Building Aleph 2

[SI]

And conciderable lower WAF.... (What, you want to put TWO of those big eye sores in here?)

Agreed. I think I'm gonna have to incorporate some pretty lights in the amps. Any more ideas: Keep me posted.😉

Btw megaamp how are your amps coming along? Post some pictures for us.😉

Regards.

 

[arold19]

Do you know if there a big difference betwen the sound of the Aleph2 and the Aleph 5 ???

 

[SvErD]

I'm building a pair of 2's. I'm planning on mounting the fet's directly on copper bars without isolation to improve heat transfer from the fet's, and isolate the copper bars from the heatsinks. This way the drains will be connected via the case to the bar. Do anybody see any problem with this arangement?
I'm pretty confident the thermal part is ok as this has been discussed previously, but I'm unsure about the electrical part.

Do you know if there a big difference betwen the sound of the Aleph2 and the Aleph 5 ???

The Master himself says he prefers the Aleph 2.

 

[MEGA_amp]

hey SI,

Not to much progress on my Aleph 2, I'm still slowly gathering parts, deciding on which parts to use and of course daydreaming about it all day. I got caught up in the chip amp forum and decided to buy one of Brian GTs kits. I just received my transformers from plitron for my A2, so things should start picking up soon. So get ready for a barrage of pics.

regards,

John H.

 

[Brian Donaldson]

Bring on the pics

 

[jleaman]

Oh a post about a aleph 2. Sweet.. Im also building a aleph 2.. Mine consists of..

in each mono block

6 x 40k Caps @ 60V
4 x 8" x 8" heat sinks
1 x 1kva Toridal Victoria magnetics Tranny
12 matched fets
Brian-GT Driver Board's.

 

[fcel]

JasonL,
When are you going to show us your completed Aleph-2? How long has it been? Three years already? Sorry, I can't help myself.

 

[Brian Donaldson]

I almost asked the same question, but I'm over a year into mine. But I have heard mine. I just need time. Maybe the wife will go out of town again.

 

[jleaman]

i don't have a job right now.. Im waiting to get a job so i can put it all together.. just needs chassis work.. that is all. then there ready to work. : O )

 

[hieroglyphics]

1 x 1kva Toridal Victoria magnetics Tranny

How much did that break the bank? I need to get a couple of them for my two Aleph-X's and I've seen some nice ones from Victoria.

 

[jleaman]

i bought mine both from peter daniel. i paid 300 some-thing.. for them both.

 

[SI]

I think they are about the same from VM. Mine are Avels and I think I paid $180 for both including shipping. They are not much to look at but hope they work okay after I put every things together.

Regards.

 

[Brian Donaldson]

I'm using Avels. Same remarks. They aren't as pretty, they're made in china, but they cost half as much and don't hum. Use VM if you plan to mount it outside of the case or put a peep hole to see inside.

 

[SI]

How to match

Hey guys, I was wondering what is the practical way to match the IRFP240's. I have read the articals on passdiy over and over but don't understand whats going on there. I guess I'm looking for a schematic with Voltage and resistor values and the test points. I guess I just want to match the Vgs. That should be enough, Right ?😕

Thanks,
SAAD.

 

[Brian Donaldson]

Heres the quick easy way. Take a good stable power supply between 15 and 40 volts. connect in series with a resistor. connect dvm across the two. one by one connect each fet to the same leads gate and drain to one and source to the other. count out 3 seconds and record reading. if you read sooner, the meter may not be stableized. if you wait longer, the fet will start heating up and the voltage will change (I think it drops because of neg temp coef). The polarity depends on p or n channel. Size the resistor to carry current appropriate for transistor. Ex. irfp244 use supply (voltage-4)/.3A. The supply needs to be dead stable. I paid $35 for an old linear +-12v 2.7A supply from a local surplus store, used 24v and a 20w 50ohm resistor.

+-------/\/\/\/\/-------+----------------
Supply ...................... DVM .................. FET
+-----------------------+----------------

 

[SI]

Thanks Brian. I see what you mean about 3 sec rule. It takes about 5-10 min for Voltage to settle for these little monsters, with controled temp. . Btw, what type of caps are recommend for C6,C7,C8.


Regards
SAAD//

 

[rif]

Hey guys, I was wondering what is the practical way to match the IRFP240's.

I also got some literature from IRF on this on their website, althought it doesn't seem simple. Check it out though -- makes for some interesting reading.

 

[SI]

Matching of the fets are done!!

Hi, Just a little update: I just got done matching the fets. It was a weired deal. The IRF9610's were from the same lot and some of them came up with identical numbers. It will be nice when I build my AX. As far as the IRFP240's go, the numbers were all over the place. I did three tests on each of them in two different current range keeping the little monsters in a enclosed tube while testing them so the air temp rise with the fet temp inside the tube and stay some what uneffected by the out side temp. Now the question is ; Do you match them in sets of 8 or 16 (I'm following brian's work with 16 fets per channel)?😕

And Also I'm getting about 60 millivolts accross the ps with a 25 ohm load connected to it. Is this a good enough reading? I'm measuring with a real time HP meter.


Regards.

 

[moe29]

match in sets of 8.

 

[SI]

Porblem

Hi guys, I just got one channel wired up, hooked it up to a variac and last night at about 60 volt ac one of the source resistor started to smoke. I pulled out the fet and tested it, it looks like the voltage drop accross it was lot less then before when I matched it. I replaced it today and the resistor. I took my time and slowly turn up the ac and about 100 v the same fet resistor started to smoke. I trun it all off and waited few minutes and turned the variac on low voltage and seems like the same fet V drop is less then what it used to be.

I stoped doing any thing to the amp asking you experts to clue me in whats going on.😕
Thanks.
SAAD//