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Amplifier measurements may require improvement

peng

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For my desktop, distance is only 1 meter, and 80 dB peak will be more than I ever listen to. Just checked Amazon, it is now C$119.99, 5% discount on checkout. It would be the cheapest amp I have ever owned.:D
 

peng

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Amir also reviewed the very similar aiyima a07 that looks uglier but cheaper.

Wonder which one I should buy? Is it possible to buy one with the 48V PS, it will be a shame to have to pay for two, the 32 V that apparently comes with the amp and the 48 V that has to be bought separately.

 
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Djano

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Amir also reviewed the very similar aiyima a07 that looks uglier but cheaper.

Wonder which one I should buy? Is it possible to buy one with the 48V PS, it will be a shame to have to pay for two, the 32 V that apparently comes with the amp and the 48 V that has to be bought separately.

You can buy V3+48V (without 32V) on Aliexpress. Also look on Fosi website, and eBay.
I can't say anything really interesting about A07 vs V3. I think I remember people who had the A07 wrote they were happier with the V3. But this if far too vague to make your decision.
I would go with the prettiest (V3)

Edit: I remember this video. It focuses on stress test and temperature management. You are probably never going to use the amp like this. But it shows that the V3 case-heatsink design is not a gimmick, and works as advertised.
 
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peng

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You can buy V3+48V (without 32V) on Aliexpress. Also look on Fosi website, and eBay.
I can't say anything really interesting about A07 vs V3. I think I remember people who had the A07 wrote they were happier with the V3. But this if far too vague to make your decision.
I would go with the prettiest (V3)

Edit: I remember this video. It focuses on stress test and temperature management. You are probably never going to use the amp like this. But it shows that the V3 case-heatsink design is not a gimmick, and works as advertised.
I watched the linked video, thanks. After that, a few more popped up, most said the V3 sounded great, one said sounded better to his Marantz NR1200, but most of those Youtubers don't even understand they had to turned to volume up to almost max not because it was less "powerful" than the other amps they compared it to, but most likely because they didn't know the V3 is really a power amp, and volume max if quite normal for normal use with an active preamp.

Andrew Robinson did one comparison review too, but iirc it was no the V3 but another Fosi model, he seemed to actually believe the 25 W Cambridge Audio amp was much more powerful than the 50 W Fosi amp, that was laughable as it really shows he has very little technical knowledge in audio, no idea the issue may not be have to do with the rated power output, but the difference in gain, and how the power amps are driven.

I ended up ordering from Amazon.ca so will be getting their stocked small brick PS. For my desktop system, it listen to no more than 65 dB average so the tiny brick should be more than adequate.

Don't know how late, but should be here today and will be able to compare it with the NAD integrated based on the silly FR method that S.T. did. For now, I ran REW based on the NAD amp., here's the results, waiting to be compared:

Speakers: KEF LS50, nominal 8 ohms, dip to 3.2 ohms min., sensitivity 85 dB/2.83V/m, 79-28,000 +/- 3 dB

From SoundStageNetwork.com:
impedance.gif
electrical_phase.gif


On my desktop, mmp about 30 inches from screen, 37 inches from speakers:

Amps: NAD C326BEE, 50 WPC 8 or 4 ohms
Source DAC: S.M.S.L. SU-8

1695122987906.jpeg


When I do the comparison with the V3, I will increase SPL to 95 dB (with earplugs on obviously) and see if I would get any S.T. style dips in the deep bass range.
 

