Here is the Mangler I built. Can't wait to compare it with the Zygote and other fuzz boxes I have built. Running it with a road rage with some Small Bear transistors.
Thanks to aestoval for tipping me off to the pre gain mod. I realize this is built in to the zygote but I didn't at the time.
Friggin sweet looking pedal man... I love the look of this one
Quote from: sgmezei on October 09, 2011, 01:09:42 AM
Here is the Mangler I built.
Thanks to aestoval for tipping me off to the pre gain mod.
Cool looking pedal. I just built a mangler and think the pre-gain would be a great addition. How was that accomplished? Thanks!
You must have a nice fuzz arsenal by now :)
That is one huge freakin knob..!
Bluestrat
I got the idea from Aestoval on the thread here:
http://www.madbeanpedals.com/forum/index.php?topic=2782.0
Bean also has the same idea on his Zygote build. Check out the 50kb "strain" knob/pot on the build document. I used the idea from fuzz central but most of the pots rotation is useless so I hope to find a better value down the road.
Quote from: sgmezei on October 10, 2011, 04:56:51 AM
Bluestrat
I got the idea from Aestoval on the thread here:
http://www.madbeanpedals.com/forum/index.php?topic=2782.0
Hey, thanks for the response. I might give this a shot. Did you use the small resistor and cap before the pot as indicated on the Zygote pdf? I wonder if that would spread out the sweep of the pot. I'm also getting some RF interference when I turn down the guitar volume knob and I wonder if those two items would help with that as well.
Hmmmm I am not sure. I will have to line up my zygote and mangler and see. Maybe some of the veterans will chime in with some info.
Quote from: Bluestrat on October 10, 2011, 01:22:01 PM
Quote from: sgmezei on October 10, 2011, 04:56:51 AM
Bluestrat
I got the idea from Aestoval on the thread here:
http://www.madbeanpedals.com/forum/index.php?topic=2782.0
Hey, thanks for the response. I might give this a shot. Did you use the small resistor and cap before the pot as indicated on the Zygote pdf? I wonder if that would spread out the sweep of the pot. I'm also getting some RF interference when I turn down the guitar volume knob and I wonder if those two items would help with that as well.
Is it RF interference or self oscillation (like a high pitch whine?). Self oscillation is common and you can do a few things to stop it. Try a small (100 ohm) resistor on the emitter of Q1 or a small capacitor (50-100pf) on Q2 from the collector to the base.
Is it RF interference or self oscillation (like a high pitch whine?). Self oscillation is common and you can do a few things to stop it. Try a small (100 ohm) resistor on the emitter of Q1 or a small capacitor (50-100pf) on Q2 from the collector to the base.
[/quote]
Hi, Jakefuzz. Definitely RF, a really weird old music radio station, happens with a few of my other pedals as well.
Seems to vary depending on which of my strats I use. I have one with really low output Lollars and that gets the best reception :o Both guitars are well shielded. I have read that using a small cap on the input might help. I'm using an AB switch at the front of my effects and that seems like a good place to experiment. Any other suggestions?
The Mangler sounds great BTW. Really happy with it.
Hmm yeah that's strange. I have heard that coming from an old treble booster I once had. You are going to want filter out only very high frequencies so I would think a really small cap to ground on maybe the input would be a good experiment to try.
For RF interference I know there is a 68k resistor right at the input jack on most amps. Well the two fenders I have built both have them there and that is what I have read they are for.
You need an RC filter (Resistor/Cap) in order to filter out those unwanted frequencies. Most pedals already have a resistor in series with the input, if not, add a small resistor like Paul suggested (100Ohms) and then by just adding a 100pF cap from input to ground, it should help you out. Tie one leg from tip and the other to sleeve (If I'm wrong, someone please correct me :) I'm merely going with my instincts here haha)
If you would like to read more about electronic filters, here's a link: http://en.wikipedia.org/wiki/Electronic_filter
:) Great pedal btw! I love how it looks, good job!
-Kaleb
Actually...now that I think more about it...your guitar is already acting like the resistance in series with the input (you did say that it happens when the volume is rolled off...) so you only need a small cap from input to ground on your pedal. (I think!) haha
-Kaleb
You can look at the formula for the complex impedance of a capacitor Z=1/(JwC) and select a capacitor on the input that will give you a cutoff frequency above the acoustic range (20Khz=200001/s). What you are doing by adding the cap from the input to ground is just rerouting the very high (unwanted) frequency part of your input signal with a lower path of resistance to ground before it is amplified and fuzzed by your Mangler.
You can plot this impedance as a function of frequency and change the capacitance in something like excel (or if you want to go crazy you can do a 3d surface in matlab!). What you would be looking for is an appreciable drop in Z around 20Khz (remember w is in radians/second). Too far into the audible range and you are cutting off your high end. Or you can just start with really low value capacitor on the input jack and just start adding them in parallel until the noise goes away :D
You don't really don't want to use and RC filter because adding a resistor in series (the low pass configuration) will change the input impedance of your FF and we all know what happens when you do that... (like the pre-gain knob).
