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Suitable transistors for the Rangemaster?

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7/16/2000 5:08 AM
Mark Abbott	Suitable transistors for the Rangemaster? The original Rangemaster uses a OC44 transistor, I was going to build a clone with a AC128, I have been told from a reliable source that many of the available Ge transistors don't have the upper frequency reponse of the OC44. What transistors are recommended for the best results? Thanks for your help. Mark Abbott.

7/16/2000 7:02 AM
Mark Hammer	Don't know about everyone else, but I used a 2SB172 because it's what I had, and it sounds fine to me.

7/16/2000 7:47 AM

I used an AC126 in the end as it had the right Hfe for the RM circuit and tested okay in circuit when I breadboarded it up.

In it's stock configuration, the RM is quite trebley as you'd expect (mine is anyway). I put in a switch to choose between the stock 'treble boost' effect and a full-range boost using a 0.1uF cap.

A rotary switch might be a nice addition to choose between, say, four different caps of different sizes, but you could also just wire up the same cap sizes of different compositions and see what that gives you.

I've only just finished & tested it a couple of hours ago through my mixer, so I can't vouch for how it will sound through my Bluesbreaker amp - hopefully pure EC 'Beano' tone with a splash of Sabbath's first LP grind.

... Ian

7/16/2000 2:57 PM

quote:
"I have been told from a reliable source that many of the available Ge transistors don't have the upper frequency reponse of the OC44."

Mark, while this may be true, considering the high-end roll-off of guitar speakers and amps, I find it hard to believe this would be a problem with ANY transistor (YMMV). The trick seems to be getting the right HFE, as pointed out above.

-Eric

7/17/2000 8:14 AM

A couple of years ago Sydney luthier Greg Fryer was asked to build copies of Brian May's original guitar, which was no problem, he also was building repro's of the treble booster BM uses (the Rangemaster). The problem with the clones was they never delivered as much top end as the original units with the OC 44 transistors.

This is the reason I ask about suitable transistors. I have a AC128 with the right hfe. however, one of the guys working with Greg Fryer told me he used a AC 127 (NPN version), and it didn't deliver as much top end as the original Rangemasters.

Yours Sincerely

Mark Abbott.

7/17/2000 3:10 PM

quote:
"A couple of years ago Sydney luthier Greg Fryer was asked to build copies of Brian May's original guitar, which was no problem"

Now that's amazing. From what I know of that guitar,
(a very quirky design, built almost entirely from home-made parts, and a very old chunk of a mahogany fireplace-mantle) "no-problem" understates Fryer's skill, if those guitars come even close to sounding like May's. Duplicating a simple circuit like a Rangemaster ought to be a walk in the park after that.

quote:
"and it didn't deliver as much top end as the original Rangemasters."

Which ones? If these things are like other germanium-based boxes from the 60's, you'll have a hard time finding two that sound the same.
Mark, my point is if you are trying to recreate mystical sounds from the past, consider ALL the variables (including the amp, the guitarist, and studio tricks). Can you (or Mr. Fryer) duplicate all of that, also? Build the box using what you have, and see how it sounds, maybe you'll like it.

This is a long winded way of saying: If you believe that your favorite old tones were created by those mythical mojo-dusted old parts (which, of course, no ne seems to have --or are outrageously expensive) You will never be satisfied with YOUR tone.

You probably know all this already, Mark

(that soapbox is appealing, sometimes), good luck in your quest.

-Eric

7/19/2000 1:46 PM

I just tried out my Rangemaster clone with an AC126 last night at rehersals and I thought it was very nice. The amount of boost seems to 'ramp' up over ten or so seconds sometimes when the effects is first switched in - very strange!

I liked the stock sound over the full range boost option that I put in there via a mini toggle switch.

I used some huge 2W metal film resistors, and it's still quite noisy, but that might be the transistor. At the end of the day, it's a treble booster though, so I suppose some degree of hiss boosting is inevitable.

I'm going to try building a few more with some AC153/AC188/AC128 transistors I have floating about.

... Ian

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