Lets have it the Class A way

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Folks,
after a two month long break, the remaining stuff for the amplifier case started to pour in and the build resumed.
Everything except the front plate is black matt powder coated.
Here are some pics i snapped during the build.
Its not complete yet, the final biasing is what is left, and the front plate needs to be bolted on.

Hope you enjoy the pics:

IMG_2573.JPG

The back plate, kept it simple and mainstream.

IMG_2574.JPG


IMG_2580.JPG


IMG_2584.JPG

Wet sanding the front panel to give it the brushed finish.

IMG_2594.JPG

Little rectangular pieces to go under the power FETs

IMG_2601.JPG

The amplifier board mounted on the heatsink.

IMG_2619.JPG

Perfect rubber feet for the heavy chassis.

IMG_2622.JPG

From the outside, not a very clear picture.

IMG_2624.JPG

From the inside.

The speakers to go along with the F5 are also ready. Just a matter of time now, you'd find a thread here on HFV.

Cheers!
 
Wish I could see the pics of heatsinks; what are their dimensions? From the pic the chassis height appears to be not more than 4" and also Ithe JFETs are not mounted on heatsinks directly but on separate aluminum plates which are in turn mated to the heatsinks.

All these factors give me a feeling that the heatsinks may not be sufficient for providing adequate cooling.
 
captrajesh said:
Wish I could see the pics of heatsinks; what are their dimensions? From the pic the chassis height appears to be not more than 4" and also Ithe JFETs are not mounted on heatsinks directly but on separate aluminum plates which are in turn mated to the heatsinks.

All these factors give me a feeling that the heatsinks may not be sufficient for providing adequate cooling.
Click to expand...

Hi Capt,
yes the MOSs are mounted on a al. plate which is mounted on the heatsink.
Both faces of the al plate and that of the heatsink were smoothed and sufficient heat sink paste (compound) was applied to minimize the transmission loss.

As far as the heatsinks go, i agree they are not as big as they were supposed to be. regret that decision. to compensate, i have kept the bias a little lower than recommended. around 0.520V on each source resistor.

Any ideas about how i could increase the heat capacity of the sinks ? maybe put in a little liquid cooling system of some sort?
suggestions are welcome :)
 
FANTABULOUS! The build looks amazing!

I haven't read the entire thread, but you could consider making use of a computer cooling fan near/around/atop the heat sinks, depending on its location. An airflow of @ 50 CFM would be sufficient, I guess. Idea is to not allow the generated heat to accumulate. Yes, natural convection would push the hot air to lift up and find its way out through the open grills on top (which should be present, I am sure), but still, some amount of pressure drop at the grill opening is encountered for the hot air to have an easy flow out. The inclusion of a fan (inside, if the heat sinks are located there) helps in moderately blowing out this air resulting in sufficient cooling.
 
Nice one!

Yes, Class A amps has special requirement of heatsink. You need to own one to experience.
 
pranavkumar said:
yes the MOSs are mounted on a al. plate which is mounted on the heatsink.
Both faces of the al plate and that of the heatsink were smoothed and sufficient heat sink paste (compound) was applied to minimize the transmission loss.

As far as the heatsinks go, i agree they are not as big as they were supposed to be. regret that decision. to compensate, i have kept the bias a little lower than recommended. around 0.520V on each source resistor.

Any ideas about how i could increase the heat capacity of the sinks ? maybe put in a little liquid cooling system of some sort?
suggestions are welcome :)
Click to expand...

Any particular reason for not mounting the trannies directly onto the heatsinks? However efficiently done, junction would always be a barrier and can never match the efficiency levels of a direct contact. Why not try and mount it directly?

As far as bettering the heat dissipation is concerned, providing liquid cooling would complicate the issue. As ghatgepatil suggested, you may consider using a fan. Make sure that the RPM is not high to avoid fan noise.
 
captrajesh said:
Any particular reason for not mounting the trannies directly onto the heatsinks? However efficiently done, junction would always be a barrier and can never match the efficiency levels of a direct contact. Why not try and mount it directly?

As far as bettering the heat dissipation is concerned, providing liquid cooling would complicate the issue. As ghatgepatil suggested, you may consider using a fan. Make sure that the RPM is not high to avoid fan noise.
Click to expand...

Well, there were some mounting issues. Keeping the PCB straight and at a distance from the sinks, i needed to raise the whole board a little.
although i definitely will have to go in for bigger sinks for my future builds :)

i plan to mount a fan at the top, centrally placed, a 120mm CPU fan. yup low rpm ones. around 1200-1500 or so if i am not wrong.
 
ghatgepatil said:
FANTABULOUS! The build looks amazing!

I haven't read the entire thread, but you could consider making use of a computer cooling fan near/around/atop the heat sinks, depending on its location. An airflow of @ 50 CFM would be sufficient, I guess. Idea is to not allow the generated heat to accumulate. Yes, natural convection would push the hot air to lift up and find its way out through the open grills on top (which should be present, I am sure), but still, some amount of pressure drop at the grill opening is encountered for the hot air to have an easy flow out. The inclusion of a fan (inside, if the heat sinks are located there) helps in moderately blowing out this air resulting in sufficient cooling.
Click to expand...

Yes, i got the top piece milled in a way so that i could incorporate a 120mm cpu fan.
lets see how much of a difference it makes.
thanks for the input:)
 
pranavkumar said:
Absolutely,
how big a heatsink did you use on the F5 V3's ?

I might build a V1 later.

:D
Click to expand...

I have V2, at 75% of max biasing. I made 2 builds of it. One has heatsink 150mm (H) X 300mm (D), 87+12mm (Finn+ base) weighing 4 Kg each. Other was vertical around 5.5Kg each.
 
pranavkumar said:
i plan to mount a fan at the top, centrally placed, a 120mm CPU fan. yup low rpm ones. around 1200-1500 or so if i am not wrong.
Click to expand...

From my PC-case experience, I'd advise aiming at less that 1,000RPM. 1200-1500 is going to be audible.

Of course, in the end, it is determined by how much air it has to shift. And you are not going to sit up-close to a power amp like with a PC.
 
Thad E Ginathom said:
From my PC-case experience, I'd advise aiming at less that 1,000RPM. 1200-1500 is going to be audible.

Of course, in the end, it is determined by how much air it has to shift. And you are not going to sit up-close to a power amp like with a PC.
Click to expand...

For fan mounting get something like wooden plank with four feet. Put Amplifier over it. Make suitable (at least 4, 2 aside) holes into the plank for fans. These fans should come below heatsink and blow air from bottom on heatsink. This makes it cool faster. :cool:
 
Thad E Ginathom said:
From my PC-case experience, I'd advise aiming at less that 1,000RPM. 1200-1500 is going to be audible.

Of course, in the end, it is determined by how much air it has to shift. And you are not going to sit up-close to a power amp like with a PC.
Click to expand...

I Won't hate to hear the ones which run directly on 220v. but i am guessing they'll be pretty loud.

as far as the cpu fans go, cooler master has the quietest fan's around. they are outstandingly silent. come's at a cost though.
 
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