# My New Favorite, The Chickenhead



## Jovi Bon Kenobi

Sweet baby Jesus this pedal sounds incredible! I couldn't even wait to label it to share my excitement. I haven't even biased it yet! I built it stock with no alterations. The hard to find 5nF cap was from Smallbear. The NPN germanium CV7112 was from reverb. The HFE is 88 and the leakage is zero! It's dead quiet except for a wee bit of crackling when turning the boost knob. I don't mind. If you haven't built a Germanium treble booster I can't recommend this enough. The boost knob is sort of like a volume and gain rolled into one. The other knob is "range" and boosts certain frequencies and can add the most creamy and warm bass or perfectly musical treble I've ever heard from a pedal. There is not a bad setting at either end of each knob. It's my new favorite sounding pedal I've ever built.


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## TomShadow

That's the smallest pcb I've ever seen and comes with such high recommendation. Definitely going into my list. Delightfully neat build as always. Very inspiring.


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## Mourguitars

Sweet looking build !


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## Gordo

Great build.  And those knobs!!!  You could adjust those puppies with skis on


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## Jovi Bon Kenobi

Gordo said:


> Great build.  And those knobs!!!  You could adjust those puppies with skis on


Those are new ones from BLMS. ?


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## Barry

Awesome, should have put it in a yellow box, it would look like a Minion!


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## Chuck D. Bones

Very nice build.  The size of the knobs is equaled only by the size of C2. ? 
Nice touch with the colored insulation on the transistor leads.
Let us know how tweaking the bias changes the tone.

I've got one of these in the works, with a PNP Ge tranny.


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## thedwest

Love this. Looking to add one to my board!


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## whgfive

What are your steps for adding the insulated wires to your transistors? Any tips? Love your builds.


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## Jovi Bon Kenobi

whgfive said:


> What are your steps for adding the insulated wires to your transistors? Any tips? Love your builds.


Thanks! That is just 3 pieces of 24AWG hook-up wire insulation. I just pull the wire out and used the insulation only. Once the wire is pulled out I just line em up and square off the ends with a craft knife so they're all the same size. Then I wiggle them onto the pins of the Ge transistor and plug it into the transistor socket. Actually, on any pedal that you have a "bias" trimpot, like the one here, it would be a smart idea to make the insulation for the "collector" pin a few mm shorter so you have an exposed section to test from. This allows you to use your DMM to probe the collector to measure and bias it in circuit.


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## HamishR

I've built a few of these on vero and can attest to their wonderfulness.  Absolutely my favourite booster.  I always build 'em NPN and have used AC127 and MP38s with excellent results.  I've even built some with a 2N2222A and a cap on the output to lose some of the highs to make it sound more Ge.  It actually works really well!  And you can obviously make it slightly brighter sounding than a Ge pedal if you want and with less noise.

The best thing about this booster is that you can bump up the lows to fatten up a Strat or drop it down a bit to get that classic Beano kinda sound with a Les Paul. It sounds so authentic.  I share your enthusiasm.


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## Jovi Bon Kenobi

HamishR said:


> I've built a few of these on vero and can attest to their wonderfulness.  Absolutely my favourite booster.  I always build 'em NPN and have used AC127 and MP38s with excellent results.  I've even built some with a 2N2222A and a cap on the output to lose some of the highs to make it sound more Ge.  It actually works really well!  And you can obviously make it slightly brighter sounding than a Ge pedal if you want and with less noise.
> 
> The best thing about this booster is that you can bump up the lows to fatten up a Strat or drop it down a bit to get that classic Beano kinda sound with a Les Paul. It sounds so authentic.  I share your enthusiasm.


Yeah I just love it. I'm quite shocked it's not noisier. I was thinking with the Ge it would be but it's so quiet. These military OC140's (CV7112) all have zero leakage. The guy I bought them from said David from D*A*M used to buy them from him and asked for 80-90 HFE when doing so...so I requested the same.
Nostradoomus helped me and said that the 5nf cap that's in this circuit is the one that controls the general tone of the range knob so it's not a bad idea to play around with that value. If you look at the new PedalPCB "Rangefinder" pedal you'll see that that cap is the one on the rotary switch, selecting different values. I couldn't be happier with the NOS 5nf from Smallbear. I think it's just perfect. I would suggest to socket it, but some of these NOS caps have really thick leads that wouldn't fit in the socket holes so take that into consideration. 5nf or even 4.7nf is just lovely.


