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SOHA II Builders Thread - Page 79

post #1171 of 1687
Quote:
Originally Posted by Killercrush View Post
Hi everyone, I got a simple questions for you guys, is the SOHA II that hard of a build for a beginner DIYer ? Should I start with something like a standalone 2-channel JISBOS to get some soldering/troubleshooting skills ?! ( I'm a student in electronics )
Anyone ?
post #1172 of 1687
Thread Starter 
MHO is that it is not a hard build at all. If you put everything in the right place and the tubes are good it will come up to working condition on the first power up.
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 #1173 of 1687
Yes its a quick build, use the mouser BOM and make sure you understand the hows & why's of mounting/insulating heatsinks (you need to do this on the Jisbos as well).
post #1174 of 1687
Quote:
Originally Posted by nattonrice View Post
nattonrice, belated thanks for the pointer, & to regal for the mods. I'm working on these now & will post results shortly.
post #1175 of 1687
Quote:
Originally Posted by Killercrush View Post
Anyone ?
My 5 cents worth - the SOHA II isn't any more difficult a build than many other amps but does require extra care with heatsink insulation (as per regal's comments), as well as power up procedure (follow doco on the SOHA website very carefully).
post #1176 of 1687
Hi

I've nearly finished my first build, the SOHA II. I've been testing it for hours, and think it sounds great. One problem thogh. The fuse blows when I turn on the power. Now I'm running it with 630mA fuse instead of 500mA that came with the kit. Is this ok?

Some picktures:

Nearly finished board in inner cabinet.

Which is going into the chassis like this

Almost finished, awaiting tube sockets for chassis-mounting and volume knob.
post #1177 of 1687
Quote:
Originally Posted by kjetinho View Post
Hi

I've nearly finished my first build, the SOHA II. I've been testing it for hours, and think it sounds great. One problem thogh. The fuse blows when I turn on the power. Now I'm running it with 630mA fuse instead of 500mA that came with the kit. Is this ok?


Almost finished, awaiting tube sockets for chassis-mounting and volume knob.
Did you use bigger caps anywhere? If not make sure your heatsinks are insulated. It could be an indication of a small short. There have been reports of the ground plane extending too far into the PS rails on the PCB.
post #1178 of 1687
Quote:
Originally Posted by regal View Post
Did you use bigger caps anywhere? If not make sure your heatsinks are insulated. It could be an indication of a small short. There have been reports of the ground plane extending too far into the PS rails on the PCB.
I've used Mundorf ZN 0,22 uF as C1L/R, but it's the same value.

What should the heatsinks be insulated from? Ground on pcb, or is it something on the regulators? I'm sorry, but I don't understand what the "rails" are.
post #1179 of 1687
Quote:
Originally Posted by kjetinho View Post
Which is going into the chassis like this

Almost finished, awaiting tube sockets for chassis-mounting and volume knob.
The design is beautiful. Well done!
post #1180 of 1687
Thanks a lot. I think I will wax the birch plywood for better finish, and I might try to build a second wooden part for the cabinet later in a darker harder wood, to see how that will look.
post #1181 of 1687
Quote:
Originally Posted by kjetinho View Post
What should the heatsinks be insulated from? Ground on pcb, or is it something on the regulators? I'm sorry, but I don't understand what the "rails" are.
Where the heatsink is soldered to the board, make sure it is an open circuit with the DMM , also make sure that the ground trace is an open circuit to the regulator output.


Edit: better explaination on power rails: put your DMM pos lead on the TB+ the neg on grd and it should not beap as a short (less than 10 ohms), do the same with TL+. My first SOHA I board had a tiny trace of the ground plane connecting TL+ with the ground plain causing it to blow fuses.
post #1182 of 1687
Thanks!

I didn't know that the heatsinks should be soldered to the board. Could this be the problem?

I will check the ground trace when I get the time come sunday evening.
post #1183 of 1687
Quote:
Originally Posted by kjetinho View Post
Thanks!

I didn't know that the heatsinks should be soldered to the board. Could this be the problem?

I will check the ground trace when I get the time come sunday evening.
They don't have to be but that is where you check that the tab is insulated (should be an open circuit between there and the TO-220 device tab.
post #1184 of 1687
I have a few quick questions that I could not find answers to by skimming the threads.

About how much are the parts for everything to build a SOHA II?

I would also like to add a DAC with UBS input to this amp. What plans do you suggest (I'd like to keep it all in one chassis).

Thanks.
post #1185 of 1687
200$ for standard version with cabinet and tubes and all parts. Without volume knob
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