Resistor Substitution/Capacitor Question - EA Tremolo

[dskinner74]

Hey,

I actually have a couple of questions.  I'm new and I hope I'm doing this in the right spot.  If not, let me know.

I'm building an EAT and have all of the correct value components but the 560k resistor.  The closest value I could get my hands on locally was a 510k.  I'm hoping that will work for this build.  Can anyone tell me off the top of their head if that's a close enough sub?

Also, the BOM calls for three 1uF caps.  I have the following:

1uF 250V Mylar/Film (looks huge, but I think it should work)
1uF 50V Multilayer Ceramic (look like tantalum - I've read that ceramic caps are noisy but I don't know how much that matters in this circuit)
1uF 50V Non-Polarized Electrolytic (I don't see why I couldn't use this, but if there's a reason not to, I'd like to know)

Which of those options (or combinations of thereof) should I go with and why?

Any insight would be much appreciated.  This is my 4th build and it's only the second that I've attempted without buying a kit...

Thanks,
Danny

[tubegeek]

An excellent thread titled "What matters, what doesn't" here:

http://www.diystompboxes.com/smfforum/index.php?topic=23386

To answer your 1st question, it'll be fine to use the 510K for the 560K, and another option would be to put a 50K resistor in series with (end-to-end with) the 510K.

The short answer to your second question is, any of them will work.

Depending on whether the cap is in the signal path or just part of the oscillator circuitry, it may not matter at all which you choose. The biggest issue you may face is, yup, the size, if you wanted to try the 1uF 250V cap.

[armdnrdy]

To answer your 1st question, it'll be fine to use the 510K for the 560K, and another option would be to put a 50K resistor in series with (end-to-end with) the 510K.

So we don't send the OP on a wild goose chase or make him look "green" to his local supplier......

The standard values for resistors in the ballpark of the 50K needed to "make" your 560K is 47K, 51K, (preferred) and 56K.

[GGBB]

For the three 1uF caps in the oscillator, I would choose the MLCCs simply for space reasons.  Those caps are not in the audio path so no worries there.  If you are looking for fast tremolo sounds I would recommend some changes.  Try going lower in value than 1uF to 0.68 or 0.47.  Of course, you will lose the slower settings if you do this.  You will probably want to increase the depth range as well to go along with the speed increase.  To do that, reduce the resistors on either side of the 250K depth pot - 68K to 18K and 120K to 33K or lower or leave it out completely, or alternatively just swap out the 250K depth pot for a 1M pot.  This will improve the depth control quite a bit which is necessary at higher speed settings.

[dskinner74]

I appreciate all the input.  You guys are great.

Thanks,
Danny