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Fosi v3 Mono - User Impressions | Owner's Thread

or are yours carrying a grater load?
That is actually an interesting question.

@Unbalanced were the amps loaded during the test - if so by how much? One thing I've noticed is your measurements show around 10C hotter than other people have reported. This may be due to the measurement method where you are using an infra red thermometer whereas I guess most others are using some form of contact thermocouple or similar.

Or it might be due to applied load during the test.
 
Then other amps have none xD
There's a gazillion other stuff,like measured performance,better thermals (by math,not eye,I posted all data during this thread),more continuous power (because of the thermals again),more power in general,looks,reselling value,cost through time,good overall record for at least 5 years,regulations and certifications compliance,etc.

Anyone can choose it's own meal.
 
There's a gazillion other stuff,like measured performance

Yeah, and that gazillion stuff makes that there always is a "better measured performance" , so you can always say about any amp that it's only value is it's price.
So it is simply nothing more than an absurd simplification especially when it comes to an amplifier that currently has an almost unbeatable price/quality ratio.

Practically the highest price/quality ratio - so you are saying that the only advantage of these amp is price? C'mon...
 
Yeah, and that gazillion stuff makes that there always is a "better measured performance" , so you can always say about any amp that it's only value is it's price.
So it is simply nothing more than an absurd simplification especially when it comes to an amplifier that currently has an almost unbeatable price/quality ratio.

Practically the highest price/quality ratio - so you are saying that the only advantage of these amp is price? C'mon...
???
All you used is (also) price,and not just the starting price but the price/quality one which is yet to be known,it needs years for this to conclude.
Let's stick to the starting price then.For that price,yes,it has it's own value.And it's own compromises.

By the same standard the stereo one represents a better value,for it's own compromises again.
What else is remarkable about it?It's starting reverse phase error?The noise introduced even with the filter (greatly reduced) cause the master-slave config was ignored?It's 80dB SINAD/1kHz/1W/31dB gain with RCA input?

I'm so done with this thread :facepalm:
 
I don't know, try using XLR inputs with two power supplies then, the price stays the same. And have you tried overcoming the phase issue by switching cables for exactly absolutely no cost?
 
Thank you all for your comments and questions. I will try to answer them all. You also found some gaps in my report. :oops: Apologies for that. I will try to address them.

Active cooling lowers temperatures, who could have expected that? ;)
Yes, we already knew it worked. It was about getting measurements of the effect of active and convective cooling. Based on my experience with PC cooling I expected a stronger effect from the convective cooling.

So two things, is there anything indicating real temperature problems, besides usual - temperature bad, look at my 70'C class A amp from the 80s, its a beast ;)

And second: what speeds was those coolers from the test and why there's no cooler on the bottom - the most logical for me - option tested?
The benefit of cooling would not be seen for years. If the unit is well designed it would probably be decades. So, why bother...Why not? It's likely my personal inclination.
In this setup the fan (Arctic P12 PWM) is running at 12V. Unregulated this fan is supposed to run at 1800 RPM. It was somewhat audible at that speed. My PWM controller is on its way from AliExpress. At slower speeds it will be inaudible.
The cooler on the bottom option wasn't tested because it would have required a more elaborate Lego rig than I was able to assemble before the end of the day. The other approaches got down to 27.3ºC so there are diminishing returns as to how cool I could get. Ambient room temperature was 21.8ºC, so I wouldn't be able to go any lower than that.
Cooling the bottom surface will yield best result. The single test you avoided to do. It's practically the equivalent of a CPU lid of of the unit, cool that, and the rest will largely follow. Your own ~2c internal/external observation supports this.
I did try having the fan blowing at the "bottom" unit on the right of the "stack" when they were sideways. I felt this was a poor approach. The V3 Mono is a little brick and blocks all air flow to the "top" unit on the left. One objective was to understand the effect of what I thought was an ineffective approach (blowing air across the two stacked units). Another objective was to test the effect of convection. I wasn't setting out to come out with the optimal cooling design, but as I mention above there is diminishing return. To cool both units in that fashion would have required another fan (which I have) but more significantly, a more elaborate Lego setup and it was getting to dinner time.

I will note that Fosi appears to be designing a desktop component rack that will accommodate four fans blowing up from the bottom. On the one hand, that's cool :p, but on the other hand I think it's overkill.

