Test Results 20 Watt Class A Amplifier with Quant Asylum QA401

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In this video 'Test Results 20 Watt Class A Amplifier with Quant Asylum QA401', I will run a variety of tests, e.g. THD and IMD. #QA401 #QuantAsylum #THD #IMD #THDplusNoise #20WattClassA
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15 сен 2024

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Комментарии : 44

@minliu2k3 Год назад

It's truly remarkable to have such a wide array of options for evaluating the performance of an amplifier, which seems to be absent from the industry brochure. In light of this, I will stick with high-efficiency speakers as a means to keep the of %THD in check.

@KissAnalog Год назад

Thanks for the great feedback! I agree - high efficiency speakers are a great start;)

@andymouse Год назад

Great video and fascinating but some of the tests worried me I am not a hifi guru but I am an engineer. For instance in all the test the roll off and performance overall was terrible even at 10Khz. Hawkwind screwed my ears years ago but I can still hear stuff up to 13 Khz and the test shows dreadful THD and THD+n @10Khz and it was rolling off there too and I think there was way too much power supply noise personally. One of the graphs clealy showed a THD of 10 % just before it rolled off at 10 Khz and that's bad. I was taught that class A had great sound and specs but very inefficient whereas class A?B had slightly worse specs but are far more efficient ? please do more on this....cheers.

@KissAnalog Год назад

Thanks for your great feedback! You pointed out the same things that I was thinking;) If I had not heard this amp I'd be worried to say it was finished product. Now that I see the test results I question my hearing;) My friend likes his music loud and maybe that covered up the noise. This amp does sound very open and clean - so I'm very surprised by the tests. There is an extreme lack of filtering around the input section. I would like to swap out the transformer/bulk caps with a switcher and filter the OpAmp stage. Also change the input filter to get the 20kHz bandwidth. I have more boards, so I think I'll keep this unit as is and give back to my friend, then build a modified unit and then give it to him to listen to - and see what he thinks;)

@andymouse Год назад

@@KissAnalog Great plan !

@versace885 Год назад

Hi Eddie, I really appreciate your positive and innovation doing these test. It really has help me a lot. Thank YOU 😄🙏

@KissAnalog Год назад

My pleasure! Thanks so much!

@JasonsLabVideos Год назад

OH OH!! I konw where you got that unit from !! :). Glad to see a vide and it working sir !! THUMB UPPPPPP!!!!!

@KissAnalog Год назад

Thanks Jason! After I got this from you I meant to do many videos but there's just so much to do;) Now that I'm more familiar with it - I'll be using it more often. Please let me know if you have any tips!

@MrMersh-ts7jl Год назад

From my experience, tubes have a lot of odd order harmonics. Push pull presents a lot of low odd and even, while Single ended has a pretty steady decline starting at the second order harmonic.

@KissAnalog Год назад

Thanks for the great feedback! Maybe I got that from tubes in Single ended topologies... Not sure.

@MrMersh-ts7jl Год назад

@@KissAnalog love the content brother. I would love to see a real audio power supply series. Keep it up.

@garydirkse9900 Год назад

Amazing amp and instruments, and video. The low output impedance is the most impressive. Eventually, we need the cleanest metal speakers plus a musician's ears to evaluate several amplifiers. Said musician will need to pick out speakers with the least coloration first. If the speakers are high efficientcy, I expect that this amp is a favorate. Good work Eddie. thank you

@KissAnalog Год назад

Thanks so much!

@TRONMAGNUM2099 Год назад

Lot of testing measurements I don't really understand too well. Would need to see more and comparisons to other amps to see differences. For 600 bucks this seems like an amazing piece of test equipment for the hobbyist market.

@KissAnalog Год назад

Thanks for your feedback! I need to do more comparison testing to see how different amplifiers stack up. Also, I'll try to improve some by adding some modifications.

@electronicengineer Год назад

Thank You for the highly interesting video Eddie! You're the man! Looking forward to our next video-hangout together. I hope you have a great day. Fred

@KissAnalog Год назад

Thanks Fred! I appreciate your support!

@vintageaudioreview Год назад

It looks like you are running an older version of the software. I have the next version, the QA402 and love it. If you are careful with the voltage level that you are probing, you can hook up a scope probe to one of the channel inputs and it becomes a great troubleshooting tool.

@KissAnalog Год назад

Thanks for the great feedback! I did actually have diff probes on input and output and was watching the waveforms. I will have to show this in an upcoming video. I need to update the software too. Was there an obvious change to the software?

@ChazzDerby Год назад

Tak! Really good video. Can´t wait to get my hands on a Quant Asylum. Love to build and repair Hi-Fi stuff.

@KissAnalog Год назад

Wow - thanks so much for your generosity!

@arfer1470 Год назад

Intersting results, maybe it could do with a little ac feedback? Also you could look at how much ripple is on the power rail's when you have both channels running like that, a regulated switcher with much less ripple might give different results!

