41Hz AMP2 upgrade?

[MotoMan_Yz400]

I've been reading on how to get more power out of the 41Hz AMP2. As they say you can get alot more power by doing a few things, however you may need to add more FETs to help with heat. They also claim that "there is room on the board for this". Umm, i could only find a few select pictures of the Tru amp and they do not have places to add more FETs. Anyone have a photo of the AMP2 board so I may conferm that this upgrade is possible?

Thank-you

[luka]

Hi

I think that was for older versions of AMP2, which could have up to 8 to-220 fets on, now you have 4 of to-247, big ones.As far as I know you only have to change current limit, I used 12k resistors to set current to 22A

[MotoMan_Yz400]

Originally posted by luka
Hi

I think that was for older versions of AMP2, which could have up to 8 to-220 fets on, now you have 4 of to-247, big ones.As far as I know you only have to change current limit, I used 12k resistors to set current to 22A

Really, thats good to hear. What are you running on yours? I can assume a +-60VDC rail, but you running bridged? what kind or load do you have. What the the C/W rating on your heat sink?

[luka]

Hi

Jup +/-60, not bridge yet, not tested at full power, still building supply for it. I will drive probably 4R, but 8R wouldn't hurt

I have no idea C/W rating does it have. It is 66mm x 135mm x 40mm(10mm solid base). It will be overkill, since I will use fan to cool chipset + inductors and heatsink all at the same time. I will use it in car, where can get damn hot, and I don't want to destroy the amp








Under construction, so not much to see

[TheMG]

Looking good!

I can't help but notice the burn mark on your breadboard. What's the story?

[luka]

Hi

Looking good? Well thanks, didn't think building is step by step, with no plan, I would even get it even to stay together, but it is strong at least something. All now depends on push pull, today I will pick up my new core for it.

That breadboard is legacy from my father, he didn't really say what happened, I guess one day got really hot
You know how those breadboards are, only low current, not that good connections + it is older then I am, but for some small and quick test is ok

[Corax]

@MotoMan & @luka,

Both PCB versions of the AMP2 are designed for TO247 devices.
The only difference is, as you already mentioned luka, the number of TO247 devices.

The "older" version was a layout of Jan himself - with 4 trannies for each channel (a total of 8 though) - designed (according to Jan himself) to bridge two channels for >1000W output power .

The "newer" version with just 2 trannies for each channel (total of 4) is the original Tripath evaluation board design - the same as shown in your pictures luka.
And I'm pleased to say it's a nice work so far.
Let us know when your SMPS is done and running (under full load).

[theAnonymous1]

It's possible to streeeeeeeeeeetch some TO-220 FETs into place. Below is a pic of my eval board with FDP42AN15A0 FETs. These are the same FETs used on the UCD400. They have much better specs than the STW34NB20.

[Corax]

@theAnonymous1:

Well, I wouldn't state that the Fairchild FDP42AN15A0 has much better specs - I would just call it slightly better.

OK, the total gate charge is doubled and the RDS(on) is a little worst if I compare it with the Fairchild, but this is most likely due to the fact that the ST MOSFET has a higher VDSS (of 200V instead of "just" 150V). This is generally an effect that always goes along with MOSFETs. The lower the VDSS the better are usually the values for i.e. Qg(tot), RDS(on), ...

Besides - on your nice picture you "bolted" the output trannies via a massive metal bar on the heatsink. In my amp I just made threads into the bar and mounted the srews from the outside. This way I got rid of fiddling around with a screwdriver inside the case. Very often the screwheads are blocked by bulk capacitors (so don't remind me about the AMP5 from Jan - nevertheless a good amp though).

[theAnonymous1]

Originally posted by Corax
Well, I wouldn't state that the Fairchild FDP42AN15A0 has much better specs - I would just call it slightly better.

Shhhhh...... their magical FETs (let me have my moment).

I don't need a 200v device when it will only ever see ~120v.

Yes, the screws for the clamps are a bit of a pain due to the supply caps, but they were already there so that's what I used for now. Maybe I will put some threaded rod into the heatsink and use a nut instead.