Juampa1989

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With a 32 v 5 amp source, with 1.5v vrms of the dac (preamplification), [the maximum it supports is 2 vrms]. At a distance of 2 meters I got 103db which already makes the ears hurt, the fosi was already with the knob at maximum. I can't imagine getting 117db out of it, it would have to be trimmed from the analog input, it doesn't give it 4 vrms and it's also a DAC for indoor environments. 117db is like for outdoor music. Nobody said it but the demand they made is outrageous. I get a maximum of 95 db peak and it can be heard loudly throughout the house. I have it in the living room which is on the second floor, the house is made of wood and is 120 m2. The living room is open. I don't know why I want more. In a closed room it will be 85db, a desk 75db, so I am deaf in one ear. For normal indoor use it has plenty of power, and as indicated only using the 32v source. My speakers are the Klipsch rp-160m. That its sensitivity should be around 88db.
 

peng

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With a 32 v 5 amp source, with 1.5v vrms of the dac (preamplification), [the maximum it supports is 2 vrms]. At a distance of 2 meters I got 103db which already makes the ears hurt, the fosi was already with the knob at maximum. I can't imagine getting 117db out of it, it would have to be trimmed from the analog input, it doesn't give it 4 vrms and it's also a DAC for indoor environments. 117db is like for outdoor music. Nobody said it but the demand they made is outrageous. I get a maximum of 95 db peak and it can be heard loudly throughout the house. I have it in the living room which is on the second floor, the house is made of wood and is 120 m2. The living room is open. I don't know why I want more. In a closed room it will be 85db, a desk 75db, so I am deaf in one ear. For normal indoor use it has plenty of power, and as indicated only using the 32v source. My speakers are the Klipsch rp-160m. That its sensitivity should be around 88db.

As follow up, I posted the following in the other thread. As I suspected, the reason I wasn't getting over 100 dB like you had, was in fact due to Dirac Live that reserved something like 15 dB or headroom. So based on yours and my findings, this tiny Fosi Audio V3 can do a very good job with even the difficult to drive LS50 and with the 32 V power supply too. I ordered my second one with the 48 V PS anyway, but only because Fosi Audio has the 20% off and they let you choose the 48 V PS, there is no such option from Amazon.

By quitting DL first before running the sweep, I was able to get about 105 dB. The only reason in that sweep I limit the range to 200 Hz is to avoid damaging my inefficient LSR50 that has a small woofer, 5-1/4 inch if I remember right. When my second V3 with the 48 V PS arrives, I will try it on my much larger R900 and see how it performs full range. I am confident that I won't get the dip that S.T. was getting.

1695298272913.jpeg
 

NoMoFoNo

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How is it not absurd and misleading to compare the $100 Fosi V3 to the $3,000 Yamaha A-S2100, and well above 100db to boot? It's hard for me not to conclude the whole exercise was a bad faith exercise IMO, certainly lacking in common sense.

Also, was it noted anywhere the signal level fed to the V3? There were quite a few comments underneath the video calling the poster out about that. His answers brought more questions about his knowledge of gain and power.

Bottom line: OK, the $100 paperback-sized amp can't hack it at the most distant margins of operation possible. For the vast majority of use cases the little Fosi is a great performer as noted by Amir's testing.
 
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Holdt

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How is it not absurd and misleading to compare the $100 Fosi V3 to the $3,000 Yamaha A-S2100, and well above 100db to boot? It's hard not to conclude the whole exercise was a bad faith exercise IMO.

Also, was it noted anywhere the signal level fed to the V3? There were quite a few comments underneath the video calling the poster out about that. His answers brought more questions about his knowledge of gain and power.

Bottom line: OK, the $100 paperback-sized amp can't hack it at the most distant margins of operation possible. For the vast majority of use cases the little Fosi is a great performer as noted by Amir's testing.
Have you honestly seen the video and read the comments? Doesn't look like it.
 

peng

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Have you honestly seen the video and read the comments? Doesn't look like it.
Seems like he did, as he got the facts (probably most of it, in case I missed a thing or two) right.
 

Holdt

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Seems like he did, as he got the facts (probably most of it, in case I missed a thing or two) right.
It wasn't just the A-S2100 but the little one as well. I react strongly to just calling people out as doing something in bad faith. But it seems like @SimpleTheater doesn't have anything more to say about it.
 

peng

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It wasn't just the A-S2100 but the little one as well. I react strongly to just calling people out as doing something in bad faith. But it seems like @SimpleTheater doesn't have anything more to say about it.

