Capacitance, anyone?

[Jarno]

Hello all,

If anybody is looking for powersupply capacitors, try BG Micro (www.bgmicro.com).
Search for "The Stubby" (68.000uF/50V).
I ordered mine two weeks ago, and I received them today. Boy, do look the business!!. I guess this means my ampchassis is going to be a bit bigger!!
Even with shipping to Europe (the Netherlands) the price is incredible (I think I payed about 6,50Euro's per can including shipping and handling).
I am making 4 channels of Aleph 5, and there are some things I still have to locate (matched sets of fets).

Regards,

Jarno.

[joensd]

capitance? does that sum up what a captain does in his job?
thanks for the hint, interesting opportunity.

You´d be better (cheaper) off to match the fets yourself.
Try Reichelt for some cheap fets. I paid 1.35€ for the IRFP240 from International Rectifier.
To be sure they come from IR (if it´s important to you) you better call them up to be safe.

Cheers
Jens

[Jarno]

Hello Jens,

How many fets do you need to get 2 decently matched sets of 6 fets each?

Regards,

Jarno.

[joensd]

How many fets do you need to get 2 decently matched sets of 6 fets each?

I recall having read a lot of suggestions of how many fets you´d have to buy to get a certain amount of matched fets.
I still haven´t matched mine so...
Just do a search here and you´ll find many answers.

It definitely helps when you call the distributor or whereever you´re buying the fets and ask if they´re from the same batch.
That keeps the probability of having fets with more or less the same gate-source-voltage quite high.

Another thing is that not all fets from one amp have to be the same gate-source-voltage. You have to group the fets working as current sources and the "gain-fets" but you probably know anyway.

Cheers
Jens

[joensd]

That´s for example one of those threads about matching mosfets.
You might also wanna read Nelson´s great article about mosfets.
(link is given in the thread as well)

Cheers
Jens

[Magura]

Not to be a party killer byt those 68,000uf 50V caps are about half the size of rifa 68,000 uF 50V.

Im quite sure that if it was possible to make a good and reliable cap half the size....rifa would have made it half the size.


Magura

[joensd]

Indeed you´re a damn party pooper, Magura.

Actually I haven´t looked at the size of the caps but at least they´re from Nichicon, a well known and one of the better cap manufacturers.
Of course size depends on temperature-rating and reliability.
Ever seen those Sikorel caps from Epcos (earlier they were manufactured by Siemens)? 105degree types that last "almost" forever.

I won´t buy any caps anyway, just bookmarked this bgmicro-shop.

Just for interest : What did you pay for shipping and all, Jarno?

Cheers
Jens - heading off for a beer

[kropf]

This capacitor looks very similar to one manufactured by United Chemi-Con (as far as I can tell the same company as Nippon Chemi-Con) and sold by Mouser - even the same U32D style, size, capacitance, voltage rating, and temperature rating.

Mouser sells it for about $36. What's the catch? Who knows.

Jeremy

[cHoc]

Originally posted by Jarno
I am making 4 channels of Aleph 5, and there are some things I still have to locate (matched sets of fets).

Regards,

Jarno.

Try AHE from the Hifi.nl Forum
he sells matched fets

[Jarno]

Hello all,

Thanks a lot for all the replies. Regarding the FETs I have contacted Specmail (well known to all the dutch guys, I think), but I will ask AHE as well.
I have also had a look at the spec sheets of the big capacitors, they have a ESR of 9,4mOhms and a rated ripple current of 24,55A. And yes, they are by United Chemi-Con. They also make a more "elongated" type which has a ESR of 6,5mOhms and a rated ripple current of 27,67A. The type is indeed U32D. Capacitors by other brands are similar:
Panasonic G-AA: 7,7mOhm 14,27A or 14,15A (depending on case)
Nichicon NT: 27,5A (68.000uF/35V)
Nichicon NR: 36,0A

So yeah, they're just your "plain-vanilla" type capacitors, but looking at the prices of the other brands, I think they'll do just fine. I paid about $38,- shipping and handling. So all in all I paid €6,50 per can which is very little, I think.

Regards,

Jarno.