Recently I decided to play with the Autorouter and see how much time it really saves. The feature is as easy to use as pressing a button. Pretty fast too. By default the autorouter wants to create a 2 layer board. If you are doing your boards by hand you’ll want to create a single layer board. In Autorouter Setup > General set 16 Bottom = N/A.

To set the trace size Go to Edit > Design Rules. In Sizes set the trace sizes. The default size is pretty small and will route traces between the pins of transistors. This might be a little tight with traces too thin for etching by hand.

I found the Autorouter to work best iterating by hand. Autroute your board. Take a look at the results and look for where you can optimize the results by moving parts around or changing their sizes. For example changing a resistor from a a .3″ span to a .2″ or .1″ span. Ripup the traces and Autoroute again.

Sometimes you run out of ideas, the Autorouter makes a nice collaborator, giving some good suggestions here and there. Sometimes the Autorouter will place an awkward trace snaking through the middle of your layout. By examining this you can often move some parts around and Autoroute again to get  a better result.

Seems like a time saver. But I would add that iterating by routing, modifying and routing again can take time. So creating a board with the Autorouter is not at the speed of clicking a button, unless you’re happy with the first results. Getting the parts into a good position in the first place really speeds up the process.

I was talking to a friend about distortion boxes and the Box of Rock came up. Which got me thinking, I’d never heard one before, and Z Vex always makes good stuff. I found a schematic in the usual place. It looked like a pretty easy build.

The Box is basically two pedals in series, a distortion followed by a booster. The Box has two foot switches, The first switch engages the distortion and the second engages the booster. The controls for the distortion are Gain, Tone and Volume. The booster adds a fourth knob, Gain/Boost.

The distortion section is made of three BS170 MOSFet stages. The first stage is a SHO followed by a Marshall style high pass filter made of a 470p cap and a 470K resistor in parallel. Then come two more BS170s configured gains of approximately 51 and 15.

Next is a BMP style tone stack followed by an extra low pass filter. The low pass filter is exactly the same as used in the BSIAB II. The BSIAB II also uses the same Marshall style, 470p and 470K, high pass filter between the first two stages.

The B of R includes an SHO booster on the output. I had one of these built already so i decided not to build the stock B of R and instead build just the distortion section. I figure I can place my SHO or any other booster after it for different sounds.

Blaxendall/James Tone Stack

I also decided to change up the tone control for a little more variety and to make this into something a little different. I had heard a few good words about the James Tone control a.k.a. Baxandall tone stack. This is a two knob type with a Bass and Treble control. A good description of this tone stack can be found here. Here’s a shorter less technical description.

Here’s an image of the James/Blaxandall tone stack. RT and RB are the Treble and Bass control. I had run into this tone control before at Freestompboxes.org in a project by forum member Mictester. It was included as part of a project called Bigmuff Plus. This was sort of a BMP on steroids. My drawing includes values for the Orange Amp tone controls and the values used in the Big Muff Plus.

Note that the Blaxandall uses the Audio taper pots for the Bass and Treble controls. These are not required but, without them the usable adjust range is bunched up at one end of the pot rotation.

Initial Schematic

I drew everything in my notebook. At this point I had the following (note this omits the extra low pass filter and volume pot):

I built everything on a breadboard to test out the idea. I tested each stage as I built it. One thing that impressed was how bad the distorted sound was without a tone stack. I shouldn’t really say “bad” as the sound wasn’t terrible. Heck, it’s distortion right, so it might sound good to somebody. What is “bad” when it comes to distortion? The sound did lack the refinement and had some extra high end hash that wasn’t helping in my opinion. Through headphone the sound was unbearable. The headphone, I’m guessing, were reproducing more high end then would come out of a guitar speaker. After adding the tone control the sound was much smoother and had a lot to recommend it.

Later I added the extra low pass filter following the tone control. This really moved the sound into the Marshall territory. This kind of extra fixed filter stage added to the end made a noticeable difference in the sound. Seems like it might be a good addition to a lot of boxes.

Building

Originally I had planned on using the Orange tone stack. Turns out I could only find a single A1M pot. Looking over Mictester’s take on the Blaxandall, he used different resistor and cap values alone with a A470K pot for the treble control. I did happen to have an A500K pot (with detents, it clicks at each of sixteen steps). So I Decided to go with those values. Some times you have to just work with what’s available.