I missed the part if he said anything "in bad faith". On that, I agree with you. In the video, S.T. did mention the little one but iirc, there wasn't measurements shown for that one so that's part of comparison is by subjective measurements (that I tend to ignore in most cases), but I might have missed a point there too if he did include measurements like he did with the A-S1100.
 

NoMoFoNo

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Have you honestly seen the video and read the comments? Doesn't look like it.
I obviously watched the entire video AND read through the comments underneath. Silly question. The entire S.A. exercise seems in bad faith, or lacking in common sense, as do some of the insistent posters who dig for bad things to say about this little amp.

Check the comments there for yourself. There has been much discussion there (and here) about the gain of this amp. To get its best requires a strong incoming signal. Read the comments for yourself.
 
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NoMoFoNo

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It wasn't just the A-S2100 but the little one as well. I react strongly to just calling people out as doing something in bad faith. But it seems like @SimpleTheater doesn't have anything more to say about it.
I react strongly to people digging for bad things to say about something like this little amp that costs $100. I also believe that the poster of that video should have known the absurdity of comparing the Fosi to the A-S2100, not to mention the absurdity of driving the Fosi well over 100db in testing.

I cannot say for sure it was done in bad faith because I'm not in his head, but I question the judgment of anyone who didn't find those aspects of this video to be 'off'.
 

NoMoFoNo

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I missed the part if he said anything "in bad faith". On that, I agree with you. In the video, S.T. did mention the little one but iirc, there wasn't measurements shown for that one so that's part of comparison is by subjective measurements (that I tend to ignore in most cases), but I might have missed a point there too if he did include measurements like he did with the A-S1100.
Watch the video again @peng. The measurements and bulk of discussion were/was about the A-S2100, not the A-S1100. The A-S2100 sells for $3,000USD. You cannot see an argument for potential bad faith, lack of common sense at minimum, in asking a $100 amplifier to match performance with one costing $3,000, all at 100+db?
 
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fpitas

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If it was bad faith (and I make no judgement), it backfired. I'm slightly more impressed with the Fosi V3 now that it's been wrung out even further.
 

peng

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Watch the video again @peng. The measurements and bulk of discussion was about the A-S2100, not the A-S1100. The A-S2100 sells for $3,000USD. You cannot see an argument for potential bad faith in asking a $100 amplifier to match performance with one costing $3,000, all at 100+db?
I think Holdt's reference of the "little one" was not the A-S1100, but something more entry level such as the A-S201 or S301 (don't remember exactly which one, but one of those two anyway, iirc). As I also said, I tend to ignore subjective views, and value reviews that have specs and measurement data.

I won't watch that video again because it really doesn't have useful information for me as such.
 

Holdt

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Watch the video again @peng. The measurements and bulk of discussion was about the A-S2100, not the A-S1100. The A-S2100 sells for $3,000USD. You cannot see an argument for potential bad faith in asking a $100 amplifier to match performance with one costing $3,000, all at 100+db?
Not if it's advertised as being as or more powerful as the Yamahas in question. -Why should it not be scrutinized for that?

Fosi-->
1695738928752.png

Yamaha A-S301-->
1695739122566.png

Yamaha A-S2100-->
1695739204281.png
 

NoMoFoNo

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Not if it's advertised as being as or more powerful as the Yamahas in question. -Why should it not be scrutinized for that?

Fosi-->
View attachment 314860
Yamaha A-S301-->
View attachment 314867
Yamaha A-S2100-->
View attachment 314868

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.
 

Holdt

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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.
Being silly for pointing out false advertising..:facepalm: -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.
 

peng

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Being silly for pointing out false advertising..:facepalm: -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.

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.
 
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