250 coming along...

[Cozybuilder]

A 10uf output capacitor after the opamp seemed to make the pedal too "fat" in my experience, so I switched it out for the correct value.

Well dang, I was hoping someone would come along and tell me it makes no difference.  Swapping parts on perf is kind of a bitch, especially when it's already boxed up!  I've mostly been playing it with the gain full up so far, and I don't think anybody would call that sound "too fat" but at the lower gain settings you might be right.

So let's see what the resident EEs with all the formulas have to say:



10uF vs 4.7uF on the opamp output...any difference?

Without knowing your layout, this might not be so easy, but perhaps you can add another 10uF cap in series to your output cap and wind up with 5uF?

[thermionix]

Without knowing your layout, this might not be so easy, but perhaps you can add another 10uF cap in series to your output cap and wind up with 5uF?

I definitely didn't leave room for that.  Not impossible to do the cap swap, just wondering if it's worth the effort.  Being "incorrect" will probably bug me enough that I eventually just go ahead and do it though.

[thermionix]

The two slider change the cap values between Y (yellow) and G (grey)

What are the differences in cap value?

[lars-musik]

What are the differences in cap value?

Here's the schematic. The changing caps are C3, C5, C6 and C7.

[thermionix]

Well, I did the output cap swap.  It was WAY easier than I had feared.  I had left the wires long enough to facilitate access to the bottom of the board, just had to pop it off the nylon standoffs and flip it over, no pots or jacks had to be loosened or removed.  Also, as luck would have it, that particular cap had both leads going straight in, not bent over to make the next connection.  Woohoo!

Does it sound any different?  Jeez, I don't know.  It didn't get shrill in the high gain settings, so that's good.  If anything, I think it might sound a little smoother.  Really I didn't spend enough time with it in the first configuration to give an accurate assessment of how much it might have changed.  I'll just say it sounds at least as good now as it did before, possibly better.

Either way, I dig the hell out of this little circuit!  I'm getting the feeling my Tube Screamers might end up collecting dust.

So what's next, a Bluesbreaker?  That's another one I've never played but think I might like.

[EBK]

So what's next, a Bluesbreaker?  That's another one I've never played but think I might like.

That happens to be my very next build, and I've also never heard one. 
(On a $0 budget for my next pedal, and I happen to have all the parts for it)

[bloxstompboxes]

The bluesbreaker is almost like a compressor to me. It is hard to tell it's on. I didn't like it. I like a lot more distortion, or at least know that it is there if I want it.

[thermionix]

Eric, I was also looking at the Guv'nor, another pedal I've never played.  Should have much more dirt than the Bluesbreaker.  Have you tried that one?  Opinions?

I took the 250 to the guitar shop today, got to hear it with different guitars and amps, and also cranked up.  I'm definitely sold on this one.  It's like "where have you been all my life?"

[bloxstompboxes]

Eric, I was also looking at the Guv'nor, another pedal I've never played.  Should have much more dirt than the Bluesbreaker.  Have you tried that one?  Opinions?

I took the 250 to the guitar shop today, got to hear it with different guitars and amps, and also cranked up.  I'm definitely sold on this one.  It's like "where have you been all my life?"

No, I haven't tried it yet. But, like 150 others, it's on my list to build. I'll get to it eventually. lol. I've built a couple of 250s. I think I like the Gray the best. I read somewhere it was the same as the YJM308 but I built one of them and it was way too trebly for me.

[thermionix]

I haven't looked too much at the YJM, but I think it has a 1n input cap instead of 10n.  That's probably a big part of the trebly issue.  I see Analogman offers a mod to put those to gray specs, so I guess you're not the only one who thinks it doesn't sound as good.  No idea what Ying-wee had in mind, you would think a Strat guy would be wary of excess treble.

[Electron Tornado]

Regarding the output cap from the op amp -

The MXR Dist + is basically the same circuit as the DOD 250. The Dist + uses a 1uF cap while the DOD250 uses a 10uF. When I built my own clone, I thought the 1uF sounded too thin, while the 10uF sounded a bit too wooly, so I used a 4.7uF. Add a switch with some caps if you want to make it selectable.

Another easy mod would be to add a switch with the diodes to select between symmetric and asymmetric clipping.

Re: the op amp -

Just to test the "op amp makes a difference" thing for myself, I tried both a 741 and a TL071. After hearing no difference, whatever is in there is whatever the last one was that I tried.

[Electron Tornado]

While graph paper is getting hard to find for real, there are online PDF generators to give you graph paper files. Just be careful of your PDF tool trying to re-size for printer.

This is what I use since I'm not in need of it on a daily basis. There are several "flavors" of graph paper available to download for free. Download what you like and print 'em as you need 'em.

[thermionix]

...the DOD250 uses a 10uF....the 10uF sounded a bit too wooly, so I used a 4.7uF.

4.7uF is correct for the gray-spec DOD 250.  I mistakenly used 10uF initially, but the DOD schematic and all photos I've seen show a 4.7uF.  I swapped mine to 4.7 and I consider the pedal done.

[Electron Tornado]

...the DOD250 uses a 10uF....the 10uF sounded a bit too wooly, so I used a 4.7uF.

4.7uF is correct for the gray-spec DOD 250.  I mistakenly used 10uF initially, but the DOD schematic and all photos I've seen show a 4.7uF.  I swapped mine to 4.7 and I consider the pedal done.

I just looked at some DOD250 gray gut shots. Wow! You are correct! I had been working off a schematic that was wrong!

[thermionix]

Yep, that's what happened to me too.