Built a Rangemaster (NPN version)

[KMS]

I have found that steel enclosures are better than aluminum for RF interference.  Shielding the audio signal inside the box will also help with shielded cable (steel shield) right up to the points of solder.

There is a capacitor trick out there to (can't remember what it is) and one more trick with some kind of beads hooked around the input jack (again can't remember what it is either).

[vanhansen]

Thanks for the suggestions.  Lots of options.

venessa: Just a little background on this for ya, this problem isn't new.  It happens only at my brother-in-laws house, not at home or anywhere else I've used these pedals.  That's what's got me puzzled and convinced that there is a tower nearby.  I've eliminated it as being a power issue within the house because all the pedals I mentioned with this problem I have running off battery power.  The amp is fine.  It was recently checked over and given a good bill of health.  I'm going to "clean up" the wiring a bit but it's pretty clean as it is.  The guitars are fine.  The radio comes through only when they are engaged.  As soon as I bypass them, no more radio. 

Since it's AM 820mHz, there has to be a formula to figure out what resistor or resistor/cap combo can be used to eliminate it.
I'll try the 10k resistor across the input, and other values, thanks Andy.  Unfortunately we don't get together again until the end of the month but that'll give me time to get things sorted out with the wiring and to add the input cap switch in.

KMS: I've seen such a trick but can't remember it either, both with a cap or with beads.  With the shielded cable, do I just need to hook up the inner conductor and leave the steel braid unconnected on either end?

[Melanhead]

Cool! ... I'm going to build one with an OC44 eventually ... It's on my TO DO list ... which seems to be getting bigger by the minute!

To bad about the radio thing. I had a friend that lived next to a tower and never figured out how to get rid of it ...

[petemoore]

With the shielded cable, do I just need to hook up the inner conductor and leave the steel braid unconnected on either end?
  For the shielding to shield, it must be connected to ground, to prevent ground loops inside the box, connect the shielding at one end of the run, trim the shielding close to the inner wire at the other end and insulate any exposed shielding copper with electrical tape, leaving only the inner conductor copper visible.

[vanhansen]

With the shielded cable, do I just need to hook up the inner conductor and leave the steel braid unconnected on either end?
  For the shielding to shield, it must be connected to ground, to prevent ground loops inside the box, connect the shielding at one end of the run, trim the shielding close to the inner wire at the other end and insulate any exposed shielding copper with electrical tape, leaving only the inner conductor copper visible.

Thanks, Pete.  That was my first thought but couldn't remember.  I believe I have some single conductor shielded wire in the stash to use too.

[vanhansen]

One more question just for clarification.

Andy (or anyone else who can answer), does it matter if the resistor (10k or less) before the input cap goes before or after the 1M anti-pop resistor?

[Speeddemon]

Cool! ... I'm going to build one with an OC44 eventually ... It's on my TO DO list ... which seems to be getting bigger by the minute!

To bad about the radio thing. I had a friend that lived next to a tower and never figured out how to get rid of it ...

I built one myself with the OC44, and I can tell you the sound is LOVELY!



The 3-position switch switches between 4n7 (middle) + either 3n3 (for mid boost) or 22nF for fullrange boost.
I tried various caps for this, and 22nF or 33nF are the best for the fullrange boost. 47nF or bigger makes the sound too wooly.

A question though: what's (besides the tone-pot) the difference between the original Rangemaster and the Java Boost?
Also, is that a Baxandall or BMP tone stack circuit?

[TheBigMan]

Speedy: The Java Boost is also wired for negative ground although it's still using a PNP and it has the three way switch for input caps.  Other than that I think it's an RM.  The schem is available in the manual at Robert Keeley's site.

I've just done a new layout for the RM.  Basically it's Philip Bryant's Rangeblaster with added input caps for mid and full range boost.  It's in my layouts gallery.

[MartyMart]

My "RangeBlaster" has an OC140 in it .... wonderful
I got a few OC44's from Ebay ( gold mil spec ) and have one in a Java Boost
equally good and I like the cap switch option on it.

MM

[Speeddemon]

Speedy: The Java Boost is also wired for negative ground although it's still using a PNP and it has the three way switch for input caps. 

Well, that's how my Rangemaster clone is too. PNP, with negative ground.

