• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Reisong A10 EL34 Hi-Fi Audio Stereo Tube Amplifier Single-end Class - A Review

NoelSmart

Member
Joined
Nov 25, 2021
Messages
6
Likes
0
Evidence?
Yes, please. I came here looking for scientific evidence to help evaluate my qualitative impressions, but instead only found a preponderance of evidence that you are a jackass. Luckily I am too.

As a “technical expert” would you care to contribute rather than dismiss and challenge? Why do you think I and so many perceive positive differences in equipment that measures similarly or poorly. Please enlighten us. Seriously, it’s why I’m here.

Why does this cheap tube amplifier which measures poorly not only sound good, but better than equipment that measures better?
 

SIY

Master Contributor
Technical Expert
Joined
Apr 6, 2018
Messages
8,283
Likes
18,592
Location
Alfred, NY
Yes, please. I came here looking for scientific evidence to help evaluate my qualitative impressions, but instead only found a preponderance of evidence that you are a jackass. Luckily I am too.

As a “technical expert” would you care to contribute rather than dismiss and challenge? Why do you think I and so many perceive positive differences in equipment that measures similarly or poorly. Please enlighten us. Seriously, it’s why I’m here.

Why does this cheap tube amplifier which measures poorly not only sound good, but better than equipment that measures better?
Merely repeating an assertion is not evidence. The way one obtains evidence of audibility and preference claims is using ears-only listening tests, no peeking, matched levels.
 

Jim Taylor

Addicted to Fun and Learning
Joined
Oct 22, 2020
Messages
810
Likes
1,574
. I came here looking for scientific evidence to help evaluate my qualitative impressions
Impressions are subjective, or emotional. Science is logical, or non-emotional. Science does not evaluate emotion. Neither does emotion evaluate science.
would you care to contribute rather than dismiss and challenge?
You made an assertion. It is incumbent on you to prove it.

Why does this cheap tube amplifier which measures poorly not only sound good, but better than equipment that measures better?

In the first place, although it may (or may not) sound good, that is your subjective assessment. It has nothing to do with other people's assessment. Yours only. For other people, the amp would merely sound DIFFERENT.

"Good" in audio is accurate, compared to a scientific standard, and to a replicable and provable degree. What is not accurate may or may not be pleasing ... especially to you ...... but in the end, it is simply an opinion. That's what your original post put forth when you said the sound was "pleasing". It was just an opinion.
I take it you're familiar with the "Kodachrome effect"? Kodachrome produces a picture that many, many people find pleasing. It is scientifically verifiable that it is not accurate. But yes, it is pleasing. (I'm not addressing here the effect of time passage.)

Why do you think I and so many perceive positive differences in equipment that measures similarly or poorly. Please enlighten us. Seriously, it’s why I’m here.

I'm not sure (yet) why you're here, but I can tell you why most people are here, me included. It's to use logic, science and verifiable measurements so as to avoid baseless and undisciplined emotional haggling.

If you wish to learn, you can do that here, and there are people here who can help you do that to a very great degree. They are logical and they are experienced. If you wish to take advantage of their knowledge and experience, they will be glad to guide you. :) Jim
 
Last edited:

NoelSmart

Member
Joined
Nov 25, 2021
Messages
6
Likes
0
Impressions are subjective, or emotional. Science is logical, or non-emotional. Science does not evaluate emotion. Neither does emotion evaluate science.

You made an assertion. It is incumbent on you to prove it.



In the first place, although it may (or may not) sound good, that is your subjective assessment. It has nothing to do with other people's assessment. Yours only. For other people, the amp would merely sound DIFFERENT.

"Good" in audio is accurate, compared to a scientific standard, and to a replicable and provable degree. What is not accurate may or may not be pleasing ... especially to you ...... but in the end, it is simply an opinion. That's what your original post put forth when you said the sound was "pleasing". It was just an opinion.
I take it you're familiar with the "Kodachrome effect"? Kodachrome produces a picture that many, many people find pleasing. It is scientifically verifiable that it is not accurate. But yes, it is pleasing. (I'm not addressing here the effect of time passage.)



I'm not sure (yet) why you're here, but I can tell you why most people are here, me included. It's to use logic, science and verifiable measurements so as to avoid baseless and undisciplined emotional haggling.

If you wish to learn, you can do that here, and there are people here who can help you do that to a very great degree. They are logical and they are experienced. If you wish to take advantage of their knowledge and experience, they will be glad to guide you. :) Jim
Thank you Jim for your thorough response! Talking with people like you to learn more is why I’m here.

Your Kodachrome example is excellent. We can measure how color is distorted in a way that is pleasing to some despite not being accurate.

Through reading the forums I learned that second order harmonic distortion can have a similar effect on the subjective enjoyment of audio reproduction. Again, it is not accurate, but it can be preferable.

