DOD250 diodes

[elfito]

i was wondering if it was posible to use germanium diodes instead of the silicon diodes on the DOD250?
if it's posible,will that give a better tone?

[anchovie]

Yes, it's possible.

Better tone? That's for your ears to decide! Someone could say it sounds awesome but you might think it's awful.

[newfish]

Or one of each.

Current 'Pedal of Choice' has this config - and it's a firm favourite to my ears.  Less '80s' than all Silicon.

You could also try LEDs, Zeners, or whatever.  Or the myriad combinations available.

[Mark Hammer]

If you do, I would recommend using a 2+2 arrangement of germanium diodes, since changing from a pair of Si to a pair of Ge will drop your maximum volume output by a little more than half.

[Joe Hart]

A pair of Ge diodes will give you an MXR Distortion+ (practically).
-Joe Hart

[elfito]

mixin diodes sounds like a goood idea!

but the volume is my concern,i think i better try them and see what happen

[Mark Hammer]

No one has yet convinced me that the differences heard between germanium and silicon diodes are more because of how they clip than because of where they clip.

Use of a pair of Ge diodes will move the clipping threshold lower.  That means that, with the exact same gain and signal amplitude feeding them, Ge diodes will result in more clipping for a greater portion of the signal's lifespan than will a pair of Si diodes.  But, they will also cap the maximum possible output level much lower, unless you stick a gain (level, actually) recovery stage after them.

If you slam a pair of Si diodes with a signal hot enough to be clipped to the same degree, the maximum output will remain nice and robust.

Although people say that Ge diodes have a 250mv forward voltage and Si have 500mv, in reality, Ge will often be down around 210mv and Si around 550mv.  So, a 2+2 setup of Ge diodes will clip at around +/-420 to 450mv (around 840-900mv peak-to-peak maximum swing).  This is lower than a standard 1+1 pair of Si (+/-550mv on average, or 1100mv peak-to-peak), but noticeably higher than a 1+1 pair of Si (+/-210mv or 420mv p-2-p).  Use of a pair made of 1 Si and 1 Ge will get you something like +550/-210 (770mv p-2-p).

The trick is to find a nice balance between output level (since you want some breakup from the amplifier too), and clipping from the pedal.  A double pair of Ge will strike that balance in my view: almost as loud as your 1+1 Si, but a little more sizzle because of the lower threshold.

[elfito]

thanks for the information mister Hammer!
it help me understand the use of diodes .
i also check the page from Joe Hart and got a lot of usefull info,i tried the asymmetrical clipping and lowered the gain resitor and i got an awesome tone out of my pedal.

[Ronsonic]

No one has yet convinced me that the differences heard between germanium and silicon diodes are more because of how they clip than because of where they clip.

Use of a pair of Ge diodes will move the clipping threshold lower.  That means that, with the exact same gain and signal amplitude feeding them, Ge diodes will result in more clipping for a greater portion of the signal's lifespan than will a pair of Si diodes.  But, they will also cap the maximum possible output level much lower, unless you stick a gain (level, actually) recovery stage after them.

I'm with you on this. I've tried comparing stacked Germs to Sili and well, I get bigger differences in changing the coupling cap to a different material.

That aside, I'm a huge fan of asymmetrical distortion. One Sili and one Germ works for me, in both level and tone.

[Mark Hammer]

I'm beginning to be more of a fan of two identical diodes and one of them with a resistance in series.  The problem is that diodes have fixed absolute forward voltages, and there is no guarantee that the difference between the forward voltage ofdiodes X and Y, or 2 vs 1 diodes, is appropriate for the signal level at that stage, or likely to generate the desired degree of asymmetry.

I might point out that the much-revered Interfax Harmonic Percolator employs 2 identical diodes with a fixed resistance in series with one of them.  The specific resistance seems to be different depending on whose copy you look at.  All of which recommends to me that a variable resistance, whethertrimpot or panel mount, is the way to go if asymmetry is your thing.

[doug deeper]

i really like using 1n4001s for clipping in circuits like this with a 10k pot on one side so you can kind of blend in some twang, to my ears it makes diode clippers sound a lot more dare i say...amp like.
also using a pair on silicon diodes followed by a pair or germaniums on a pot is kind of nice as you can blend in the more saturated clipping over the more open sounding clipping.
fun stuff!