I've tried OC44's, AC126's, AC128's and even (Si) 2N3906's;
the OC44's definitely sounded best, with the AC126's second. the AC128's sucked (all of them). Noisy, low output, nasty tone.
The 2N3906 is actually a good choice, if you play hard rock/metal with the Rangemaster, since it's very low noise (compared to Ge NPN trannies) and the added 'richness' of a Ge trannie gets lost anyway in a high-gain setting.

[spudulike]

Speedy: The Java Boost is also wired for negative ground although it's still using a PNP and it has the three way switch for input caps.  Other than that I think it's an RM.  The schem is available in the manual at Robert Keeley's site.

The schem at Rob Keeley's site is WRONG. Theres also a hand-drawn schematic floating about thats wrong.

Use this one please - its been verified several times.

[vanhansen]

Andy (or anyone else who can answer), does it matter if the resistor (10k or less) before the input cap goes before or after the 1M anti-pop resistor?

[vanhansen]

Just bumpin this up for my last question about the resistor.

[vanhansen]

Well, no answers to my last question so I'm going to take a stab at it with a few things.  First, shielded wire from the jacks to the switch.  Don't have enough to go from the switch to the board right now so hopefully that's enough.  Next, a 220pf cap to ground right after the 1M pull-down resistor at the input.  I'll know in a few weeks if it eliminates the RF or not.

Tonight I just added in a DPDT on-on switch to toggle between two different input cap values; 0.0068uf (stock) and 0.01uf.  Not much room left in the 1590B, but it all fits with a few minor adjustments. 

[petemoore]

  Put one on both sides, you can always jumper...
  I think just putting it to the left of the cap will be fine. Before the 1m [<]is where I'd put it.

[vanhansen]

Thanks, Pete.  I hadn't thought about putting one at the output as well.

[brianwenz]

Hello Hello--
     Just curious......
Has anybody built a RM type booster without the footswitch??    The original treble boosters [RM and others]  never had a footswitch and were designed to be either "on" or "off".    I've built both versions....it's pretty interesting to control the sound with the volume control on yer guitar instead of popping in-and-out with a footswitch!
Brian.

[mac]

You may wan't to add Phillips temperature stablilty mod.

I'm not really sure why Phillip has a temp diode in his layout/shem. Having taken the idea from the Plate to Plate 'Brit-Face' article (http://www.geocities.com/SunsetStrip/Studio/2987/britface.html they outline in what application you would use one.

The why... In the Brit-Face article they are saying that the temperature 'run-away' is only in Q1 of a Fuzz Face. Q2 does not need one as it is covered by the 1k emitter pot.

In the Rangemaster it has a the 470k off the bass, the 3.9k resistor off the emitter and has a 10k pot off the collector. This should provide the same type temperature stability as the Q2 of the fuzz face in the above article. I quote the GEO article "The 470K resistor, in conjunction with the input divider helps set and stabilize the bias point against drift and temperature variations".

Not to mention that use of a diode does bring noise into the circuit. You need to have a diode that has very low leakage to avoid this in a Fuzz Face and if you don't need one in the Rangemaster why would you use one?

If you increase hFE from 50 to 150, the collector voltage goes down only 0.2 - 0.3V. The temp drift is minimal so no need for a diode.
Increasing Re from 3.9k to 4.7k makes the collector voltage goes up 0.2 - 0.3V. If no leakage is present one can calculate that Vc is about 6.8 - 7.1V. Ge transistor leakage (at least a good one with < 200uA ) makes Vc decrease so upping Re is one solution. Another one is to increase the 470K or decrease the 68k.

mac

[vanhansen]

Well, so much for the small cap to ground on the input.  Didn't do squat.  Still getting RF with the RM.  I'm gonna put one on the output too but doubt it will do anything at this point.

I did some testing, or process of elimination.

Plugged the guitar straight in to the amp, guitar volume down, no RF.
Guitar in to RM, with RM on and guitar volume down, getting RF.
Guitar in to DS-1 in to RM, with RM on and guitar volume down, getting RF.

The source is definitely the pedals.  I did notice that with the DS-1 before the RM, the RF isn't as bad and I believe that to be because of the bypass buffer in the DS-1.  Gave me an idea, like maybe putting an input buffer on the RM circuit or something.