I’m seeking further evidence in the differences in how amplifiers measure which might further explain some of the qualities I hear in the A10 as opposed to my other amplifiers.

For instance I seem to find more small details with distinct presence in my listening sessions with the A10 than with the Cambridge CX81. Tonal differences aside, I perceive a fidelity difference with the same source.

What measurements would I look to that might help scientifically evaluate the possible differences I’m perceiving?

The more I understand measured and proven physical differences the better I can shape criteria for how to best continue my pursuit of music enjoyment and share those evidence based differences with others for enjoyment of the hobby. Thanks!
 

SIY

Master Contributor
Technical Expert
Joined
Apr 6, 2018
Messages
8,283
Likes
18,592
Location
Alfred, NY
Thank you Jim for your thorough response! Talking with people like you to learn more is why I’m here.

Your Kodachrome example is excellent. We can measure how color is distorted in a way that is pleasing to some despite not being accurate.

Through reading the forums I learned that second order harmonic distortion can have a similar effect on the subjective enjoyment of audio reproduction. Again, it is not accurate, but it can be preferable.

I’m seeking further evidence in the differences in how amplifiers measure which might further explain some of the qualities I hear in the A10 as opposed to my other amplifiers.

For instance I seem to find more small details with distinct presence in my listening sessions with the A10 than with the Cambridge CX81. Tonal differences aside, I perceive a fidelity difference with the same source.

What measurements would I look to that might help scientifically evaluate the possible differences I’m perceiving?

The more I understand measured and proven physical differences the better I can shape criteria for how to best continue my pursuit of music enjoyment and share those evidence based differences with others for enjoyment of the hobby. Thanks!
You skipped past Step 1: Can you actually hear a difference? That MUST come first and you haven't done any sort of experiment to create a starting point.

Now IF (and it's a significant "if") you can hear a difference, then the fun can begin. If you can't, then you've learned something and saved yourself a lot of work.

Let's say you can positively hear a difference with controls implemented. Then start with frequency response measured at the speaker terminals. That's nearly always the principal cause of audible differences between power amps. And then you can EQ until you find something pleasing.

But you must start with Step 1, otherwise you're chasing fairies.
 
Last edited:

NoelSmart

Member
Joined
Nov 25, 2021
Messages
6
Likes
0
You skipped past Step 1: Can you actually hear a difference? That MUST come first and you haven't done any sort of experiment to create a starting point.

Now IF (and it's a significant "if") you can hear a difference, then the fun can begin. If you can't, then you've learned something and saved yourself a lot of work.

Let's say you can positively hear a difference with controls implemented. Then start with frequency response measured at the speaker terminals. That's nearly always the principle cause of audible differences between power amps. And then you can EQ until you find something pleasing.

But you must start with Step 1, otherwise you're chasing fairies.
I have identical pairs of Klipsch RP-150m I use for a separate theater setup and some little Rolls mixers for switching sources and outputs as well as a db phone app for level matching. I use these as a crude but somewhat controlled setup to subjectively test various equipment in the intended listening environment to decide if I want it to become a part of one of my systems. That coupled with reading forums like this where people have different and more advanced equipment and methods helps inform my findings and choices.

That’s my “step one” for any of this, and was for the A10 as well. It definitely sounds different than my other amplifiers (in a way I enjoy). The terminal frequency response graphs here don’t seem to fully explain why. Yes, there’s a high end roll off and some harmonic distortion, which explains some of the tonal character difference between amplifiers, but like I mentioned before there seems to be other differences. I can pick out more detail and can form a more complete sense of position in the recording space with the A10 vs some other amps when using the same source and same speakers.

Given the collective experience here are there any hypotheses why that may be? and how to investigate it?
 

SIY

Master Contributor
Technical Expert
Joined
Apr 6, 2018
Messages
8,283
Likes
18,592
Location
Alfred, NY
I have identical pairs of Klipsch RP-150m I use for a separate theater setup and some little Rolls mixers for switching sources and outputs as well as a db phone app for level matching. I use these as a crude but somewhat controlled setup to subjectively test various equipment in the intended listening environment to decide if I want it to become a part of one of my systems. That coupled with reading forums like this where people have different and more advanced equipment and methods helps inform my findings and choices.

That’s my “step one” for any of this, and was for the A10 as well. It definitely sounds different than my other amplifiers (in a way I enjoy). The terminal frequency response graphs here don’t seem to fully explain why. Yes, there’s a high end roll off and some harmonic distortion, which explains some of the tonal character difference between amplifiers, but like I mentioned before there seems to be other differences. I can pick out more detail and can form a more complete sense of position in the recording space with the A10 vs some other amps when using the same source and same speakers.

