Fosi v3 load dependency with Elac dbr62 - A problem?

[Theodore8]

Hello, I have also a Elac DBR62 and Fossi V3 with 48V supply since two days ago, and thanks to all the folks of this forum. For my surprise, the total volume at full knob is not really loud, and it has been tested with a Arylic BP50 and a Topping E30II DAC with similar results. In fact , it is only a tiny fraction of the output power of my Yamaha Pianocraft amplifier and speakers (60w/channel). I have to set the DAC at 100% power and Fossi V3 at 75% or so for a loud listening. Is it ok or maybe i have a faulty Fossi V3? On the other side, the sound is amazing, clear, pristine, full of detail, a really please to listen.
Would like to know your opinion, and how could i measure the current speaker output volume and compare with the one of other person with similar configuration (maybe with a smartphone?). Thanks

Thanks for sharing. I have a similar set up (smsl d6s balanced > XLR > 2x Fosi V3 Mono with 48V/10A power supply > 3m banana speaker cables > ELAC DBR62), and also found that max volume is not that loud. I also had a Yamaha Pianocraft 60W amplifier with matching Yamaha NX-E400 speakers, and confirm my perception that the prior set up could get louder.

I attribute the difference to the low sensitivity of the DBR62 vs. the Yamaha speakers. That said, with an EQ boost to the bass, the DBR62 are delightful. And in any case they are only tasked with background music in the dining room.

 

[burkm]

The "problem" ist, what are the levels or the signal feeding Your setup ?
The V3 Monos have more output power, than Your Yamaha setup, but the sensitivity of the inputs (gain) are probably lower on the Fosi Audio V3 Monos, thus it does not reach the same loudness at the current input levels. This is a spec which is often misunderstood, because no one thinks about this beforehand...

 

[Theodore8]

The "problem" ist, what are the levels or the signal feeding Your setup ?
The V3 Monos have more output power, than Your Yamaha setup, but the sensitivity of the inputs (gain) are probably lower on the Fosi Audio V3 Monos, thus it does not reach the same loudness at the current input levels. This is a spec which is often misunderstood, because no one thinks about this beforehand...

Thank you very much for sharing "the problem". I like how you describe it.

The reason I did not expect the outcome is that according to the manufacturer, the SMSL d6s outputs 5V to its XLR outputs. Granted, it is not the 10V of an RME-ADI2-DAC XLR out, but I thought it was sufficient to get very loud. And the full volume does get loud enough (and certainly more than I can run for a few minutes without getting the upstairs neighbour knocking at my door, as is his habit when I listen to opera on my main system).

All I was saying is that the d6s/Fosi V3/DBR62 combo is not ear-bleeding loud, to the level that I can get with the RME-ADI2-DAC>Boxem 4215/E2>Focal 926 (rated at 91.5db, but measured at 88db). Which I did not really expect. But I did expect the Fosi V3 combo to get a bit louder than it does.

Anyway, this is all subjective stuff!

 

[TurtlePaul]

All I was saying is that the d6s/Fosi V3/DBR62 combo is not ear-bleeding loud, to the level that I can get with the RME-ADI2-DAC>Boxem 4215/E2>Focal 926 (rated at 91.5db, but measured at 88db). Which I did not really expect.

What is your source and what material are you playing? Windows volume 100%? No negative gain preamp in EQ APO? Spotify not set to quiet volume normalization?

 

[burkm]

Thank you very much for sharing "the problem". I like how you describe it.

The reason I did not expect the outcome is that according to the manufacturer, the SMSL d6s outputs 5V to its XLR outputs. Granted, it is not the 10V of an RME-ADI2-DAC XLR out, but I thought it was sufficient to get very loud. And the full volume does get loud enough (and certainly more than I can run for a few minutes without getting the upstairs neighbour knocking at my door, as is his habit when I listen to opera on my main system).

All I was saying is that the d6s/Fosi V3/DBR62 combo is not ear-bleeding loud, to the level that I can get with the RME-ADI2-DAC>Boxem 4215/E2>Focal 926 (rated at 91.5db, but measured at 88db). Which I did not really expect. But I did expect the Fosi V3 combo to get a bit louder than it does.

Anyway, this is all subjective stuff!

What is the input voltage to the DAC ?
That 5V is the max. volume (signal) an input can reach from the DAC.
The (sum) gain structure for all in the setup included units is responsible for the corresponding output voltage and thus the loudness, which can be reached.

 

[Theodore8]

What is the input voltage to the DAC ?
That 5V is the max. volume (signal) an input can reach from the DAC.
The (sum) gain structure for all in the setup included units is responsible for the corresponding output voltage and thus the loudness, which can be reached.

