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SOHA II Builders Thread - Page 76

post #1126 of 1686
Thread Starter 
Happy to help. While you're waiting it would be a good idea to check all of your solder joints on the board and all your resistor values. Make sure everything is well connected and in the right place.
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 #1127 of 1686
Quote:
Originally Posted by FairyTales View Post
I will try to source another regulator (see the edit in my previous post) tomorrow and see if it solves the problem as everything else seems to be ok.

Thanks for helping me out as i don't really understand how all the bit and pieces works together, i know how to solder and the basic functions of the components but when it comes to solving those kind of issues i'm completely lost.

Arnaud
With the new reg, make sure it is isolated from the heatsink. Also check for shorts between TL+ and ground before you power up.
post #1128 of 1686
The regulator was faulty now i have the following values

TL+ 15,05V
TL- -15.06V
TH -12.66V
TB+ 118V

But now i have another problem on step 2 when you have to strap jumpers, i put one jumper on both poles of 12.6 and the other jumper on both pole of TPR, i power up and started to see smoke coming from R3P, so i unplugged it quickly and the resistor was super hot

So i assume i should change R3P but where could the problem come from? The resistor itself?

Arnaud
post #1129 of 1686
Thread Starter 
I suspect that you have the jumpers turned sideways. They should be aligned with the sides of the board from front to back and not side to side. Can you post a photo?
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 #1130 of 1686
You're right i did turn them sideways now they are set according to the diagram of the PS on the site. Parrallel to the longer side of P1L. Stupid me.

When i try the buffer settings part i don't get any values across R10L/R10R, so if i understand correctly i've toasted R3L?

Arnaud
post #1131 of 1686
Thread Starter 
I think you mean R3P? You can verify its condition by looking at the tube filamaments. Are they lit?

And the buffer adjustments should be independent of the tubes or the heater supply.

You get absolutely nothing across R10 on either channel and the trimpot P2 doesn't change anything?
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 #1132 of 1686
Yep i mean R3P, when i put the tubes in only the very top of the filaments gets orange ,in the upper part of the tube you have 3 leads on each side, the outer one are holding what i would call a heatsink in the middle of the tube, only the filament in the middle of the 3 leads gets orange, even after a few minutes.

I've got nothing on R10L and R10R using two different meters(my Fluke 87V and an old metrix DMM), and turning P2L doesn't change anything.

Arnaud
post #1133 of 1686
Thread Starter 
Can you post any pictures of your board?

Please check the LV supplies again. Are they really 15V?
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 #1134 of 1686
Hope this pic will do.



Let me know if you need a picture of a specific part of the board.

LV supplies are as follow

LV+ 1st pin= 22.91V
2nd pin= 0V
3rd pin= 15.05V

LV- 1st pin= 0V
2nd pin= -22.8V
3rd pin= -15.06V

1st pin is the one on the left, with the same orientation as in the pic.

Thanks again for helping me out!

Arnaud
post #1135 of 1686
Thread Starter 
This is what we needed. You'll need to strap and solder a wire across jumpers J1 and J2. These are marked on the board as two sets of pads for each jumper with a white line between them.

Once the buffers are working you can strap J3 to adjust the HV.

The instructions at Cavalli Audio talk about the setup procedure and which order to connect the jumpers. I'm sure you've read this many times by now, but all you need to do is wire the jumpers and follow the instructions.
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 #1136 of 1686
When reading the instructions i was thinking that strapping the jumpers means putting the small plastic pieces over the 6 pins thingy, where you select the voltage, as the one below the HTR logo is marked as 1, i thought it was jumper 1....

Will do the strapping right now and report back, thanks a lot!
post #1137 of 1686
Thread Starter 
Great. Please follow the instructions and do just J1/J2 first to set the buffers and then J3 for the HV.
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 #1138 of 1686
I did and everything is working perfectly, all the values are fine now, i won't have time to test it tonight, but will put it to work tomorrow.

How did your learn so much about electronic? I have other projects that i want to start (a DAC to complete my setup) but with those little issues i had, i realize that learning how things work would be really helpful. I was lucky to have you help me out on this one and wouldn't have figured it by myself

Thanks a ton for your help, time and patience!

Arnaud
post #1139 of 1686
Thread Starter 
Ah, good news. Let us know how it sounds.
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 #1140 of 1686
Hey,

I've been able to listen to the amp for a few hours and it's been pretty impressive so far, it brings out details in songs i wasn't able to hear with my previous setup (PC as a source on a M-audio 2496 soundcard direct to my AT ATH-A900), bass are nice and tight and guitars are a real joy to listen to. At times you have the feeling the group or instruments are right in front of you, sometimes a tad too much on certain songs but it may be due to the fact that i use closed cans, or poor audio enginering from the disc makers.

I have a few questions:

1) I have a slight hum even at low volumes and it becomes really present when i turn the volume knob a little more than half way up(3/4), is it possible to get rid of this or to make it less present?

2) Is it possible to implement a source switcher like in the following pics



3)Would cat6 cables be better between the RCA and amp input than the cable i'm using?


4) Temperature inside the case is 122°F (50°C) is it ok or should i add ventilation holes on the case?

5)There is a pretty loud snap (clac?) sound that goes thru the cans when i power down the amp is it normal, or should i remove the jack plug before powering down?

Arnaud
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