@KissAnalog Год назад

Thanks for your feedback! I think I'll do what I can to modify it and make it test much better - if I can;)

@hoobsgroove Год назад

Why the distortion at the high frequencies 10% would it help to have a better filtering on the power or and drive transistors at 10k. I would like to see the third harmonic lower at least another -3DB especially when you're playing digital sources through the amp can make a big bearing on sound quality Could you get the power supply noise down to minus 130 db? That would be good lol

@KissAnalog Год назад

Great questions! I was a bit surprised at the results. I will have to see what I can do to see if there's some easy mods to get this to test better;) I think some high frequency filtering at the OpAmp voltage rails.

@hoobsgroove Год назад

@@KissAnalog op-amp right Are those chips quite noisy? Thats probably why people go with discrete. You didn't check square wave you're not getting ringing? You had a lot of side band on the main frequency quite high I thought, isn't that usually a sign of ringing? How could you reduce the side bands further? Could you noise cancel them out by reversing the input phase? Is that feasible for every single? What is the damping factor of the amp got a figure. How do you describe the sound of the amplifier?? does it have a good sound stage front and back and side to side, is it quite airy a lot of separation of the instruments easy placement. What is the VA of the transformer? Doesn't seem to look that big on the picture, I think something like a 2,000 VA would be a greatly better and not particularly expensive at 130$, not the ones i have seen made in Poland, they go up to 6,000 VA. to be truly class A you need a big transformer. Oh I like the approach of having two transformers one smaller for the preamp and one larger for the main amp that works better I believe. That's something you could do in a separate box connected with a din plug to the amp or go battery! We don't see enough good battery amplifiers these days considering the power of the batteries and the ease of recharging, I would have thought there'd be more of there these days.

@gregwmanning Год назад

I reckon InterMod Distortion sounds horrible and noisy, whereas Harmonic Distortion sounds good it adds body to the music. You should not be able to hear any 50/60Hz hum .

@KissAnalog Год назад

Thanks for your feedback! I tried to isolate so that the 50/60 Hz hum didn't come through. It did at first, but the inductors in the Chassis ground connections seem to have solved that issue.

@jameswarren1831 Год назад

Did the first test show loss of gain above 10Khz? If so can you make it more linear?

@KissAnalog Год назад

Great question. I think we can change one capacitor and change the bandwidth. I'll test it in Microcap simulation tool first;)

@jameswarren1831 Год назад

@@KissAnalog If you have time it would be great to see how it’s done! Thanks for the videos:)

@Paxmax Год назад

I kind of look at valves/tube amps like I look at steam engines... "Intresting" but I would not like to have my car fitted with one.

@KissAnalog Год назад

I love that!

@nigeleyeit Год назад

Keep up the good videos. I went to kissanalog.com but doesn't look like much is there.

@KissAnalog Год назад

Thanks! I have had trouble getting my website built;)

@robertkovar8710 Год назад

Its realy bad amplifier..

@KissAnalog Год назад

Thanks for your feedback, but why do you say that? Is there a particular test that you didn't like?

@handryraya2853 Год назад

i would like to know if the result is in line with the simulation result. yes nice test equipment, but it is bad result for class A that burn so much power, it is way worse than a cheapo LM1875. freq response already roll off way in the audio band. not to mention the THD. maybe the setup test is not correct?

@MichaelBeeny Год назад

If this is an example of class A I'm not impressed. Of course, it sounds like a valve amplifier because it has the same high THD, the same rolling HF. If you are saying it's OK to have such high THD why worry about crossover which will add an almost undetectable rise in THD. Which of course is absent anyway with a correctly biased class AB. All that THD distortion is colour, it's an additive to the signal, much like adding extra sugar to a cake. It may be pleasing to some people, but it is an additive after all. HiFi is all about as near as possible hearing the original signal, not adding stuff to it that can make the signal seem better. I think I will stick to my crossover free class AB amplifier. Nothing I've seen here would make me feel the need to go class A. Plus it's VERY un-green in today's politically correct speak!

@KissAnalog Год назад

Thanks Michael. I agree with everything you said. I want to mod this amp to see if I can improve it. But, I do have other Class A amps that I want to build and test. I'm surprised how great this amp sounded - but we were playing it at high levels and it was rock n roll so maybe the color did add something - or maybe those levels are low enough not to actually matter? I'm not sure but I want to experiment with my friend on other amps to see what he thinks.

@Obsfucation 9 месяцев назад

Eddie: You mentioned at 15:05 that class A amplifiers, especially tube amps have higher distortion. From what universe is that coming from? It’s true that a topology with a single ended output will be susceptible but, a competent Lin design with a class A push pull output is capable of the lowest possible distortion of ANY amplifier. You don’t explain anything about the topology of the amplifier you’re measuring. If it’s a class A push pull output then I’d say the design of the preceding stages are pretty poor. There is nothing commendable or acceptable about the distortion performance of this amp. And anybody who believes that high(er) levels of distortion sound better needs to take some critical listening training.

@scaponostorm8806 Год назад

🤑this amplifier is complete garbage.

@KissAnalog Год назад

You are right - the tests would make you think so, but it actually sounds really good. But then we do listen to Rock pretty load;) Which spec do you feel is more important?