Rangemaster clone - volume question

[yeeshkul]

I am going to add a volume pot to the RM output.
Does it make any difference if i put the output cap on the output lug of the volume pot instead of leaving it before the pot (where is should be normally)?
thanks
Jan

[JHS]

YES. The first sulution is technically crap. with the 10k pot on zero and with closed Vol-pot you produce a short cut in the power supply.

JHS

[yeeshkul]

guys what pot would you use for the RM volume? 100k, 250k, 500k audio pot?

[Gus]

I would not use an external vol pot.   I would build it stock with a pot for the collector resistor

[Dragonfly]

Alternately, you could set it up normally, except using a 20k trimmer instead of the normal volume pot....then put a 100k-a pot AFTER the cap, wired like you would normally wire a volume pot.....set the trimmer where you like the sound BEST....that way you have the best of both worlds.

[yeeshkul]

thanks, i'll check it out

[DougH]

Why do you want a volume pot?

[yeeshkul]

I am making RM for my friend who wants less/no difference between volume of the clean sound and when RM is on, but he wants to keep the full RM sound. I mean a normal RM, just not that loud when the Drive(collector pot) is full blast.

[tenchijin2]

Guys, I'm pretty new to this but...

The point of a treble booster is to boost the signal and overdrive the amp. So if you reduce the volume after you boost it isn't it going to *not* drive the amp? The pedal doesn't actually distort the guitar sound directly.

I use a Brian May Range Maistro pedal (a Rangemaster variation). Really it's best to leave it on all the time and use the guitar volume pot for altering the tone/overdrive while you play.

It sounds like your friend wants an actual distortion pedal, which has an output control that allows the distorted output to be equivalent to the bypassed output.

I don't think that's at all viable with a treble booster.

Aric

[yeeshkul]

i'd say RM distorts the signal  - it is biased to -7V not to -4.5V as usuall.

[Gus]

Jan carefully read the writeup at Geofex about drive to the first grid.   If you ADD a volume pot you are adding series resistance when the pot is not at max.

Now this might not matter or it might if your friend likes the sound of the stock circuit into a certain amp (guitar, treble boost, amp)

You should be able to set the pot to a certain level and just.  Now if it turns out your friend likes the drive into the grid

Add a EF

OK
treble boost
10K (whatever one likes) collector resistor
collector to a 1uf to 100k lin pot as volume
1uf cap to base
NPN 2n5088 as an emitter follower
10K emitter
1meg base to ground
470k base to +9V (yes offset on purpose)
1uf film out 100K, 1 meg etc pulldown

One can do the math with the 1uf caps for different values and use what type you like.

[yeeshkul]

Gus please tell me what is the reason for EF stage here (at the end of the circuit)?

[yeeshkul]

I mean i was playing with Astrotone fuzz some time ago - it has EF after the gain stage as well. In the end i put the EF in front of the gain stage ... and i was really happy with the sound and fairly big input impedance. Here you suggest to use EF after the gain stage again which makes me a bit confused ...

[mattumbi]

Gus please tell me what is the reason for EF stage here (at the end of the circuit)?

You'll have to read the GEO article, its about driving the grid of the amplifier.

[DougH]

I am making RM for my friend who wants less/no difference between volume of the clean sound and when RM is on, but he wants to keep the full RM sound. I mean a normal RM, just not that loud when the Drive(collector pot) is full blast.

Well, the "full RM sound" is partially due to the way it drives the amp. You can try it on a breadboard with a volume pot on the output. I suspect it won't sound very impressive. It will distort slightly and will emphasis treble, but it's not the same. The RM is a very synergistic effect- it combines with the sound of your amplifier and the overall sound depends a lot on the interaction between it and your amp. Over the years I've seen a few diy designs of overdrives with "rangemaster input stages". Some people use an RM to drive their fuzz face or other distortion or overdrive boxes too. You may want to investigate some of these ideas too, to get a "volume controlled" rangemaster effect. All you can do is read up on what makes it do what it does, and try things out on the breadboard until you find something you like.

[yeeshkul]

All right i understand. To be honest i had the board made for it already, so i am a bit trapped now since i promised to make it soon . I will see what i can do and put the result here soon. I will try to add one germanium diode after the output cap (switchable). If i understand well, due to the bias that is not in the middle one diode may be enough. That may help to distort the sound although it won't be rangemaster any more - that's why it will be just optional.

[DougH]

If you mean you are going to add a Ge diode as a shunt on the output- that's a bad idea. Why? Ge diode fwd voltage drop is less than .5v, usually around .3v or .4v. You will be severely limiting the output voltage swing available, and your volume control will barely reach unity gain when it is turned up all the way.

edit: You can string multiple diodes in series to increase the effective fwd voltage. I still don't think it will sound "right", but give it a try.

[yeeshkul]

Dough thats true, but i just want to reach what my friend wants - no volume step between clean and distorted sound. I know that RM is really a bad choice for this request. I am just going to do things now so i will see in a little while. But i completely understand what you mean.

[d95err]

If you want something like the distortion sound associated with the Rangemaster, take a look at e.g. the May Queen. It's an overdrive designed to sound similar to a treble booster pushing a low gain tube amp:

http://www.runoffgroove.com/mayqueen.html

If you want to salvage the circuit you're already building, try adding a FET gain stage after the Rangemaster (to simulate the first stage of the tube amp being pushed into distortion), and then a master volume. It should be possible to do with just a few components. No need for a PCB, just connect the component legs point-to-point. Checkout the Fetzer Valve and use the appropriate parts of that circuit:

http://www.runoffgroove.com/fetzervalve.html

Trust me, the Rangemaster by itself sounds thin and buzzy and generally terrible. You couldn't possibly imagine that it could be turned into something good, just by turning it up and having it push an amp...

[d95err]

Another note (not sure if it was described by anone else) - the regular volume control on a Ragemaster is exactly that - a volume control. It does not change the amount of distortion created in the circuit. So it makes no sense to add an extra volume control after it.