What is your source and what material are you playing? Windows volume 100%? No negative gain preamp in EQ APO? Spotify not set to quiet volume normalization

Qobuz > Roon server (Intel NUC) > Roon End point (Rpi4 running Ropieee) > USB-A/USB-C cable (1.2V according to Raspberry specs) > SMSL d6s > XLR cable (2x) > Fosi V3 mono (2x)

Device volume choice on Roon, and headroom or volume limits.

 

[PoorAudioGuy]

I recently got a pair of DBR62s open box for 300EUR + 50EUR shipping. I'm running them using an old Onkyo TX-8255. The Onkyo transformer makes a humming noise that's driving me crazy so I'm thinking to get a V3. This thread has quite assured me that it'll be generally OK with V3. I also have the some sibilance issue as some others have reported that I have not been able to fix using EQ. I'm worried that a class D amp like V3 is going to make it worse.
BTW, I also have the option to pick a used NAD C326BEE in good condition for about 150EUR. Will NAD be a better option?

 

[Theodore8]

I recently got a pair of DBR62s open box for 300EUR + 50EUR shipping. I'm running them using an old Onkyo TX-8255. The Onkyo transformer makes a humming noise that's driving me crazy so I'm thinking to get a V3. This thread has quite assured me that it'll be generally OK with V3. I also have the some sibilance issue as some others have reported that I have not been able to fix using EQ. I'm worried that a class D amp like V3 is going to make it worse.
BTW, I also have the option to pick a used NAD C326BEE in good condition for about 150EUR. Will NAD be a better option?

For what it’s worth, the Fosi 48V/10A transformer is totally silent.

Also, relative to my earlier comments, my subjective impression is that after about 20hrs my perceived performance of the DBR62s improved.

While I am a believer that “required break in” is a myth, in this case, it seemed to have an impact. Or maybe I just got used to the DBR62s sound. Who knows.

 

[wyup]

I'd get the Nad. It seems muscular at the bass which is what the DBR62 need. V3 is not enough (to me). This is a difficult speaker. It eats all the power you give to grip that woofer.

 

[burkm]

I have gotten about 5x Fosi V3 Monos (using those individual 48V/5A power supplies and some fans for ventilation above 30°C) and I am "totally" satisfied with them (strangely using Elac DB62s speakers too) in this context. I don't know, where your mentioned "sibilance" comes from but mine don't have any I could recognize. I don't know about the sound of the mentioned NAD AVRs, but wonder, what they should do with my Elacs, if the "straight wire with sound" acronym still holds true especially in the bass region without adding any coloration of their own to it. The V3 seem to be utterly "neutral" in this respect.

 

[PoorAudioGuy]

I am new to the hobby so please bear with me! I asked Gemini if V3 is a good match for DBR62s. It cautioned me that the result might potentially be too bright. I already find my Elacs to be too bright with my A/B amp so I asked it to expand on why there might be even more brightness. Here is its response below:

"Many budget-friendly Class D amplifiers (like the Fosi V3, and others using chips like the Texas Instruments TPA32xx family without Post Filter Feedback, or PFFB) use an output filter to clean up the high-frequency switching noise. This filter's performance is affected by the speaker's electrical impedance at high frequencies. The speaker's impedance acts as the "load" for this filter. The amp expects a flat impedance, typically 4 to 8 ohms. ELAC DBR62 speakers have a relatively high and rising impedance in the crucial treble region (above 5 kHz), often staying well above 10 ohms. This mismatch causes the output filter to resonate, resulting in a measurable boost in the high-frequency response (a "rise in treble") for that specific amp/speaker combination."

To be fully honest I don't fully understand what it's saying. Can someone smarter than me enlighten me if it's something I need to be worried about? Ideally I would like to get the V3 because of cost but if I know it's needed I will pay extra and go with something like O-Noorus D1 to get PFFB to mitigate this issue? (two V3 mono blocks would do it too but would be out of my budget) or perhaps stick with another A/B amp like NAD C326BEE

A bit of context: I listen at moderate levels in a medium size room and I am in my late 40s so not the most ears either!

 

[burkm]

Just read available discussions and comments on the "sound quality" of the V3 Monos on the internet to make up your mind yourself, not just a single statement as provided by someone...
I wonder, if any in the 40s of their life will realize any of those statements, because audibility of high frequencies diminishes quite strongly with age (at an age of 70 you probably won't hear anything above 8 kHz, at an age in the mid 40s this upper limit (average) will be somewhere around 13 kHz). A reason, why the frequency response of your hearing is usually only measured up to around 8 kHz during medical examination.
But "subjective" impressions will always influence the outcome of this (opinions!). "Hearing" is really very subjective, because no one else has the same ears and brain as yourself.
Even a stronger markup of higher frequencies would barely be audible considering the biological age of the listener. Other factors like different kinds of (dynamic ?) distortion might influence this opinion too...
Most listeners (Gauss curve) in their 40s won't be "hearing" anything above 13 kHz (undamaged) as scientific evidence proves (formulars available for some time already, thus not really "new" !), but some "audiophiles" are still ignorant of this...

