SOHA II Builders Thread
Oct 24, 2008 at 3:43 AM Thread Starter Post #1 of 1,694

runeight

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Hello SOHA II Builders. Now that the two stage prototype process has finalized the board and amp we're starting the buidlers thread. The original SOHA II thread is still around for parts questions, design questions, and other similar issues. This thread is here:

SOHA II - Super SE Hybrid

The builders thread is for discussing and showing the builds.

I don't have a picture of my stuffed board handy at the moment, but here is a 3D image created by Eagle 3D. Most of the parts are simulated on the board.

SOHAIIBoard3D.jpg


For complete information on the SOHA II Super SE Hybrid amp see:

Cavalli Audio

A group buy is in the works and should be announced very soon.

Happy building.
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Oct 24, 2008 at 9:28 PM Post #2 of 1,694

Ferrari

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Well, my build is a bit unusual and has not much in common with the 3D image in the previous post, but here are a couple of pics to start.
I encourage everyone who are building or have completed the build to share your builds and experiences here.
We are here to learn form each other!
smily_headphones1.gif


Afbeelding560.jpg

Afbeelding555.jpg

P1010218.jpg
 
Oct 25, 2008 at 1:59 AM Post #3 of 1,694

pabbi1

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Ferrari, I like how you suspended the tubes, and am looking at something similar, but isn't that aluminum a bit frail for inserting tubes, especially the more obstinate ones, and would channel of 2"w x 1"d have provided better support? Granted, I am looking at this for el34, s have to have channel...

Other than that, IFF builders pay close attention to the transistors orientation, especially the plastic case (with no metal tabs), and the opamp orientations, this will go smoothly, assiming you can connect your power connections correctly (a not so subtle plea that a picture to help guide that is worth thousand of words in that one case). The stuffed board image is a great start toward that.
 
Oct 25, 2008 at 10:32 AM Post #5 of 1,694

Ferrari

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Quote:

Originally Posted by GeWa /img/forum/go_quote.gif
@Ferrari

What value of cap did you used for C2R / C2L?

Regards



The red ones on the pic above are BG-NX 10µF/50V. On my other board, I'm using Wima MKS 10µF/16V.
BTW, how is the second Europeans SOHA II build going?
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Oct 25, 2008 at 10:54 AM Post #7 of 1,694

Ferrari

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Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif
Ferrari, I like how you suspended the tubes, and am looking at something similar, but isn't that aluminum a bit frail for inserting tubes, especially the more obstinate ones, and would channel of 2"w x 1"d have provided better support? Granted, I am looking at this for el34, s have to have channel...



I’m actually using aluminum L-profile (50mm x 20mm, 3mm thickness).
The tube sockets are mounted on the 50mm side, while the 20mm side (not visible on the pic above) provides the stability for the whole construction. I’s very rigid and I have experienced no frailness.

I think that channel of 2"W x 1"D can provide better support, however U-profile is also an option and probably easier to construct.
 
Oct 25, 2008 at 1:06 PM Post #9 of 1,694

runeight

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Quote:

Originally Posted by GeWa /img/forum/go_quote.gif
Can I substitute the BD139 with 2SC2238?

Regards



Probably, but I can't be sure of the range on the O/P stage CCS. You may or may not be able to dial up 100mA with the values specified for the BD139.

Give it a try and let us know. When you fire up the O/P stages make sure that P2L and P2R are set to their maximum resistance (fully counterclockwise). And then dial up the current from there.
 
Oct 25, 2008 at 2:37 PM Post #11 of 1,694

meat01

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Keep taking pictures as you put on more components GeWa, this is great
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Oct 25, 2008 at 2:39 PM Post #12 of 1,694

Ferrari

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Quote:

Originally Posted by GeWa /img/forum/go_quote.gif
Can I substitute the BD139 with 2SC2238?

Regards



I have not named it explicitely but Toshiba 2SC2238 output devices were tried out on this proto build a while back.
Works like a charm, absolutely no problem to bias the quiescent current to 110mA (slightly above the design goal).
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