I drilled a box fit all the parts and wired up the standard box connections. I drew up a perf board layout which placed all of the transistors in a row. I noticed at this point that the BS170 is DGS while the 2n7000 (another MOSFET) is SGD, seems like it would possible to swap these.

First test

I’m not the greatest at making flowery descriptions, but here goes. The sound is tight and crunchy. You can dial in a surprising amount of low end with the bass control. The bass is tight and doesn’t get muddy. It’s got a sound you would associate with Marshall amps. I’d say it does AC/DC to Van Halen. It doesn’t quite get to metal.

The added low pass along with the higher impedance tone stack cut the output noticeably. The volume needs to about 3 o’clock for unity gain. Might be good to add another transistor on the end to boost the volume. Then again maybe tinkering with the volume pot might be enough.

I hate that name. Then again it’s a play on the name Meatball. The Meatball, if you are not familiar, is an envelope filter based on the Mutron III. The Meatball was made by Lovetone who went out of business in the early to mid 2000s. Lovetone seems to be coming back. Hard to tell from their site. The Mutron III was made by

The Mutron III is a envelope controlled filter produced by Musitronics in the 1970s. An envelope filter is a filter effect controlled by the dynamics of the input signal. The volume of the input signal determines how much sweep is applied to the filter effect. Think of it like a wah where the action of the treadle is controlled by the dynamics of the input. Some would refer to this as an auto-wah. The Mustron III had three filter modes  High Pass, Band Pass and Low Pass. It had an input Gain control and a peak control which set the resonance of the filter. It also included a Low and High Range switch and a sweep switch to set the direction of the filter sweep to either Up or Down.

The Meatball added several controls the original Mutron. With six knobs and four multi position switches the Meatball has a lot of options. Besides the original options in the Mutron III the Meatball adds Attack and Decay to control the filter sweep, Intensity controls the range of the sweep, Blend blends the original signal with the effected signal. A Bandwidth control which sets the range of input signal is used to control the envelope. One of the bandwidth settings disables the envelope sweep. The Meatball also adds an Effects loops. This is an important option with the envelope filter since many effects placed before the effect may compress the signal flattening dynamics which confound the envelope generator.

The Meatsphere is essentially PCB that can be used to make a clone of the Meatball. I suppose you could use it to make a Mutron III also. The PCB is available at MusicPCB.com.

I had started a Meatball on perfboard some years ago. I put the thing on a shelf due to not finding an enclosure I was happy with and lacking enthusiasm for the copious amount of wiring required. Hmm let’s see, thats 6 pots, 3 * 6 = 18, plus 4 3 pole 4 position switches, that another 3 * 4 * 4 = 48 wires. Then there’s the four jacks. Two of which are switching, include power jack, LED and foot switch and there’s more wires than I can count. The original Meatball I started has remained on the shelf.

The Meatsphere is a brilliantly conceived PCB. All of the pots and switches (excluding the foot switch) mount to the PCB. This reduces the amount of wiring to a minimum. The PCB neatly fits a 1790NS enclosure available at smallbearelec.com. This enclosure is slightly larger than the common 1590BB boxes used by many DIY stompbox builders.

After thinking about this new PCB and how easy it would make the whole project I ordered two boards and parts to build a pair. The PCBs were $17 each and the enclosures were another $11.25. With switches parts and shipping on everything I figure the cost to be about $60 each. Fairly steep for a DIY project. This is a large project but looks to be a more simple build than most thanks to the MusicPCB Meatsphere PCB.

Here’s a link to a discussion of the Meatsphere on DIYStompboxes.com.

The Meatsphere PCB

The PCB looks great. The production quality is amazing. The board itself is well thought out with pads for external parts well placed. The is two sided and planned so the pots and rotary switches mount on the backside. All of the off board wiring is neatly arranged near the edges of the board.

The board is well labeled. I could easily read all of the part values and soldered everything up without referring to the PDF instructions. I made sure to read the discussion and the notes before starting in case there were any errors.

The Box

I started with the box. Using the drilling template provided by Vince b on the Stompbox forum. The template made things simple and easy. I printed the template taped it to the box and marked each hole with a punch before drilling.

