Building a Ge SkyRipper

[duck_arse]

AC series transistors are known/can be/might sound 'darker' in circuit. higher internal capacitance [?] tends to cut the treble response. maybe. sometimes. it has happened.

[BetterOffShred]

I've heard that, I have some MN426's, but they are all mid 80's or lower.    I personally think I can tell J201's are darker than other FETs,  but yeah it could just be me..

What is "too leaky" for an AC128? I built that Geofx germanium tester and these guys are like .200ish.  It's crazy to watch them change rapidly if you warm them up in your hand.. I guess that's why we switched to silicon   

Thanks for looking

[BetterOffShred]

Well once I got the Rangemaster part working this thing really .. rips!  . I went a little bigger on the 4 range caps, 682, 103 104 and 224..  the 224 really gets some crazy suboctave going with the ripper engaged.  The box is getting primed right now and then I'll paint it up and put it all back together.  Really great project.  This thing is super fun. I haven't even fooled around with the send loop yet.  Maybe a reverb and a delay in there.

I'll put up a few more pics when I get it painted
Thanks for looking

[digi2t]

I haven't even fooled around with the send loop yet.  Maybe a reverb and a delay in there.

Try it with a wah. 

[BetterOffShred]

I got a 535Q around somewhere with the 18V power supply.. It's been a long time since I used a Wah.. maybe my functioning Gristleizer with the VCA.. hehe.  Thanks

[BetterOffShred]

Little update: 

I got it sounding pretty good with my AC128's, but I figured out they are a little lower gain than I anticipated because my tester doesn't account for leakage.  So using the GeoFx tester I discovered they were about 10% lower gain than previously expected.   The leakage on both is below 200, (ma I believe? ..) and like I said the circuit sounds good to me as is... Buuuut... I ordered a bag of MP20B's from Russia which are reported to be min 80 hFe, and up to the 200 range with pretty good leakage specs.   So I may box this up, but hold off on soldering in my AC128's until the other's arrive and I can pick out a nice candidate in the 90 range, and another fine fellow in the 150 range.   I also have a few audio taper pots coming for the suggested locations, Range, Vol, and Pre gain - but they are easy to get to with my enclosure so once again I may just box it up for now and let the good times roll. 

I Painted the box sky blue..  and have been wet-sanding it to get a smooth finish.   I don't etch or do anything cool like that yet, so I use a laser printer to print out labels on clear shipping labels and then clear coat the whole shebang once I've got everything positioned.  It's not ideal, but I just don't have the time to get all fancy.  I'd like to try waterslides, that seems pretty efficient.   
Thanks for looking!

[digi2t]

MP20B's are great. As I mentioned before, you may also try 2N2904A in Q2, and a 2N2905A in Q4. I pulled my germaniums out a long time ago in favor of these. Silicon means no leakage, or temperature sensitivity. Sound-wise, maybe a tad different to your ears, but sounds plenty fine to me. Besides, in Ripper mode, as long as a Ge diode is used, all the same effects can be had regardless of what you decide to use up front.

Sidebar; I'm pretty sure Spaceman Effects ripped off the Ripper idea for the Sputnik's. Which would make it a "ripped off Ripper".

[BetterOffShred]

I think the 2N2904/5's cost more than Measured Germanium singles!    Initially I got into this hobby because I'm kind of crafty and .. well cheap.   Now I'm tracking down NOS Russian parts and holding my pinky out while I drink tea and solder!   Seriously though, I love the stability of Silicon stuff I guess,  but these effects are my "Living Room Hero" arsenal and will probably never be used anywhere else.  The AC128's with the pre down and the rangemaster engaged and boosting my amp quite a bit.. so smooth and nice.  I'm sure this can be had with other fuzzes, but this is the first Germanium thing I've built, and now I've got bags of Ge transistors coming from all over.  I guess my quest for being cheap turned into something else! 

That's interesting about the Sputnik.. I mean the Ripper is a pretty fantastic design IMO.. it's pretty wild all the stuff it's capable of doing.  It's really like 4 pedals in one, or more.   

I am curious though if anyone who has one or knows about it cares to comment.. What exactly is the purpose of the buffer?  Just to regain signal like standard buffers?  Does it interact with the circuit in any other way?  When I have it engaged I find it to cut volume considerably and usually turn it all the way up    ..  I checked it over a few times and the wiring is good on it, so I'm just not sure what it's all about!

[davent]

MP20B's are great. As I mentioned before, you may also try 2N2904A in Q2, and a 2N2905A in Q4. I pulled my germaniums out a long time ago in favor of these. Silicon means no leakage, or temperature sensitivity. Sound-wise, maybe a tad different to your ears, but sounds plenty fine to me. Besides, in Ripper mode, as long as a Ge diode is used, all the same effects can be had regardless of what you decide to use up front.

Sidebar; I'm pretty sure Spaceman Effects ripped off the Ripper idea for the Sputnik's. Which would make it a "ripped off Ripper".

