# “Correct Leakage Numbers”



## Big Monk (Nov 23, 2021)

I’ve seen this said quite a few times lately. 

I’m not sure I understand. I’ve never considered leakage desirable enough for those to be a “correct” value for leakage. 

My thought has always been that leakage should be the lowest possible value to bias a “no-bias” or “leakage bias” stage and that’s literally the only place it’s desirable. 

Obviously, you put up with certain high leakage devices, along the lines of the OC75 for instance, because of the frequency content they may have. In that case, you do t mess with the vintage circuit because they bias up properly with leaky units. 

Other than that, I would want low leakage devices and to then tweak the circuit to accommodate them.


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## benny_profane (Nov 23, 2021)

Big Monk said:


> you do t mess with the vintage circuit because they bias up properly with leaky units.


I’m pretty sure you answered your question. Where else are people using them? I can’t think of a time someone wanted them for anything other than a vintage circuit. Although, people may be seeking certain qualities such as gating too. 

Of course, you can always make a non-leaky Q leaky but not the other way around. There’s a lot of mystique at play here. I think most people see published leakage specs and want those exact specs in their devices. Additionally, the internet is riddled with dubious part-specific tonal quality claims that send people on quests for exact part numbers. I think that’s a bigger issue than not simulating leakage.


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## Big Monk (Nov 23, 2021)

benny_profane said:


> I’m pretty sure you answered your question. Where else are people using them? I can’t think of a time someone wanted them for anything other than a vintage circuit. Although, people may be seeking certain qualities such as gating too.
> 
> Of course, you can always make a non-leaky Q leaky but not the other way around. There’s a lot of mystique at play here. I think most people see published leakage specs and want those exact specs in their devices. Additionally, the internet is riddled with dubious part-specific tonal quality claims that send people on quests for exact part numbers. I think that’s a bigger issue than not simulating leakage.



I was also thinking about leakage ONLY being important if:

a.) You NEED the vintage transistor

b.) You feel the need to stick to the vintage circuit values.


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## peccary (Nov 23, 2021)

When I said it earlier today I meant generally high or low. I found one today with an hFE of 88 and leakage of 1.2 mA 😲


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## Big Monk (Nov 23, 2021)

peccary said:


> When I said it earlier today I meant generally high or low. I found one today with an hFE of 88 and leakage of 1.2 mA 😲



Some of my GE 2N169s have been < 10 micro amps!

I could not get them to bias in a MK II. I’ve found 15 micro amps as a sort of lower cutoff.


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## HamishR (Nov 24, 2021)

There are quite a few modern circuits which use Ge - the Hudson Broadcast being a notable example. I guess it comes down to how we define "modern"!


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## jjjimi84 (Nov 25, 2021)

Does anyone feel like having the “golden” transistor label is just a dick measuring contest?

Instagram is full of these really cool builds with these rare expensive parts and I love looking at them but really wonder how they sound.

I personally could give a shit less if its vintage period, oc75, guaranteed to make your dick bigger transistors, its about how the circuit sounds.

A friend loaned me there nkt Analogman Sunface and it sounded really nice. Do you now what sounded better? My Monsterpiece GE fuzz and he is just using whatever and it sounds glorious.


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## peccary (Nov 25, 2021)

jjjimi84 said:


> Does anyone feel like having the “golden” transistor label is just a dick measuring contest?
> 
> Instagram is full of these really cool builds with these rare expensive parts and I love looking at them but really wonder how they sound.
> 
> ...


I mean if it's a _guarantee......_


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## jjjimi84 (Nov 25, 2021)

peccary said:


> I mean if it's a _guarantee......_


Not falling for that scam again


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## fig (Nov 25, 2021)

I believe it more to be a Iceo _limit_ in most cases, but I am a non-trained novice. When I trade or offer transistors I want that person to get the best piece or set for their build, so if there is a _known or preferential _threshold for leakage, because Ge is leaky, so if it is a circuit with Ge, there simply will be leakage (unless you buy in lots of 1000 and only save 0 Iceo samples), sooooooo......how much leakage are you willing to accept?


