Bazz Fuss w/Gain - schematic check

[ecoli]

Like many others in this forum, I'm a beginner at building pedals and stumbled on this site while looking for other pedal related items.  Specifically, when I was looking for size of 1590A enclosures and found a whole thread dedicated to various pedal builds (truly impressive!).

For my first "real" pedal (aside from an A/B pedal) I've decided that a Bazz Fuss is a good start.  I'm fine with the onboard schematic, but hooking up the rest of the components (pots, jacks and switch) has me feeling a little wary.  I think I have it figured out, but would appreciate someone with more knowledge having a look at this schematic and seeing if everything will work.  The one twist is that I've added in a gain knob in addition to the volume knob.  Seemed like a simple addition (seemed being the operative word!).

Should note that in my diagram cobbled together from various sources, red is the +9V path, blue is the IN path, green is the OUT path, purple is the gain path, and dark grey are the grounds. 

Thanks in advance for the help.  Hope to be able to show some completed functional projects in the future!

Chris

[mcknib]

Doesn't look as if your actual board is grounded unless I've followed the wires wrong! there's no connection from the DC jack ground lug on that part which goes from IN jack sleeve to Gain lug 3 to board ground the other part goes from DC jack ground to Level lug 1 to OUT jack sleeve to 3PDT which would ground those parts and light your LED so you'd want to put a jumper from OUT sleeve to IN sleeve to complete your grounding.

Your Input cap looks a tad big at 2u2 the biggest I've seen is 220nF (0.22uF) for the basic layout yours would be 2200nF and from your drawing they look like electrolytics, I'd use film caps there and perhaps sockets so you can try different values

Here's a couple of links that may be useful:

http://www.home-wrecker.com/bazz.html

https://fuzzbeardpedals.wordpress.com/fuzzpedalbuilds/fuzzbeard-murk-box-modded-bazz-fuss-clone/

I wire my 3PDT's like this I find it easier to remember IN's on the left OUT's right and LED + ground in the middle:



The wire you see running diagonal from 1 to 6 is to ground the input in bypass mode

Anyway good luck with it

[smallbearelec]

Breadboard it first! Back up in this same section:

http://www.diystompboxes.com/smfforum/index.php?board=43.0

and you'll find my tutorial on how to use a breadboard. Different circuit, but the ideas are applicable. Breadboard the Bazz Fuzz without LED or DC power jack and make that to work. Then read the article on how to go from breadboard to box. It explains clearly how bypass switching and power work, and the pics will help you wire correctly when you commit to solder.

If you would like me to walk you through planning and building this circuit, I'll do that; just let me know in your reply. You don't have to buy the parts from my shop, and it would probably benefit others as well to see the whole thinking process in a series of replies here. We'll do the breadboard setup together and then I'll talk about how to lay out a board in a systematic way.

[ecoli]

Thanks for the replies so far.  Mcknib, I agree, I missed a ground wire in there.  I think easiest would be from the gain pot to the level pot.  I really like the 3PDT schematic you provided, that really makes a lot of sense to me.  Does a good job of explaining everything in one tidy little picture.  The 2.2uf seemed to be inline with what I found on the web, the home-wrecker link even specifies a 4.7uf, although everything I've read also says there's a lot of options and adding sockets is a good way to test out what works best for guitar or bass.

Smallbearelec, I really appreciate the offer to help me through this.  The breadboard looks like it's part voodoo to a newbie like myself, but I think that would be a great idea to walk through the steps of this build here if you're up for it.  I just need to order in all of the parts plus some different values for caps and diodes which would help others see how changing these affect the sound.

Thanks!

Chris

[mcknib]

You're right on the input cap Chris what I should have said is the biggest I've used is 220nF on the schematics I have, maybe that's where I went wrong eh? I've seen them at 10uF.

You learn something everytime you're on here 

As smallbear says breadboarding's the way to go you learn a whole hell of a lot more about the circuit you're building in a practical way.

[smallbearelec]

The breadboard looks like it's part voodoo...

Only until you have done it once successfully. Do you have a breadboard already? The one I use in my tutorials for simple circuits is this size:



and it is available from many sources. Reply here when you have everything together and we'll go at it.