I'm going to have to try some 2904's, i'm sure i have a small collection but it's been a long time since i went searching.

dave

[BetterOffShred]

This is the color I went with. Got a few coats on to get it nice and shiny with some wet sanding in between

[digi2t]

I am curious though if anyone who has one or knows about it cares to comment.. What exactly is the purpose of the buffer?  Just to regain signal like standard buffers?  Does it interact with the circuit in any other way?  When I have it engaged I find it to cut volume considerably and usually turn it all the way up    ..  I checked it over a few times and the wiring is good on it, so I'm just not sure what it's all about!

At the heart of it, you have a Fuzz Face type circuit. I think the buffer is there to maintain a proper impedance so as the fuzz section "plays nice" with anything you decide to throw in front of it. Fuzz circuits sometimes don't sound right when placed after certain effects/buffers/etc, so the I believe the buffer is there to show the circuit a certain desired impedance level. This is probably important where the Ripper section is concerned as well, since the oscillation effects are really dependent on seeing a certain impedance up front, hence the high degree of interactivity with guitar control manipulations.

If I'm off the mark here, I'm sure one of the gurus (or Joe himself) will be along to set me straight.

[BetterOffShred]

That makes sense.  I wasn't thinking about the input level/strength of signal while it's ripping.  I've seen this before with the Parallel Universe 2.. I dial in a good oscillation and then hit it with a booster or something and it changes everything. 

Thanks for the comment, I'm really pumped to try it out with a bunch of stuff before and after now to see how the buffer makes it behave Hah! 

I'm going to try and print the labels at work today and finish the box so I can get back to ripping!

[duck_arse]

Sidebar; I'm pretty sure Spaceman Effects ripped off the Ripper idea for the Sputnik's. Which would make it a "ripped off Ripper".

you mean ....... someone's jacked the ripper?


on topic, but veering - @better - if you wanted to go a bit silly w/ you s/ripper and those low gain germs, you could put two of them in a darlington config, and see what that does - besides overwhelming hFE numbers.

[BetterOffShred]

Yeah I think the lowest I have is a few around 20.. that's still 400ish in a darlington config.. maybe it sounds good haha!  Might be worth a try!

[digi2t]

PU II is definitely impedance sensitive. Stick a buffer in front of it, and it will kill the oscillation completely. That one had me scratching my head for a while when I changed my setup.

In this regard, I cheated it into working with buffers in front by using an AMZ pickup simulator. This creates an impedance that the circuit
"likes to see" for the oscillation to work properly when using buffers, or buffered effects, in front of it. I added it to my vero, and there will be a PMowdes Parallel Universe II PCB out soon with the pickup sim already integrated into it. This is the sim I used;



The switch gives a single or humbucker level, and the pot adjusts within that range. The 330pF cap (I think) is for cable length simulation, and can be adjusted to taste. I used the 330pF, it works fine. My ears ain't that good no more.

My PU II vero is here;
http://www.aronnelson.com/gallery/main.php/v/digi2t/veros/Parallel+Universe+II/PU+II_NEW.jpg.html?g2_imageViewsIndex=1

I've seen a couple of circuits on the market with some sort of audio transformer pickup sim incorporated into the circuit, such as the Wyllie Moonrock, and the Spaceman Gemini III.

[BetterOffShred]

My PU2 was one of the first pedals I ever built and it's still one of my favorites but I'm thinking about redoing it in the near future and I'll probably use your layout Dino.  I like the idea of having that simulator up front.  When I was getting it working I was using a telecaster with Texas specials a lot at the time and the oscillation stuff never sounded right.  Then I plugged in my LP and it was off to the races.  I also found out that it's fairly sensitive to 386 chips.. I tried like 20 and found the ones that had the best range with the oscillation on.  I also wired it up for an expression pedal to control the oscillation "tune" though I've never used that feature yet.

I also have the Gemini III parts and transistors sitting there ready to go.. I started a sonic Titan yesterday instead (Well deafbutpicky's Kronos)  but I'll probably get to the Gemini this weekend.  Hey, if nothing else.. I myself am a Gemini 
I'm waiting on those 2SB172's for Harvey Dent .. or the MP20B ..
Stuff takes a while to come from Russia and Bulgaria hah!

[BetterOffShred]

It isn't a Skyripper unless it looks like a disco scuba divers symbol .. 

[BetterOffShred]

I'll have some time tomorrow to box this up, though I spent some time reading the articles Steve from smallbear posted in that recent germanium transistor thread.. and I may try and build a little "Darlington Breakout Board" to see if I can achieve relatively close to 150 hFe out of a few of my low gain MP42B's.   I also ordered 2 measured AC125's at 128 hFe so I'll try one of those in the fuzz section, and then probably stick the other in a "Phat Phuk B" boost I Hope to build for another project.   The nice thing about most of the Germanium circuits (most) is that they have a relatively small footprint so building a darlington board with a couple transistors and associated resistors on it isn't going to overload your available space.  I like to build most things in a 125B or a 1590BB anyway!    I have big feet. 

[duck_arse]

,,,,,,,,  I have big feet.

and lots of them, from your profile pic.

[BetterOffShred]

Thats a beard man! 

So I'm putting my labels on and clear costing this when I get back from my boys 9:00 swim lesson.  I also put stickers and labels on my Kronos so I'll post pics of that too
Thanks for looking dudes