New Aleph Mini PCB GB

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jleaman

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Joined 2002
plus.google.com/photos/104656656065604242634/albums/5725366675475046257?banner=pwa&gpsrc
1) you would never even know if the cap was in backwards or not, it is extremely hard to know the difference in sound.

2) run 2/3 shielded wires from your input right to the board, depending if you are running balanced or line level. then run your 3 wires for your power right to the psu board. twisting / braiding really helps.

3) i can post pictures later on when i arrive hoe if you wish. I run 4 of these amps ( smd ) ones tho.

Jase
 
G

gil-garcia

Member
Joined 2006
Hello,

j'am,just starting to realize a 5 channel Mini A with PCB and PSU from chipamp. It is the most beautifull pcb j have never seen .
One small problem, impossible to find in europe the small resistances.

The project is :

2 transformers 300VA, 2x15V (one for front two channel and one for the others tree channel)
4 PSU board (2 for the front channel, 2 for the 3 others channel)

As j am a beginner and as j have read a lot of thread with the impression that everybody do not speak always about the same schématic and references of resistors j am a bit lost.

Can you help me

Accordind to the part list from the site :


R6 optional, for closer matching of Q1 and Q2

R12 : 750 initial value, could be optimized for expected power/load conditions
R13 : 47.5K initial value, could be optimized for expected power/load conditions

R17 : 100 initial value, could be optimized for expected power/load conditions


j would like to have a bias about 1,3 with something like 18-20V with my 2X15V transformer.

Could you tell me the values for R6, R12, R13 and R17. Do j have others componants to change the value.

in this configuration, could you tell me what would be the best configuration in order to connect the psu board, which value for the res of the psu (pi filter), what kind of condensator and value at the end of the psu. If it is necessary, j have others psu boards in advance.

Thanks a lot and excuse me for my poor english, j hope it is clear?

An externally hosted image should be here but it was not working when we last tested it.
:xeye: :xeye:
 
BrianGT

BrianGT

Retired diyAudio Moderator
Joined 2002
chipamp.com
FYI, I have more of black Aleph pcb sets, and put them back up on the website for $9 a pcb set.

An externally hosted image should be here but it was not working when we last tested it.

(set still includes 2 amp boards and 4 output device boards)

Here is the parts list that I generated back in 05 when the first run of boards were made:
http://www.chipamp.com/diyaudio/miniALEPH-parts_list.xls
Let me know if you spot any issues, and I can correct it. I built a set of MiniA amps with the list, and had no issues.
Here is a newer one that I found that has a bit more detail:
http://www.chipamp.com/diyaudio/mini-A.xls

--
Brian
 
Coulomb

Coulomb

Member
Joined 2002
diyaudio.com/wiki/index.php?page=Active+Group+Buys
imix500 said:
Dude, I really like those toroid mounts. Did you machine them?
Click to expand...

Yes I spun them from some Delrin that I had kicking around in the Machine shop.

I machined them down from larger stock on a lathe and put a taper on the back end to really lock into the toroid. Drilled a bolt hole and machined out clearance for the bolt head so it locks in place. I blind mounted them with three screws from the backside on to flat Delrin stock and mounted that to the front panel. I was careful to sink the threads only deep enough to support the assembly without protruding out the front.

I also machined the Heatsinks from 4 scrap pieces to make them look like 2 nice new peices an a Bridgeport Mill, I set the shoulder hieght at .90 for the top cover, .125 for the back and .375 for the bottom. The shoulder width is .500 so I had lots of room to drill and tap to give all the surfaces the flush mount finish. It took a whole day just to finish the chassis.

I think the proffessional look really comes from Brian's boards though. The P/S solution is the best I have seen so far.

Anthony



Anthony
 
BrianGT

BrianGT

Retired diyAudio Moderator
Joined 2002
chipamp.com
Coulomb said:


Yes I spun them from some Delrin that I had kicking around in the Machine shop.

I machined them down from larger stock on a lathe and put a taper on the back end to really lock into the toroid. Drilled a bolt hole and machined out clearance for the bolt head so it locks in place. I blind mounted them with three screws from the backside on to flat Delrin stock and mounted that to the front panel. I was careful to sink the threads only deep enough to support the assembly without protruding out the front.

I also machined the Heatsinks from 4 scrap pieces to make them look like 2 nice new peices an a Bridgeport Mill, I set the shoulder hieght at .90 for the top cover, .125 for the back and .375 for the bottom. The shoulder width is .500 so I had lots of room to drill and tap to give all the surfaces the flush mount finish. It took a whole day just to finish the chassis.

I think the proffessional look really comes from Brian's boards though. The P/S solution is the best I have seen so far.

Anthony
Click to expand...


Looks good! How much bias current do you have per channel, and how warm do those massive heatsinks get?

I think that it would look even better if you used the current black PCBs :) I have had the boards made in blue, red and black, and black has been my favorite.

An externally hosted image should be here but it was not working when we last tested it.


I made my 8 channels with blue boards also though.

--
Brian
 
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