Fosi Audio V3 Mono Amplifier Review

[staticV3]

On the other hand I found this:

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

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...

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?

 

[Toroid]

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

Not that I've seen. Just taking Jay's Iyagi's word for it.

 

[staticV3]

Not that I've seen. Just taking Jay's Iyagi's word for it.

If you ever get curious, the Dayton Audio Test System is all that you need to measure your speakers' impedance response.

Although Tekton's lead designer may try to sue you if you publish the results
(Link)

 

[Elder]

I was all set on ordering the Behringer A800 to mount underneath my desk and power 2x subwoofers in my small office, but these Fosi amps sure are tempting me.

Since I plan to mount underneath my desk, does anyone think I'll be risking thermal issues running 4ohm subwoofers with these?

 

[ninetylol]

I just removed my 30% super early bird order, so theres one spot left if anyone wants it.

 

[Yannick]

I just removed my 30% super early bird order, so theres one spot left if anyone wants it.

Thank you, much appreciated!

 

[ninetylol]

Thank you, much appreciated!

No problem i hope you will have a lot fun with them

 

[Talisman]

I was all set on ordering the Behringer A800 to mount underneath my desk and power 2x subwoofers in my small office, but these Fosi amps sure are tempting me.

Since I plan to mount underneath my desk, does anyone think I'll be risking thermal issues running 4ohm subwoofers with these?

It seems like a bad idea, the Behringer A800 is a professional amplifier, extremely powerful and robust, perfect for driving passive subs, the Fosi have much better measured performance but useless for subs and lack power compared to the A800 which instead is a characteristic very useful for this task.

 

[rvsixer]

It seems like a bad idea, the Behringer A800 is a professional amplifier, extremely powerful and robust, perfect for driving passive subs, the Fosi have much better measured performance but useless for subs and lack power compared to the A800 which instead is a characteristic very useful for this task.

Interesting generalization, IRL it all depends on the application. I have DIY 4 ohm passive subs that require 70W max (f3=23Hz, 100dB output each). This Fosi would be much more than adequate for them.

 

[Zuiko]

*Simplified V*A=W power per channel calculation with different bricks: (*not power to speakers)

2x V3 Mono & 2x 48V 5A = 240W/channel (or 1x 48V 10A split)
2x V3 Mono & 2x 36V 6A = 216W/channel
2x V3 Mono & 2x 36V 5A = 180W/channel
2x V3 Mono & 2x 32V 5A = 160W/channel
V3 Stereo & 48V 5A = 120W/channel
V3 Stereo & 36V 6A = 108W/channel
V3 Stereo & 36V 5A = 90W/channel
V3 Stereo & 32V 5A = 80W/channel

Interestingly there are a couple of potential sweet spots using the V3 Mono with 36V or 32V power adapters: Smaller & less expensive bricks, less heat, yet still lots of power.

I likely would of opted for a 36V option in the Mono Kickstarter if it were available. Maybe they can still add it to help crack that $500K goal?!

ps. looks like 250 people or so are getting the 2x 48V 10A ... If you're here, what speakers are you driving or what are your reasons for 480W/channel?

pps.: I edited and took out the 2 x 48V 10A line based on feedback.

 

[antcollinet]

Simplified power per channel calculation with different bricks:

2 x V3 Mono & 2x 48V 10A = 480W/channel
2x V3 Mono & 2x 48V 5A = 240W/channel
V3 Stereo & 48V 10A = 240W/channel
2x V3 Mono & 2x 36V 6A = 216W/channel
2x V3 Mono & 2x 36V 5A = 180W/channel
2x V3 Mono & 2x 32V 5A = 160W/channel
V3 Stereo & 48V 5A = 120W/channel
V3 Stereo & 36V 6A = 108W/channel
V3 Stereo & 36V 5A = 90W/channel
V3 Stereo & 32V 5A = 80W/channel

Interestingly there are a couple of potential sweet spots using the V3 Mono with 36V or 32V power adapters: Smaller & less expensive bricks, less heat, yet still lots of power.

I likely would of opted for a 36V option in the Mono Kickstarter if it were available. Maybe they can still add it to help crack that $500K goal?!

ps. looks like 250 people or so are getting the 2x 48V 10A ... If you're here, what speakers are you driving or what are your reasons for 480W/channel?

How are you getting those calculations? You can't just assume that all the PSU power can be output to speakers.

 

[staticV3]

2 x V3 Mono & 2x 48V 10A = 480W/channel
2x V3 Mono & 2x 48V 5A = 240W/channel
V3 Stereo & 48V 10A = 240W/channel
2x V3 Mono & 2x 36V 6A = 216W/channel
2x V3 Mono & 2x 36V 5A = 180W/channel
2x V3 Mono & 2x 32V 5A = 160W/channel
V3 Stereo & 48V 5A = 160W/channel
V3 Stereo & 36V 6A = 108W/channel
V3 Stereo & 36V 5A = 90W/channel
V3 Stereo & 32V 5A = 85W/channel

Green is confirmed with measurements.
Yellow is corrected power numbers (as measured by Amir).
Everything else is yet-to-be confirmed.

If there are measurements that I've missed, then please tell me.

 

[Roger285]

Simplified power per channel calculation with different bricks:

2 x V3 Mono & 2x 48V 10A = 480W/channel
2x V3 Mono & 2x 48V 5A = 240W/channel
V3 Stereo & 48V 10A = 240W/channel
2x V3 Mono & 2x 36V 6A = 216W/channel
2x V3 Mono & 2x 36V 5A = 180W/channel
2x V3 Mono & 2x 32V 5A = 160W/channel
V3 Stereo & 48V 5A = 120W/channel
V3 Stereo & 36V 6A = 108W/channel
V3 Stereo & 36V 5A = 90W/channel
V3 Stereo & 32V 5A = 80W/channel

Interestingly there are a couple of potential sweet spots using the V3 Mono with 36V or 32V power adapters: Smaller & less expensive bricks, less heat, yet still lots of power.

I likely would of opted for a 36V option in the Mono Kickstarter if it were available. Maybe they can still add it to help crack that $500K goal?!

ps. looks like 250 people or so are getting the 2x 48V 10A ... If you're here, what speakers are you driving or what are your reasons for 480W/channel?

Really? 480 watts per channel? This can't be right...

 

[Elder]

It seems like a bad idea, the Behringer A800 is a professional amplifier, extremely powerful and robust, perfect for driving passive subs, the Fosi have much better measured performance but useless for subs and lack power compared to the A800 which instead is a characteristic very useful for this task.

Thanks for getting back to me.

I think I will take your advice and stick to getting the A800 for my use case. I will probably be driving the subs hard at times and would hate to overheat the Fosi.

Still a really interesting little amp, crazy what you get for the money.

 

[rvsixer]

Really? 480 watts per channel? This can't be right...

It's not, and covered in the thread already. Fosi has already confirmed the 48V10A supply does not result in any appreciable power output increase over the 48V/5A supply (in a single amp/single power supply scenario).