MXR Distortion Plus - question about schematic...

[jimosity]

I'm new to this pedal building stuff, but recently finished up a "3 Legged Dog" from the runoffgroove.com site and that got me hooked.
I want to build the "MXR Distortion Plus" pedal that is shown on tonepad.com and I placed the order for all the parts I need (small bear) and got the IC741's from eBay.
While looking over the schematic (and please remember, I'm super-new to this stuff...) but the parts list shows "R1" but no part listed and none shown on the schematic.
The schematic I'm talking about is here:
http://www.tonepad.com/getFile.asp?id=4

Why is that?

[Bernardduur]

LOL; you're right

I guess it was the pull down resistor but they left it from the board........

Just don't use it I guess! The schematic works

[Mark Hammer]

It is an optional (though very useful) component, and goes in parallel to C3.  It provides a path for C2 (and C3 to a lesser extent) to discharge.  This essentially prevents a popping sound from occurring every time you step on the stompswitch to engage the effect.

No value is shown because it can be anything over a fairly broad range.  I would imagine that anything between, say, 470k and 4.7meg would be entirely appropriate.  Lower resistance tends to provide a lower input impedance for the pedal, and higher resistance tends to prevent the cap from discharging quickly.  Most people find a value of 1M-2.2M to be just about right.

[jimosity]

OK - I have started working on my MXR Distortion Plus project and I have a couple questions.

1) There are two diodes shown in the diagram from tonepad.com (D1 & D2)
    They don't mention what diodes go here, but I have some 1N914, 1N4001, & 1N4007's... Would some combination of these work well in this project?  If so, which should go where?  If these won't work, what diodes should I put in their place?

2) I purchased my parts from Small Bear and thought I had ordered the right parts for my project, but I'm having some problems understanding the line item description from Small Bear with the diagram.  Specifically, what I need to know is about C1 & C5

Which of this (if either) is the right part for C1 (or which would work best if they are both 'usable')?
   Capacitor, BC Components, 1 mf. 63V
   Capacitor, CDE DME Series, 1 mf. 100 V

and does this sound like the right part for C5?
   Capacitor Silver Mica 500V 10 pf. - 150 pf.  (10 pf.)


Thanks for your help!

[MikeH]

1)  You can use any diodes you want.  Swap them out and see what your tastes like.

2) I don't know if those caps specifically are what you need for C1 (and C6).  As long as they are "electrolytic" or any kind of polarized caps they will work fine.  Not the orientation.  The dot on the layout is the positive side.  You could use a ceramic for C5, but if all you can get is mica, it will work fine.  They're just more expensive.


Thanks for your help!

[/quote]

[Ronsonic]

Like the instructions say, try different diodes to taste. If you just want to get the build done and running without experimentation and fuss, just stick in the 1N914s and be done. You can also run one of them in one direction and two in series going the other way. Either of those options will sound just fine - different from one another but both good.

C1 is the least critical capacitor in this entire circuit. Any electrolytic would be fine. Sorry, I'm not going to look up your part numbers. Actually ANY cap that says it's 1uF or over with a voltage rating upwards of 16V and not just bad rotten old broke and decayed will work fine in that hole.

C5 needs a 10pF cap. If you've got one of those, use it. Mica's okay, so's ceramic or any other technology for making a twee little cap like that. There may possibly be some difference in tone with different materials, but the one you propose there should work fine.

Enjoy.
Ron

[jimosity]

Thank you guys, I appreciate your help!
I've only done two other builds and neither had involved diodes or working with pF values (only uF), so this ones a tad different for me.