Notes: Your drawing shows mono jacks and no battery. If you intend to build in a 1590A ("Twinkie Box"), this is OK. My preference is for a larger enclosure and provision for battery or external power. If you want to consider this, when you buy jacks, buy one mono, one stereo and a DC power jack with internal switch. The "why/how" is explained in the breadboard-to-box article.

[ecoli]

No, nothing yet.  I was posting the schematics so I knew what to order and/or pickup locally.  Breadboard will now be on the list!  I should say I do have a stereo jack in the spare parts box, so can set-up a build with a 9V battery circuit too, so will add a 9V battery snap.

Maybe to get started, a better understanding of what types of components I need to buy is in order.  While I've got them listed, some quick tips or links would be helpful:

1. Potentiometers - the schematic calls for 100k linear for the volume/level pot.  Would this suffice for the gain pot as well?  What specific diameter should I be looking for (given answer to 3 below)?

2. Capacitors - huge variety, but it looks like there are basically 3 major types; electrolytic, film, and ceramic (I think ones like PIO fall into one of these categories).  I know from wiring up guitars there's big size differences for the same value cap (orange drops are quite large I find), and I'm assuming this is due to the voltage ratings.  So, for pedals (or this build in particular) is there one type that is recommended over others? 

3. Enclosure - for this build, and being a beginner, would a 1590B enclosure be a good size, or even bigger? 

4. Perfboard - anything specific to look for, or is perfboard perfboard?

Thanks again!

[smallbearelec]

what types of components I need to buy

Potentiometers - the schematic calls for 100k linear for the volume/level pot.  Would this suffice for the gain pot as well?  What diameter?

Linear taper will always work, but might not be ideal in every situation. For volume or level, audio taper usually has a better "feel". For gain, this kind of circuit often responds best to reverse audio taper, but that usually has to be mail-ordered. Linear taper will work.

You are right that the size of the enclosure is one factor that dictates the size of the pots. 16mm will be fine.

2. Capacitors - huge variety, but it looks like there are basically 3 major types; electrolytic, film, and ceramic. for pedals (or this build in particular) is there one type that is recommended over others? 

For the input capacitor, 16 Volt or 25 volt radial electrolytic. For the output, 50 volt or better poly film.

3. Enclosure - for this build, and being a beginner, would a 1590B enclosure be a good size, or even bigger?

Good questions! You sensed, correctly, that the enclosure for your first build should leave you room to work. 1590B will be OK; I prefer the 125-B:

http://smallbear-electronics.mybigcommerce.com/small-bear-125-b/

They are usually similar in cost.

4. Perfboard - anything specific to look for?

Some shops still sell phenolic, and it will work. If you have a choice, buy FR-4 epoxy glass, pad-per-hole.

http://smallbear-electronics.mybigcommerce.com/pad-per-hole-perfboard-for-125-b-enclosure/

Don't worry about the exact size. These materials can be cut down with hand tools, and I'll direct you to the How-Tos later. I also prefer to build with push-in terminals:

http://smallbear-electronics.mybigcommerce.com/push-in-terminals/

and I always mount the board on standoffs:

http://smallbear-electronics.mybigcommerce.com/board-mounting-hdw-aluminum-1-4-bag-of-4/


Note: For another few cents, buy two 1N4148 (or 1N914) diodes. Then you can try the circuit with diodes back-to-back and see what it sounds like.

Reply when you have everything in hand.

[smallbearelec]

The OP of this thread says that he's ready for the walk-through. I'll do this very slowly, and with a lot of attention to beginner issues like interpreting a schematic, identifying components, relating connections in the schematic to the physical breadboard and doing the layout.

I have re-drawn slightly the schematic on the Homewrecker site to eliminate, for the moment, the power switching provided by a stereo jack on the input. We'll add that later when planning the transition to the soldered build. For the moment, I want the simplest possible implementation with a minimum of off-board connections. If this is your first build, please feel free to follow along. If you do everything exactly as I tell you, I promise that you will wind up with a working build on the breadboard.

When I set up a simple circuit like this on breadboard, I typically work from input on the left to output on the right. I emphasize that this choice is arbitrary. Do it the way I show you for now, and you'll learn enough to go your own way with future setups.

Looking at the schematic, the one from Homewrecker shows the MPSA13 as a single NPN transistor; it's actually two cascaded devices in one package-a Darlington stage as it's called--but it behaves as one very high-gain transistor. The pic on the right shows the relationship between the physical device and the schematic symbol.