Given the collective experience here are there any hypotheses why that may be? and how to investigate it?
Until you do the basic experiment, commentary is worthless. Stop making excuses, do a decent level match, don't peek, and do Step One. Don't ask other people to chase your fairies.
 

Bob from Florida

Senior Member
Joined
Aug 20, 2020
Messages
492
Likes
376
View attachment 109683

Reisong A10 Amazon Link
China HIFI Audio Link

I recently purchased a Reisong A10 amp from Amazon. This is a low powered Single Ended Triode (SET) Tube Amplifier. I wanted to give tubes a try and this seemed like a good starting point. As you will see by the measurements below, this amplifier does NOT measure well at all, even for a Single Ended Tube amplifier, the distortion measurements are high.

However, while I know that this site focus is measurements, I will have to say that the amplifier sounds significantly different then the Class D, Class A and Class AB solid state amps I have here. It sounds closest to the Pass clone Aelph 3 amplifier I also have and previously measured. The tube amplifier is low powered so sensitive speakers 89db or better is advised. Turning the volume up 75% on the knob makes my 89db sensitive speakers very loud in my medium sized room. The tube amplifier adds a certain richness to vocal and acoustical music that gives a "you are there" feeling making music sound live.

Clone Aelph 3 measurements

With the descriptive prelimiary comments out of the way, lets move on to the real reason we are here, the measurements. Interested readers can review my DIY test setup and equipment here:

DIY test setup (Panasonic XR57 example)

One additional test setup note, I am mostly measuring only one channel. However tube amps don't like to be turned on with out a speaker load on the output taps. So I have a dummy 4 ohm load on both the channel I am measuring as well as a separate one on the channel unused.

Below is the REW EQ measured frequency response with the volume set to 50% (approximately .78watts into 4 ohm). Note the high frequency drop off (that is characteristic of all EL34 SET amps or just this one?):

View attachment 109685
Below is the measurement of a 1khz source, 4ohm load, 30% volume control setting, .51vrms (approximately .04w). Note that we are at 1% distortion already at this volume level. You will note a significatant 60Hz power spike. I did try to make some measurements with my REW EQ laptop on battery power and the 1khz source DAC connected via TOSLINK optical. That setup did not reduce the 60hz spike. The DAC was 3 prong (grounded outlet) electrically powered on the same power strip as the 3 prong Reisong A10 amplifier.

View attachment 109686

Below is the measurement of a 1khz source, 4ohm load, 50% volume control setting, 1.77vrms (approximately .78w). This is the max level I typically listen at in my room with my bookshelf speakers (89db sensitivity):

View attachment 109687

Below is the measurement of a 1khz source, 4ohm load, 70% volume control setting, 2.67vrms (approximately 1.78w):

View attachment 109688

Below is the measurement of a two tone 19K and 20K source, 4ohm load, 70% volume control setting:

View attachment 109689

Again, the measurements here have a disappointingly high amount of distoration even at low 1-2 watt outputs. SET amps are famous for mostly 2nd harmonic distortion that is said to give the amp a "warm" sound. But this amp (although progressively less at higher harmonics) has high levels of distortion. The amp measures poorly but qualitatively has a very pleasing sound to listen too. All measurements taken with the factory default tubes.

Comments welcomed on my findings and test setup. I am open to trying other measurements to better characterize my new tube amplifier.

View attachment 109695

View attachment 109696
Looking at the picture of the internals I see some areas of concern. Your measurements show a lot of 60 HZ and 120 HZ plus plenty of even and odd harmonics of those fundamentals. I see separate filament windings for power tubes - 6.3 VAC, preamp tubes - 12.6 VAC, and rectifier tube - 5 VAC. Rectifier high voltage windings have no center tap to ground which explains the extra silicon rectifiers to make it a full wave bridge. Filament winding wiring is not laid out well and parallel in some areas to other wiring - some 60 HZ coupling. Another error is the preamp tubes are wired for 12.6 VAC operation with one pin grounded. This is almost certainly a source for some of the 60 HZ. All they had to do was move the ground to pin 9 - center tap for the dual heaters - of each preamp tube to see if some 60 HZ reduction would occur. Being Single Ended Ultralinear - the B+ supply needs to be very low noise. Looks like a CLC filter but I guarantee the downstream side of the choke capacitor is not large enough. A 1000 uf cap would help a lot - if there was a place to put it. For the current $399 selling price the expectation should not be too high.
 
Last edited:

steve-z

Member
Joined
Nov 4, 2018
Messages
49
Likes
35
Location
Rotherham, South Yorkshire, UK
Not checked in on this thread for a while, I was wondering if any A10 users had converted the 6n2p driver tubes to 12ax7 using a socket adapter ? and if so did it produce any noticeable improvement ?
 
Top Bottom