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SOHA II Builders Thread

post #1 of 1675
Thread Starter 
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.



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.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #2 of 1675
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!



post #3 of 1675
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.
post #4 of 1675
@Ferrari

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

Regards
post #5 of 1675
Quote:
Originally Posted by GeWa View Post
@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?
post #6 of 1675
Quote:
BTW, how is the second Europeans SOHA II build going?
I'm kinda this far.



Regards
post #7 of 1675
Quote:
Originally Posted by pabbi1 View Post
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.
post #8 of 1675
Can I substitute the BD139 with 2SC2238?

Regards
post #9 of 1675
Thread Starter 
Quote:
Originally Posted by GeWa View Post
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.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #10 of 1675
Thanks Runeight but I think I'll stick with the BD's than. I hate to desolder stuff, especially on plated through holes.

Regards
post #11 of 1675
Keep taking pictures as you put on more components GeWa, this is great
post #12 of 1675
Quote:
Originally Posted by GeWa View Post
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).
post #13 of 1675
Quote:
Keep taking pictures as you put on more components GeWa, this is great
Another one with the coupling caps and LV+ / LV- regulators in place.


Quote:
Works like a charm, absolutely no problem to bias the quiescent current to 110mA
Good news, thanks Ferrari. Think I will give them a try than.

Regards
post #14 of 1675
Looking good! (especially as my boad hasn't arrived yet ) Auricaps huh? not building to a budget then
post #15 of 1675
Quote:
Auricaps huh? not building to a budget then
Yes I do, they were simply calculated into the budget.

Regards
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