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## Nostradoomus

Soooo...where’d you get the transistor? PM me  I’ve got secret stash peeps too


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## HamishR

I find 4n7 is close enough - and you can obviously get closer to 5nF with the range pot anyway I guess. I really love it with the range knob at around 10.00 with a Gibson.  Still has that classic honk but also a bit more grunt than a stock Rangemaster.  I am tempted to build one with a Sozo 4n7 cap to see if I can hear a difference but I doubt I could!


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## geekmacdaddy

secret weapon...


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## ChrisSchwarzkopf

I am about to Build this thing and since the CV7112 is impossible to find, I was wondering what a good substitute is...OC140? ASY28?


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## Jovi Bon Kenobi

The CV 7112 is a British military spec oc140 so yeah, but any NPN germanium with low leakage and HFE gains around 80-90 hfe would work. Socket it so you can a/b. Smallbear has a good selection.


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## ChrisSchwarzkopf

Jovi Bon Kenobi said:


> The CV 7112 is a British military spec oc140 so yeah, but any NPN germanium with low leakage and HFE gains around 80-90 hfe would work. Socket it so you can a/b. Smallbear has a good selection.


Tranks, i can get some OC140s on ebay so I will try these


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## zgrav

roll those dice and place that ebay order....    I've had good luck overall ordering some transistors from ebay, but have been disappointed with counterfeits a couple of times.


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## chongmagic

ChrisSchwarzkopf said:


> Tranks, i can get some OC140s on ebay so I will try these











						OC140 NPN Germanium Transistor NKT Fuzz
					

OC140 NPN Germanium Transistor NKT Fuzz



					www.pedalhackerelectronics.com


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## ChrisSchwarzkopf

Tj


chongmagic said:


> OC140 NPN Germanium Transistor NKT Fuzz
> 
> 
> OC140 NPN Germanium Transistor NKT Fuzz
> 
> 
> 
> www.pedalhackerelectronics.com


thanks but its 35$ shipping to Germany ?


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## chongmagic

ChrisSchwarzkopf said:


> Tj
> 
> thanks but its 35$ shipping to Germany ?



Ah, sorry about that.


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## Chuck D. Bones

The Bias adjustment makes this circuit pretty flexible.  Try any NPN germanium that you have.  HFE in the 50 to 80 range is preferable.  I built a similar boost and used a  Russian MP38A with good results.


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## ChrisSchwarzkopf

I finally built the pedal and agree: its absolutely* killer! *One thing: I‘ve got 2 OC140, one is 120 hfe and the other one 75. which one would you recommend for this circuit?


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## Chuck D. Bones

Either will work because the Bias trimmer can accommodate a range of hFE.  Personally, I'd use the 75 because the old RangeMasters didn't have high-gain transistors in them.  You most likely will not hear the difference.  Save the higher gain OC140 for a pedal that will benefit from it.


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## ChrisSchwarzkopf

Thanks man!


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## zgrav

In general, would you set the bias for 4.5 volt operation with this?  or slightly lower for more compression?  The demos for the Red Rooster do not sound squished so I would think the bias would be at half the incoming voltage.


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## Chuck D. Bones

For maximum headroom, we want the collector voltage 1/2 way between the power supply and the emitter voltage.  In this circuit, the emitter will be around 1V, depending on hFE, so we shoot for 5V on the collector.  Setting the bias higher or lower will reduce the headroom, increasing compression.  Transistors clip a little softer when biased cold, meaning less collector current.  For that, you would set the collector voltage higher.  I'd say start at 5V, see how you like the sound and then tweak from there.  Be sure to explore the RANGE settings as well as the guitar's Volume and Tone controls because this circuit interacts with the guitar's pickups and controls.


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## zgrav

Thanks.  Yet another pedal wanting to be the first effect in the chain.  : ^ )  I had noticed that the voltage on the emitter was staying close to 1 volt when adjusting the bias.


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## Chuck D. Bones

Try putting a buffered bypass pedal in front of this one just to hear the difference.


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## ericwood

HamishR said:


> I've built a few of these on vero and can attest to their wonderfulness.  Absolutely my favourite booster.  I always build 'em NPN and have used AC127 and MP38s with excellent results.  I've even built some with a 2N2222A and a cap on the output to lose some of the highs to make it sound more Ge.  It actually works really well!  And you can obviously make it slightly brighter sounding than a Ge pedal if you want and with less noise.
> 
> The best thing about this booster is that you can bump up the lows to fatten up a Strat or drop it down a bit to get that classic Beano kinda sound with a Les Paul. It sounds so authentic.  I share your enthusiasm.