After drilling I checked all of the hole sizes against the parts they would fit, resizing holes with my trusty reamer as needed. From here I assembled the rotary switches and pots. Then I aligned the switches with the PCB. Discussion on the forum seems to say that the rotary switches can fit in any orientation. At this point I wanted to make sure that everything aligned. The drilling template seems to be spot on. Everything aligned perfectly.

On closer inspection I noticed that the height of the rotary switches is taller than the pots. This leave the legs of the pots a little too short to reach the PCB. I tried bending the legs of a pot to make it reach the PCB. This might have worked, but I didn’t like the idea of the extra stress it might place on the solder connection. I decided to solder some wire extensions on to the legs of the pots. I tinned the pots first then soldered a short approximately 3/4″ length of solid copper wire to the leg. A small heat sink work well to hold them in place while I soldered.

I tested one pot in the box after I was done. This looks like it will work well. At this point I figured I’d assemble the whole things and make sure everything fit. I tested out a few different knobs and decided on plain black with points for the pots and some chickenhead pointers for the rotary switches.

Soldering the PCB

I started soldering with all of the resistors. Then followed with the diodes and caps. After the resistors I soldered all of the non-polar caps followed by the polarized caps. Next I soldered the ICs. The Meatsphere uses two ICs a TL074 a quad op-amp in the DIP 14 pin package and a LM1458 in a DIP 8. There was some talk on the forum about the LM1458. The claim is that this chip is a must and should not be subbed with another variety. This seems odd but credible. I decided to use socket.

LED and LDRs

The Meatsphere uses two LED and LDRs to affect it’s filter sweep. These parts are notoriously varied. The board shows VTL5C3 as the part value. These parts are well made and easy to use, but cost more than discrete parts. I used the VTL5C3 for the first board. I think I might use a socket for the next build and test out some of the other LED/LDR parts to see what the difference might be.

Box and test

Once I had everything in the box the first test failed. The envelope did not seem to function. I remember the notes about the LM1458. I had used an MC1458. I tested a few chips from my parts bin and found one that worked. Turns out this chip is also labeled MC1458N, though it appears to be different from the other chips labeled MC1458.

A box with ten controls, six knobs and four multi-position switches, is pretty confusing to operate. I had to label everything. I chose to point the two outer rotary switches straight down in the center position and point the two inner rotary switches to the  inside. I just marked everything with a sharpie and placed a big dot at each position to make the choices clear.

This was a pretty easy project, I already had a PCB and all of the parts on hand. The PCB I had did not have any space for the tone control. The Big Muff tone control requires, besides the pot, fours parts, two resistors and two capacitors. I remembered seeing an article on the Big Muff tone control over at Beavis Audio research where they mentioned soldering all of the parts on to the pot. I thought about this but decided against it. I have been using and planned to use these 12MM pots. Which seemed too small. Plus the box was going to be a little crowded and didn’t want to risk the parts shorting against something.

[picture of 12mm pot]

I decided to mount the tone control on a tiny piece of perfboard.Using small multilayer ceramic caps would make the whole thing fit easily.

[image of perf layout.]

Last was to run the output of the Ugly Face into the tone control before going to the volume.

[Picture the interior of the box]

I decided to do this box in a plush purple fur.

I’ve seen exactly two projects that make use of this. The first was a project from the now defunct Stompboxology Newsletter named Tremolo-Matic X. The other is the Vibrotrem by Bajaman ove at Freestompboxes.org. Basically the circuits do the same thing though they use different methods. The input signal is split and routed through a high pass and low pass network. A tremolo effect is applied to each of these signals with the cycles being 180 degrees out of phase. As the high pass increases in volume the low pass signal is decreasing and vice versa.

The Tremolo-Matic X uses a NE570 chip as two VCA. It uses a couple op-amps for a LFO and a few more as a buffer and the high and low pass networks. I built this and posted some notes here and here. The circuit had a great sound and was not difficult to build. The NE570 may be hard to get or cost prohibitive to some.

The Vibrotrem uses a LED/LDR to control the level of the high and low pass sections. Bajaman seems to have done thorough study of this type of tremolo and has optimized the filter section. I have not built this project, but have no doubt it would sound as good or better.

