Fosi Audio V3 Mono Amplifier Review

[antcollinet]

If you are worried about thermal performance, just place it on its side, raised a little to keep the ventilation holes open, and, maybe, stuck a low profile heatsink on the former underside.View attachment 368773View attachment 368774

Maybe you have around an old external 3.5 hdd or router accesory.

Agreed. Messing about with thermal paste is pointless. You are more likely (IME) to make things worse, than better.

 

[Doodski]

Agreed. Messing about with thermal paste is pointless. You are more likely (IMO) to make things worse, than better.

A thermal paste MOD is pretty much 100% guaranteed to be a waste of time but these are a MODers paradise machine.

 

[somebodyelse]

Given how cheap these amps are, how quick the tech is improving, the time/cost associated with the aftermarket thermal paste, the potential to messing up the unit and the likelihood of never needing it, why would anyone go down this path?

Personally I wouldn't, just as I wouldn't change the opamps, but if people insist on doing it they should put the aftermarket paste in the place where it has a chance of making an improvement. People who have paste left over from a PC build probably have the skill to do the job without much risk. Turning it on its side and/or using a fan would probably be more effective in improving cooling if you really need it.

 

[mgbpuff]

Just because it feels warm does not mean it has a problem. It was designed with the temperature rise in mind. This reminds me of my motor days with Reliance Electric when customers would say they wanted smaller frame sizes and then would complain that they run so hot that you could not even touch them. Well, they were designed for that and had high temp insulation and eddy current dissipating frame designs just so they could put more hp in smaller frames.

 

[antcollinet]

People who have paste left over from a PC build probably have the skill to do the job without much risk.

This might be an assumption too far. PC motherboards/CPU sockets are designed to make this pretty foolproof, with standardised, well engineered, robust, and tightly toleranced fixing methods for the heatsink down to the CPU.

The same does not apply to TPAchip amp based designs. The clamping force between chip and heatsink/spreader is highly dependent on the mechanical design, and fixing methods. Consistency of this may be highly dependent on the assembly process. It will also depend on the designed for viscosity of whatever paste is specified, and the designed for quantity and application method. None of which is known by the modder.

I have a number of unhappy experiences of heatsink paste incorrectly selected or applied causing problems in a high volume power electronic manufacturing environment.

 

[Doodski]

It will also depend on the designed for viscosity of whatever paste is specified, and the designed for quantity and application method. None of which is known by the modder.

I have a number of unhappy experiences of heatsink paste incorrectly selected or applied causing problems in a high volume power electronic manufacturing environment.

If one delves a little deeper into the MX-4, MX-5 and MX-6 thermal compounds that are so popular these days due to their 8 year service warranty they will find that there are tiny improvements in thermal conductivity but the major differences are viscosity like you say that is so important.

 

[Toroid]

Do we know if these could drive a 2 ohm speaker but highly efficient 95db at not insane volume? (One that only dips to 2.3 ohm, but never goes over 2.8 ohm)

 

[motorstereo]

^^^^^Mine has been running 2 pair of IMF supercompacts wired in parallel since it arrived here last week. It does get warm from the 4 ohm load but I'm thinking it would handle a 2 ohm load as long as it's not driven too hard.

 

[antcollinet]

Do we know if these could drive a 2 ohm speaker but highly efficient 95db at not insane volume? (One that only dips to 2.3 ohm, but never goes over 2.8 ohm)

Yes. You are only going to need to average 1 or 2 watts with such speakers.:

 

[Sokel]

Yes. You are only going to need to average 1 or 2 watts with such speakers.:

View attachment 369121

Assuming that this 2 Ohm speaker must be subs (what else is a constant 2 Ohm load?) and for proper integration there's surely some EQ involved it may need a little more than a watt or two to balance the loss.
If filling dips too (not advisable but people do it anyway) can go way-way higher.
But yes,test showed that can do it (in it's time constraints) .

 

[staticV3]

Assuming that this 2 Ohm speaker must be subs

What sub has a 95dB efficiency?

I'd imagine that @Toroid is talking about a fancy horn system or CBT speaker, or perhaps a panel-type speaker.

 

[Sokel]

What sub has a 95dB efficiency?

I'd imagine it's a fancy horn system or CBT speaker.

These are usually 8 or even 16 Ohm.
I'm really curious!

 

[staticV3]

These are usually 8 or even 16 Ohm.
I'm really curious!

I bet it's a dipole panel speaker

 

[Sokel]

I bet it's a dipole panel speaker

On the other hand I found this:

DS18 PRO-M6.2NEO 6-1/2" Professional Water Resistant Neodymium Full-Range Speaker 2 Ohm

Motorcycle and ATV audio enthusiasts demand the highest quality for their high-end speakers because of the open-air environment that they love to be in. With hard riding comes with rigorous vibration and that can damage your speakers. DS18 wants motorsport lovers to feel confident in their...

www.parts-express.com

 

[staticV3]

On the other hand I found this:

DS18 PRO-M6.2NEO 6-1/2" Professional Water Resistant Neodymium Full-Range Speaker 2 Ohm

Motorcycle and ATV audio enthusiasts demand the highest quality for their high-end speakers because of the open-air environment that they love to be in. With hard riding comes with rigorous vibration and that can damage your speakers. DS18 wants motorsport lovers to feel confident in their...

www.parts-express.com

Peaks at 45Ω whereas the speakers in question don't exceed 2.8Ω

 

[Toroid]

What sub has a 95dB efficiency?

I'd imagine that @Toroid is talking about a fancy horn system or CBT speaker, or perhaps a panel-type speaker.

Nope, I'm wondering if these amps might pair well with the 2 ohm Pendragons.

 

[Sokel]

Nope, I'm wondering if these amps might pair well with the 2 ohm Pendragons.

...as if there's was no controversy enough with Tekton

 

[staticV3]

Nope, I'm wondering if these amps might pair well with the 2 ohm Pendragons.

The Pendragon can't possibly have these impedance characteristics, right?

(One that only dips to 2.3 ohm, but never goes over 2.8 ohm)

Surely the two woofers peak to >10Ω somewhere below 100Hz.

 

[Toroid]

The Pendragon can't possibly have these impedance characteristics, right?

They specifically designed them that way

 

[staticV3]

They specifically designed them that way

Did they share any impedance response graphs with you to confirm their design work?