Amplifier ZA3 power indicator light is very dim
- Thread starter kiddad23
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OhmSweetOhm
New member
I’m experiencing the same issue with my Fosi Audio V3 Mono. The amp with the dim light turned off yesterday when I touched it (not sure if it went dim because of this event) although everything seems fine today. I’ve only had these amps for two days, so any feedback would be greatly appreciated.
Bittybo Tootkins
New member
I noticed a difference between the power LED brightness of the V3 Mono 25/31dB and the later 19/25dB version. I prefer the dim LED of the later version that I own now. The amplifier shutting down after touching it, makes me think of electrostatic discharge (ESD). I read somewhere that we can easily carry a 5 - 10kV charge in dry indoor settings. Touching something grounded for a second will probably help. I think I'm going to make that part of my (winter) routine.
A sudden and momentary flow of electric current between two differently-charged objects when brought close together or when the dielectric between them breaks down, often creating a visible spark associated with the static electricity between the objects.
ESD can create spectacular electric sparks (lightning, with the accompanying sound of thunder, is an example of a large-scale ESD event), but also less dramatic forms, which may be neither seen nor heard, yet still be large enough to cause damage to sensitive electronic devices. Electric sparks require a field strength above approximately 4 million V/m in air, as notably occurs in lightning strikes. Other forms of ESD include corona discharge from sharp electrodes, brush discharge from blunt electrodes, etc.
ESD can cause harmful effects of importance in industry, including explosions in gas, fuel vapor and coal dust, as well as failure of solid state electronics components such as integrated circuits. These can suffer permanent damage when subjected to high voltages. Electronics manufacturers therefore establish electrostatic protective areas free of static, using measures to prevent charging, such as avoiding highly charging materials and measures to remove static such as grounding human workers, providing antistatic devices, and controlling humidity.
A sudden and momentary flow of electric current between two differently-charged objects when brought close together or when the dielectric between them breaks down, often creating a visible spark associated with the static electricity between the objects.
ESD can create spectacular electric sparks (lightning, with the accompanying sound of thunder, is an example of a large-scale ESD event), but also less dramatic forms, which may be neither seen nor heard, yet still be large enough to cause damage to sensitive electronic devices. Electric sparks require a field strength above approximately 4 million V/m in air, as notably occurs in lightning strikes. Other forms of ESD include corona discharge from sharp electrodes, brush discharge from blunt electrodes, etc.
ESD can cause harmful effects of importance in industry, including explosions in gas, fuel vapor and coal dust, as well as failure of solid state electronics components such as integrated circuits. These can suffer permanent damage when subjected to high voltages. Electronics manufacturers therefore establish electrostatic protective areas free of static, using measures to prevent charging, such as avoiding highly charging materials and measures to remove static such as grounding human workers, providing antistatic devices, and controlling humidity.
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OhmSweetOhm
New member
Thank you for the reply! Its works flawlessly now.
Now I have the option to use 25db or 19db gain setting. So what to pick..?
Im using these Fosi audio Monos with quite hard to drive 4ohm 86db speakers in combination with a Denon x3800h AVR pre out.
Checking the users here and on audioscience review is confusing and contradictory. measurement of the x3800h pre out is about 1.4v.
I know i need to take AI advice with a pinch of salt but I Google AI and it recommended to use 19db but Chat GPT didnt like this at all and preferred 25dB. It said:
“It is generic AI-generated advice that misunderstands how AV-receiver pre-outs work compared to DACs.
Let me break it down with facts, not guesswork.
✔ FACT 1
Denon X3800H pre-out voltage is
not high output
Multiple independent measurements show:
A “high output source” in audio normally means 2 Vrms standard DAC output or even 4 Vrms balanced.
So the Denon is not a high-output source.
It is medium at best.
This already invalidates the advice in the screenshot.
✔ FACT 2
Your speakers require more gain, not less
You have:
✔ FACT 3
Fosi V3 Mono at 19 dB gain is too low for most AVRs
Users who tested Denon and Marantz with the Fosi V3 Mono report:
25 dB solves all that.
✔ FACT 4
25 dB will NOT cause clipping
The screenshot wrongly assumes that higher gain = automatic clipping.
