Fosi Audio V3 amplifier discussion

[Matias]

Amir's review just came out. I was hoping for better, I'm a little disappointed.
@Fosi Audio when will we be able to have an amplifier without load dependence?

When a manufacturer designs a class D chip that includes post filter feedback loop with a low price.

 

[Talisman]

When a manufacturer designs a class D chip that includes post filter feedback loop with a low price.

in reality the Topping pa5 was exactly what you say, a cheap little amplifier with very low noise and distortion and no load dependency. If Topping hadn't had the wicked idea of sticking all those resin op-amps it would have been a fantastic product. So evidently it can be done, and it can be done at humane prices

 

[potfur]

in reality the Topping pa5 was exactly what you say, a cheap little amplifier with very low noise and distortion and no load dependency. If Topping hadn't had the wicked idea of sticking all those resin op-amps it would have been a fantastic product. So evidently it can be done, and it can be done at humane prices

Topping PA5 was relatively cheap, but not THAT cheap. US $350 is more than three times the price of the Fosi V3.

 

[Matias]

@Talisman You are right, I forgot those.

@Fosi Audio when will we be able to have an amplifier without load dependence? Hint: Infineon Merus MA5332MS chip is 4-5 usd / piece depending on quantity (link).

 

[Talisman]

Topping PA5 was relatively cheap, but not THAT cheap. US $350 is more than three times the price of the Fosi V3.

this is absolutely true, however I believe that price was purely commercial in nature, it was due to the high performance in the amplifier Certainly not the cost of the components, in any case I would be happy to pay double what the V3 now costs for the same amplifier but without load dependence

 

[Freezak]

this is absolutely true, however I believe that price was purely commercial in nature, it was due to the high performance in the amplifier Certainly not the cost of the components, in any case I would be happy to pay double what the V3 now costs for the same amplifier but without load dependence

I didn't know about the load dependency issue. Would it cause audible issues when driving Elacs DBR62 using Fosi Audio V3?

 

[Talisman]

I didn't know about the load dependency issue. Would it cause audible issues when driving Elacs DBR62 using Fosi Audio V3?

as I also wrote in the review thread, the Elac DBR62s have a fairly high impedance of about 12/13 Ohm between 10 and 20 kilohertz, so a higher frequency boost is to be expected compared to the flat, probably audible response if you can hear above 14.khz

 

[maty]

We recorded a video demonstrating the V3 using various op-amps including NE5532, JRC4580D, Sparkos SS3602, MUSES02 and OPA2604. After uploading to YouTube, the audio quality might not be the best, but you can still use it as a reference.

Ranking:

Sparkos SS3602, OPA2604 and...
JRC4580D, NE5532 small differences
MUSE02 the worst! Weird sound, where are the bass?
Sparkos is too expensive (85€ x2), then OPA2604 is the best choice.

To the future, maybe OPA2828 with DIP adapter
NE5532 vs OPA2604 -> the second is more musical, better voice

OPA828 DUAL with DIP8 adapter

 

[tgrauss]

@Fosi Audio
It would be nice if Fosi Audio create an ecosystem of reference gears around the V3 amplifier using the same enclosure.
The next step would be a reference DAC.

This DAC would have the RCA output at the same place as the RCA input of the V3 amplifier.
This way, Fosi could sell as accessory a special rigid U-shaped RCA "cable" with just the right size to connect the output of the DAC to the input of the V3 amplifier when the amplifier is sitting on top of the DAC.

In the same way, if the DAC use the same voltage range as the V3 amplifier, we could reuse the expensive power brick (and it would reduce e-waste and we could spend more on the quality of the DAC itself) of the amplifier, plug it in the DAC power input. The DAC would have a relay controlled power output where we could connect the power input of the amplifier using a rigid U-shaped "cable".
These very short cables would unclutter the back of the DAC and amplifier.
When we turn on the DAC, it would turn on the power of the amplifier, and when we turn off the DAC, it would mute the output and turn off the power of the amplifier.

To please those who want to buy multiple DAC/amplifier pairs in a multi-channel setup, an HDMI/SPDIF (like the HD951B) switcher (with HDMI 2.1 out pass-through but no DAC) with SPDIF output (3 or 4 SPDIF outputs) would allow to control these multiple pairs of the DAC/amplifiers. It does not need to include any media decoding as the bluray player can do the decoding and send multi-channel PCM on the HDMI link.
A way to set the delays, to manage the LFE channel and a 12 bands equalizer on each channel. The TI TAS3103 could do the job for the delays and the equalizer. It can even manage the volume. So there is no need to program a DSP. From what I can see in the datasheet, we could use it to manage the LFE channel too. This device should not be very expensive to manufacture.
The device should have trigger outputs to turn on/off the DAC/amplifier pairs and a remote control to set the volume and turn on/off.
As input and outputs, it should have 4 HDMI 2.1 inputs, 1 HDMI 2.1 output with ARC, 2 or 3 spdif input, 1 USB input (for USB DAC), 1 Bluetooth input, 4 SPDIF outputs, the same enclosure as the V3 amplifier.
The Bluetooth should be disconnected when not selected on the switcher. To keep the front plate simple, and as we set the equalizer only once, a RS232 port (using a TRS socket to keep this small) could be used to change the inputs, set every parameters of the switcher and especialy the equalizer, set the delays, the LFE parameters.
This HDMI/SPDIF switcher would be like a digital "preamp".

