NPN Rangemaster Built

[DougH]

Build pics and schematic here: http://www.aronnelson.com/gallery/v/DougH/NPN_RM/

[aron]

Looks great! The sound clip sounds cool too! Good Tone!

[RDV]

That amp sounds great too!

RDV

[stopstopsmile]

nice build, i am curious what was the hfe?  And how did you source the npn? 

Also I am still learning but do you need to do much with biasing according to your schematic?  I guess how did you bias it, I don't understand how a rangemaster is biased. 

[Dragonfly]

Also I am still learning but do you need to do much with biasing according to your schematic?  I guess how did you bias it, I don't understand how a rangemaster is biased. 

If you replace the 39K with a 50k-100k trim pot, you'll be able to dial in a wide variety of transistors.

[stopstopsmile]

thanks dragonfly, would this be done just by sound? or am I measuring something with the trim pots. 

[Dragonfly]

thanks dragonfly, would this be done just by sound? or am I measuring something with the trim pots. 

most people like RMs collectors to read about 7.2v...i prefer the voltage a bit lower, in the 6v-6.5v range....

set your multimeter to 20 volts (or something similar)...with the effects battery installed (be sure to put a plug in the input jack !)...touch the black lead to ground, and the red lead to the transistors "collector" leg, and read the voltage....then turn the trim pot till you get the setting youre looking for....

[stopstopsmile]

awesome thanks dragonfly, and thanks doug
what kind of transistors can I try that will work good? and what hfe should I try and get?
is there anything cheap that sounds amazing?  or is it all mullard, and expensive?

I never played a rangemaster, I can wait to try it out. 

[birt]

great sounds!

stopstopsmile: for NPN you should look for AC127, AC187, OC140, GC521... or take a look here: http://www.datasheetarchive.com/advancedsearch.php?t=0&q=GE+NPN&manystr=&sub.x=0&sub.y=0

[DougH]

Looks great! The sound clip sounds cool too! Good Tone!

Thanks, Aron. I powder-coated the box.

That amp sounds great too!

Thanks, Ricky. I will post some stuff on the amp when I'm through with it. I'm almost finished with the woodwork on the cabinet.

i am curious what was the hfe?  And how did you source the npn?

Also I am still learning but do you need to do much with biasing according to your schematic?

I will edit my notes- transistor hfe is 89. This is a transistor Aron used to sell in his store. Basically, the biasing and tweaking was the project in this case, Rangemasters are so simple. This is the 2nd one I've built. I found I preferred the sound with the 180k instead of the 470k base resistor. It sounded "sweeter" to me. I suspect it may be because the 180k setup is supplying more current to the base. I also preferred the sound of the lower collector voltage, less fizz, which is why I chose the 39k. After that, I calculated the Fc of the input HPF on a "standard" Rangemaster schematic. The .0082u input cap comes pretty close, and coincidentally removed the last bit of "edginess" I was getting with a .0068u.

You can work out whatever bias you want on paper with Ohm's law. You may get slight variations on the breadboard due to parts tolerances but it comes pretty close. As Andy mentioned, you can just stick a pot in place of the 68k and turn it until you hear what you like. But in this case there was more to tweaking than just the collector voltage- Fc of input/output HPF's, Zin, base current, it all plays a role.

[John Lyons]

Yes, that does sound nice Doug! The RM/amp combo cleans up very nice with the guitar volume knob as well. I know your a fan of that...

John

[Gus]

Now Doug why did you give that away?  People should be able to figure this out on their own.  I chuckle when I see all the RM and TS builds and people don't even go to books to read about different bias setups and input R and RC time constants.

others

The top resistor in the string should be the adjustable one to min the input resistance change fixed R and Pot That is what I do.  Think about it.  Friends that try my Si build of the RM circuit set it different, player, guitar, amp Try it down even lower like 3 V. 

The lower the input bias string R value the more stable the bias but there are trade offs

You can google and find good write ups on bias setups

I sent Aron a NPN Si design some time ago

[DougH]

Yes, that does sound nice Doug! The RM/amp combo cleans up very nice with the guitar volume knob as well. I know your a fan of that...

Hey John, I have two more wet-sanding steps and a buff and this cabinet work will be finished except for adding the grills etc. (I need to get the faceplate made too.) It's looking real pretty! I'll put a folder for it in my gallery section when I'm done and you can see how it turned out.

Now Doug why did you give that away?  People should be able to figure this out on their own.

I agree, Gus. It's common sense and people should always put it on a breadboard and tweak it and/or work it out on paper before just slapping it together. In a small way I guess I'm trying to demonstrate that. It's a simple and common circuit that most people don't give much thought to when they build it, or they over-obsess about Vc alone, without considering any of the other circuit sections.

[Gus]

I was thinking some "newtweeker" just got some free design work and will have an improved RM on the market

[DougH]

Who cares? So he can go out and compete with the other 500 builders selling the "ultimate" Rangemaster clone. That whole scene bores me to death. Yawn...

In any case I think it's just a personal preference thing anyway. I compared this to my other Rangemaster which is a "by the book" build with an AC188, |7|v holy grail bias point, etc,etc. I prefer the new one, but the old one still sounds good, just different. Some would argue the old one sounds better, etc ad nauseum... 

[markm]

Thanks Doug!!
 

[DougH]

No, thank you, Mark! 

[Gus]

No  I just find it strange with all the information on the web that somethings are not improved but just cloned

I am all for building something stock first

The R.G.s write up seemed to be the start of all the RM type circuits.  There was the Butler one and the real one and the different Brian May stuff but after the write up more RM types appeared.  How many clones are set to 7.2 because of R.G.s write up?

Having a little fun with this thread  I think Doug understands.
been on the effect forums for to many years and watching things not change much is kind of funny.
Mark, Doug and I have talked. 

[Dragonfly]

The R.G.s write up seemed to be the start of all the RM type circuits.  There was the Butler one and the real one and the different Brian May stuff but after the write up more RM types appeared.  How many clones are set to 7.2 because of R.G.s write up?

When Doug was first playing with these mods, we talked, and I thought it was interesting that both he and I prefer to bias our RM type circuits low (in comparison to the RG article)...I keep them in the 6V-6.5V range, and IIRC, Doug likes them right around 6V as well.

When you think about it, its amazing how much you can learn from some simple, classic circuits like the Rangemaster, Fuzz Face, D+, etc...+ they're all tweakable to give a multitude of sounds.

[markm]

Mark, Doug and I have talked.