This is false, because clipping in your chain will happen first at:
✔ FACT 5
Better dynamic range = 25 dB
You want the Denon running at moderate volume levels, not maxed out.
With 19 dB Fosi gain, you will need to push the Denon too high.
✔ FINAL ANSWER
Use 25 dB gain on your Fosi V3 Mono with the Denon X3800H.
This is the correct setting for:
Now I have the option to use 25db or 19db gain setting. So what to pick..?
Im using these Fosi audio Monos with quite hard to drive 4ohm 86db speakers in combination with a Denon x3800h AVR pre out.
Checking the users here and on audioscience review is confusing and contradictory. measurement of the x3800h pre out is about 1.4v.
I know i need to take AI advice with a pinch of salt but I Google AI and it recommended to use 19db but Chat GPT didnt like this at all and preferred 25dB. It said:
“It is generic AI-generated advice that misunderstands how AV-receiver pre-outs work compared to DACs.
Let me break it down with facts, not guesswork.
✔ FACT 1
Denon X3800H pre-out voltage is
not high output
Multiple independent measurements show:
- Typical clean output: 1.2 to 1.5 Vrms
- Absolute max before distortion: around 2 Vrms (only near reference level)
A “high output source” in audio normally means 2 Vrms standard DAC output or even 4 Vrms balanced.
So the Denon is not a high-output source.
It is medium at best.
This already invalidates the advice in the screenshot.
✔ FACT 2
Your speakers require more gain, not less
You have:
- 4 ohm impedance
- 86 dB sensitivity (which is low)
✔ FACT 3
Fosi V3 Mono at 19 dB gain is too low for most AVRs
Users who tested Denon and Marantz with the Fosi V3 Mono report:
- 19 dB = too quiet
- Requires high volume on AVR
- Reduced dynamic peaks
- Not enough headroom
- Sometimes forces the AVR into pre-out clipping earlier
25 dB solves all that.
✔ FACT 4
25 dB will NOT cause clipping
The screenshot wrongly assumes that higher gain = automatic clipping.
This is false, because clipping in your chain will happen first at:
- The Denon pre-out
- Or the speaker itself
- NOT the Fosi at 25 dB (it has plenty of room)
✔ FACT 5
Better dynamic range = 25 dB
You want the Denon running at moderate volume levels, not maxed out.
With 19 dB Fosi gain, you will need to push the Denon too high.
✔ FINAL ANSWER
Use 25 dB gain on your Fosi V3 Mono with the Denon X3800H.
This is the correct setting for:
- 4 ohm speakers
- 86 dB sensitivity
- Medium-output Denon pre-outs
- Movies and music with wide dynamics
- Avoiding Denon pre-out strain/clipping
- Achieving reference level properly
Bittybo Tootkins
New member
I think it's best to use the lowest possible gain setting on the V3. To keep the signal as clean as possible. If needed, you can choose a higher gain setting.
OhmSweetOhm
New member
Yeah but check this:
This was at the fosi v3 19db settings. So my Denon AVR needed to really boost the front pre-puts. And the distortion of the Denon pre outs starts to kick in at 1.4v already.
So maybe 25db is better…
This was at the fosi v3 19db settings. So my Denon AVR needed to really boost the front pre-puts. And the distortion of the Denon pre outs starts to kick in at 1.4v already.
So maybe 25db is better…
Bittybo Tootkins
New member
Yeah, I think it is. Anything to keep that nasty distortion in check. Try it and see what happens. By the way, the GR70 has an output of 1.2Vrms and everything is plenty loud in my setup.
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OhmSweetOhm
New member
I dont have any distortion atm I think.. but AB testing is hard.. but pushing the denon to +9db might involve more than 1.4v
OhmSweetOhm
New member
Wait I misunderstood.. so you are saying to change my gain from 19 to 25db also?
Bittybo Tootkins
New member
Two speakers, two cables, two power amplifiers, two power LEDs. A perfectly harmonious dual setup. Any difference in LED brightness can drive a man crazy. It can certainly drive me crazy ;-)
Well, since your Denon AVR struggles a bit, why not try it?
OhmSweetOhm
New member
Yes I tried it, I had to do the roomcorrection again
anyway I did not notice any distortion. So ill keep it on 25db and let the Fosi do the heavy lifting instead of the denon
