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new batch of mini Aleph amplifier and PSU boards

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#182
Thank you John65b for the advice.

I'll try this configuration : 10000uf/R47/15000/22000uf/.1uf.
BTW the config, according to BrianGT PSU PCB will be :
10000uf/15000/R47/22000uf/.1uf. (C/C/R/C)

I've simulate with PSUDII but I can only notice some differences without the required knowledge to explain the differences.

Where R47 should be placed on BrianGT PSU boards ?
There are left spaces from R3 to R12.
R1 and R2 seems to be bleeder resistors, I'll use 3K3/3W.

Nice to see you care ! 🙂
 
#183
korben69 said:
Thank you John65b for the advice.

I'll try this configuration : 10000uf/R47/15000/22000uf/.1uf.
BTW the config, according to BrianGT PSU PCB will be :
10000uf/15000/R47/22000uf/.1uf. (C/C/R/C)

I've simulate with PSUDII but I can only notice some differences without the required knowledge to explain the differences.

Where R47 should be placed on BrianGT PSU boards ?
There are left spaces from R3 to R12.
R1 and R2 seems to be bleeder resistors, I'll use 3K3/3W.

Nice to see you care ! 🙂
Click to expand...

As for the resistive section in the CCRC supply, I simulated this a long time ago, and IIRC was running quite a low value resistor. You actually probably don't even need to use it for the Aleph amplifier.

I don't suspect that you will get much power supply ripple with those capacitor values.

As for R1 and R2, I am using 3W 3.3k resistors there.

--
Brian
 
#187
MiniA PSU PCB and footprint from BrianGT.
 

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#188
BrianGT said:


As for the resistive section in the CCRC supply, I simulated this a long time ago, and IIRC was running quite a low value resistor. You actually probably don't even need to use it for the Aleph amplifier.

I don't suspect that you will get much power supply ripple with those capacitor values.

As for R1 and R2, I am using 3W 3.3k resistors there.

--
Brian
Click to expand...

Thank you Brian !
So I just have to solder a copper strap on R3 and R12, without using any R47.
Ok, for R1 and R2, 3K3/3W resistor.

Hope it will sound soon 😎
 
#189
I've got some questions too, if you don't mind.

I successfully made a dual mono LM3886 chipamp using BrianGT's boards and now want another challenge. So I ordered the amp & psu pcb's from BrianGT...

I'm gonna make a mini-A and I'm planning on using 10,000u/10,000u/R33/10,000u for the psu. I'm gonna make the R33 using three 1R wirewounds in parallel.
1. Are wirewounds OK for this or should I use metal film?

2. Are 2K2 bleeder resistors for R1 and R2 OK to use?

For rectifier diodes I wanna use four HFA08TB60's.
3. Should I go for diodes that can handle more current?

I was thinking about using a 225VA toroid.
3. Will 225VA be enough?
4. 2x12V or 2x15V?

I have difficulty in sourcing the 3 ohm resistors (R0) for the amp pcb's. A value of 3 ohm apparently is an American value. In Europe it's either 2R7 or 3R3. How critical is the value of R0?
5. Could 2R7 or 3R3 work too?
6. How 'bout creating ~3 ohm with a 5R6 and a 6R8 in parallel?

Thanks!
 
#190
Beftus said:
I've got some questions too, if you don't mind.

I successfully made a dual mono LM3886 chipamp using BrianGT's boards and now want another challenge. So I ordered the amp & psu pcb's from BrianGT...

I'm gonna make a mini-A and I'm planning on using 10,000u/10,000u/R33/10,000u for the psu. I'm gonna make the R33 using three 1R wirewounds in parallel.
1. Are wirewounds OK for this or should I use metal film?
Since a wirewound resistor is a wire wrapped around an insulator, it is also a coil, in a manner of speaking. Using one could change the behavior of the circuit.