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## fig (Nov 25, 2021)

jjjimi84 said:


> Does anyone feel like having the “golden” transistor label is just a dick measuring contest?
> 
> Instagram is full of these really cool builds with these rare expensive parts and I love looking at them but really wonder how they sound.
> 
> ...


If I were _buying_ a pedal I would agree. For _building_ a pedal....I like my mojo...because it's _my_ way of adorning my work (at least for the moment). Seeing that capacitor I tracked down and waited for _just_ for this build is likened to tying flies, building a model, et al. It's not about any better sound (necessarilly) or magic....or is it?


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## jjjimi84 (Nov 25, 2021)

fig said:


> If I were _buying_ a pedal I would agree. For _building_ a pedal....I like my mojo...because it's _my_ way of adorning my work (at least for the moment). Seeing that capacitor I tracked down and waited for _just_ for this build is likened to tying flies, building a model, et al. It's not about any better sound (necessarilly) or magic....or is it?


Very interesting perspective, I would have never thought of it that way. My caveman brain just plugs in, turns up and bends out of tune until i get that chill. 

That is the way i measure leakage, if its coming out my d


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## fig (Nov 25, 2021)

jjjimi84 said:


> Very interesting perspective, I would have never thought of it that way. My caveman brain just plugs in, turns up and bends out of tune until i get that chill.
> 
> That is the way i measure leakage, if its coming out my d


That's where the rubber meets the road. When you rock it, none of the pretty matters!


Wait, we ARE still talking guitar pedals...right? 😎


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## Big Monk (Nov 25, 2021)

It’s definitely become a thing to produce these fuzzes with pulled parts and NOS transistors. So much so that you see people building with whatever is available from the old suppliers and charging premium. 

Many times they don’t sound like the originals. For instance, if I hear a Fuzz Face or MK II that sounds like a splatty, spluttery cacoaphoby, I know that person does not know what they are doing. This units in particular, along with the 1.5 and Supafuzz, are what I refer to as “refined” fuzzes. 

Frankly, all the NOS Mojo fuzz builders now seem to be going for the sputtery, glitched out thing. I understand that some fuzzes definitely fall in that category from the standpoint of vintage units but it does lead to ear fatigue and has on more than one occasion led me to question whether my builds sound right. 

In the end, I think the market is driven right now by people who don’t really know what fuzz is supposed to sound like and the makers are simply providing that.

I could be totally off base as well.


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## Coda (Nov 25, 2021)

I don’t think fuzz has a single description. The Fuzz-Rite and the FY-6 are both fuzzes, yet sound nothing alike. I think the current fascination with the glitch-tone fuzz comes from the influence of the Fuzz Factory…a pedal which is very popular, yet impossible to get. So now everyone is doing glitch monsters to compensate.


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## benny_profane (Nov 25, 2021)

We already had this discussion:

https://forum.pedalpcb.com/threads/what-the-glitch-is-going-on.8420/


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## Big Monk (Nov 25, 2021)

benny_profane said:


> We already had this discussion:
> 
> https://forum.pedalpcb.com/threads/what-the-glitch-is-going-on.8420/



That we did. My bad. I could never resist a good derail. 😜


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## Big Monk (Nov 25, 2021)

Back to my OP. 

Let’s take a circuit I know pretty well: The Classic Tonebender MK II. 

If you take 3 middle of the road OC75s with medium to high leakage, that stock circuit will bias up to vintage spec almost as an afterthought. The OC75 does have a desirable and definite upper frequency thing going on. Let’s bookmark that. 

Now you can pretty much take any low leakage Germanium transistor in a reasonable gain range (60-100 hFE) and tweak the circuit for bias and get most of the way there. What you can them do is tweak the input, treble bleed and emitter caps to get back some of that OC75 “zing”. 

What you get with the tweaked circuit that you don’t with the vintage spec is temperature stability. You can make the tweaked circuit sound like the Vintage spec but the Vintage spec will never have the bias stability that the tweaked circuit will. 

That’s my whole beef with leakage in a nutshell.


