@bigo
Forum Replies Created
-
Posts
-
The ToneTweq instructions will help to show you where to connect. You can connect the ToneTweq to the Lug 3 solder pad of the volume control of the Exemar, or to the “out” solder pad of the Exemar I believe. Connecting to the Lug 3 solder pad elimates the Exemar volume control and connecting to the “out” solder pad gives you 2 volume controls, but you have to be careful about turning up the Exemar volume.
I am in the middle of building the same thing, but am wiring the “Out” solder pad of the Exemar to a DPDT switch so I can bypass the ToneTweq if I want to. I am about 75% done building the pedal. I need to wire everything up and then I will be finished.
Found I mis-typed. That is a High Pass Filter configuration. I’m probably going to use a 47nF output cap. A modified Messenger Fuzz schematic I found shows the person who tinkered with the circuit added a 47nF output cap with a volume control. I should have figured out what he did. The 1nF cap actually makes the fuzz too fizzy, so I suspect the output cap from the original circuit board is likely higher than a 1nF, which was a guess from those trying to reconstruct the circuit. It likely is 10nF or higher.
Thanks Wilkie!
Stupid me! I should have recognized that the output of the circuit of a capacitor paired with a variable resistor is a Low Pass Filter. With the full 500K of the pot, and a 1n cap, the 3db cutoff frequency is 318 Hz. This is above the lowest frequency of 82 Hz typical for a standard guitar. Raising the cap value to 10n gives a cutoff frequency of 31.8 Hz, below the lower guitar frequency of 82 Hz.
I was thinking about using the Emerald with a paramix. I’ve got the parts for the Paramix, but I still have to put it together.
I do have a question for Barry about the Sriracha Fuzz + Emerald demo. Was the track recorded with the Sriracha Fuzz > Emerald or Emerald >Sriracha Fuzz?
Follow-up.
I’m done trying all kinds of different component swaps on this circuit. I used the neck single coil pickup of my very expensive Squier 51 guitar (cost a whopping $99 new in 2007) to simulate the neck pickup of Farner’s Messenger guitar since I don’t own a thinline hollowbody with single coil DeArmond pickups. I get pretty close to the sound of the GFR live in 1969 sound (Inside Looking Out and Paranoid) when playing along with the video.
I finally settled on pretty much doing the stock circuit, but using higher gain transistors. Others have used BC108/109 transistors, which can be around 400-600 Hfe. I am using 2N5088’s that have Hfe’s around 575. This gives quite a bid of distortion and one can get some of the octave up distortion heard on the Inside Looking Out solo, but it is not as prominent as in the recording unfortunately.
For the emitter leg of Q1, I tried going straight to ground (most distortion), a Ge diode some have tried (cleans up some of the fuzziness), and various Inductors ranging from 10uH to 1mH. The Inductor value doesn’t seem to matter much.
I’m leaving off the 470k resistor to ground at the output since it didn’t do a whole lot. I am not going to use a Gain pot at the input because the guitar volume pot works fine here. I am planning to use a 100nF Input cap switchable with a tone control (blendable cap network as in the schematic). I also tried a 47nF Input cap but it didn’t make much of a difference.
At the output, I will use a A500K Volume pot that can be switched to a direct out path as in the schematic.
Interestingly, I compared the fuzz to the Grand Fuzz Railroad pedal I built a few years ago, which is based on a Heathkit TA-28 Fuzzstortion circuit that I modified. The Messenger fuzz I breadboarded and the Grand Fuzz pedal I built sound very similar, but the Grand Fuzz has less to maybe zero octave effect high on the neck (primarily above 17 frets) compared to the Messenger. There is some octave like effects from the Grand Fuzz when I changed the PNP Si Q2 to a PNP Ge Q2 that has around a 275 Hfe gain and low leakage, but there is less overall output from the pedal. One of these days I will get around to building this on veroboard.
Final diagram below:
I would be up for a Grand Funk NostalgiTone. And you posted my absolute favorite GFR live performance.
I thought I would revisit the circuit a little as some new information was provided to me by friends.
I spent last weekend at the Penn State Arts Festival (Central PA Festival of the Arts) where I have been meeting up with my college friends nearly every summer for many years. Out of the 4 guys, I am the only one who is not an electrical engineer. Speaking about this circuit with one of my engineer friends, he told me “well you know that inductors can act somewhat as both a resistor and a capacitor and is frequency dependent.” Intrigued, I read up some more about Inductors (emitter leg of Q1 of the circuit) and it is true.
For DC current, the “resistance” of the Inductor is pretty much nil. However with AC, as in a sine wave guitar signal, the resistance to current flow is technically Impedance (or Reactance with an inductor). That is, DC current will pass straight through an Inductor which basically acts a straight wire.