2. Are 2K2 bleeder resistors for R1 and R2 OK to use?
According to BrianGT PSU BOM posted before, 2K2 works too...

For rectifier diodes I wanna use four HFA08TB60's.
3. Should I go for diodes that can handle more current?
Not skilled enough to give you an advised answer

I was thinking about using a 225VA toroid.
3. Will 225VA be enough?
4. 2x12V or 2x15V?
I'll use a 300Va/12V from Antek. 12 or 15V depends on your choice for the rail value. 12V will give about 15.5V DC

I have difficulty in sourcing the 3 ohm resistors (R0) for the amp pcb's. A value of 3 ohm apparently is an American value. In Europe it's either 2R7 or 3R3. How critical is the value of R0?
5. Could 2R7 or 3R3 work too?
6. How 'bout creating ~3 ohm with a 5R6 and a 6R8 in parallel?
Don't know if it's a critical value or not... I'm using Panasonic 3R/3W, ref ERX-3SJ3R0 available from Digikey

Thanks!
Click to expand...
 
#192
The bleeder resistors have no effect on the sound. All it does is discharge the caps when the amp is turned off. There is no magic about its value. Anything over 2k2 is fine.

A single 10K is ok. The higher the resistor, the longer it will take to discharge the caps.

Someone correct me if I am mistaken.
 
#193
Of course it does not affect the sound, but as I understand the dissipation here is a matter to consider. For that reason it is not recommended to use 2W 3k3 here, but 3k3-3W or 2k2-2W. Correct me if I'm wrong.
Since I have a source for 2W metalfilm resistors (but no 2k2) I thought it is the simplest for me to parallel 3 of those 2W 10K for this job. I just wanted to check if I got the math for paralleling right. Resistor Wattage is added when paralleled, isn't it? So I figured I get about 3k3-6W with this configuration.
 
#194
korben69 said:
Click to expand...

Thanks for sharing your thoughts Korben69.

I'm aware Digikey can supply me with the 3 ohm resistors, thing is I have the majority of parts already ordered @ www.hifituning24.de. Just ordering the resistors @ Digikey is likely gonna cost me a fortune in shipping compared to the price of the resistors. Digikey isn't an option for me, I'm on a budget and have a wife you now! 😀
 
#198
I imagine C1 and C2 are snubbers and would be .1uf. I will go with that.
Reading back through and still unsure about R3-R12 as well as R0.
I am noticing that people are using 22kuF, 15kuF, 22kuF and other combos.
Whats the deal with the different capacitances? BOM states 10 or 22 kuF depending on using mini or 30 style Aleph. I would do mini monos. 12V toroid. Was going to purchase a bunch of 10kuF Nichicon KG caps. Any reason to not just use 10kuF on each cap?
Uriah
 
#199
udailey said:
I imagine C1 and C2 are snubbers and would be .1uf. I will go with that.
Click to expand...
Yup, they are snubbers. 0.1uF will do fine. I think that's what Brian suggested in the BOM.


R3-R12 are said to be replaced with a short. ? Why? What situation would warrant using resistors here? What value would they be?
Click to expand...
As a matter of you want one big C or CRC. CRC will have a bigger voltage drop but lower ripple.
From what I have seen, the resultant value of 0.1R seemed to be the most commonly used for the R which can be a bunch of 0.47 in parallel or one BIG 0.1R. The only thing to look at is to make sure the resistor's rating is adequate.

[/B]
Reading back through and still unsure about R3-R12 as well as R0.
I am noticing that people are using 22kuF, 15kuF, 22kuF and other combos.
Whats the deal with the different capacitances? BOM states 10 or 22 kuF depending on using mini or 30 style Aleph. I would do mini monos. 12V toroid. Was going to purchase a bunch of 10kuF Nichicon KG caps. Any reason to not just use 10kuF on each cap?
Uriah [/B][/QUOTE]
I have 71K uF per rail for my mini and can remove the 35,000uF very easily. Quite frankly, to my not so sensitive ears, I don't notice any different with only 36,000uF per rail.
 
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