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Subjective impressions of Fosi Audio BT20A Max
- Thread starter Balinus
- Start date
Dr Schweinsgruber
Member
I returned mine though it was free: could not get the potentiometer knob off without damaging anything (don't have a pipe wrench), and did not have the right to nut driver. I am testing gear and am a consumer advocate, but I am not a plumber.
And no paying early adaptor should have to undergo this procedure either paving the way for the "Pro" model 3 months down the road that addresses the shortcomings.
A fan in an amplifier is unheard of (pun intended). I made sure all my computers are fanless...and I would never put this thing on my desk. Burson does it right, they increase the chassis' surface by their corrugated design and therefore get an effective heat dissipation without fan.
The fan in my unit was probably to specs, but once the unit got hot, there were all sorts of metallic vibrations ("ringing") joining the regular fan noise.
So much to measurements...there's much more to a product evaluation than that. In this case, measurements are completely irrelevant except perhaps the SPL.
Life's too short and sometimes free can be too expensive. Although I get a lot of free review gear, most of the stuff I actually use I bought myself...and I spent good money on it.
A positive word on Fosi's customer support: they were very responsive and tried to help, but couldn't really. And, yep, I agree that the BT20A Max sounds pretty good.
And no paying early adaptor should have to undergo this procedure either paving the way for the "Pro" model 3 months down the road that addresses the shortcomings.
A fan in an amplifier is unheard of (pun intended). I made sure all my computers are fanless...and I would never put this thing on my desk. Burson does it right, they increase the chassis' surface by their corrugated design and therefore get an effective heat dissipation without fan.
The fan in my unit was probably to specs, but once the unit got hot, there were all sorts of metallic vibrations ("ringing") joining the regular fan noise.
So much to measurements...there's much more to a product evaluation than that. In this case, measurements are completely irrelevant except perhaps the SPL.
Life's too short and sometimes free can be too expensive. Although I get a lot of free review gear, most of the stuff I actually use I bought myself...and I spent good money on it.
A positive word on Fosi's customer support: they were very responsive and tried to help, but couldn't really. And, yep, I agree that the BT20A Max sounds pretty good.
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Gee, I'm always pretty good with "free." I too was a reviewer/tester for them and have been happy with the unit so far. It is IMO fine for setups that are non-nearfield.
(I drew this thread to Fosi's attention so they would know that experiences with the fan and fan noise are varying widely among users.)
I generally like passive cooling too, I think this amp is a bit of an experiment for them to address people who were jumping up and down for "more cooling!" But we shall see.
dtaylo1066
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Whether in an amp, desktop PC power supply or my refrigerator, I generally determine that a fan will cause issues down the line, if not a raquet, and I do not enjoy replacing them. Ball bearings or grease in an amp, no bueno.
- Thread Starter
- #46
Here's the video Fosi sent me when I told them my fan was making unusual noise
https://drive.google.com/file/d/1ryzRDZ-i4eHXpaDRMymBKajoZWoXJASh/view?usp=sharing
By the by, I recently swapped things around (because I am testing something for Fosi), so put Fosi gear back into my main workroom system. I am using the 48v/5a GaN power brick with the Fosi V3 amp and P4 preamplifier, and the V3 gets a bit warmer than when using the 36v/5a brick, but not by very much. I'm of the opinion that the active cooling fan was not something that was really necessary for the BT20A MAX, but was an additional product feature that some users said they wanted ("even more cooling to extend the life of the device") and Fosi was happy to oblige.
Guddu
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Let me add my 2 cents here on Fosi BT20A Max
BT20A Max chassis is a notch up than their other ones, has decent weight overall with slightly stylish looks comparatively. its heavy enough not to be dragged by heavy cables.
Tone knobs has middle/center hold to make is easy to put on position. Tone Bypass (on the back) bypasses Bass & Treble, however Volume Control remains variable.
Motorized volume works nicely, responds to remote without any issues.
Sub out is volume controlled.
Remote is plastiky but still decent overall, works fine.
Active FAN under the hood makes faint noise which is mildly audible when nothing is playing.