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## danfrank (Nov 25, 2021)

Big Monk said:


> Some of my GE 2N169s have been < 10 micro amps!
> 
> I could not get them to bias in a MK II. I’ve found 15 micro amps as a sort of lower cutoff.


There you go, you answered your own question. Sometimes a leaky transistor needs to be used in order to bias the transistor correctly in the circuit so the transistor "turns on" and conducts in order to pass signal. MK2 is an example of this. Cathode-base resistors can be used but I feel it's a "cheat" and a deviation of the original circuit.


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## Big Monk (Nov 25, 2021)

thewintersoldier said:


> View attachment 19179



I think this is hilarious.

I’m also 100% confident in my opinion. 😉


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## Big Monk (Nov 25, 2021)

danfrank said:


> There you go, you answered your own question. Sometimes a leaky transistor needs to be used in order to bias the transistor correctly in the circuit so the transistor "turns on" and conducts in order to pass signal. MK2 is an example of this. Cathode-base resistors can be used but I feel it's a "cheat" and a deviation of the original circuit.



It doesn’t take much though. Like I said, 15 microamps is all it takes to get a no-bias Q1 like the MK II to work.


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## jeffwhitfield (Nov 25, 2021)

Big Monk said:


> Back to my OP.
> 
> Let’s take a circuit I know pretty well: The Classic Tonebender MK II.
> 
> ...


As with anything, the answer is always: it depends.

High leakage, low leakage, high hFE, low hFE....really depends on the circuit itself and what you're going for. Personally, I haven't paid too much attention to leakage. I tend to focus more on hFE which gives me an indication of how much gain I can expect. Now, some of the circuits I've tried run the gamut of either being the typical sputtery fuzz or something that's more tame and yields more of an overdrive quality. One thing I've noticed is that there can be quite a difference in circuits that default to PNP transistors as opposed to NPN ones.


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## Big Monk (Nov 25, 2021)

jeffwhitfield said:


> One thing I've noticed is that there can be quite a difference in circuits that default to PNP transistors as opposed to NPN ones.



I’ve noticed many PNP devices simply have higher leakage and the circuit design is different to compensate for that.


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## Big Monk (Nov 25, 2021)

Short story long: I like talking about Fuzz and the minutia involved!


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## Harry Klippton (Nov 25, 2021)

Big Monk said:


> I think this is hilarious.
> 
> I’m also 100% confident in my opinion. 😉


The proof is in the pudding, and so far we don't have any. I'm waiting 🤨


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## jeffwhitfield (Nov 25, 2021)

Harry Klippton said:


> The proof is in the pudding, and so far we don't have any. I'm waiting 🤨


Eat pie then.


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## HamishR (Nov 26, 2021)

It's funny - I've made a heap of great fuzz pedals. Some of them I really like, some are just meh, some I have taken apart and used the bits for other things or given to guys who like them. 

But I never use one on my board. I have zero use for them.  Maybe one day!


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## Chuck D. Bones (Nov 27, 2021)

HFE and AC signal gain are not the same thing.  I discussed this at length in The Boneyard.
Some circuits are sensitive to HFE and most are not.
Some circuits need high leakage, some need low leakage and some don't care.  Big Monk is right about leakage biased circuits being inherently unstable thermally.  The TB Mk 1 is the only leakage-biased Fuzz that I've bonded with, it just sounds right to me.  But I know it will drift all over the place if it gets hot.  There are ways to make a circuit insensitive to leakage variation.  I did that with my FET-Ge Boost.  The Ge transistor has a large emitter resistor and smallish base bias resistors.  That's all it takes.  The emitter resistor is bypassed with a cap so I don't lose gain with the emitter resistor.  I'm more interested in building a circuit that sounds good than building a circuit that is an exact duplicate of something else.  If I want to get fancy and stabilize the bias without emitter resistors, then a servo is in order.

Vintage PNP Ge transistors are lower leakage and lower noise than vintage Ge NPN.  Because they performed better, they were more desirable and more plentiful.  That is why so many vintage Ge circuits, not just guitar pedals, used PNP.  The difference in PNP & NPN performance was a consequence of the manufacturing process at the time.  The Ge transistors manufactured in the 70s & later had much better performance and there was less difference between the NPN & PNP transistors.  My experience with the Russian transistors I've used (mainly MP38A & P28) is that the PNPs have significantly lower leakage.