You're the man Paul! :D
Thank you for sharing your knowledge with us
-Kaleb
Hey, all great suggestions for taming the RF. Turns out the station I'm picking up is Georgia Tech and I'm only about a half mile from them and it's a strong signal. I'm going to give the small cap a shot. Analog Man made the same suggestion.
I'm running a "FatPants" first in my chain and when I have that on I don't have any noise with the FF. My guess is it's filtering out the RF interference. I'd like to use the FF without the FP so it's cap time ;D
BTW, it was your demo of the Mangler JakeFuzz that made me want to build it. Thanks! I Love the pedal.
:D awesome. Glad to see my noodling inspired you. The fuzz face is by far my favorite circuit, it is so incredibly simple and yet sounds so good. I really like to see how the bandwidth and internal capacitance of the different types of devices effects the sound and dynamics of the effect, something unintentional and in almost every other application totally undesirable.
I just bought two OC44's, an OC81, a 2SB77, and a 2SB75 all in the gain ranges for a FF. Not to mention the Russian germs I have coming in soon! Gonna be some testing and reporting in my future.
By the way Scott, which trannies did you end up with in here, those look sort of like the AC128's I have right now. How do they sound?
Quote from: k.rock! on October 11, 2011, 03:11:14 PM
You need an RC filter (Resistor/Cap) in order to filter out those unwanted frequencies. Most pedals already have a resistor in series with the input, if not, add a small resistor like Paul suggested (100Ohms) and then by just adding a 100pF cap from input to ground, it should help you out. Tie one leg from tip and the other to sleeve (If I'm wrong, someone please correct me :) I'm merely going with my instincts here haha)
-Kaleb
Whoo Hoo ;D I added the 100pF to the input jack as you suggested Kaleb and it works perfect! No more interference even with the gain cranked all the way and it doesn't matter what the guitar volume is. It also cleaned up the RF noise I was getting further down the chain of effects as well. No change in the sound, just no more funky radio! I didn't need to add the resistor. Thanks again for the suggestion.
I will have to take a look. I got them from small bear and I believe I know they are not AC128's because those went into my zombii.
Which brings me to my next question. I can't afford to keep buying matched pairs from SB and I have seen other folks talking about different transistors and buying bulk lots and such (the russian germanium thread). I have no idea what I would be looking for and all of the codes and labels are gibberish to me.
Where do you recommend I start looking for some different sources of transistors?
Also, any recommended reading on this topic?
Quote from: sgmezei on October 12, 2011, 05:23:55 AM
I will have to take a look. I got them from small bear and I believe I know they are not AC128's because those went into my zombii.
Which brings me to my next question. I can't afford to keep buying matched pairs from SB and I have seen other folks talking about different transistors and buying bulk lots and such (the russian germanium thread). I have no idea what I would be looking for and all of the codes and labels are gibberish to me.
Where do you recommend I start looking for some different sources of transistors?
Also, any recommended reading on this topic?
There is a big thread over at FSB called "Germanium Transistors" that documents some pretty sad failures in finding bulk lots. But they also list the most promising Russian transistor number codes to look for. I've pretty much given up on finding bulk lots of the rare stuff. Most people with a lot of these bulk transistors know how much people are willing to buy them for. I pretty much wont buy any transistors unless they have been tested and guaranteed for gain and leakage, are super cheap or I can obtain a sample to test myself. Ive literally asked a ton of surplus store owners and they say bulk buys are very difficult to come by these days. Most people have been ripping apart old transistor radios to find some of those OC and 2SA/B types. To be honest I've been feeling more and more like SB is a really good deal for what you get and the time you save. I have also tried contacting DSI who apparently makes modern reproductions from the same photo lithography masks as the originals, but they never answered me back. Their reproductions include the OC81D, The OC44 and according to Mark Hindes the OC140 too.
Quote
Whoo Hoo ;D I added the 100pF to the input jack as you suggested Kaleb and it works perfect! No more interference even with the gain cranked all the way and it doesn't matter what the guitar volume is. It also cleaned up the RF noise I was getting further down the chain of effects as well. No change in the sound, just no more funky radio! I didn't need to add the resistor. Thanks again for the suggestion.
Haha awesome! Yeah, Paul indicated that the resistor wasn't necessary to add to the circuit, for which I agree. Although I sort of think that, in a way, you did end up using an RC filter using your guitar impedance as the Resistor and the Cap at the input to ground ;D So that's pretty cool!
I'm glad it worked out, and thanks to Paul as well. You rock dude!
-Kaleb
Wooohooo! Nice looking pedal there buddy! I'm glad to see the little pregain trick got some use. Now I have to build another one and show off some guts. ;D Keep on rockin'!
Awesome graphics work. And rarely have I learned more in a show your build thread :)