Author Topic: Mangler build with pregain  (Read 5030 times)

Bluestrat

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Re: Mangler build with pregain
« Reply #15 on: October 11, 2011, 11:35:19 AM »
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.

JakeFuzz

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Re: Mangler build with pregain
« Reply #16 on: October 11, 2011, 05:42:27 PM »
 :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?

Bluestrat

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Re: Mangler build with pregain
« Reply #17 on: October 11, 2011, 08:46:45 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.

sgmezei

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Re: Mangler build with pregain
« Reply #18 on: October 11, 2011, 11:23:55 PM »
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?

JakeFuzz

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Re: Mangler build with pregain
« Reply #19 on: October 11, 2011, 11:45:13 PM »
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.  

k.rock!

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Re: Mangler build with pregain
« Reply #20 on: October 12, 2011, 07:16:29 AM »
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

aestoval

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Re: Mangler build with pregain
« Reply #21 on: October 13, 2011, 09:20:56 AM »
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'!

TNblueshawk

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Re: Mangler build with pregain
« Reply #22 on: October 15, 2011, 06:53:12 AM »
Awesome graphics work. And rarely have I learned more in a show your build thread  :)
John