Rangemaster clone, will this work?

[Ell]

I've tried to plan a layout of a Rangemaster, based on R.G. Keen's mods at http://www.geofex.com/Article_Folders/Rangemaster/atboost.pdf

In the article it suggests using pulldown resistors at the input and output.
Firstly, have I done this correctly? Secondly, should I bother?

I use a Fuzz Face very often straight after my guitar (it's an onboard effect), as well as an onboard Orange Squeezer.
I understand that the Rangemaster likes to SEE the guitar directly.
Should I do the pulldown resistors to help all of these pedals get along better?

I ALSO like to use a Nurse Quacky that I recently built using advice I read on this website. This is another pedal that likes to see the guitar first. I was wondering if running the Rangemaster first would actually help the Nurse Quacky, by raising the volume of the high notes before they hit the envelope filter?

P.s.
Thank you everyone for all your help over the years. I don't always comment, but I do often search and find the answers that I need. I was having lots of problems with Nurse Quacky, and spudulike's experiments with opamps and transistors was invaluable, as was Mark Hammer's advice on 3mm red LEDs, and all of his contributions to this pedal. I learn a huge amount from everyone on this forum. This is a wonderful resource.

[FSFX]

Why don't you try building my version that overcomes lots of the original problems with noise and power.

[Ell]

Why don't you try building my version that overcomes lots of the original problems with noise and power.

Looks good! I'll give this a go. I'll try to build both, and I can socket the transistor and switch them about, maybe try some silicons for a more stable build. Thank you FSFX!

So, just so I have all of this right. It works with an OC44, AND it's negative ground? And, I can use pretty much use any PNP transistors that I happen to have around?
What would you call the 500k pot? Is that the frequency control?

[FSFX]

So, just so I have all of this right. It works with an OC44, AND it's negative ground? And, I can use pretty much use any PNP transistors that I happen to have around?
What would you call the 500k pot? Is that the frequency control?

Absolutely. I designed it to work with OC44s and any other PNP transistor and to work correctly with negative ground without using those silly charge pumps that everyone complains about being noisy. As this was designed to reduce all of the noise that standard DRMs suffer from then it would have been a bit daft to then use a charge pump with all their noise issues.

The 500k pot and the capacitor is optional to allow you to change the frequency response from a standard DRM type treble boost to a much flatter type of response by allowing more bass. It is an alternative to what a lot of people do with having switched capacitors on the input to do a similar thing. 

I did a full analysis of the DRM and its issues for another builder who specialises in the DRM.

My changes reduce any noise on the power supply getting to the output by a massive amount whilst allowing the negative ground operation and retaining all of the audio characteristics of the original DRM.

It works with germanium or silicon PNP transistors by adjusting the bias accordingly.

You can read the full PDF document with design options here www.fleetingspider.com/files/DRM-V2b.pdf

[Steben]

Why don't you try building my version that overcomes lots of the original problems with noise and power.

this is so good stuff and absolutely no high order rocket science analog electronics.

[FSFX]

this is so good stuff and absolutely no high order rocket science analog electronics.

It has been built by quite a few experienced pedal builders and beginners who have all commented that it performs exactly as I said it would in my documentation. I have published full build documentation which describes various build options that can be used with a little PCB design I did for it. The full documentation also contains circuit analysis details and results showing the vast improvement in noise performance.

[mac]

I understand that the Rangemaster likes to SEE the guitar directly.

The mic inductance and the input cap make a bandpass filter with a peak near 1khz to 1.5khz.
The resistance of the mic between 5k and 10k, and on the other side the base-emitter resistance, 0,026mV/0.3ma*70 = 6k @ typical RM hfe and DC current; base resistances drop it a bit more.
If you add resistance between guitar and RM, or don't fully bypass the emitter the peak begins to flatten.
I posted a simulation of this interaction.
Treble booster? ... a low Q fixed wah wah 

https://www.diystompboxes.com/smfforum/index.php?topic=128816.msg1242559#msg1242559

I ALSO like to use a Nurse Quacky that I recently built using advice I read on this website. This is another pedal that likes to see the guitar first. I was wondering if running the Rangemaster first would actually help the Nurse Quacky, by raising the volume of the high notes before they hit the envelope filter?

A low Q fixed bandpass hitting a variable high Q bandpass, please try it!

mac

[FSFX]

The mic inductance and the input cap make a bandpass filter with a peak near 1khz to 1.5khz.

This chapter of the book 'The Physics of the Electric Guitar' makes interesting reading regarding all of this.

https://www.gitec-forum-eng.de/wp-content/uploads/2019/02/poteg-10-08-05-3-range-master.pdf

[Ell]

Why don't you try building my version that overcomes lots of the original problems with noise and power.

Sorry I never replied, I haven't had time to do this yet, but I will post my thoughts when it's all done and I've played through it.
I noticed that there are a few differences between the schematic above, and the schematic on page 6 of your pdf document. Which one do you think I should focus on? Are the differences significant?
In terms of the bias control, in the picture you posted you have a 100k variable resistor, but in the document you have a 10k one and then a diode. Is one approach better than the other? R.G. Keen also suggests that the resistor attached to the transistor's emitter may need adjusting for use with some transistors, but I guess I should build the thing first, and I can always tweak this later if needed.

I'm very excited to have this up and running, thank you for all of your input. I used to have a basic, unbiased, rangemaster clone in England. I took the transistor out of the socket when I left the country and I still have it with me haha. I think this could be a really useful tool to have back in my arsenal. Also looking forward to interesting combinations like Mac has suggested with Nurse Quacky!

[FSFX]

My main document discusses and presents various options to the builder. There is no right or wrong, they all work.
I have built and tested all of the versions as have many that I have supplied PCBs to.

