[Navyblue]

Thanks guys for all your advices. I'm glad that you guys might have averted me a disaster.

What I can't do:

- Move the S22 to the transformer enclosure

What I might be able to do:

- Mount the PCB vertically, with all 4 boards on the same horizontal plane. And use a shorter 1.5" heatsink if necessary to make them fit.
- Stack the 3 B22 boards vertically like a staircase, the heatsinkless half would be covered with the board on top, and the heatsink half uncovered. The ground channel that dissipate the most heat would be at the top of the stack uncovered. The S22 board would be beside the stack uncovered.

What I know I can do:

- Mount it the way the picture shows and put 2 x 1" computer fan underneath, either pointing to the S22 heatsink or the bottom of the B22.

Please tell me:

- If any of the above would work?
- If those little computer fan emit significant RFI?

Btw:

- The case top would be about half covered and half holes.
- The case will be relatively spacious horizontally with the configuration shown in the picture.

 

[cotdt]

With the stock S22 heatsinks it's a terrible idea, because the S22 gets really hot as it is when powering 3 boards. With bigger heatsinks on the S22 you can pull it off though, so long as you give it decent ventilation.

I would give the S22 bigger heatsinks anyway, simply because they burn my fingers every time I touch the heatsink, and that's when they're only powering 2 amp boards.

 

[holland]

Quote:

Originally Posted by Navyblue /img/forum/go_quote.gif - The case will be relatively spacious horizontally with the configuration shown in the picture.

why can't you use 3 on bottom and 1 on top? Why do you need this inverse pyramid configuration or a 3 stack? You're looking at a 7" high case?

What case are you using?

 

[Navyblue]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif With the stock S22 heatsinks it's a terrible idea, because the S22 gets really hot as it is when powering 3 boards. With bigger heatsinks on the S22 you can pull it off though, so long as you give it decent ventilation. I would give the S22 bigger heatsinks anyway, simply because they burn my fingers every time I touch the heatsink, and that's when they're only powering 2 amp boards.

So the main issue is the S22 and not so much of the B22?

If so how about let the S22 swap place with one of the B 22 boards?

While we are at this topic, how hot is the transformer?

 

[Navyblue]

Quote:

Originally Posted by holland /img/forum/go_quote.gif why can't you use 3 on bottom and 1 on top? Why do you need this inverse pyramid configuration or a 3 stack? You're looking at a 7" high case? What case are you using?

I knew that this question will come sooner or later.

I'd disclose the enlosure at a later time.

But an upright pyramid configuration won't fit.

 

[cotdt]

Quote:

Originally Posted by Navyblue /img/forum/go_quote.gif So the main issue is the S22 and not so much of the B22? If so how about let the S22 swap place with one of the B 22 boards? While we are at this topic, how hot is the transformer?

Yes, the S22's tend to get more hot than the B22's. The B22 does OK with the recommended 150mA quiescent current, and you can lower it to make it run cooler. This will also make the S22 run cooler. The transformer barely even gets warm.

 

[n_maher]

If your transformer gets hot you've got a much different problem.

 

[luvdunhill]

Quote:

Originally Posted by Navyblue /img/forum/go_quote.gif I'd disclose the enlosure at a later time.

I think this thread is pretty much pointless. How can people help you when you have some sort of mystery case you'll be using? How do you know that it's not just another bad idea?

 

[holland]

agreed. this thread is silly. i'm out.

 

[Navyblue]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif Yes, the S22's tend to get more hot than the B22's. The B22 does OK with the recommended 150mA quiescent current, and you can lower it to make it run cooler. This will also make the S22 run cooler. The transformer barely even gets warm.

Thanks.

I hope those would not be the only good new I have today.

But how much do I throttle so that it remain well in class A operation?

 

[Navyblue]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif I think this thread is pretty much pointless. How can people help you when you have some sort of mystery case you'll be using? How do you know that it's not just another bad idea?

The dimension and basic shape of the enclosure are pretty much shown in the pictures, minus the skin, which naturally is a little larger than the frame. And if it matters, the skin is made of metal.

Edit: What other information are relevant?

 

[Navyblue]

Quote:

Originally Posted by holland /img/forum/go_quote.gif agreed. this thread is silly. i'm out.

Thanks for being helpful.

 

[cotdt]

Quote:

Originally Posted by Navyblue /img/forum/go_quote.gif But how much do I throttle so that it remain well in class A operation?

Headphones don't require much current so you can cut the bias current dramatically and still be in Class A. However, the transistors are more linear when biased at its optimal point, and this point tends to be well beyond what's required for Class A anyway.

 

[Navyblue]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif Headphones don't require much current so you can cut the bias current dramatically and still be in Class A. However, the transistors are more linear when biased at its optimal point, and this point tends to be well beyond what's required for Class A anyway.

Thanks.

I guess the default is the optimal point, may be I'd just stick to the lower range.

 

[Navyblue]

I realised that I can mount them on the same plane if I arrange them the right way. Are these Head-fi approved layout?