Rangemaster - what should be the gain of the tranny?

[yeeshkul]

Hello guys, does anyone happen to know what should be the gain of the transistor in the Dallas Rangemaster?

[captntasty]

http://www.google.com/search?hl=en&q=rangemaster+transistor+gain+hfe&btnG=Google+Search

Google is a great search engine

"They call me the seeker, I've been searching low and higheeeee..." -The Who/Pete Townshend

[yeeshkul]

hehe thats right  . So at least for the others - somethig between 65-100. But needs some fiddling about to have it working properly ...

[petemoore]

  Socket the Q position...try a batch out in there...a fairly common ploy.

[yeeshkul]

I just finished it. It worked immediately without adjusting anything. Such a nice sound! Reminds me of early Peter Green's Fleetwood Mac.

[captntasty]

Isn't that a great feeling when it fires right up?      It really is a great sounding effect for such a sparse amount of components...  I wonder if you could settle something for me:  I've built 2 and my latest doesn't behave a thing like my first.  The first was really just a great sounding overdrive whereas the second seems to boost to the point where it is unuseable - too much volume boost before that nice slight/crispy/soft/creamy crunch!  The ONLY difference between the two was the tranny, but they were BOTH OC44's (different gains for sure but I don't remember exact #'s).  How is your's?  Overdrivey or Boosty?

[yeeshkul]

i am very sorry my friend i am just a beginner at stompboxes, i am learning myself ... i don't think i have any reasonable ansver for your trouble.

[yeeshkul]

ah ok sorry, the volume goes up quite a lot as i turn up the pot. the sound is very crispy. actually i have to check it out at full volume of my vox 15 amp tomorrow, it it the late night here ...

[yeeshkul]

i guess found the answer for your trouble in R.G Keen's article on building Rangemaster clones. The transistor has to be biased to be quite close to cutoff to have the proper sound.
The ge transistor you used for the second clone had different gain so it was differently biased by the standard values of the 68k and 3.9k. resistors.  What you need to do is to substitute those resistors with pots and keep fiddling with them untill you get collector to ground voltage between -6.6 to -7.2 volts. Then measure the resistance of the pots and replace them back with resistors of the closest possible values.
If the originally 68k resistor appeares now to be bellow 27k or above 82k OR the originally 3.9k resistor appeares to be bellow 2.7k or above 5.1k then you have to try another transistor.
After this you can also modify the 0.005uF cap to +/- 50% to get the right sound.
good luck
PS: for more info just read the whole article http://www.geofex.com/Article_Folders/Rangemaster/drm.htm

[yeeshkul]

I've just found out that the collector-ground DC voltage on my unit is -6.23V so i have to change the 68k resistor to 42.2k to get the proper - 6.98V.

[captntasty]

Thanks, I've read it and reread that article several times - great article.  I used the trim pots for the resistors in the second one to dial the gain in to about 7v.  Unfortunately, my first build is floating out there somewhere on somebody else's pedal board .
I was just curious about comparing another's experience with the build.  My first one I put a larger input cap to boost some more mid frequencies.  My second I went all out and used an on/off/on dpdt to switch between 3 different input cap values for a normal(treble)/middle/full frequency boost, kinda cool but nothing to write home about - I guess that's why I'm writing it here!
Was this your first build?  Let us know how it sounds thru your 15...
Peace

[petemoore]

How is your's?  Overdrivey or Boosty?
  Yupp...which one..just like yours...
  Finikky little job do-ers, finding the right one...well seems it's a matter of just diddling around until you get something usable.
  Or diddling around some more with transistors
  Or Bias,
  Or two of them, pitting them 'against each other until the pitter is satisfied that the performance of one of them is 'up to specifications' which again could more simply be described as 'usable'.
  @@ny rate, IMO these things need to be diddled with, and are subject to large changes if anything their output or input sees changes.
  And need to be hand tailored to the application for best results. One transistor may 'tell the part of the story' which you can use, more than a few will tell it differently.
  Guitar Volume pot adjusted less than full, directly connected to>22k>.0047?uf to ground> ~Rangemaster circuit [10k output pot/collector bias resistor value diddled with], also base bias may have been altered...lots of transistors fiddled and played on, does jest fine now...decided to play it like it means it instead of further trying to figure out what it means.
  Or...Guitar with volume at least slightly off 10, into ~RM>BmP !!!
  It's Not a clean boost, not as 'DirtyOD' as I've ~RM'd in the past, [doesn't get overload 'gakk' with HB's either], pretty well mannered these days.
   

[yeeshkul]

finally i managed to finish mine. I just biased the transistor exactly according R.G. Keens article and added a switch to the input capacitor (0.005 / 0.15uF). It sounds just amazing through my vox15. Such a pleasure, the sound changes a lot depending on the input capacitor. The overdrive is slight, but gives the tone very reasonable sustain.
I just can't stop smiling since yesterday.

[Dragonfly]

congrats...RM's are coool little circuits...pretty darn useful too....

you might look into pete's "rangepig" as well...its pretty cool too...


AC

[Stompin Tom]

I bought a trannie from small bear for a RM some time ago... I was never happy with it... too thin, not enough distortion. So I bought a pile of russian trannies off ebay. I went through several and found the perfect hi mid creamy response I was looking for. I put it in a box with a FF... I guess the FF starved the RM (both running off one battery) and made it even better! Smoother! Then the pedal was stolen (and it was ugly. don't know why anyone would've taken it). I've been tweaking a new RM for about a month now, and I cannot find another 'good' transistor in my pile... I feel like the gain can be right, but there's just a little something else that has to be there, too... what is it? How do you measure it? Man, I want my old RM back!!