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Aleph 5 with Brian GT boards. (help)
Aleph 5 with Brian GT boards. (help)
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Old 13th June 2006, 04:17 PM   #11
PolishedSteel is offline PolishedSteel  Germany
diyAudio Member
Join Date: Jun 2006
Hello, I just received my BrianGT Aleph boards as well, and as I couldn't find any component lists on the chipamp site nor coming with the PCBs, I spent my afternoon in the sun, trying to figure it all out using the original Aleph 5 service manual schematics and the PCBs at hand. Now I think that worked out ok - there are just a few changes that I noticed:

-The 10k resistor called R8 on the original schematics connecting the unbalanced input to the balanced + in is missing (probably neither very important, nor hard to fix).

-the 680pF cap called C6 in the original schematics, which is connecting C7 and R8 (or C4/R15 on the BrianGT boards) to Q4 and the G- connector, is missing completely. I have the feeling that this would be a rather important component, and I'd rather have it in my circuit than not - does anybody know anything about the results of not having a cap in this place, or how to get it in there without too much hassle?

My component list so far (BrianGT board numbers):

R1: 10k Ohm
R2: 10k Ohm
R3: 100k Ohm
R4: 221 Ohm
R5: 10k Ohm
R6: not used
R7: 221 Ohm
R8: 221 Ohm
R9: 10k Ohm
R10: 10k Ohm
R11: 221 Ohm
R12: 453 Ohm
R13: 221k Ohm
R14: 4,75k Ohm
R15: 100k Ohm
R16: 1,5k Ohm
R17: 75 Ohm
R18: 392 Ohm
R19: not used
R20: 1k Ohm
R21: 221 Ohm
R22: not used
R23-26: 0,47 Ohm, 3 Watt
R27,28: not used
R29-34: 221 Ohm
R35-40: 1 Ohm, 3 Watt

C1-C3: 220 F
C4: 10pF
C5: 47nF
C6: not used
C7 (not on board yet): 680 pF

Q1-3: IRF9610
Q4,5: MPSA18/ZTX450
Q8-13: IRFP240

Any comments/critizism/advice is absolutely welcome!

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Old 31st July 2006, 06:15 PM   #12
elvenears is offline elvenears  Germany
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Join Date: May 2006

i got Brians miniAleph Boards too and worked the forums to find out any information why Brian skipped/changed parts/values.

btw, thx Brian , these red boards are just phantastic
great site, good work !

To PolishedSteel :

The Original R8, at the unbalanced input, is a 1000Ohms,
and yes its missing in Brians boards. I wonder why.

Your Component List is wrong. Go see the xls-sheet at :


Amplifier board
Capacitors value
C1-C3 220uf
C4 10pf
C5 1nf
C6 47nF

Diodes value
D1-D5 9.1v zener

Resistors value
R0 3.0
R1 10.0K
R2 100K
R3 68.1K
R4 221
R5 4.75K
R6 optional
R7 221
R8 221
R9 10.0K
R10 68.1K
R11 221
R12 825
R13 47.5K
R14 1.50K
R15 100K
R16 1.50K
R17 392
R18 392
R19 not used
R20 1.00k
R21 221
R22 not used
R23 0,47
R24 0,47
R25 0,47
R26 0,47
R27 not used
R28 not used
R47 0,47
R48 0,47
R49 not used

Transistors value
Q1-Q3 IRF9610
Q4-Q5 ZTX450
Q6-Q7 not used

Output boards
Q8-Q13 IRFP240
R29-R34 221
R35-R40 0,47

To Brian or any1 that wants to contribute:

1. Brian added R0 3Ohms 3Watts, pulling the zehner diodes to gnd. why?


3. Original R13 / Brians R5 have different values.(10k/4.75k)
4. Original R17 / Brians R14 have different values (4,75k/1.5k)
5. ...solved...
6. Original C7 47nF sitting between C and E of this MPSA18 has changed position and value to 1 nF in Brians. Now between C and B of this ZTX450.

7. The Original C6 680pF is missing...

I cant wait to get the parts together to build my 1st Aleph-5 , hehe.

I just finished my PS1-Powersupply with 2 toroid transformers.
Used LT1084 for each Voltage-rail muuuuahhrrharrr
Unluckily , this dude at the shop sold me the 12Volt fixed ones and i didnt noticed it untill i ran the tests this morning...
now i had to order 2 new ones at reichelt.....

Thank you Nelson Pass , it was the simplicity of the circruity that made me consider diy. ...bows..
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