However, the magnetic field generated by AC current flowing through an Inductor will induce a resistance to current flow. The effective Impedance (think resistance) of an Inductor is dependent on the frequency with increases in frequency causing an increase in the Impedance/Resistance. Also, the larger the Inductor, the more resistance there is to higher frequency current flow. Therefore higher frequencies don’t flow as well through the Inductor and the larger the Inductor is, the greater higher frequency current flow is impeded. This explains why when I put larger value Inductors on the emitter leg of Q1, there appeared to be greater lower frequency content in the output signal. The higher frequencies were basically being filtered out.
For example, the “resistance” of a 100uH Inductor for a typical lower guitar signal frequency of 82Hz is 0.05 Ohms, and 3.1 Ohms for a higher 5 KHz guitar signal frequency. Therefore: Higher Frequency = Higher Resistance and less high frequency content.
Also the Magnetic Field of the Inductor stores electrical energy as does a capacitor, just in a different fashion. When the current to the inductor is turned off, the magnetic field of the Inductor continues to cause current flow through the Inductor as it gradually dies down (gradually collapses) until it is completely collapsed to the point that there is no more induction of current. This is somewhat similar to a discharging capacitor causing a continuation of current flow for a certain period of time. Inductors store electrical energy in a magnetic field and a capacitor stores electrical energy in the form of a charge.
I agree the early Mark Farner tone is somewhat unique. The guitar used, a Musicraft Messenger was a fairly big part of the early GFR sound/tone. Hollow body with single coil pickups and an aluminum neck. The guitar itself sounds really good clean with low gain, but kick in the onboard fuzz and it’s a signature sound.
I can’t believe someone else is doing what I am currently working on, but I am so busy this summer I won’t be able to finish it until the fall. I’m going a slightly different route and going to use an On-On DPDT switch to add the tone Tweq or bypass it to go to a stock 250 configuration. Got the main boards built but that’s as far as I have progressed.
I would ditto Steve’s response, but Barry I think would be the final say on this.
Agree with Barry. You may have to internet search for the data sheet, which is what I used to do. Fortunately I invested in a DCA-55 and use that to give me the pinouts and I have found it to be an invaluable tool for that and other things such as measuring forward voltages on diodes.
I am awaiting an individual “uni-vibe” style circuit board, like the individual 60’s and 70’s modules, because that is what I am interested in. Hopefully that will be available soon.
Already have built a “Gypsy” style fuzz, so I am not in need of something like that, although I note the circuits are not very similar.
A follow-up to this topic.
Purchased an isolated switch mode (not linear mode) power supply and tried all the pedals that had significant noise with the 1-Spot power supply. There was no audible noise greater than that heard with a 9V battery as I switched back and forth between battery power and the new 9V power supply. The 1-Spot is just plain noisy, especially with circuits that don’t have power filtering built-in.
Lesson is – get an isolated, low noise power supply for your pedals if not using a battery.
Here is what I have been doing for the past few years. I mainly use waterslide decals, but also at times use Barry’s photo techique printed on a laser printer, usually with bigger builds/enclosures. I had trouble with the photos smearing with the Armor All after I ran out of my original laser photo paper and bought new stock. I was then forced to clearcoat the photos done on a laser printer with acrylic lacquer.
I use Paint.net for designing graphics, which is a free program. It has been a Godsend for me and it has been relatively easy to use. With this program, you add layers to the graphics and can name them other than 1,2,3,4 etc. You can also move the layers around. I usually start with things like outlines, etc. and hole centers, circles for the holes, then circles for the Knob size I am going to use, etc. This helps to layout where you can place different graphics pictures, labels, etc. With layout lines such as ones to keep letter labels even, after placing the letter graphics, you can deselect the label lines so they don’t stay in the final image for printing. I also use Paint.net for the drill templates.
Waterslide decals done on an inkjet printer require spraying lacquer on them after printing (I wait about 24 hours for the ink to dry). I use clear acrylic lacquer and it works fine. After applying the decal to the enclosure, I spray some additional clearcoat on the decal for further protection.
With photo graphics, after application to the enclosure, I spray the Armorall on top (over the clear coated photo).
I use White enclosures, either painted white (auto spray paint works best IMO) or powder coated white from a vendor if I am using a colored label. I use lighter color painted or powder coated enclosures with black and white graphics.
Examples are below:
Drill Template:
Barry Style Photo Graphics:
Colored Waterslide Decals (More Recent Builds):
Black and White Graphics on Colored Enclosure:
Thank you Barry. This is an excellent idea, but a lot of work to implement.
I have been using Tayda enclosures for awhile now. Their powder coated enclosures are a good deal and I have adopted some of the Pedal PCB drilled ones for some pedals, although they don’t really work for GPCB boards except for ones you use solder lug pots.
Seeing Chuck’s response up above, it supports the thought I have had about a new thread category – Tips and Tricks. I have a few things I do when building pedals that help me and may help others. There are a lot of experienced builders on this forum who probably have loads of tips. Remember, there is more than one way to skin a cat.
