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Old 8th June 2010, 08:40 PM   #1
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Default Mini-Aleph-J Question

I have two months of "spare time" and a little extra cash, so I would like to finally build an Aleph or two. Ideally, I want a 50+ watt per channel Aleph to drive my B&W 705 in a dedicated two-channel system, but I think that may cost more than I have available at the moment.

So, I think my best bet is to build a mini-Aleph-J, which will probably end up in my office (to power Klipsch RB-3). I hope to make it as small as possible, my idea being an 8.5-inch cube enclosure.

1. Can I use the Chipamp PCBs for an Aleph-J?

2. Are these heatsinks, cut to 8.5" length, sufficient?

3. Does anyone have the mini-Aleph circuit that used to accompany the Chipamp PCBs?

4. Am I wasting my time building the low-power circuit when I really want the high-power one?

Thank you all for your suggestions.
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Old 8th June 2010, 10:13 PM   #2
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The mini AJ would work well with the RB-3s. I have built Js with the chipamp boards, you just twist the jfets legs to fit. Don't know about the sinks, it will get hot. Why not his 10" wide cut 6" long. I have a copy of the schematic with the J changes on it, email me.
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Old 16th June 2010, 10:03 PM   #3
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Is 500VA tranny sufficient for a full Aleph-J? I am thinking about this tranny.

Does the Aleph-J circuit not support three output transistors?

And, would a 200VA tranny be sufficient for a single-output-transistor mini-Aleph-J?

Thanks
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Old 16th June 2010, 10:24 PM   #4
JimT is offline JimT  Canada
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I have been thinking about a mini Aleph J for an office system. If you have LTSpice, you can look at this circuit. I have not built it and I expect it needs more thought and work, but may be of use to you. You will have to rename to file to remove the .txt.

Jim
Attached Files
File Type: txt AlephJ-mini2.asc.txt (8.1 KB, 175 views)
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Old 16th June 2010, 10:52 PM   #5
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Quote:
Originally Posted by needtubes View Post
Is 500VA tranny sufficient for a full Aleph-J? I am thinking about this tranny.

Does the Aleph-J circuit not support three output transistors?

And, would a 200VA tranny be sufficient for a single-output-transistor mini-Aleph-J?

Thanks
400va 18-0-18 is plenty

If you want a true J, not without some changes.

200va 15-0-15 will do, more volts just gets you more heat
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Old 17th June 2010, 05:49 AM   #6
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I have been working to reconcile the Aleph-J schematics with the Chipamp PCB schematics and noticed something...

On the Chipamp PCB schematic, R5 (4.75k) is connected to ground, while the analogous Aleph-J part, also R5, is connected to V-. Is this a known issue with the Chipamp PCBs?
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Old 17th June 2010, 11:55 AM   #7
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It's not really an issue. Previous discussions revealed that it is slightly quieter taking it to V-. I left mine to ground but YMMV.
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