BF862
H = Super CMOY 1688
Here is the summary of the test data from the amps on the day the test was made:
Note that the pocket class A has since been made into a real PCB with larger output caps and bigger rail caps so performance is even more improved (dynamic range is 94.2dB, stereo crosstalk is -72dB, noise floor is -126dB, freq response is +/-0.5dB 15Hz to 40kHz).
I do want to say that all these amps sound just great and I would be happy with them as daily listeners. However, given a choice, I will take my portable pocket class A amp any day. For sitting down and desktop amp listening, like many of you, I prefer the 2SA1837 CFP amp - it is my reference headphone amp. Now, if only one could squeeze the performance of the big 2SA1837 CFP onto a pocket amp to take with me... 🙂
Attachments
Last edited:
Argghhh, missed voting, but my preference was F - the Pocket Class A amp.
Thanks X for setting this up. 🙂
- Status
- Not open for further replies.