Later, Fosi could create a reference ADC which could connect to one of the SPDIF input of the controller/switcher.

If Fosi could sell empty V3 enclosures, it would be nice for those who want to create some DIY audio gears so that the look will match the V3.

Doing this, Fosi would create the first system which could evolve from stereo, to 2.1, 4.0, 5.1 or 7.1 just by buying more DAC/amplifiers. It would be a modular AVR.

 

[meringo]

as I also wrote in the review thread, the Elac DBR62s have a fairly high impedance of about 12/13 Ohm between 10 and 20 kilohertz, so a higher frequency boost is to be expected compared to the flat, probably audible response if you can hear above 14.khz

This is making me sad :-( I bought this to use with my DBR62s. Should I sell off? Have the A07 now.

 

[Zek]

Should I sell off?

First, let some time pass by listening to both amplifiers, and then decide which one you will keep.

 

[Talisman]

This is making me sad :-( I bought this to use with my DBR62s. Should I sell off? Have the A07 now.

Absolutely not, the fosi v3 is an improvement over the aiyima a07 in every respect, probably also with regard to load dependency, which the aiyima clearly suffers from as well, so if you've been using it up until now with your loudspeakers and you liked the sound then surely it will be fine also with the V3.
And in any case your speakers have a flat impedance from 10khz to 20khz, this means that equalizing, if you wanted to, would be very easy.
Enjoy your new Fosi which is much better than aiyima.

 

[meringo]

Absolutely not, the fosi v3 is an improvement over the aiyima a07 in every respect, probably also with regard to load dependency, which the aiyima clearly suffers from as well, so if you've been using it up until now with your loudspeakers and you liked the sound then surely it will be fine also with the V3.
And in any case your speakers have a flat impedance from 10khz to 20khz, this means that equalizing, if you wanted to, would be very easy.
Enjoy your new Fosi which is much better than aiyima.

Thanks for this. Looking forward to delivery!

 

[meringo]

Ugh.... mine arrived defective. I have to spin the volume all the way up to like 3/4 to get reasonable volume. Is anything worth checking? I opened it up to make sure nothing was loose inside, looks fine. It gets about half as loud as the 32v A07 it's replacing.

Looks like I'll have to figure out a swap via Kickstarter, hopefully not a nightmare.

 

[Joe Smith]

Ugh.... mine arrived defective. I have to spin the volume all the way up to like 3/4 to get reasonable volume. Is anything worth checking? I opened it up to make sure nothing was loose inside, looks fine. It gets about half as loud as the 32v A07 it's replacing.

Looks like I'll have to figure out a swap via Kickstarter, hopefully not a nightmare.

Some production issues getting worked out, no doubt...sorry, I'm sure it will work out, but bummer...

 

[Talisman]

Ugh.... mine arrived defective. I have to spin the volume all the way up to like 3/4 to get reasonable volume. Is anything worth checking? I opened it up to make sure nothing was loose inside, looks fine. It gets about half as loud as the 32v A07 it's replacing.

Looks like I'll have to figure out a swap via Kickstarter, hopefully not a nightmare.

Do not return anything!
The new Fosi audio amps, luckily, have implemented the taper A volume control, most of the watts come out in the last quarter turn, this helps fine tuning the volume at lower volumes, but in the case of the power supply at 32V it means that the first 3/4 of the excursion will have few watts.
Don't be afraid to use the volume knob.

 

[TonyJZX]

i think you can thank Toku for taper A

 

[Talisman]

i think you can thank Toku for taper A

Yes, but not only.
In the tb10d thread there were many (including me) who complained about the difficulty of adjusting the volume at the lowest levels, this implementation is the result of the excellent work of Fosi in listening to user feedback.

 

[Tangband]

We recorded a video demonstrating the V3 using various op-amps including NE5532, JRC4580D, Sparkos SS3602, MUSES02 and OPA2604. After uploading to YouTube, the audio quality might not be the best, but you can still use it as a reference.

Nice .
The lm4562 is also an alternative ( I think its the best sounding in Aiyima a04 and a07 ). Its also a bipolar Op amp, just like the ne5532. Lm4562 also offer slightly better measurement results ( as pma has shown in Aiyima a07 ).

 

[meringo]

Do not return anything!
The new Fosi audio amps, luckily, have implemented the taper A volume control, most of the watts come out in the last quarter turn, this helps fine tuning the volume at lower volumes, but in the case of the power supply at 32V it means that the first 3/4 of the excursion will have few watts.
Don't be afraid to use the volume knob.
View attachment 294115

Thanks for the reply! I'll keep this is mind during some more testing later this evening. I thought the headroom would go up significantly with the 48v power supply for the V3. Maybe I just need to adjust my expectations.