[Ell]

My main document discusses and presents various options to the builder. There is no right or wrong, they all work.
I have built and tested all of the versions as have many that I have supplied PCBs to.

Okay, thank you for helping me out with this. If I design a veroboard layout for this, do I have your permission to post it here with credit given?

[glops]

Why don't you try building my version that overcomes lots of the original problems with noise and power.

I built a rangemaster this past year with a charge pump (and it's a cheap one from a Chinese eBay seller) and don't remember it being noisy at all. Now I am curious to see if it's noisy. I believe I used old caps and carbon comp resistors pulled from old radios too. I also usually just play it by itself but on a few occasions threw it after a buzz around and a zonk. I'll report back.

[FSFX]

Okay, thank you for helping me out with this. If I design a veroboard layout for this, do I have your permission to post it here with credit given?

You are welcome to do your own Veroboard layout for this. Some others have also done their own layouts to build on Veroboard.

[FSFX]

I built a rangemaster this past year with a charge pump (and it's a cheap one from a Chinese eBay seller) and don't remember it being noisy at all. Now I am curious to see if it's noisy. I believe I used old caps and carbon comp resistors pulled from old radios too. I also usually just play it by itself but on a few occasions threw it after a buzz around and a zonk. I'll report back.

You may be lucky with the noise. I design on theory, fact and well established electronics design principles.

However, the whole PSRR of the original DRM design is extremely poor and unless the power is well filtered or you use a battery then it can be noisy.

You only need to look at the circuit of the standard DRM to see that if you turn the output level control down to zero, then the output signal comes direct from the power supply line via the output coupling capacitor.

This image shows the difference in the output noise between the standard DRM (blue trace) and my modified version (green trace) when there is random noise on the power supply.
You can hardly see any noise at all if you look at the green trace. In fact, you can hardly see the green trace as it is buried in the noise of the blue trace.

[glops]

I built a rangemaster this past year with a charge pump (and it's a cheap one from a Chinese eBay seller) and don't remember it being noisy at all. Now I am curious to see if it's noisy. I believe I used old caps and carbon comp resistors pulled from old radios too. I also usually just play it by itself but on a few occasions threw it after a buzz around and a zonk. I'll report back.

However, the whole PSRR of the original DRM design is extremely poor and unless the power is well filtered or you use a battery then it can be noisy.

You only need to look at the circuit of the standard DRM to see that if you turn the output level control down to zero, then the output signal comes direct from the power supply line via the output coupling capacitor.

This image shows the difference in the output noise between the standard DRM (blue trace) and my modified version (green trace) when there is random noise on the power supply. You can hardly see any noise at all if you look at the green trace. In fact, you can hardly see the green trace as it is buried in the noise of the blue trace.

I always use a onespot which I have always assumed to be a well filtered power supply although never paid much thought to it. I think the only time I run into noise issues is when I have my two Fluorescent work lamps on when I am at my work bench. Your explanation makes total sense though. I built a battery powered RM over 10 years ago and then sold it last year or the year before when I had some hefty vet bills to pay so ended up whipping up a board in Eagle and built another one. I remember thinking the output was odd not being a standard volume control and coming out from the power line but didn't think much to it. I was thinking of building another one as the one I built this past year I had implemented an input cap blend control in case I wanted less of a treble boost and I either implemented the blend control incorrectly or didn't use a wide enough range between the 2 caps so it's mostly thicker sounding and I don't get any of the more traditional treble boost sounds from the unit so would like to revisit at some point. I will say it does sound incredible as is, maybe one of my favorite pedals I have built for myself. I will have a look at your version and try it out!

[Ell]

Okay, thank you for helping me out with this. If I design a veroboard layout for this, do I have your permission to post it here with credit given?

You are welcome to do your own Veroboard layout for this. Some others have also done their own layouts to build on Veroboard.

Thank you again! I just had a chance to throw this together. I'm going to test it out as soon as possible. I'm quite new to making my own layouts so this probably has a couple of problems that I'll soon discover haha

[Ell]

Okay, thank you for helping me out with this. If I design a veroboard layout for this, do I have your permission to post it here with credit given?

You are welcome to do your own Veroboard layout for this. Some others have also done their own layouts to build on Veroboard.

Thank you again! I just had a chance to throw this together. I'm going to test it out as soon as possible. I'm quite new to making my own layouts so this probably has a couple of problems that I'll soon discover haha

So, I tried to build this last night but it doesn't work. So, this particular layout is unverified.
I'm unable to find any mistakes in the layout, but it's possible that my board has it's own errors because I had to do some substitutions to make the correct values (such as parallel and series resistors).

If anyone is able to take a moment and find any mistakes in the layout, I would greatly appreciate your help.

My current plan is to build a vanilla negative-ground Rangemaster and get that working, and I can always add the extra components afterwards to lower the noise as per FSFX's suggestions. I'll post the vanilla layout here soon.

[FSFX]

So, I tried to build this last night but it doesn't work. So, this is definitely unverified.

You must have a mistake somewhere because the PCB versions all work perfectly as many others that have built it have proved.

[Ell]

So, I tried to build this last night but it doesn't work. So, this is definitely unverified.

You must have a mistake somewhere because the PCB versions all work perfectly as many others that have built it have proved.

Sorry, I didn't make that clear. I meant my particular layout is unverified.

[FSFX]

Sorry, I didn't make that clear. I meant my particular layout is unverified.

I did realise that is what you meant. Just clarifying it.

Anyway if you want to hear a demo of what it should sound like then it is here:

www.fleetingspider.com/files/rm_sound.mp4

I hope you get it working OK. If not then message me for help.