Amplifier measurements may require improvement

[NoMoFoNo]

Being silly for pointing out false advertising.. -Have we really gotten so used to cheap toy amps with nice SINAD values that we just don't care?

And no, I wasn't at all surprised it can't do what proper amps do. It was all expected and since the ASR review I figured it was a matter of time before it was pointed out. There will be more.

Careful. Your true intent and possibly underlying motivations are edging closer to the surface now.

 

[Juampa1989]

And why not compare your $3000 usd amplifier with another $30,000 one if in the end we compare regardless of whether they are fair comparisons. No one intends to say that the fosi v3 is the holy grail of music. Only for its price vs performance, in addition to basic use, perhaps to place a desktop stereo system or dual-channel TV, it performs quite well. Now if you want to have a top audio system why not look at brands like Mcintosh if the money invested does not interest you. For me, a DAC and an amplifier of 100 dollars each are enough to have a stereo television system and what better if the performance is outstanding. If my goal were to equip a professional audio studio for dua lipa, Beyoncé or similar I would be looking for a system with several more zeros. You should measure why you want the product, how much you can spend and how much extra benefit it gives you and not just criticize a device that works almost magic to offer so much for so little money.

 

[Holdt]

Careful. Your true intent and possibly underlying motivations are edging closer to the surface now.

 

[Holdt]

Out of curiosity, I am going to ask if you consider other manufacturers websites (including Denon, Yamaha, Marantz, Sony, just to name a few) also contain info that you would call false advertising? Example, for a long time D+M's website still stated the DAC chips used in their AVRs were the AKM one that in fact had already been replaced by the TI chip. They eventually remove those reference from the website, but it took them months. That's just one example.

Of course. But e.g. Yamaha has shown a track record of being conservative or precise in their specifications. Same with NAD. I wouldn't know of e.g. Denon or Yamaha have made false claims of power ratings.

 

[AdamG247]

Now you're being silly. It is widely known that the typical amp specs advertised by the ChiFi companies are incomplete at best. If the argument was that you wish the ChiFi amp makers would create and publish full, complete specs of their equipment then you'd find no argument from me. I'd love to know dynamic power and damping factor for their gear, but this is $100 we're talking about from makers who are in their relative infancy.

The thing in this particular case is that long before this thread was launched, you already had in hand Amir's substantive testing results for the V3, showing something like 88wpc/8ohm and 144wpc/4ohms and good SINAD performance relative to the other amps tested by ASR. That the Fosi can't match the output of a $3,000 integrated amplifier, at 100+db, from one of the historical greats in the industry should not surprise you.

Hi NoMoFoNo,

I know you don't mean this in a derogatory manner but let's avoid the term Chi-fi as it can have negative connotations for such companies. Thank you for your cooperation and understanding.

 

[NoMoFoNo]

Hi NoMoFoNo,

I know you don't mean this in a derogatory manner but let's avoid the term Chi-fi as it can have negative connotations for such companies. Thank you for your cooperation and understanding.

Apologies and I will make note! Thank you for letting me know and of course you are right.

 

[SimpleTheater]

There's no point in discussing this any further as my testing is easily replicated.

To summarize:
1. Yamaha A-S2100 amp - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 105 dB
2. Yamaha R300 amp - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 93 dB
3. Fosi v3 - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 77dB

Gain? I don't even know how to respond. You expect people to buy a sub $100 amp and then add some type of additional gain from the incoming signal to achieve it's best output. That's far beyond what anyone buying this would actually do - except for a few people tinkering. Everything is the same - I didn't add any gain to the other amps, why would I do that for the Fosi.

My last post on this thread. Any and everyone is welcome to do their own testing.

 

[NTK]

There's no point in discussing this any further as my testing is easily replicated.

To summarize:
1. Yamaha A-S2100 amp - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 105 dB
2. Yamaha R300 amp - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 93 dB
3. Fosi v3 - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 77dB

I strongly recommend against replicating SimpleTheater's test with white noise. There is a real risk of frying the tweeters in your speakers if you send white noise to your speakers at full power.

