[izquierdaste]

Hello,

Since this is my first attempt at diy, I have some really stupid questions. I have read some of the other threads in here, but I just want to make sure that I don't screw anything up. I decided to go ahead and get some 12uf paper in oil caps to try as coupling caps for my dac-ah. (Note, I want to keep using the opamps for now.) Here are some pictures to help with the story:

http://www.unc.edu/~bmaskery/Existing_caps.htm

1. when I take out the old capacitors, I assume that I solder the underside of the board to dislodge the caps (as opposed to just soldering from the top side).

2. Since the paper in oil caps are much bigger, I will need to place the caps near the power supply. So... can I just use shielded wire to connect the caps back to the board at the holes from the previously removed caps. If so, does the type of connecting wire matter (i.e. silver vs. regular).

3. My caps have two "wires" one extending form the top and one from the bottom. How should I attach the connecting wire to the ends of the cap. Should I just twist the wires around the caps' top and bottom extensions or should I solder the shielded wire to the caps? Also, what should I put around the connection?

4. Do I need to add a resister when I install the new caps or is the existing setup ok?

5. What is the best may to connect the caps to the case so they don't move around too much. I was thinking that poster tac may be sufficient.

Thanks a lot for any help with my first diy project.

Cheers,
Brian

 

[quicksilver96]

1. You want to find some desoldering braid/wick and place this between a hot, tinned, soldering iron and the hardened solder blob that you are desoldering. There will most likely be some solder the braid could not wick out from between the mounting lead and the pad on the pcb. You will have to heat up the pad and lead while pulling on the top side part of the lead.

2. I'll let someone more versed in shielding/emi field this question

3. There is no reason I can think of that you would need to install a resistor. Is there something that made you think you need a resistor? What is the capacitance value of those you are installing vs. those you are removing?

4. Blue tac should be sufficient.

 

[izquierdaste]

Thanks for the reply. I am replaceing 22uf/40V electrolytics with the 12uf/100v paper in oils. The only reason I asked about adding resistance is because I am so new to modding, I didn't want to screw it up.

Thanks again for the help. I'll report how it goes in a few days.

 

[izquierdaste]

Succees thanks to your help!!

After some trying times whilst learning how to desolder, my capacitor upgrade is now complete for the dac-ah. I replace the two dac chip power supply caps with panasonic fm 1000uf. i replace the dac chip caps with 0.11uf polypro bc caps and I put two vitamin q acushnet 12uf coupling caps on the opa627's. I have to say that I am very impressed with my work. The dac is much smoother with improved dynamics. Overall, it just sounds very natural, dare I say analog?

Here is a pic of the finished product if you are interested:

http://www.unc.edu/~bmaskery/dac-ah_mod.htm

Next, I am thinking of doing running a passive bypass with a second set of outputs, just to hear the difference. My pio caps came in a lot of 4, so I have a couple extra anyway. I read of some people over at audio asylum doing this. Would this splitting degrade sound at all? I guess we'll see.

 

[TheMarsVolta]

Congrats on your mod. Were the panasonic 1000uf caps larger in diameter than the stock caps, or the same?

 

[izquierdaste]

The pin spacing was the same. The panasonic caps may have been slightly fatter and were definitely taller. The polypro caps on the dac chips were quite a bit bigger (though same pin spacing).

 

[regal]

What type of wire did you use connecting the large p-i-o caps to the board ? Any humm from the transformer?

As far as splitting the signal, it won't hurt as long as you don't use both sets at the same time.

 

[izquierdaste]

Hey,

Thanks for the advice on splitting the signal. I just used some extra radio-shack speaker wire I had on hand. My dac has always had a slight noise floor if I crank the volume all the way up. That (unfortunately) is still there, but I don't hear anything at normal volume.

 

[pelayostyle]

Quote:

Originally Posted by izquierdaste Thanks for the reply. I am replaceing 22uf/40V electrolytics with the 12uf/100v paper in oils.

What made you decide to go with that value cap?