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## Big Monk (Nov 27, 2021)

thewintersoldier said:


> I say the same thing all the time. I can love riffing on a fuzz alone but in my personal playing I find it hard to use. I have built so many that I realized it's for certain occasions. I generally find my RAT to be easier to use and gives more favorable results tonally.



This is a pretty key point I think. 

For starters, I don’t play in bands so my Fuzz knowledge is all personal (plus some feedback from a handful of commission builds I’ve done) and also confined to me riffing in my bonus room. 

I always seem to think of Fuzz as this wild sound but all my favorite recorded fuzz sounds (barring a few wild ones like on The Stooges records, etc.) are really more refined and/or modified to provide a sort of fuzzy overdrive sound.


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## Big Monk (Nov 27, 2021)

thewintersoldier said:


> Most fuzz that has the fuzz sound is scooped in the mids. Unless your playing in a dou or using the right gear in a trio, I find fuzz doesn't work well if you want to be heard in the mix. I find the adding a mids knob to a fuzz makes it easier to cut thru but changes the tone of the fuzz in an unpleasant way. It takes away all the fuzz character and turns it into an overdrive on steroids.



It always seems to a study in compromises. I always have a Pre-Gain pot (input resistance) on my MK II/Supa/MK 1.5/Fuzz Face builds. 

When you get them so your power chords crunch instead of mush out, the lead sound is gone and vice versa. 

It’s still such a compelling sound though. It’s so much fun to play and maybe that’s because I’m simply a hobbyist and I don’t have to sit in a mix anywhere.


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## fig (Nov 27, 2021)

Big Monk said:


> It’s so much fun to play and maybe that’s because I’m simply a hobbyist and I don’t have to sit in a mix anywhere.


Let's jam! You bring the fuzz...I'll play rhythm


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## Harry Klippton (Nov 27, 2021)

thewintersoldier said:


> I agree it's a cool sound but everything is in the right context. I find for the most usable fuzzy sounds are amp pushed past the edge like a Marshall or tweed fender.


I was gonna say a lot of my favorite fuzz sounds end up being cranked amps and stuff that's just really overblown


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## fig (Nov 27, 2021)

Strat into that li'l 2-watter I built sounds really creamy dimed. I use the guitar for whatever tone or volume adjustment.


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## Chuck D. Bones (Nov 27, 2021)

To paraphrase Carl von Clausewitz...

_“The enemy of a good fuzz is the dream of a perfect fuzz.”_


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## peccary (Nov 27, 2021)

thewintersoldier said:


> Most fuzz that has the fuzz sound is scooped in the mids. Unless your playing in a dou or using the right gear in a trio, I find fuzz doesn't work well if you want to be heard in the mix. I find the adding a mids knob to a fuzz makes it easier to cut thru but changes the tone of the fuzz in an unpleasant way. It takes away all the fuzz character and turns it into an overdrive on steroids.



I tried to use a Bass Big Muff in a live setting a couple of times. I might as well have just unplugged, it just dropped right out. Sounded good at home, though!


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## peccary (Nov 27, 2021)

thewintersoldier said:


> This is the problem with fuzz. Sounds awesome alone at home or when your doing corrective EQing in a daw but live shit just disappears. Also why I don't understand the love of full frequency boosts and drives. Everything turns to mush and gets lost in a mix. Then all the mod threads to cut bass lol


I've been preaching the church of the Vario Boost to everyone who plays guitar or bass. It's one of the most useful pedals a person can have, IMO.


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## Big Monk (Nov 27, 2021)

thewintersoldier said:


> I agree it's a cool sound but everything is in the right context. I find for the most usable fuzzy sounds are amp pushed past the edge like a Marshall or tweed fender.



I agree. With some “ass” behind it, it tends to sound better.


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## benny_profane (Nov 27, 2021)

Use all the fuzzes or whatever in the studio. Live, get a Rat and you're set.


