Granger Boost 2N1308

[ac30irons]

Hey there, looking at building a Granger Boost but can only get a transistor with a hfe of 250ish and leakage of 0.574.

What would be acceptable parameters in peoples opinion ?

Thanks

 

[jwin615]

That leakage may be a little bit much.
Looks like a modded range master. IIRC, those didn't have super high hfe(for Ge) but low leakage is a little more critical. I probably have one or two I could ship you. Can check tonight. Are you stateside?

 

[ac30irons]

That leakage may be a little bit much.
Looks like a modded range master. IIRC, those didn't have super high hfe(for Ge) but low leakage is a little more critical. I probably have one or two I could ship you. Can check tonight. Are you stateside?

Hey there, thanks for a quick reply. Unfortunately I’m in the UK which makes sending anything a pain in the ‘a’.

I know the original RM was in the 70 - 120 rage with 0.25 on the leakage. I wonder why such a contrast for this one ???

 

[jaspinwall]

Hey there, thanks for a quick reply. Unfortunately I’m in the UK which makes sending anything a pain in the ‘a’.

I know the original RM was in the 70 - 120 rage with 0.25 on the leakage. I wonder why such a contrast for this one ???

FWIW, I used a CV7351 that was about 95-100 hFE and it sounds like the real Thorpy Have Blue pedal I have sitting next to it - and coincidentally, using RG Keen's method of measuring the transistor in the Thorpy pedal, I get ~90 hFE with ~.098 mA for the leakage. I get ~85 hFE with ~.115 mA for the leakage with a DCA55, and the DCA75 with the default test @ 5mA is some kind of stupid value at ~171 hFE with ~.138mA leakage.

If you look at the transistor values that were also measured for the Tacit Blue, they're also high for a Fuzz Face and more likely than not, because of the DCA75 running test currents so high, right in the normal margin for Q1 and Q2 FF transistors.

I don't know why the measurement was so high on the one that was traced for the build doc, but I would be willing to bet it's an anomaly rather than the norm and he was able to make it bias and hold that bias, so it shipped.

 

[ac30irons]

FWIW, I used a CV7351 that was about 95-100 hFE and it sounds like the real Thorpy Have Blue pedal I have sitting next to it - and coincidentally, using RG Keen's method of measuring the transistor in the Thorpy pedal, I get ~90 hFE with ~.098 mA for the leakage. I get ~85 hFE with ~.115 mA for the leakage with a DCA55, and the DCA75 with the default test @ 5mA is some kind of stupid value at ~171 hFE with ~.138mA leakage.

If you look at the transistor values that were also measured for the Tacit Blue, they're also high for a Fuzz Face and more likely than not, because of the DCA75 running test currents so high, right in the normal margin for Q1 and Q2 FF transistors.

I don't know why the measurement was so high on the one that was traced for the build doc, but I would be willing to bet it's an anomaly rather than the norm and he was able to make it bias and hold that bias, so it shipped.

Thanks dude, I really struggle with the whole gain/leakage thing. That combined with trying to get some stuff in the UK makes it difficult to try out. What do you pay over there for a Ge like this ?

 

[jaspinwall]

Thanks dude, I really struggle with the whole gain/leakage thing. That combined with trying to get some stuff in the UK makes it difficult to try out. What do you pay over there for a Ge like this ?

You can look at Small Bear Electronics to get an idea of what they charge for pre-sorted and tested PNP and NPN transistors and that might translate to what you'd pay in the UK after factoring in the exchange rate.

I'd look for 2N1306 or eve 2N1304s or their military equivalents too, because they'll be in the Rangemaster gain range as well.

 

[ac30irons]

Amazing, thanks so much for all your help.

 

[ac30irons]

@jaspinwall woudl you be able to tell me how I check what’s pre-sorted ? I’ve had a look on small bear and can’t work it out. All I can see is a rough per 100.

 

[jwin615]

I'm not certain small Bear sorts anymore. Not like they used to anyway(new ownership).
Have you tried your transistor?
Just socket it or if it has long leads, barely solder it in, leaving it standing proud.
If it sounds good....
Also, if it doesn't work out, there are some reputable UK sellers on ebay. langrex comes to mind but I know there are a couple others.
UK in stock is another. I've used both sellers and been very happy. There's been some debate about Langrex selling rebadged AC12Xs, or at least the ones made in the 80s 90s, but I haven't purchased any of those and have no feedback on that. Searching the forum for "Langrex" should supply some results on that.
Here's some UK CV7351s, though I have no experience with that seller.
There are also some Bulgarian sellers that carry some nice wares including old Tesla transistors, if Bulgaria imports are VATed to hell(I'm stateside, so no idea).

I'll also echo, the JAN(mil-spec) 2N130X are, in my experience, all speced really well. I happened across a load of harvested JAN2N1308s a while back and of 38, 2 didn't work. The rest all were extremely low leakage. A couple were high hfe and one was low, the rest were firmly within a +/- 20 hfe window of each other.
Anyway. Maybe some of those UK sellers will help. I'd advise getting at least 3, preferably 5+, not 1.
Hope this helps.

 

[ac30irons]

I'm not certain small Bear sorts anymore. Not like they used to anyway(new ownership).
Have you tried your transistor?
Just socket it or if it has long leads, barely solder it in, leaving it standing proud.
If it sounds good....
Also, if it doesn't work out, there are some reputable UK sellers on ebay. langrex comes to mind but I know there are a couple others.
UK in stock is another. I've used both sellers and been very happy. There's been some debate about Langrex selling rebadged AC12Xs, or at least the ones made in the 80s 90s, but I haven't purchased any of those and have no feedback on that. Searching the forum for "Langrex" should supply some results on that.
Here's some UK CV7351s, though I have no experience with that seller.
There are also some Bulgarian sellers that carry some nice wares including old Tesla transistors, if Bulgaria imports are VATed to hell(I'm stateside, so no idea).

I'll also echo, the JAN(mil-spec) 2N130X are, in my experience, all speced really well. I happened across a load of harvested JAN2N1308s a while back and of 38, 2 didn't work. The rest all were extremely low leakage. A couple were high hfe and one was low, the rest were firmly within a +/- 20 hfe window of each other.
Anyway. Maybe some of those UK sellers will help. I'd advise getting at least 3, preferably 5+, not 1.
Hope this helps.

I’m currently talking to Langtex about some 1304s. I’ve had BJTs from them before. They tested the CVs your talking about and they where all 30 - 40s HFE . The 1304s work out at £2 a pop, I will take a punt.

Thanks for all your help.

 

[jaspinwall]

I’m currently talking to Langtex about some 1304s. I’ve had BJTs from them before. They tested the CVs your talking about and they where all 30 - 40s HFE . The 1304s work out at £2 a pop, I will take a punt.

Thanks for all your help.

I guess now Small Bear sells kits for NPN or PNP transistors for Rangemasters, Fuzz Faces and Tone Benders. They're not as expensive as paying to have them select individual transistors for the gain/leakage you want but they're not far off. Add shipping to the UK and you've got a pretty expensive pedal.

I second Langrex because I've bought from that seller before and it's always worked out well.