Idle power usage is about 16 watts when no music is playing, also remains around 16watts under low volume listening volumes as well.
While I can not measure frequency response flatness, but here is quick look at difference in frequency response with 3e A7 and Aiyima A20, in my setup & room, UMIK-1 stays at the same location and sweep levels were voice-matched. It does tell me somewhat that there isn't any considerable high freq. peaking.
Fosi BT20A Max vs 3e A7 vs Aiyima A20, HPF OFF
Subwoofer-Out and HPF: 80 Hz
Subwoofer-Out is main volume controlled and has roll off starting around 80 Hz to 150Hz complete cut-off
When HPF is ON, subwoofer-out has 4-5 dB higher gain compared to when HPF is Off
Performance wise, it did work very well for Revel M16 speakers with subwoofer out.
Bluetooth Output - I never had any issue at all connecting with any devices I used with like iPhone 16, Windows Laptop, nVidia Shield Pro, Google TV box etc.
Sound quality wise, surely inferior compared to a nice DAC connected on RCAs but that’s reasonable. It is more like a convenience feature than HiFi.
Overall, pretty good. I totally liked 2 RCA inputs which is more practical in my opinion. Making it good option for me to compare 2 different RCA inputs like 2 DACs, Pre-Amps etc.
BT20A Max chassis is a notch up than their other ones, has decent weight overall with slightly stylish looks comparatively. its heavy enough not to be dragged by heavy cables.
Tone knobs has middle/center hold to make is easy to put on position. Tone Bypass (on the back) bypasses Bass & Treble, however Volume Control remains variable.
Motorized volume works nicely, responds to remote without any issues.
Sub out is volume controlled.
Remote is plastiky but still decent overall, works fine.
Active FAN under the hood makes faint noise which is mildly audible when nothing is playing.
Idle power usage is about 16 watts when no music is playing, also remains around 16watts under low volume listening volumes as well.
While I can not measure frequency response flatness, but here is quick look at difference in frequency response with 3e A7 and Aiyima A20, in my setup & room, UMIK-1 stays at the same location and sweep levels were voice-matched. It does tell me somewhat that there isn't any considerable high freq. peaking.
Fosi BT20A Max vs 3e A7 vs Aiyima A20, HPF OFF
Subwoofer-Out and HPF: 80 Hz
Subwoofer-Out is main volume controlled and has roll off starting around 80 Hz to 150Hz complete cut-off
When HPF is ON, subwoofer-out has 4-5 dB higher gain compared to when HPF is Off
Performance wise, it did work very well for Revel M16 speakers with subwoofer out.
Bluetooth Output - I never had any issue at all connecting with any devices I used with like iPhone 16, Windows Laptop, nVidia Shield Pro, Google TV box etc.
Sound quality wise, surely inferior compared to a nice DAC connected on RCAs but that’s reasonable. It is more like a convenience feature than HiFi.
Overall, pretty good. I totally liked 2 RCA inputs which is more practical in my opinion. Making it good option for me to compare 2 different RCA inputs like 2 DACs, Pre-Amps etc.
Thanks.. I got impatient and ended up de-soldering/cutting the cables on the back. Waiting to get another Sparkos op-amp and then I'm going to install it with a quieter Noctua fan, without those tiny holed grills. Also replaced the knobs
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- Thread Starter
- #50
I would be interested to see the final product you came with the Noctua fan (like them, I have that in my custom PC build). Will you try to change the dimension of the fan? Alternatively, I'm wondering if I should just get the 36V PSU and simply remove the, as people seem to report that it runs cooler with the 36V PSU.
Seems to fit perfectly, it has the same dimensions as the stock fan. I have yet to put it all together and test it out because I needed to order a new Bluetooth antenna cable.. shouldn't of cut it.. whoops. I also upgraded to a 48V PSU
Links to everything I ordered:
https://sparkoslabs.com/product/dual-discrete-op-amp-ss3602
https://www.amazon.com/dp/B00NEMGCIA
https://www.amazon.com/dp/B0CN6PTR35
https://www.amazon.com/dp/B0D48JNKD2
https://www.amazon.com/dp/B0DK2QK7C7
https://www.ebay.com/itm/372806499045
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I just got this today for a subjective take on it compared to my Topping PA7. Did not know it had an active fan, that should be interesting as time goes on given dust getting in the fan and heatsink will result in more air turbulence over time and less thermal control.