PFFB as provided by the V3 Monos (to my knowledge Purifi and Hypex/Ncore are using this already for some time) will counterbalance this "phenomenon" just at the origin.
Older Class D designs without this will have some influence on this, because the speakers impedance influences then the high frequency outcome to a certain extent (low impedance = lower output of higher frequencies above appr. 10 kHz, higher impedance = higher output of higher frequencies above appr. 10 kHz, usually~ +-1.5 db. Phase modulation (inductance, capacitance etc.) will additionally take part in this too even at some frequencies mostly above 4 kHz. As a result the "real" frequency response of Your "standard" amp might be influenced by this.

 

[wyup]

The V3 monos don't have good press, it was Fosi's first PFFB design and according to some it sounds lean. And they heat up a lot. Not really efficient for class D. Normal V3 and ZA3 have better reviews but still, it's geared for desktop and small speakers. The DBR62 are suckers and demand amplifiers well above their price to make the best of them, otherwise they sound soft or lifeless, as they've been qualified.
I would get the NAD just for the better power supply.

 

[PoorAudioGuy]

V3 Monos are too expensive for me. I have contacted two NAD listing that are in good condition and good price. No reply yet which usually means they are sold. I'll wait a bit longer and pull the trigger on a V3 if I don't hear from them. I can buy a V3 + 48v PSU for 70EUR from AE shipped from Germany. I'll try to deal with the effects of load dependency with EQ on my source if I can hear it.

 

[burkm]

The V3 monos don't have good press, it was Fosi's first PFFB design and according to some it sounds lean. And they heat up a lot. Not really efficient for class D. Normal V3 and ZA3 have better reviews but still, it's geared for desktop and small speakers. The DBR62 are suckers and demand amplifiers well above their price to make the best of them, otherwise they sound soft or lifeless, as they've been qualified.
I would get the NAD just for the better power supply.

Sorry, that I disagree. The PFFB design has been provided by (T)exas (I)nstruments for this 3255 chip set and Fosi Audio was following this design. Others did not. So it doesn't make much of a difference if they did it the 1st time or not, does it ?

Additionally the Fosi Audio V3 Monos got in sum much better comments about their specs and sound quality than most other comparable amps and they sold a lot of it, as has been stated before. Subjective assessments might disagree, but they are what they are: subjective

I don't want to get into a discussion with anyone else about the sonic qualities this amp has. Everyone is - naturally - invited to follow due diligence assessments about the quality they deliver or not...

 

[wyup]

What I see is that Fosi have favoured themselves the ZA3 over the V3 monos for their new preamp pairing kits. I even asked them why.
Also YouTube reviewers favour ZA3 over V3 monos for sound quality. The monos heat more than the ZA3. This to me doesn't look like a good design. Gosh, some are using fan farms with them and burning their fingers.

This amp is a toy, not for the DBR62, believe me. Think near field or desktop use for Fosi.

There are also reports that the V3 doesn't have enough volume gain to drive this speaker.

There are more achieved products than others. That the V3 mono is PFFB does not mean that it will sound as good as no PFFB, Texas Instruments approved or not.

 

[burkm]

Following usual logic. Fosi Audio probably has more ZA3 left in store than V3 Monos for whatever reasons, thus they will be offered more at a reduced price to get rid of them
I think, that offer has more to do with the enlarged case of the ZA3 for cooling purposes than anything else. This means by my interpretation of the situation, they (Fosi Audio service) have less questions to answer in this respect.

It is not a PFFB design either. Why not ?
Everyone was waiting for this as commented repeatedly here and at other places, just read all the comments on the internet. This seems to me a drawback, because PFFB has - in the past - only been part of better designs (Purifi, Hypex Ncore and others). A linear frequency is on the table and an impedance independent design has its advantages to be sure.
I read a lot on the internet about both designs and found - contrary to Your post - a majority of those considering their sonic quality been very positive about the V3 Monos less about the ZA3s

But everyone may pick his choice by listening to both designs and then decide himself what he likes best: In Your bubble it's the ZA3, in my bubble it's the V3 Mono.
Note: The DBR62 are definitely small (and rather cheap) speakers (I got them myself) and thus have their draw backs. It's his choice to decide what he likes more in his personal context...

 

[wyup]

Sure, DBR62 rather small, 8 kgs.. for desktop use. Rather cheap, 550€ at Amazon. Much cheaper than V3 burning monos. Your choice. Buy without listening and without reading.