Well that was above and beyond the call of duty. But I certainly appreciate the effort.
Thank you for your feedback. I have become a little paranoid about heat and cooling. I had a NAD 7020e sitting in a shelving unit a couple of years ago. It was working fine until I left it running on for a couple of days. It now has a hum and is waiting patiently for me to recap it. I replaced it with a 7220e and I have a pair of fans venting the air. It runs cool as long as I have the fans on. Yes, I know, the NAD is 40+ years old and there are all kinds of age related factors. It's just me.

Dust. Now there's an interesting consequence. I will have to keep an eye on that. I suppose active airflow is going to be worse than what falls into most of the units over years. I appreciate the warning.

Yes, the amps were under load. I was listening to music at a comfortable level the whole time. I was aiming to mimic a daily usage scenario.

Finally, I think we got off on the wrong foot on this topic. In the end I learned a few things about cooling. Thanks for that.
 
I suppose active airflow is going to be worse than what falls into most of the units over years.
Just look at your average PC CPU fan/heatsink cooler after a year of operation. Also your typical inlet/outlet fan filters (if filters exist)

Finally, I think we got off on the wrong foot on this topic. In the end I learned a few things about cooling. Thanks for that.
No problem. Sometimes I come across as a little abrupt. Apologies if so in this case.
 
Just received V3 #5. One QC sticker. Wires not crossed inside to correct the phase. Odd thing is, this was ordered direct from Fosi's site, shipped from their California warehouse. The two I got a few weeks ago, also ordered direct from Fosi, but shipped from China, were 2 QC sticker and wires crossed and re-soldered inside to correct the phase. The two I got just before that, via Amazon in early August, were 1 QC sticker, and uncorrected phase.

Is Fosi now sending out 1 QC sticker V3s with the phase corrected earlier in the circuitry rather than in the wires to the terminals? Or did a container load of the uncorrected V3s get to California on a slow boat from China, and now I've got one of those? I'm not deeply bothered. I've connected it initially assuming it's got the phase reversed. Just questioning my assumption.
 
Is Fosi now sending out 1 QC sticker V3s with the phase corrected earlier in the circuitry rather than in the wires to the terminals? Or did a container load of the uncorrected V3s get to California on a slow boat from China, and now I've got one of those?
Unlikely to be either of these.

You are most likely just experiencing the effects of stock management. Unless the warehouse in California had been set up from the start to ensure first in first out, it is very difficult to achieve consistently from manual processes.
 
Is Fosi now sending out 1 QC sticker V3s with the phase corrected earlier in the circuitry rather than in the wires to the terminals? Or did a container load of the uncorrected V3s get to California on a slow boat from China, and now I've got one of those? I'm not deeply bothered. I've connected it initially assuming it's got the phase reversed. Just questioning my assumption.

I don't think even fosi is clear on exactly what units are affected, and whether both inputs are. Probably from the logistical mayhem the kickstarter campaign caused when they actually had to manufacture and ship things out which took a few weeks beyond what they said and was probably slightly rushed. They also use "might be" in their original PSA, with focus on Amazon UK on later statements. I've mailed with them back and forward a bit about my own 2 units with V0.6 boards, and they insisted my units were reversed in the start, with rather unclear statements, but after proving to them it isn't by clear tests done (at least via RCA) they said it must have been a corrected unit. I still won't trust XLR though without testing, if I ever bother to use it.

I've learned that it's probably a good idea to test phases on equipment in general, at least if you're gonna mix equipment. So not gonna hate on fosi for it, but perhaps wish it was consistent on all units. Probably will be, going forward.

(had to create new account, lost previous login, contact us form never answered, I'm nitpicker1 from previous posts in this thread)
 
For what it's worth, the newly-arrived V3 (one QC sticker, wires not re-soldered/crossed inside) hooked up assuming phase reversed does not sound, as a center between two V3s (two QC stickers, wires re-soldered/crossed inside) out of phase, nor does Yamaha YPAO detect it as out of phase. It looks like extra lag in some Fosi distribution paths.