Placement of parts on the breadboard is completely arbitrary and pragmatic. However, since the transistor is at the center of this circuit, I'm going to locate it more-or-less at the horizontal center of the physical board. I want to spread out the layout some for clarity, so I have inserted two leads, each spanning three holes, at Collector and Emitter. Set up this much first, and I'll come back.

[Dito]

You are right that the size of the enclosure is one factor that dictates the size of the pots. 16mm will be fine.

Correct me if I'm wrong, but 16mm seems to be the most common. There's also a wide variety of knobs meant for that size pot. Mix and match to taste.

If Mr. Small Bear sells them, get the nice ones with the rubber seals around the base. One less bare metal surface to worry about coming into contact with.

[ecoli]

My big thanks to smallbearelec for continuing on with this.  Hopefully others find this useful as well.  As I mentioned, the breadboarding is a bit of a mystery to me, so this should help clarify things!

Glad to see you're spreading out the layout.  When I bought the input caps, I figured higher voltage was better, so I got 400V caps.  They're a bit bigger physically and voltage wise than needed!  Live and learn.

I do have a few varieties of diodes and transistors, so similar to the homewrecker recommendations, I can try a few combos to see what I like.  Also bought sockets so I can always switch out components later on as well. 

But, first step; I have placed the transistor and leads in place !

[smallbearelec]

OK, let's add a few components. A convention of drawing a schematic is that this:

indicates that leads join electrically. When you see this:

leads cross in the drawing but do not join in the physical world. So the schem is telling us that the Collector of the transistor connects to:

--One side of a 10K resistor
--The anode (+) side of a diode
--One side of the output capacitor

Form the leads of a 10K resistor (Brown, Black, Orange, Gold) to span five holes. The resistor goes from the Collector of the transistor to the positive power supply bus. A short jumper makes the connection on the power side.

Form the leads of the diode (1N914, 1N4148 and many others will work) to span four holes. The cathode (negative) side has the bar, both in the schem and on the package, and that plugs in at the transistor Base.

The output capacitor is .1 mf. (microfarad). One possible source of confusion is the modern use of mf. in some documents to mean "millifarad". That's a very large capacitance, and what's meant is usually clear from the application.

I have applied color in the schem to show what's been connected and where we are at.

   

Set up this much and I will return tomorrow.

[ecoli]

Done.  Not quite as neatly since I left the leads long, but the same layout.  A couple of questions at this point:

1. The output cap I have is a metallized film cap (white box) as opposed to mylar film.  Will that matter?

2.  I have 3 types of diodes (aside from leds), the on I put in is the 1N4148.  I have the 1N914 as well, but they lack any black band.  They appear to be red inside with a pale brown end.  Is there an easy way to tell which is the cathode and anode?

Electric compnent convention is a bit different than I'm used to from analytical chemistry, where cations are + and anions are -.  We also use m to represent milli, and u for micro.  Just need to get past that!

[smallbearelec]

Done.  Not quite as neatly since I left the leads long, but the same layout.  A couple of questions at this point:

That's why I stopped here; I guessed that there would be a few questions.

1. The output cap I have is a metallized film cap (white box) as opposed to mylar film.  Will that matter?

Mylar film caps Are "metallized film". Both the one I used and yours are made of similar materials but are of different physical construction. Both will work. In most cases, knowledgeable ears will not hear a difference.

2.  I have 3 types of diodes (aside from leds), the one I put in is the 1N4148.  I have the 1N914 as well, but they lack any black band...Is there an easy way to tell which is the cathode and anode?

Use the diode test scale on your multimeter. When the device is connected in its forward direction, the meter will read .6 to .7 volts.

[smallbearelec]

Moving on:

Add the input capacitor, in this case a 2.2 mf. electrolytic. The negative side is usually marked by a black stripe. For clarity in my pic, I formed the leads to span six holes. I also added a short jumper to bring the input more to the left side.

