New Aleph Mini PCB GB

Status
Not open for further replies.
Jump to Latest
#441
http://www.arcade-electronics.com/c..._catid=243&sid=7@mDZ21En7rl3Dg-16105447801.9c

Arcade Electronics that SKLIMEK posted has the same thing

but if you want to call the place near me

www.cablesandconnectors.com

they have it too.



Oh, for my Aleph 2's, i used a 280k resistor for r19, and 2k for r21, then put pots across them, 100k and 2k respectively to adjust bias and ac current gain...this way there is always a resistor in the circuit when i put a switch and fixed resistors in...so i can switch bias and ac current gain to a lower level when i want to run the amps at low power 🙂

-Matthew K. Olson
 
#442
fcel said:
Jason,
Per what Matt said, could you include a pot (for extra fee) that would fit the board as part of the kit so that we're able to adjust the bias to our liking? For A30, I'm not sure which is the bias resistor though. From my recollection, 200K pot is good to start with.

Matt,
Do you happen to have the address of Berlin TPK? Do they do mail order?
Click to expand...

Give me the digikey part number and ill put them into all kit's ( if price is cheap enough )

j'
 
#444
AC current gain

Matt,

Thanks for the link. And the suggestion - an easy way to adjust bias!

Regarding adjusting DC bias and AC current gain, let's say the target is 3A for your Aleph 2, you'll adjust R19 FIRST, and then R21, UNTIL the meter reads 3A? I'm trying to refresh my memory regarding adjusting AC current gain.
 
#445
heres a pretty good link using a 200k trimpot for bias adjustment that I found trying to get everything straight in my head as well;
http://www.diyaudio.com/forums/showthread.php?s=&threadid=8727&highlight=

the procedure for R21 is alittle more elusive but look here;

http://www.diyaudio.com/forums/showthread.php?s=&threadid=51808&highlight=

Netlist provided a link that takes you to Nelson article on page three for ac bias adj.

also, the WIKI on The AlephX talks about ways of going about it.

I actually went to sleep thinking of R19 and R21 one night trying to sort it all out. How sad is that?

Stan
 
#446
You don't have to do it the way i did. 100k and 1k pots will work fine in place of r19 and r21. I have not tried adjusting r21 yet, so i don't know how much it'll effect bias, though i think bias effects ACIG more than ACIG effects bias. I'd set the bias first, its amazingly stable, then fiddle w/ acig until you're satisfied. I doubt the meter will move much while you are adjusting acig. I could be wrong though...haven't done it yet. Soon 🙂 maybe this weekend i'll fiddle w/ it. Later!

-Matthew K. Olson
 
#451
Coulomb said:
Brian does C1-C3 220uF need to be 50V? Can it be 35V?

Your parts list calls out an IRF044, but the general consensus was for an IRFP240 was it not? The 044 has twice the input capacitance as the 240 but half the RDS.

Regards

Anthony
Click to expand...

As far as I have read, the 044 should work better when there are no parallel devices. I listed the IRFP240 for the Aleph30 amp with parallel devices. I am sure that the IRFP244 will work fine for the Mini-Aleph version as well.

As for the caps, use your own judgement, I listed 50v for all kits, as they fit on the board. Lower voltage caps should be fine for lower power setups. (for all of the caps on the boards)

--
Brian
 
#452
BrianGT said:


As far as I have read, the 044 should work better when there are no parallel devices. I listed the IRFP244 for the Aleph30 amp with parallel devices. I am sure that the IRFP244 will work fine for the Mini-Aleph version as well.

As for the caps, use your own judgement, I listed 50v for all kits, as they fit on the board. Lower voltage caps should be fine for lower power setups. (for all of the caps on the boards)

--
Brian
Click to expand...

Hummm it makes more sense to go with one FET for all applications I think, so the IRFP240 is what Jason wants. You have no objections design wise correct brian?

Regards

Anthony
 
#459
big enough

Hi,

I built a stereo aleph50 using 4 heatsinks a little bigger than the one in the picture. Mine are about 9 x 9, the reason it became a stereo 50 was because it ran too hot with the rails and idle current at the correct point for an aleph60...

With an ambient of 20c each of the sinks I have is good for about 75w with the fins vertical and a surface temp of 55c, I used 4 devices on each of 4 faces, arranged to make a cube... though I'd could probably have got lower temps using more parts, I just didn't have enough matched.

If all else is equal you should get approx 80% of the cooling performance from each one of the plates you use, so ~60w...is that enough for what you are trying to make?

Stuart
 
Status
Not open for further replies.
Top Bottom