 

[peng]

I strongly recommend against replicating SimpleTheater's test with white noise. There is a real risk of frying the tweeters in your speakers if you send white noise to your speakers at full power.

Agreed, he said that was his last post on this thread so your post is timely.

It also need to be said that he seems to be implying the V3 can only produce 77 dB versus his 30 W rated Yamaha R300's that managed to produce 93 dB. That could mislead someone to conclude the R300 is therefore much more powerful.

All else being equal, 10 dB more spl needs 10X the power, there is no way the R300 is that much more powerful or at all.. Yhe 16 dB less he got from the V3 was due to the way he compared the two amps, not because the R300 is so much (or at all..) more powerful.

I don't think anyone said he did his tests incorrectly as such. Some are just saying that such tests are not the right kind of tests if goal is to conclude which duts are more, or less powerful than the other, and by how much. Nor are those tests sufficient to establish the power output of the Fosi amp, whereas the test results from Amir's review on that amp are quite sufficient for all intents and purposes.

 

[Juampa1989]

I insist, I get 105db with a 2v rms input with 88 sensitivity speakers, with the 32v and 5a source. I don't know what more I could require for indoor use in the living room. It is difficult to exceed 95db because it already makes the ears uncomfortable because it is very loud.

 

[mhardy6647]

I insist, I get 105db with a 2v rms input with 88 sensitivity speakers...

Out of curiosity 2 V RMS input of what? White noise, pink noise, 1 kHz sine wave, 1 kHz square wave?

SPL reading at 1 meter?
One loudspeaker (channel) or two?
Weighting (A, C, unweighted)?

"105 dB with a 2 V RMS input" doesn't specify enough from which to draw much meaningful information, I'm afraid.

 

[Juampa1989]

Por curiosidad entrada 2 V RMS de qué? ¿Ruido blanco, ruido rosa, onda sinusoidal de 1 kHz, onda cuadrada de 1 kHz?

¿Lectura de SPL a 1 metro?
¿Un altavoz (canal) o dos?
¿Ponderación (A, C, no ponderada)?

Me temo que "105 dB con una entrada de 2 V RMS" no especifica lo suficiente para extraer mucha información significativa.

Fue con ruido rosa de YouTube. Agregué el enlace

A un metro db spl, dos canales, ponderación z

 

[antcollinet]

I insist, I get 105db with a 2v rms input with 88 sensitivity speakers, with the 32v and 5a source. I don't know what more I could require for indoor use in the living room. It is difficult to exceed 95db because it already makes the ears uncomfortable because it is very loud.

Please don't put 105dB into your ears without some form of protection. Even 95dB can cause hearing damage in a relatively short time.

Permissible Exposure Time for Noise SPL sound pressure level and duration Guidelines How long can a person endure a certain noise level before hearing damage occurs health sound level noise hearing ears impairment tinnitus damage - sengpielaudio Seng

Sound Pressure Level SPL and duration and permissible exposure time for noise guidelines How long can a person listen to noise of a certain sound level before hearing damage occurs health sound level noise hearing ears impairment tinnitus damage - Sengpielaudio - Eberhard Sengpiel - Audio Tutorials

www.sengpielaudio.com

 

[Juampa1989]

No ponga 105 dB en sus oídos sin algún tipo de protección. Incluso 95 dB pueden provocar daños auditivos en un tiempo relativamente corto.

http://www.sengpielaudio.com/PermissibleExposureTime.htm

tnk u

 

[peng]

I insist, I get 105db with a 2v rms input with 88 sensitivity speakers, with the 32v and 5a source. I don't know what more I could require for indoor use in the living room. It is difficult to exceed 95db because it already makes the ears uncomfortable because it is very loud.

Me too, got it up to 103 dB anyway but could have room to go.

I received my second V3 the other day, used with my much larger (than the LS50) KEF R900 speaker that is 8-ohm nominal, 3.7 ohm minimum, based on KEF datasheet. I used my Oppo HA-1 that is rated 2.3 V unbalanced, 4.6 V balanced to drive it. Sitting from about 8-9 ft, I had no trouble getting over 100-103 dB peak average 82-85 dB, and it still sounded good with no audible sign of distortions at the very high spl.