Sorry to revive an older thread but I'd love to hear more about the output cap you're using for the 2n2222a builds! I'm doing a build with those already and since they're cheap and Tayda stocks them I was thinking about having a go at this circuit with them. I'm guessing without the cap it still sounds pretty decent? Thanks!


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## music6000

It's a Cool Booster, This Build is a few years ago with Eyelet Board:


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## HamishR

Eric it sounds excellent with the 2N2222A and no treble snubber. It's just brighter than a stock Red Rooster. The 1nF to ground can go from Boost 3 or the Collector and I would recommend it.


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## ericwood

HamishR said:


> Eric it sounds excellent with the 2N2222A and no treble snubber. It's just brighter than a stock Red Rooster. The 1nF to ground can go from Boost 3 or the Collector and I would recommend it.



That's great news! I'll play around with it, thanks for the reply!

The more I think about it the more upset I am they didn't name the original the "rooster booster." Huge missed opportunity.


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## music6000

ericwood said:


> That's great news! I'll play around with it, thanks for the reply!
> 
> The more I think about it the more upset I am they didn't name the original the "rooster booster." Huge missed opportunity.


Hey Eric, Rooster Booster would be a good name for your pedal!


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## bretvh

So, I just built one of these boards up for a friend and in testing, I am hearing a pretty prominent ocean/white noise sound when I am not playing. I can mitigate it a little by turning the gain way down (where is the fun in that?) or biasing it to a very low voltage, but I am wondering if I got a bad transistor (got mine on Reverb as well) or wired it up wrong. I notice yours has the red dot on the right side of the PCB, and I assumed the red dot goes to the tab side of the PCB footprint. Or does it matter with these transistors? I have not taken the time to desolder and swap it yet, but thought I'd ask here how much noise is "normal" and what is the correct orientation for that CV7112?

Edit: I just found this, which confirms you can put the CV7112 in either orientation:






						About Ge OC140 (CV7112 black glass military germanium)
					

About Ge OC140 (CV7112 black glass military germanium)



					www.diystompboxes.com
				




I'll have to look at the schematic. It could be I have it in the higher gain orientation, which is causing the noise.

Thanks!

-Bret



Jovi Bon Kenobi said:


> Sweet baby Jesus this pedal sounds incredible! I couldn't even wait to label it to share my excitement. I haven't even biased it yet! I built it stock with no alterations. The hard to find 5nF cap was from Smallbear. The NPN germanium CV7112 was from reverb. The HFE is 88 and the leakage is zero! It's dead quiet except for a wee bit of crackling when turning the boost knob. I don't mind. If you haven't built a Germanium treble booster I can't recommend this enough. The boost knob is sort of like a volume and gain rolled into one. The other knob is "range" and boosts certain frequencies and can add the most creamy and warm bass or perfectly musical treble I've ever heard from a pedal. There is not a bad setting at either end of each knob. It's my new favorite sounding pedal I've ever built.
> 
> View attachment 2171
> View attachment 2172


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## bretvh

Ok, never mind. I flipped the transistor and the noise is gone. More importantly, it sounds SO MUCH BETTER. At first I was like, "Huh, this is what people are all crazy about?" Now I get it, really nice range of gain and tones available!



bretvh said:


> So, I just built one of these boards up for a friend and in testing, I am hearing a pretty prominent ocean/white noise sound when I am not playing. I can mitigate it a little by turning the gain way down (where is the fun in that?) or biasing it to a very low voltage, but I am wondering if I got a bad transistor (got mine on Reverb as well) or wired it up wrong. I notice yours has the red dot on the right side of the PCB, and I assumed the red dot goes to the tab side of the PCB footprint. Or does it matter with these transistors? I have not taken the time to desolder and swap it yet, but thought I'd ask here how much noise is "normal" and what is the correct orientation for that CV7112?
> 
> Edit: I just found this, which confirms you can put the CV7112 in either orientation:
> 
> 
> 
> 
> 
> 
> About Ge OC140 (CV7112 black glass military germanium)
> 
> 
> About Ge OC140 (CV7112 black glass military germanium)
> 
> 
> 
> www.diystompboxes.com
> 
> 
> 
> 
> 
> I'll have to look at the schematic. It could be I have it in the higher gain orientation, which is causing the noise.
> 
> Thanks!
> 
> -Bret
> 
> View attachment 5272View attachment 5273View attachment 5274


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