Prepare the potentiometers by soldering short leads to each lug, and install the gain pot first. In the way that this circuit works, the gain will increase as the resistance from Emitter to ground is lowered. Connecting the Wiper and the CCW (counter-clockwise) pin to ground as shown accomplishes this. Compare the physical layout with the schematic and be sure that you understand what is happening. The level pot is connected a little differently; it's a voltage divider. The output capacitor is connected to the CW (clockwise) "hot" side of the pot, the wiper gets closer to it as it is turned and the volume level rises. Again, compare the layout with the schematic and be sure that you understand how the control works.

     

[smallbearelec]

Now we prepare for the acid test by setting up the input and output jacks and power. Here is a close look at the contacts of typical stereo and mono jacks. done for one of the articles I wrote for this Forum.



Add short leads to the Tip and Sleeve contacts, and terminate as shown so that you have connectors that can be re-used for other builds. Pay close attention to which contact is which, especially on the stereo jack. One of the most common beginner errors is reversing Tip and Sleeve, which then grounds the guitar signal.

[smallbearelec]

ARE YOU READY TO ROCK??

Plug in the input jack, set both controls to their midpoints, connect your gear and then connect a battery. Got action? CONGRATULATIONS! If  it does not work, back up and figure out what's not connected correctly.




Once you have the effect working, you are free to experiment with different diodes and capacitors.

The next step is to go from breadboard to a soldered build on perfboard, Veroboard or PCB. You can find some of my ideas about how to go about this in this article:

http://diystompboxes.com/beginnerboostbreadboardtobox/BeginnerBoost.htm

The Beginner Boost is another two-knob build, but the thinking-out process to get to a pedal is similar. Questions are welcome.

If you enjoyed this tutorial, please bookmark the thread and recommend it to other beginners who ask about the Bazz Fuzz.

[ecoli]

Thanks on the diode test.  Makes sense that's what that symbol is for!

I've got some more soldering to do, but the layout you presented makes sense to me.  A couple of questions for clarity:

1. For the gain pot, lugs 1 and 2 are connected together (2 connected to 1 via the 3 hole lead on column I) and from lug 1 it goes to the ground "channel" at the bottom, correct?
2. For the level pot, lug 1 is going to ground, correct?  The jumpers are simply being used to connect the different sides of the breadboard?
3.  Overall, the breadboard is like a non-soldered veroboard.  Differences are that strips run across the numbered rows, but up and down the power and ground columns on either side?  The channel in the middle is also a split, primarily for IC use?

Just trying to confirm what I'm fairly sure I'm seeing on the layout.  It makes sense to me if my thinking is right and really does help explain how everything flows.  I'll hopefully have everything soldered, wired and working tonight!  If it does, I'll post up photos.

[smallbearelec]

1. For the gain pot, lugs 1 and 2 are connected together (2 connected to 1 via the 3 hole lead on column I) and from lug 1 it goes to the ground "channel" at the bottom, correct?

Yes. I made the connection from wiper to CCW with a jumper on the board, but it could also be made by wiring the lugs together. Again, my choice for clarity.

2. For the level pot, lug 1 is going to ground, correct?  The jumpers are simply being used to connect the different sides of the breadboard?

Yes.

3.  Overall, the breadboard is like a non-soldered veroboard.  Differences are that strips run across the numbered rows, but up and down the power and ground columns on either side?

That's a way to think of it. However, Don't make the mistake of trying to duplicate the physical breadboard layout on Vero or perf! I can't emphasize this enough, because I see the same mistake A Lot. These are all different media, and you must think out the layout for each on its own terms if you want to come up with a workable breadboard layout or board design.

The channel in the middle is also a split, primarily for IC use?

Correct. Also, I have been known to run a jumper in it when a layout is tight and I need to get from upper to lower holes.

Yea, let us know how it goes and we can talk about committing to solder.

[ecoli]

It's alive!  Not without issues at first though.  I followed the layout provided but as you can see, my breadboard has the positive track located on the opposite side.  While this really doesn't matter as long as you're consistent in your ground and positive/power track, the problem was the jumper lead from the resistor was going to the ground.  Solved that and then had sound.  I found I didn't really like it in any position but full fuzz (rock on!) So I pulled that pot.  Then no sound again.  Careful looking through and I realized  I didn't ground the emitter leg of the transistor.  Quick fix and it's all good!  Now to transfer to veroboard.

Thanks again for the help and easy to follow steps.  I really did learn enough to be able to troubleshoot when things weren't working, which is of course an essential skill in building pedals.