[Top Top]

strange... I am not into "parts mojo" at all, but I built the os mutantes fuzz with silicon diodes at first and then switched it to GE, and it sounded WAY different to me. It has more of a "soft" fuzz sound - not less fuzzy, but less "grindy" I guess, and a little thinner perhaps, which was fine in the case of that fuzz). That fuzz has a lot of output, so the volume drop was not an issue.

[stompboxmaker]

Would using two 1N4004 be wrong for this project. I used them on my circuit and I'm not getting any kind of distortion sound.

[Ronsonic]

Would using two 1N4004 be wrong for this project. I used them on my circuit and I'm not getting any kind of distortion sound.

Those should be clipping and distorting just fine. Is the ground end connected?

[elfito]

Would using two 1N4004 be wrong for this project. I used them on my circuit and I'm not getting any kind of distortion sound.

i had the same issue when i build mine ,i checked the layout and the diodes where not place correctly(i used a perfoard),i used 1N4148 on mine but i don't know if the ones you are using are rong.

[stompboxmaker]

Would using two 1N4004 be wrong for this project. I used them on my circuit and I'm not getting any kind of distortion sound.

i had the same issue when i build mine ,i checked the layout and the diodes where not place correctly(i used a perfoard),i used 1N4148 on mine but i don't know if the ones you are using are rong.

The ground is connected but I'm not sure. I attached the negative side of a 9V batter to the ground rail and the sleeve portion of the jack to the same ground rail. I'm using the diagram from tonepad. Do you know if the diode placement is wrong. I followed the how to attach everything closely and still no distortion.

[Electron Tornado]

I'm beginning to be more of a fan of two identical diodes and one of them with a resistance in series.  The problem is that diodes have fixed absolute forward voltages, and there is no guarantee that the difference between the forward voltage ofdiodes X and Y, or 2 vs 1 diodes, is appropriate for the signal level at that stage, or likely to generate the desired degree of asymmetry.

I might point out that the much-revered Interfax Harmonic Percolator employs 2 identical diodes with a fixed resistance in series with one of them.  The specific resistance seems to be different depending on whose copy you look at.  All of which recommends to me that a variable resistance, whethertrimpot or panel mount, is the way to go if asymmetry is your thing.

I've experimented with a few "warp" controls form AMZ, but this sounds like an interesting twist. What resistor values have you been using?

[Electron Tornado]

Just for discussion's sake -

I recently finished working on a DOD250 / Dist + clone. I tried a lot of various diode combinations and came up with 8 to use. (Sounds like a lot, but I've got the diodes and a switch, so why not.) I tried various combinations of 1N34, 1n4148, 1n4001, LEDs, and I think I also tried BVY-27s. None of the final 8 used LEDs or the BVY-27s (however, I am using the BVY-27s in another distortion pedal.) When playing chords, there were only 4 combinations that sounded noticeably different to my ears. Where the differences were really noticeable was when playing individual notes. I've accepted that I have to turn up the output level when using 1N34s - or, turn it down when using 1n4001s, depending on your point of view, but so far, I don't see that as a "problem".

Mark Hammer gave some good info on diode clipping, and I have to agree with Top Top that there's no special mojo in parts. The point is to research some diode basics, like Mark posted, get some diodes, and experiment and see what sounds good to you.


On the BVY-27s - I salvage these from some defunct (but not old) consumer electronics. To me, a pair of them sound like something between Ge and Si, maybe leaning more toward Si. I found they work well in both hard and soft clipping, and give a bit more "Ge feel" in soft clipping where Ge's don't want to clip. 

[Mark Hammer]

I'm beginning to be more of a fan of two identical diodes and one of them with a resistance in series.  The problem is that diodes have fixed absolute forward voltages, and there is no guarantee that the difference between the forward voltage ofdiodes X and Y, or 2 vs 1 diodes, is appropriate for the signal level at that stage, or likely to generate the desired degree of asymmetry.

I might point out that the much-revered Interfax Harmonic Percolator employs 2 identical diodes with a fixed resistance in series with one of them.  The specific resistance seems to be different depending on whose copy you look at.  All of which recommends to me that a variable resistance, whethertrimpot or panel mount, is the way to go if asymmetry is your thing.

I've experimented with a few "warp" controls form AMZ, but this sounds like an interesting twist. What resistor values have you been using?

A 10k pot should do you nicely.

[lovric]

what counts when playing is the difference in sustain. when you equalize for the output of diff diode pairs with the level knob you get the longer sustain with Ge. the longest.

how much off the attack is left is another story.