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Aleph J for Universal Mounting Spec
Aleph J for Universal Mounting Spec
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Old 17th September 2020, 08:38 PM   #831
zygibajt is offline zygibajt  Poland
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Halo guys,

I have built few Alephs in the past but have had some brake from DIY. I have bought a set of PCBs from DIY Audio store for AJ. Just to double confirm, the schematics from the beginning of the post use pots for bias, offset etc.. but I just want to build it as original and have it at hand as one of the amps I use depending on the speakers, can I simply use this schematics? I would use pairs of J74s 7-8mA matched. Obviously IRFP240 matched also. I mainly mean the resistors values, is it actual valid schematic of original?

Click the image to open in full size.

Thanks in advance

Last edited by zygibajt; 17th September 2020 at 08:42 PM.
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Old 17th September 2020, 08:41 PM   #832
6L6 is offline 6L6  United States
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Aleph J for Universal Mounting Spec
Yes. Of course.



EDIT: I would suggest one change, you really want a 2K pot at R7 to adjust DC offset.

Last edited by 6L6; 17th September 2020 at 08:51 PM.
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Old 17th September 2020, 08:47 PM   #833
zygibajt is offline zygibajt  Poland
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Many thanks! I just edited my question, that I mainly mean resistors values if they are correct as I'm just making the list to order Dale RN60D from Mauser.

And also out of couriosity, maybe this question has been asked already I saw in 6moons review the picture of original, some of the resistors are brown Dale, but part are some blue metal film, any reason for that?

I had been living with my own made Aleph 3 for quite few years in the past so hope building AJ will not be a problem for me.

Many thanks, and thanks for the tip with R7.

Last edited by zygibajt; 17th September 2020 at 08:59 PM.
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Old 18th September 2020, 02:55 PM   #834
RainfallSky is offline RainfallSky  Russian Federation
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A new atemp was made.
Board size now 250mm x 63mm.

That took longer than I expect.
Need to rest for now and do something else.
Attached Images
File Type: png kicad_layout-a.png (75.4 KB, 144 views)
File Type: png kicad_layout-b.png (80.9 KB, 144 views)
File Type: png Aleph_J-3D.png (152.5 KB, 138 views)
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Old 18th September 2020, 03:16 PM   #835
TungstenAudio is offline TungstenAudio  United States
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Those are some good looking boards. It's good to have options for us semi-obsessive DIY builders.
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Old 18th September 2020, 09:32 PM   #836
RainfallSky is offline RainfallSky  Russian Federation
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Thank you!
Small changes possible but I am mostly happy how it went right now.
Need to calm down and relook it with a fresh eyes later.
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Old 19th September 2020, 12:35 AM   #837
Extreme_Boky is offline Extreme_Boky
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Quote:
Originally Posted by zygibajt View Post
Halo guys,

I have built few Alephs in the past but have had some brake from DIY. I have bought a set of PCBs from DIY Audio store for AJ. Just to double confirm, the schematics from the beginning of the post use pots for bias, offset etc.. but I just want to build it as original and have it at hand as one of the amps I use depending on the speakers, can I simply use this schematics? I would use pairs of J74s 7-8mA matched. Obviously IRFP240 matched also. I mainly mean the resistors values, is it actual valid schematic of original?



Thanks in advance
Yes. The bias will be around 1.25A per each "leg" and you will not be able to change it.

Also, match the R16-R19 in addition to matching the MOSFETs
The DC offset may not be a bang-on zero...
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Old 22nd September 2020, 12:37 PM   #838
RainfallSky is offline RainfallSky  Russian Federation
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Yet another revision.
Small changes in traces, pads, a bit of footprints edit, some parts moved etc.

A place for wire jumper added in case only ubalanced (RCA) output will be used.
Lead space for jumper is 5mm

Inputs holes size is 1.2mm
I don't think someone would want to use thicker wire.
But some use coaxial cable and outer braid shield will go to.. hmmm.. GND?
Anyway all input pads have 1.2mm hole size.

"Aleph J" symbol as a copper pad now which I expect to be pretty with ENIG finish.
Also added text "Circuit by Nelson Pass. Layout by bla bla bla"..
Attached Images
File Type: png Aleph_J-3D-Front.png (155.8 KB, 95 views)
File Type: png Aleph_J-3D-Back.png (51.0 KB, 34 views)
File Type: png kicad_layout-a.png (80.6 KB, 27 views)
File Type: png kicad_layout-b.png (83.1 KB, 25 views)
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Old 22nd September 2020, 11:58 PM   #839
Variac is offline Variac  Costa Rica
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Aleph J for Universal Mounting Spec
Generally, np uses blue Panasonic for the 3w resistors


Quote:
Originally Posted by zygibajt View Post
Many thanks.
.... I saw in 6moons review the picture of original, some of the resistors are brown Dale, but part are some blue metal film, any reason for that?
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Old 24th September 2020, 05:39 AM   #840
toto34 is offline toto34
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Aleph J for Universal Mounting Spec
4K75 R5 caution must be 1 Watt
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