My PC setup is also deathly silent so any form of fan noise is often annoying to my ears which are sensitive enough to be annoyed by Chinese wall warts plugged in across the room if they have poor circuitry causing cap noise whine etc.
Will be interesting to see if there is any audible difference in noise floor too given it has no balanced connectivity, and how imbalanced low volume listening levels are.
Going by all reviews online it appears to be a mostly transparent amp with a slight lean on warmth and good staging, whilst the PA7 is undeniably transparent with swathes of headroom/power.
Should be kinda fun I guess.
My PC setup is also deathly silent so any form of fan noise is often annoying to my ears which are sensitive enough to be annoyed by Chinese wall warts plugged in across the room if they have poor circuitry causing cap noise whine etc.
Will be interesting to see if there is any audible difference in noise floor too given it has no balanced connectivity, and how imbalanced low volume listening levels are.
Going by all reviews online it appears to be a mostly transparent amp with a slight lean on warmth and good staging, whilst the PA7 is undeniably transparent with swathes of headroom/power.
Should be kinda fun I guess.
I could hear the fan in a nearfield system with the amp about 1 yard away from my left ear. Once music was playing, I was no longer aware of it. My nearfield system also uses an older Lenovo tower running Linux, and I can hear its fan with no music playing, but it does not bother me. The BT20 works perfectly for a system where your head is not going to be very close to the amp. In my bedroom system now, I keep a little cloth cover on it between uses to keep dust from accumulating in the top vent.
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Alright used it all evening.....
... The annoying thing for me as due to sensitive hearing the fan airflow noise is a distraction for desktop use since the rest of my workstation is deathly silent. It's more audible than a standard laptop fan, but not audible when music is playing until you get to a quiet passage in the track etc.
It defeats the objective of having an amp/DAC etc that has a totally silent noise floor and the ironic thing is with other power amps that I have used or integrated amps, the RCA connections always have had a very faint noise floor hiss, not so here, it's blackness even with my ear right against the speakers regardless of volume setting, but you can hear the fan lol.
Another issue is that it has low volume channel imbalance which is typical of a potentiometer pot, the problem is that when you feed it a line level signal from a pre/DAC, you have very little room to modulate low volume, by the time you get sound that is channel matched, the volume is too loud, and that's on my Comete 40th, an easy to drive speaker that leaves loads of headroom on the table.
Edit*
video:
Oh yeah at the start when the power cord is plugged in notice there's a very faint ticking pulse noise coming from inside, this sounds like a ticking watch movement, it only goes away once you press the power button to go out of standby, but then the fan comes on lol.
... The annoying thing for me as due to sensitive hearing the fan airflow noise is a distraction for desktop use since the rest of my workstation is deathly silent. It's more audible than a standard laptop fan, but not audible when music is playing until you get to a quiet passage in the track etc.
It defeats the objective of having an amp/DAC etc that has a totally silent noise floor and the ironic thing is with other power amps that I have used or integrated amps, the RCA connections always have had a very faint noise floor hiss, not so here, it's blackness even with my ear right against the speakers regardless of volume setting, but you can hear the fan lol.
Another issue is that it has low volume channel imbalance which is typical of a potentiometer pot, the problem is that when you feed it a line level signal from a pre/DAC, you have very little room to modulate low volume, by the time you get sound that is channel matched, the volume is too loud, and that's on my Comete 40th, an easy to drive speaker that leaves loads of headroom on the table.
Edit*
video:
Oh yeah at the start when the power cord is plugged in notice there's a very faint ticking pulse noise coming from inside, this sounds like a ticking watch movement, it only goes away once you press the power button to go out of standby, but then the fan comes on lol.
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