The Aleph30 PCB layout

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#381
If I want to omit 2 of the output devices (and sacrifice output power), do I just need to omit 2 resistors per device (omitting Q7 and Q10), or will I need to change any other resistor values?
Click to expand...

It soulds like you want to build an Aleph 3 with an Aleph 30 front end. (4 output fets per chan?) I did one of those a while back. It worked fine - I use it all the time. I believe I just sort of combined the schematics of the two, where it seemed applicable.
 
#383
Some Parts Questions

Hi all,

I got PD's A30 boards a while ago, and I am going to start on the building now, here are some questions I have for parts,

1) What are the recommanded brand/series of resistors used for the 0.47R resistors?

2) Dales RN55 are rated for 1/8W mil spec, and 1/4 in real life, can I use them for all other resistors?

3) I am looking at the Conrad MF35-151.5, with .21C/W thermal resistance, will that be enough for a standard A30? What about a slight increase of bias for later?

4) I would like to get a quality Plitron transformer, but they do not have 500VA+ 20V-0-20V available anymore. What is a good solution here?

Thanks,
Peter
 
#384
I think a lot of you questions can be answered here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=95055

as for my opinion I think 1/8w resistors would be fine. I looked at those sinks too but the freight to the states was a little high so I got the ones I mention in the above thread. They are really nice sinks, though I haven't actually used them yet since I have too many other projects.

~michael.
 
#385
Re: Some Parts Questions

peterpan188 said:
1) What are the recommanded brand/series of resistors used for the 0.47R resistors?

2) Dales RN55 are rated for 1/8W mil spec, and 1/4 in real life, can I use them for all other resistors?

3) I am looking at the Conrad MF35-151.5, with .21C/W thermal resistance, will that be enough for a standard A30? What about a slight increase of bias for later?

4) I would like to get a quality Plitron transformer, but they do not have 500VA+ 20V-0-20V available anymore. What is a good solution here?
Click to expand...

The resistors are 3W Panasonics from Digi Key, part# P0.47W-3BK
I still have some left so you can contact me for details.

RN55 Dales are fine for all other resistors.

I'm not familiar with Conrad heatsinks.

You can get 400VA Plitron instead.
 
#386
Thanks Bugg for the link.

I should be using CRC as my power supply filter. Using 20000uF-0.33Ohm-20000uF and a 24VAC secondary, I get about 25.2VDC and 20mV ripple. That looks like a pretty good result for me. The question is how big the power rating of the 0.33 resistor be? 5W? 10W?


Thanks,
Peter
 
#388
Hi,
I have daniel's board, I want to do grounding like original Aleph30.
I use only single ended input. This is my grounding scheme, is correct?
The R0 power resistor in the original aleph is 3 ohm. Is not easy found it. Is a critical value?
In alternative is possible use 3.3 or 2.7 ohm?
giorgio
 

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#392
Current inrush

Looking at the A30 schematic, the power ground goes through a thermistor-CL-60 via the chassis, out the power chord. Does this thermistor act as the current inrush limiter or should there be another CL-60 on the 120vac line before the transformer?or can I use both? These are 10 ohm and apparently drop in r during operation to what? 3-5 ohms? may drop the available voltage some.
 
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