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## HamishR (Nov 30, 2021)

peccary said:


> I tried to use a Bass Big Muff in a live setting a couple of times. I might as well have just unplugged, it just dropped right out. Sounded good at home, though!


This is why Skreddy adds a flat or pushed mids switch to so many of his Muffs. They work. When making a Skreddy fuzz I generally leave the switch off and just build the version with more mids.

The Marshall Supa Fuzz was made for Marshall by Sola Tone. It uses bigger caps and has a huge sound, not unlike a Big Muff. But it has plenty of mids, so should be heard.

This all relates to why I love Gretsch guitars so much. For a long time I would turn up to rehearsal with my Tele or Strat all dialled in with whatever new Fender amp I had and use the onboard dirt on the Fender amp. (This was a long time ago - think Rivera-era Fender amps)  And my sound would be soooo thin in the band context.  So I would try a 335 or something and my sound would be all mids and no cut. Tiny little sound, even though at home it sounded like Angus Young.

Then one day I took a '64 Gretsch 6120. At home it sounded a bit rough but in the band all of a sudden I had this broad, expansive tone which sat beautifully in the mix but still sounded huge. It cut though like a Fender but retained the body of the sound - heavenly!

Ever since I have used Gretsches. I still have some wonderful Gibsons but for gigs it's usually a Gretsch. Sometimes a Gibson with P90s.


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## Big Monk (Nov 30, 2021)

HamishR said:


> The Marshall Supa Fuzz was made for Marshall by Sola Tone. It uses bigger caps and has a huge sound, not unlike a Big Muff. But it has plenty of mids, so should be heard.



What's interesting about the Supafuzz is that when it was produced by Sola Sound, it was just a re-branded MK II. Same circuit.

When Sola Sound ended the contract to produced them for Marshall, Marshall took over production in-house. That's when the 10 uf Input and Emitter caps came in. Interestingly enough though, they also removed the treble bleed cap at some point. However, it seems there was a period where they were still built with the treble bleed cap.

I've breadboarded both many, many times. The 10 uf/0.01 uf combo has a lot of "Ass" (for lack of a better term) and it should considering the treble rolloff at the input from the 0.01 uf. The 10uf/no treble bleed combo is interesting because it is actually a little brighter than the stock MK II but also just a touch fatter because of the bigger input and emitter caps.


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## HamishR (Dec 1, 2021)

Big Monk said:


> What's interesting about the Supafuzz is that when it was produced by Sola Sound, it was just a re-branded MK II. Same circuit.
> 
> When Sola Sound ended the contract to produced them for Marshall, Marshall took over production in-house. That's when the 10 uf Input and Emitter caps came in. Interestingly enough though, they also removed the treble bleed cap at some point. However, it seems there was a period where they were still built with the treble bleed cap.
> 
> I've breadboarded both many, many times. The 10 uf/0.01 uf combo has a lot of "Ass" (for lack of a better term) and it should considering the treble rolloff at the input from the 0.01 uf. The 10uf/no treble bleed combo is interesting because it is actually a little brighter than the stock MK II but also just a touch fatter because of the bigger input and emitter caps.


Well I'd never heard that! All I know is that I like the Marshall version a lot more than the original TB. This place is a wealth of information.


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## Big Monk (Dec 1, 2021)

thewintersoldier said:


> This is the problem with fuzz. Sounds awesome alone at home or when your doing corrective EQing in a daw but live shit just disappears. Also why I don't understand the love of full frequency boosts and drives. Everything turns to mush and gets lost in a mix. Then all the mod threads to cut bass lol



I goofed around a little bit after modifying my Ge Fuzz Face yesterday with a low gain Side 1 of my Paragon Mini and my Vick Audio Overdriver into the Fuzz Face. 

The Vick Audio Overdriver was nice because it retained that transistor fuzz feeling and let me kind of turn the Fuzz Face into a MK II with a single stomp.


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## Big Monk (Dec 1, 2021)

thewintersoldier said:


> Push the fuzz face with a range master. Make sure to have a spare set of pants



I've got 5 or so GE 2N169s between 55-70 hFE. I have not built a Rangemaster in a long time.


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