The sound field also is better blended than when the center was using an Emotiva PA-1, which had a different tonality, flatter, drier. Replace the L-R amps first for stereo play. Also using ZA3s (stereo mode) for the surrounds and heights now, which also blend well for AV. Wish I knew, technically speaking, what the audible difference between the ICEpower 300-based amps I was using before and these TI-based amps consists of, since the ICEpower stuff (especially those PA-1s) tests as not far behind. With the PA-1's I used (ICEpower) XTZ amps for the other channels -- which blended well for that tonality. Seems like in matching amps for AV, matching the core architecture counts.
 
My V3 mono with attached heat sink using a 2mm thermal pads and turn to vertical ventilation. Looks ridiculous but cool enough.
 

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Question about powering up and down.

Typically with my other equipment I power down the components when I am done listening, usually at the end of the day. With the V3 monos, there are power switches on the units themselves, but the power supplies do not have any power controls. The monos do have standby mode, but even with standby I don't want to keep the system energized 24/7/365. To address this I have plugged everything into a smart plug that I have programmed to turn off at the end of the day. Ideally I would like to leave the units in auto mode and have them power up in the morning via the smart plug. The end result is that the smart plug is powering the system on and off rather than the switches on the units themselves. Everything I know says that this should be fine, but I have been finding that things are not always what they seem.

Good idea? Bad idea?
 
Nothing I know of that would make that a bad scheme. A similar option is a power strip that turns on some of it's outlets only when a device in an always-on trigger outlet is powered. Since I only use the amps when the pre-amp is on, it and the amps are plugged into a TrickleStar TS1104. I've run this way (with various amps) for years with no problems evident.
 
Nothing I know of that would make that a bad scheme. A similar option is a power strip that turns on some of it's outlets only when a device in an always-on trigger outlet is powered. Since I only use the amps when the pre-amp is on, it and the amps are plugged into a TrickleStar TS1104. I've run this way (with various amps) for years with no problems evident.

Thanks. I wasn't aware of TrickeStar. Now I am wondering how I could leverage that in my scenario. The Monos are fed via a WiiM Pro Plus. The Pro Plus is on 24/7, so I can't use that to trigger something like the TrickeStar. The Pro Plus does have a trigger output that can be used to signal amps to power up. However, I can't see an obvious way to use the WiiM trigger to control the power to the Monos.

Is there some sort of other intermediary device that I could use? I see that TrickleStar has a variety of products, but I didn't see anything that could activate power outlets in response to something like the trigger signal from the WiiM.
 
Haven't used this, but there are reports elsewhere it will work from 12V triggers. I've been using hardware from this firm for years in a computer context: https://www.digital-loggers.com/iot2faqs.html. Requires stripping an end of your trigger cable and getting the polarity right in connecting it.
 
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Hi all,

Not sure this has been addressed in this thread. Does the amp have any output protection system utilized? Has anyone had any good/bad experience?
 
New poster here, after reading a lot. I have received the package with two V3 Monos, the 10A power supply and the filter.

I am quite disappointed, I got a hum in the lower/middle frequencies, despite the filter. It vanishes if I pull out one power cable from one amp.

I am driving Wharfdale Diamond 12.2s, using a Wiim Pro Plus as input. The bass is very lean compared to the Alesis RA 150 poweramp I used before and am now using again. I will return them. The sound is very transparent, but it simply lacks bass. The Alesis is much more powerful in producing bass frequencies. Well, this is all subjective of course, but personally I do not think the amps live up to the hype.
 
New poster here, after reading a lot. I have received the package with two V3 Monos, the 10A power supply and the filter.

I am quite disappointed, I got a hum in the lower/middle frequencies, despite the filter. It vanishes if I pull out one power cable from one amp.

I am driving Wharfdale Diamond 12.2s, using a Wiim Pro Plus as input. The bass is very lean compared to the Alesis RA 150 poweramp I used before and am now using again. I will return them. The sound is very transparent, but it simply lacks bass. The Alesis is much more powerful in producing bass frequencies. Well, this is all subjective of course, but personally I do not think the amps live up to the hype.

Shame about the hum. That is perhaps further evidence that two separate power supplies are better than one shared.

FWIW, the Wharfedale Diamond 12.2 doesn't extend very far into the lower bass region. (See spec below.) I have Diamond 225s and added an SVS subwoofer to fill in the bottom. On their own, the Diamond bookshelf speakers won't cover the bottom notes on a bass guitar—or anything below that.

Diamond.jpg
 
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