OK- Built 2 Rangemasters- 1 NPN, 1 PNP

[jimbob]

I had originally posted my build report of a PNP Rangemaster using GEO/GGG for the layout and values and a OC44 with GREAT results. It was a fantasic sound. Now, I was FORTUNATE enough to have aquired some NPN OC140 CV7112 military version. Black glass package, NOS.-- AWSOME AS WELL!! Though I notice a VERY small difference between the two  as I compared the two side by side. Both added some treble, nice amount of boost, and something else I cant explain. (mojo maybe ) I would recommend building both NPN and PNP. Maybe youll be better at explaining the differences or for that matter, the characteristics other than my (it great, sounds awsome!) description.  Its an easy quick build that did have me stumped for a few over changing it to accept an NPN trannie. Thanks to Phillips site/layout it made more since. And those who responded to my thread were right as well ( reversing the 47 uf's needed to happen)

Also- for those silicon fans- I test a pnp bc556. and it actually sounded good- not great like the germs- but good enough to warrent a little more testing with the idea of silicon.

[Marcus Dahl]

Wow! I haven't been here in a while.... I thought I'd drop a line and say hi.

I'm working on a silicon variant of the Rangemaster. I've already done 2 for my guitar player. He didn't like the germainum one as much as the silicon that I built from scratch. That being said, I think it is all in relation to what transistor is being used and also being able to set your forward and back bias. The 2 react different as to where their bias points are. I'd put in trim pots in those positions and play around. Silicon versions can sound just as good. I'd also play around with the input cap value. The silicon version I've been working on sounds best with a .022 input cap.

[jimbob]

If I place a trimmer there does it matter which end connects to the wiper? Cause I know Ill nee 2 ends where there resistor was leaving an extra lug (the middle one)

thanks- good 2 c ya back

[petemoore]

If I place a trimmer there does it matter which end connects to the wiper? Cause I know Ill nee 2 ends where there resistor was leaving an extra lug (the middle one)

thanks- good 2 c ya back

Trimmer for bias? if it's linear pot it makes no difference, but I like to figure out which way CCW or CW makes the resistance rise. Use the DMM to see what your pots it actually doing once, very info and EZ to remember when you twist the knob and watch the meter. I like to tie the third lug down for stability, also if the wiper dies, you'll still have the pot wafers resistance between the two connections.
 I'll just leave this typing under here also.
 The outside lugs of a pot connect just like a resistor. The middle wiper lug is a divider...a lin pot set to the exact middle...you have two equal value *resistors now one is lug 1 to wiper, the other is lug 3 to wiper, turned CCW one *resistor gets smaller and the other *resistor gets larger.
 A centered 10L pot will measure 5k/5k. Then it ranges the resistances between wiper and outside lugs [one outside lug sees larger values the other sees smaller values] like percentage wise 60/40 or 30/70 or 100/0.
 Hope this helps.

[jimbob]

thanks pete!

[TheBigMan]

Hey Jimbob, I've just got hold of a load of CV7112s as well.  What sort of hfe and leakage figures did you get for the ones you used?

[jimbob]

I have no idea- Sounds damn good though  :lol:

[remmelt]

How did you go about chaning the schem to NPN? Just reversing the polar caps and battery? Or does it need more?

[petemoore]

PNP Tranny...Power Supply Pos to Gnd, which means the emitter bypass caps + goes to Gnd also.
 NPN Tranny neg grounded power supply, - of cap goes to ground.
 Basically you always want a polarized caps - terminal to the 'most -' side so you don't run them at reverse polarity.
 Same for transistors, *PNP *Pos Ground, *NPN *Neg Ground
 ...or otherwize whatever alternative ps wiring scheme you 'Know', the ones I refrain from...