Fosi v3 Mono - User Impressions | Owner's Thread

[fritobugger]

Ditto for me, click but no pop, however I am using the xlr inputs.

RCA here

 

[Lednek]

The gain mentioned in old marketing and new marketing are the same for the balanced.

Fosi responded to me regarding this when they warranted one of my units. The XLR is unchanged and the RCA gain was changed. I cant remember the exact gain settings off hand, but there is an option that will allow the old units to be used with the new units to keep the gain the same.

 

[burkm]

They use a different RCA gain on the "new" version of the V3 Mono amps. There is a common gain value between the two, which is "25 db", but the other gains between "old" and "new" are somewhere around "31 db" and "19 db", if I remember it correctly. As far as I know, nothing else has been changed between the two versions.
There will always be a small amount of defective units returned, because of defects during the 2 year warranty period, but none should end unaltered at the "sender" of a warranty unit...

 

[HairyDog]

Here's how I set mine up. Start with some Thermal Grizzly Duronaut. Removed the stock feet and put a 150mm heatsink on the bottom with a thermal pad between. I used stitching twine to secure it but thin zip ties can be used as well. I then flip the amps upside down and use them that way. All heat goes straight out the top. Lastly applied some 15mm feet to the bottom (formerly the top). Then I just call the system TipTop. Pushing a couple NHT C3s, Schiit Saga 2 preamp, Bifrost 2/64 source, Lokius EQ.

 

[Down South]

Here's how I set mine up. Start with some Thermal Grizzly Duronaut. Removed the stock feet and put a 150mm heatsink on the bottom with a thermal pad between. I used stitching twine to secure it but thin zip ties can be used as well. I then flip the amps upside down and use them that way. All heat goes straight out the top. Lastly applied some 15mm feet to the bottom (formerly the top). Then I just call the system TipTop. Pushing a couple NHT C3s, Schiit Saga 2 preamp, Bifrost 2/64 source, Lokius EQ.

What a lot of work NOT to achieve the best way to dissipate heat. I gave the answer way back in this thread - remove the copper coloured side plates, stand the amp on one side supported on some simple material 25/30mm - heat rises, as it rises it pulls in cooler air underneath - conductance, simple science - problem solved.

 

[HairyDog]

What a lot of work NOT to achieve the best way to dissipate heat. I gave the answer way back in this thread - remove the copper coloured side plates, stand the amp on one side supported on some simple material 25/30mm - heat rises, as it rises it pulls in cooler air underneath - conductance, simple science - problem solved.

That’s a good idea too ! Cheers.

 

[Lednek]

Here's how I set mine up. Start with some Thermal Grizzly Duronaut. Removed the stock feet and put a 150mm heatsink on the bottom with a thermal pad between. I used stitching twine to secure it but thin zip ties can be used as well. I then flip the amps upside down and use them that way. All heat goes straight out the top. Lastly applied some 15mm feet to the bottom (formerly the top). Then I just call the system TipTop. Pushing a couple NHT C3s, Schiit Saga 2 preamp, Bifrost 2/64 source, Lokius EQ.

Nice job! I have done a similar thing. I replaced the thermal compound, added bottom heat sinks, and 3d printed stands/risers, and added a laminar flow 100mm case fan to direct airflow over and under the v3 monos. The one furthest from the fan barely gets warm to the touch, the other two run at damn near ambient temperature. I have similar set up for my two channel system as well. Specifically the Minidsp generates a lot of heat. All very well mitigated.

 

[iLoveCats]

I find all of this heat dissipation crazy. I've had mine on 24/7 since the Kickstarter units shipped. Are they warm? Yes. Have they failed? No.

 

[DenonMate]

I find all of this heat dissipation crazy. I've had mine on 24/7 since the Kickstarter units shipped. Are they warm? Yes. Have they failed? No.

just give it a minute two.
What I find crazy that the costumer has to dance some cooling limbos instead of the product designers.

 

[HairyDog]

just give it a minute two.
What I find crazy that the costumer has to dance some cooling limbos instead of the product designers.

I’m not sure it’s necessary, probably depends on your use case. I’m a tinkerer so for me it’s just fun. Overbuilt ? … yeah, but I’m solving a potential problem without setting up a thermal gradient across the circuit board or sucking dust into the enclosure. I would though, recommend everyone at least replace the pitiful squirt of stock thermal paste with something that spans the entire thermal plate.

 

[iLoveCats]

I would though, recommend everyone at least replace the pitiful squirt of stock thermal paste with something that spans the entire thermal plate.

That makes sense. I have nothing else to do today and I have pasted on hand.

 

[rgpit]

If you have to take these extreme measures to keep the amps from overheating you've bought the wrong product for the application. I bought two of them when they were released and they barely get warm.

 

[HairyDog]

Agreed, I see a lot of people on Amazon using these for subwoofers. In that use case you should definitely do something extra for the heat cause you’re probably gonna get a lot of it. I’m about to try one of these with a 48V 10A PSU on a Dayton 300 kinetic transducer. It might be too much, wish me luck !

 

[antcollinet]

just give it a minute two.
What I find crazy that the costumer has to dance some cooling limbos instead of the product designers.

The customer doesn't have to. They just choose to.

 

[Talisman]

If the product doesn't dissipate heat properly for its intended purpose, it's clearly poorly designed. Everyone can decide to fix it as they see fit, but this should never be considered normal.
Besides, I don't see many reports of failures, so I don't really understand this frenzy. Even mine, used as a center channel power amp, hasn't had any problems after months of use without any particular care.

 

[HairyDog]

I have not yet begun to frenzy ... but I will !
stay tuned

 

[iLoveCats]

Ok upgrading the thermal paste makes a lot of sense to me. I'm sure there's pictures in the thread somewhere and I forgot about doing it. There's a pathetic amount on it from the factory. Wipes off with an alcohol wipe.

Before and after.

 

[Down South]

I find all of this heat dissipation crazy. I've had mine on 24/7 since the Kickstarter units shipped. Are they warm? Yes. Have they failed? No.

No they havn't failed but you will pay the price in significantly shortened component life. Try checking out white papers from the 1950s.

 

[HairyDog]

No they havn't failed but you will pay the price in significantly shortened component life. Try checking out white papers from the 1950s.

That bottom mounted thermal solution turns your amp into a cute little oven for all your components. A design is a good design if it gets your money.

 

[DavidM1]

This is how I set mine up. They've been in use every day since the Kickstarter delivery. Are they happy? Heck yeah! Currently amplifying Julian Lage Scenes From Above so we're both happy.