getting closer to delivery (Aleph5)

MEGA-amp · 21st March 2007, 03:06 AM

I built two of these chassis to originally house Aleph2's, and they've been sitting for quite some time now. So I've decided to build stereo Aleph5. If all goes well, it should be finished by the weekend

-john

MEGA-amp · 21st March 2007, 03:08 AM

#2

MEGA-amp · 21st March 2007, 03:10 AM

#3

Luke · 21st March 2007, 06:54 AM

good work. I like simple, big amps:-)

MEGA-amp · 28th March 2007, 08:34 PM

ITS ALIVE!!! Worked on first power up..no smoke. Left channel 25mv offset, Right Channel 9mv!!! With one 800Va, 30V secondaries, and CRCLCLC; .22R, 2.2mH, 49KuF, final voltage is at 36v. After 4 hours I could have fallen asleep on the heatsinks, so I guess they pass the 10 second rule and way beyond. It sounds excellent and is also amazingly quiet considering my wiring job is far from adequate. (pics later)

Input network question:

R3, R10 are 68.1K on brian bells board (A30 front end)

R4, R5 are 10K in the Original Aleph 5

I used 22k in both of these spots, I'm running them unbalanced, so should I go with 68.1k, 10k or keep the 22k?

-John

And of course, a big thanks to NP!!!

MEGA-amp · 31st March 2007, 06:51 AM

Referring to the above:

R10 - increases input impedance when running unbalanced.(?)

R3 - part of the feedback loop? By my using 22K here, am I lowering feedback?

MEGA-amp · 8th April 2007, 12:49 AM

I tested at +/-20, 36, 46 volts, 46 volts sounds much better. Everything else is stock Aleph 5, with the exception of the removal of R19(221K). The plan is to run it at 36 volts, with 3.5amps DC bias, 0.50R source resistors. With a 42W fet dissipation, I'm sure I'll be OK, but if a mosfet fails, does it send DC to the speaker?

-john

MEGA-amp · 10th April 2007, 11:21 PM

Found the SWEEEET spot!!

I'm STILL a major noob at this, if I burn FETs up, will it send DC to my speaker??

MEGA-amp · 10th April 2007, 11:22 PM

Pretty much the same as Blue's Supercharged Aleph3 with one extra pair of fets and higher rail voltage.

edit - R13 is removed

MEGA-amp · 11th April 2007, 10:55 PM

To answer my own question because it seems like no one wants to help out. I decided to put it through a torture test. I connected the big 38v 1500va trafo, unhooked the speakers and connected multimeters to the outputs. In between the smoke stack, I was able to see full rail voltage on the meters before I pulled the plug. You learn something new everyday, guess its time to rebuild.

legalese:
I DONT RECOMMEND TRYING THIS, IF YOU DO; YOU DO SO AT YOUR OWN RISK...but you already knew that.

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21st March 2007, 06:54 AM	#4
Luke diyAudio Member Join Date: Sep 2001 Location: Wellington NZ	good work. I like simple, big amps:-)

31st March 2007, 06:51 AM	#6
MEGA-amp diyAudio Member Join Date: Oct 2003 Location: Newington, CT	Referring to the above: R10 - increases input impedance when running unbalanced.(?) R3 - part of the feedback loop? By my using 22K here, am I lowering feedback?