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SOHA II Builders Thread - Page 18

post #256 of 1686
Thread Starter 
Oh, TB+ is ok. I will pull down when it's loaded by the tubes.
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 #257 of 1686
Quote:
Originally Posted by runeight View Post
Right. No heater switches on the main BoM. However, on the PS Parts list page on the website, at the very bottom, there are some part numbers for switches that should fit the footprint.

And another reminder that the switches work opposite to the jumpers so the board markings are reversed when using a typical switch.
Great, how about the PCB? I've tried contacting Jeff @ glassjar to no avail... are the production boards ready for sale?
post #258 of 1686
Thread Starter 
I am still waiting to hear from Jeff on availability of boards and kits also. Last time we exchanged emails the board house was late in shipping them out due to their error.
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 #259 of 1686
Late last week he was trying ot track down the boards. He had everything else ready.
post #260 of 1686
Who here has done the high-current heater mod? I know Ferrari has, I'm trying to find a replacement heatsink for H- and with the size constraints of the BOM case... Would mounting the regulator off-board right to the case provide enough of a heatsink? Or maybe even adding this under it: Mouser PN 532-507222B00
post #261 of 1686
Quote:
Originally Posted by bmwpowere36m3 View Post
Who here has done the high-current heater mod? I know Ferrari has, I'm trying to find a replacement heatsink for H- and with the size constraints of the BOM case...
I've done the high current mod (although I put in a switch to toggle R3P in and out as desired, so as not to heat up the regulator unnecessarily with low current heaters). The heatsink I used is Mouser P/N 567-647-15ABP - it just fits inside the Hammond case in the BOM, if the board is placed in either of the lowest two slots. (Note that it's also twice as wide as the BOM heatsink, and won't fit in the same space on the PCB, but you could build that part of the power supply separately on perfboard.)
post #262 of 1686
Quote:
Originally Posted by bmwpowere36m3 View Post
Who here has done the high-current heater mod?
I mounted the regulator directly on the case, works fine. The case has more surface area than any heatsink which would fit in the case.
post #263 of 1686
Great news. I just finished my second SOHA2 prototype, this one has no hiss with the Denon D2000. It's strange because I have the transformer closer to the board in the same case and the PSU wires are longer.

The only real difference I can imagine is that I'm using Teflon caps and an Alps RK27 pot while the first one had VitaminQ caps and a stepper.
post #264 of 1686
Hey FallenAngel,

Can you give a comparison of the SOHA II against the SOHA with Jisbos?
post #265 of 1686
Quote:
Originally Posted by m0b1liz3 View Post
Hey FallenAngel,

Can you give a comparison of the SOHA II against the SOHA with Jisbos?
Soon, very soon. I'll take the SOHA+JISBOS home from work tomorrow and do some listening. The SOHA2 isn't burned in at all so I don't know if it's fair, but we'll see anyway.

I still really want to figure out why the other one is buzzing, but with one working it's not as pressing of an issue.
post #266 of 1686
Thread Starter 
Quote:
Originally Posted by FallenAngel View Post
Great news. I just finished my second SOHA2 prototype, this one has no hiss with the Denon D2000. It's strange because I have the transformer closer to the board in the same case and the PSU wires are longer.

The only real difference I can imagine is that I'm using Teflon caps and an Alps RK27 pot while the first one had VitaminQ caps and a stepper.
Ah ha. It is great news.

I don't think the caps would make this difference, but the attenuator/pot difference might. But, mostly this seems like a ground noise issue to me.
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 #267 of 1686
i use vit q and stepped att in my build as well. will try grounding the terminal blocks directly (remove pot) and see what happens. i put 3 pin terminal blocks on the rk27 pads for easy removal since the pot is air wired.
post #268 of 1686
Bump for status on prod PCB's
post #269 of 1686
Thread Starter 
I've just emailed Jeff asking him to post a status update.
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 #270 of 1686
It really might be a grounding thing. With the HV board air-wired and the ground connected to case at the center, that means the HV board ground needs to travel half the board. I'll see if I can just connect the HV ground to center of the board. Might help.

I also thought that perhaps it's an issue with the fact that I'm using MJE243 instead of BD139. If I don't get it fixed by playing more with ground, I'll change those out to something else.
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