Adding Resistors for Volume Pot - Correctly [resolved]

[adydula]

Hello, I just finished my Crack and it checked out ok all resistances and voltages and sounds great with my Beyer DT90's which are 250 ohms.

Absolutely wonderful sound.

I have a small issue with the volume can only be adjusted to 8am - 9am o'clock before it gets really loud... the hair trigger issue I believe.
I have a speedball kit coming and I hear it will add more gain and may make this issue even more difficult.... in volume sensitivity.

I can't really tell what tubes I have, because they are marked well at all, the larger tube has RCA on the phoenix base but no actual identifiers other than what looks like the tube tester ratings.... same thing with the smaller 12 AU7 I presume, again no markings etc....I am not unhappy with these tubes they sound great to me!

So In the FAQ it states to get 2 - 75K Ohm and 2 - 33K Ohm resistors and install the 75K Ohm's in series with the RCA inputs to the pot's. That I understand.

The 33K resistors should go across the end points of the pot? I assume this means the 33K's are in parallel with the 100K pot winding?

If this is correct then I know how to install these resistors.

I hope you can clarify this for me and several others that seem to ask the same question....(smile!).

Thanks in Advance!!
I am really enjoying the sound!

Alex Dydula
Raleigh. NC

[Paul Birkeland]

So In the FAQ it states to get 2 - 75K Ohm and 2 - 33K Ohm resistors and install the 75K Ohm's in series with the RCA inputs to the pot's. That I understand.

The 33K resistors should go across the end points of the pot? I assume this means the 33K's are in parallel with the 100K pot winding?

Yes, that is correct.

-PB

[adydula]

Thank your for the reply!!
Ordered resistors from Mouser...

Alex

[adydula]

I just added the 4 resistors and they did the trick!

Depending on the replay gain on the flac source file I can adjust the volume all around the pots range...worked out really ok fine!

Thanks
Again......Speedball next!!

Alex

[Colin]

You can add a picture for this(after install 4 resistors)? I have the same problem with you, don't understand with the text. Thank yoi

[adydula]

Colin,

I will take some pictures and post..... hopefully later tonight.

You remove the red and white wire from the RCA input jacks.... they are soldered one to each of the pots..remove the wires there one at a time and solder a 75K ohm resistor to the tab on the pot that the red wire was attached to, the other end is soldered to the red wire.

The second 75K ohm resistor is soldered to the tab on the other pot where the white wire was attached. Then solder the free to the white wire.

Now you have the 2 - 75K ohm resistors soldered from the pots tabs to the red/white wires that go over to the RCA input jacks.... they are in series with the inputs.

Then you have 2 - 33K ohm resistors to install. These get soldered from one outside tab to the other outside tab. One goes to the tab you just soldered a 75K ohm to and then the free end of this 75K ohm resistor get soldered to the same pots other outside tab, lay the resistor over top of the middle tab.... you do this for the lower pot, closet to the mounting plate ..ie solder a 33K Ohm resistor from the tab that you installed the other 75K ohm resistor over the middle tab to the lower pots outer tab.....

The lower pots 33K ohm resistor is a little harder to get under the upper pot but take your time and solder carefully.

I got my resistors via Mouser.com. I found some 1% and 2% very inexpensive.

Let me know how this sounds to you.]

Alex

[Paul Birkeland]

The pictures are much more difficult to take properly than you'd imagine.  There's a lot of wiring up there already, and it make s a lot of sense to cover up all the resistors with heat shrink tubing when you're done.

-PB

[adydula]

Yup its a bit crowded in this area for sure, the heat shrink in the series resistors is a great idea.

Alex

[Colin]

Like this(nathan post)? And 1 more question, is it possible to add(change) pair capasitor with the 75ohm resistor(red), read from some diy review, as coupling? I blind of this(include soldering) before built crack

[Nathan]

Yup- that's my picture but since taking the photo I moved the 75k ohm resistors from being soldered to the RCA's to being folder to the volume pot

Looking at the pot the resistors go to the upper left tab and the lower left tab