Hello,
I just completed my first pedal project ever, the rangemaster. How much gain should be on tap from this pedal? The knob I installed on the boost pot is numbered 1-10 and unity gain seems to be around 7, that doesn't leave much room for boost. Is this typical of this pedal? I remember reading a post on "The Gear Page" (TGP) from someone selling a Beano boost because there was too much gain on tap for bedroom use, that's what I was expecting from this pedal.
If my pedal should have more boost than it does, where should I start in the troubleshooting process, what could be the likely culprits of low gain?
Thanks,
Doug
Your transistor may be backwards.
It does not appear to be, there is a little red circle with a "c" in it that I assume is the collector. This is the pin that goes to number 3 on the boost pot. The triangular shape pinout of the transistor lines up with the triangular shape on the PCB too. I will take some close up pics and post them. I noticed that there is a thread that details what I should've done before I posted here, something about checking voltages and the like. I will do that also and report back.
Is this pedal a low gain pedal? It seems to operate fine just not much boost.
Thanks
It should provide a significant boost...
http://www.youtube.com/watch?v=tr7pNQ2vITY here's a comparison for you.
Here is what I found:
- Red lead to voltage in on board - 8.53v
- Red lead to ground in on board - 0v
- Voltage in on board to ground in on board - 8.53v
- Red lead to collector - 6.70v
- Red lead to emitter - .53v
- Red Lead to base - 6.70v
Here are some pics:
<img src="http://i.imgur.com/uNfFN.jpg" alt="" title="Hosted by imgur.com" />
<img src="http://i.imgur.com/VlUVh.jpg" alt="" title="Hosted by imgur.com" />
The diode looks like it might be shorting to ground but it's not
<img src="http://i.imgur.com/zuZDA.jpg" alt="" title="Hosted by imgur.com" />
<img src="http://i.imgur.com/tk6bv.jpg" alt="" title="Hosted by imgur.com" />
Thanks
this is a positive ground effect. you should be getting -9v rather than positive. if you are running it with a negative ground power supply, then you will need to switch the voltage polarity. you can do this with a road rage board or by running on batteries. there are other ways, but i recommend the road rage.
i don't know for sure if that's the problem just by looking at it, but be sure to check your polarities.
Quote from: dwstanford on March 11, 2011, 01:09:00 AM
this is a positive ground effect. you should be getting -9v rather than positive. if you are running it with a negative ground power supply, then you will need to switch the voltage polarity. you can do this with a road rage board or by running on batteries. there are other ways, but i recommend the road rage.
i don't know for sure if that's the problem just by looking at it, but be sure to check your polarities.
If you look at his voltages in the post above yours, they're all listed as -...
That's not the problem. It looks to me like you've got the voltage right, however it's a bit low. Have you tried it with a fresh Battery?
Jacob
Well, I have to admit, I wasn't looking if the meter registered -/+, I was just recording the values. I am running on a 9v battery so that shouldn't be an issue, should it?
make sure the positive side of the battery is running to the ground connection and the negative side is running to the 9v connection. it's the opposite of most modern pedal layouts. if the polarity is reversed, you will get a very weak sounding effect similar to what you have described.
I believe that the battery terminals are connected that way, they are just like the offboard wiring diagram listed here on MB.
Someone PM'd me and asked if the RM is working. It is, but again I don't know how much gain it should have. Here are two quotes from the Analogman website about the beano boost, which is a rangemaster clone also.
At 9:00 the Beano Boost is unity gain and may not sound very special into a clean amp. At 12:00 it starts to boost the volume and get thicker. At 3:00 it should be waking your tubes up like a passing jet plane.
Can boost volume quite a bit. Has about the same output level ON and OFF with the vol knob set at 9:00. At 11:00 there is about a 10dB boost, which sounds twice as loud. At 12:00 there is a 13dB boost, and up all the way is about an 18dB boost which is nearly twice as loud as it was at 11:00.
My pedal has no where near that kind of boost but I don't know if the MB version should have that kind of gain? Does anybody know how the two pedals compare?
I did try it with a fresh battery and it seems to have a little more bite but nothing dramatic.
One other thing, the bias resistors are a little different value than the ones listed on MB. I bought the transistor at small bear and two resistors came with the transistor.
MB values:
68k
3.9k
SB values:
62k
3k
Would that make a difference?
Each transistor biases a bit differently in this circuit, so since you socketed those, try a few different values. The ones from small bear usually do a good job of biasing the circuits, but since the differences are minimal, it wouldn't hurt to try something else. You can always go back to what you had.
Quote from: madbean on March 09, 2011, 04:14:00 PM
Your transistor may be backwards.
That's exactly what was wrong with mine, would boost the treble but only boosted to about unity gain. Switched the transistor around when troubleshooting (totally by accident) and it worked great.