If I get a quiet alone moment in the house, I will push it a little more for a little longer, but with people in the house, at that level someone will be screaming too loud for me to hear the music, so I had to turn it down quickly. At that level, I will be wearing earplugs if the test duration is going to be longer than even 2 minutes.

 

[JayGilb]

There's no point in discussing this any further as my testing is easily replicated.

To summarize:
1. Yamaha A-S2100 amp - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 105 dB
2. Yamaha R300 amp - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 93 dB
3. Fosi v3 - white noise played using cd on Yamaha CD-S2100 - achieved a dB rating of 77dB

Gain? I don't even know how to respond. You expect people to buy a sub $100 amp and then add some type of additional gain from the incoming signal to achieve it's best output. That's far beyond what anyone buying this would actually do - except for a few people tinkering. Everything is the same - I didn't add any gain to the other amps, why would I do that for the Fosi.

My last post on this thread. Any and everyone is welcome to do their own testing.

I just don't understand your methodology. I only want specs on the Fosi, not comparisons to equipment I don't own, it has zero meaning to me.

 

[antcollinet]

I will be wearing earplugs if the test duration is going to be longer than even 2 minutes.

Even 2 minutes might be long enough to damage your hearing. Just put earplugs in before testing starts. Apart from anything else you could make a mistake resulting in SPL much higher than expected.

And make sure anyone else in the house is wearing them too - or lock the test room door.

 

[Sokel]

I am all for manufacturers (such as Hypex) and reviewers (such as Amir) to specify their tests/measurements conditions as clearly and understandable as possible. On the manufacturers side, It looks like Icepower did a better job, at least based on the examples you posted, irrc, McIntosh's not too bad either, Hypex's is still better than most other manufacturers though.

On the reviewers side, Amirs are top so far, Gene's came close or even a little better at times, depending on the specific review/measurements he did. Others not too good, but I don't count Stereophile as they tend to measure many things I am not interested in. Maybe you should do more of your own, but I understand it is difficult to get people to send in devices for test even if you are willing to do it. So, our best hope is for the manufacturers themselves to take the initiative to improve on their specifications and publish their own tests and measurements.

Brilliant example for test conditions coming from one of our own:



(more as thread continuous)

And many more here same as @VintageFlanker .
Stating the test conditions is paramount.As an example take my own measurements few posts above.
I could narrow the view to 20-20Khz,scrap the screenshot and only show the graph and present it either as 105.7db SINAD, 102.7db SINAD or 101.5db SINAD,in all three the visuals would be the same.

I don't question Hypex's measurements,not at all (although some hard-core objectivists would as lacking info).

(and no,I would not test other peoples stuff,I'm too cannibal and newbie for this,that takes decades of experience)

Edit:unitless numbers corrected

 

[Holdt]

Me too, got it up to 103 dB anyway but could have room to go.

I received my second V3 the other day, used with my much larger (than the LS50) KEF R900 speaker that is 8-ohm nominal, 3.7 ohm minimum, based on KEF datasheet. I used my Oppo HA-1 that is rated 2 V unbalanced, 4 V balanced to drive it. Sitting from about 8-9 ft, I had no trouble getting over 100-103 dB peak average 82-85 dB, and it still sounded good with no audible sign of distortions at the very high spl.

If I get a quiet alone moment in the house, I will push it a little more for a little longer, but with people in the house, at that level someone will be screaming too loud for me to hear the music, so I had to turn it down quickly. At that level, I will be wearing earplugs if the test duration is going to be longer than even 2 minutes.

Which kind of music did you use? -Which tracks?

 

[mhardy6647]

Even 2 minutes might be long enough to damage your hearing. Just put earplugs in before testing starts. Apart from anything else you could make a mistake resulting in SPL much higher than expected.

And make sure anyone else in the house is wearing them too - or lock the test room door.

The US's OSHA exposure guidelines (PEL = permissible exposure limits), straight from the web to you!
source (a third party): https://www.jespear.com/preventing-noise-induced-hearing-loss/
OSHA regulations: https://www.osha.gov/noise/standards

... and don't forget that the effect is cumulative