Caitlinbread makes a box, the Pareidolia that does a similar effect, without the controls for Bass and Treble. From their description it sounds like the Bass and treble fix at an optimal point where they share a midrange cross over. The clips on the site sound pretty good.

Now days you can get these everywhere and the prices seem to get as low as $3.50 each, though the price seems to have settled around $5 on average.

When I began doing this DIY stuff I made a few boxes with the Carling DPDT switch. To get an LED to work with one of these was a difficult proposition. A few people, mostly R.G. Keen, came up with a handful of ingenious circuits that would allow an LED to work with the DPDT. The most famous of which is the Millennium Bypass. At the time I felt this was a little beyond my skills so I never attempted to use one of these in a box. Mostly my boxes went without an LED.

Then I found the 3PDT switch and all of a sudden even I could have an LED. Provided of course I was willing to invest $13 into a box. Now days it’s not even a question of how to get the LED to light, this is the standard switch used by everyone professional and amateur. Heck this is the standard switch even when you don’t need an LED. I think Zvex still uses the Carling DPDT in the Fuzz Factory, I think the Fuzz Factory still doesn’t have an LED. Is the Fuzz Factory the new old school?

As long as we’re talking switches here’s a few pictures of switches. The first is the Fulltone 3PDT. Next is the Carling DPDT, I like to think of these as the vacuum cleaner switch. Third is the current ubiquitous 3PDT. Not sure where I got this one. Fourth and fifth is the X-Wing type DPDT. The sixth is a miniature 3PDT  switch from Mammoth Electronics. I had high hopes for this switch when I first saw them. After ordering a few I was less enthusiastic. The switches are not very tall often shorter than the knobs on a box. The holes in the solder leads are too small to fit most wire through. The body is a bit smaller than the standard blue 3PDT so they do save some space (I wrote more about this here). The last image shows a size comparison of all of the switches. Mammoth Electronics makes a 4PDT switch which I haven’t tried but might be good for something.

It plays pretty good. The strings are much larger than a regular guitar about half way to a bass guitar. The neck through body construction makes playing the upper frets very comfortable and natural. The frets are large. The guitar has a nice balance to it like other guitars in this body style. The body has the strat style cutaway.

At some point I decided a Sustainiac would be a good thing here. Not sure why? I had the guitar routed by Gary Brawer for a 9V batter case and installed the sustainer. The sustainer is fun. I’m thinking about doing a couple posts about sustainers in the future.

The one problem I have had with the guitar has been the sound. Physically it’s just a six string with bigger strings. You’d think it would then sound like a typical six string tuned to a low B. This is not exactly the case. The G string is a solid non-wound type, but much heavier than normal. Rather than the bright sound of the typical solid strings in a regular gauge the string has a dull metallic twang. It sounds more like wire than the string on a musical instrument. From what I understand baritone strings are available with a wound G string. I think I will try a set like this the next time I change strings.

The pickups also sounded dull or muddy. I changed the bridge pick up for a Duncan Invader. This didn’t sound that great either. At this point I started thinking about what type of pick up would work well in this type of guitar. It seemed to me that the heavier strings produce more output from the magnetic coils in the pick ups. The guitar it self produces more bass. Seems this is a recipe for mud.

It seems this type of guitar would benefit from having a lower output pick up. Hopefully one that handled bass frequencies elegantly. The original pick ups measure 8.4K for the neck and 16.7K for bridge. Wow those are pretty hot. The Invader is listed as 16.8K. I think I need to go the other direction. Maybe a Jazz type pickup, something with a lower output.

I started with a length of aluminum L bracket from the hardware store. I had to buy 4 feet of the stuff. So I cut it into 4 one foot pieces and decided to make three test rigs.I drilled a hole every inch starting a half inch from the edge. This gave me 11 holes to work with. After the input, output and bypass switch that leaves 8 holes, which should be plenty for almost any project. I’m going to leave the post out and just install them for what every is currently on the breadboard.

The other parts are not too critical, figure cheap switch and jacks is not a big deal when working with a bunch of parts on the breadboard, better to save the expensive parts for the final build.

I headed to RS to some jacks and a switch. I got a big DPDT toggle switch to switch the effect on and off. I figure this will be easier to use and cheaper that using a stompswitch. I considered adding an LED but decided the extra wiring and hassle wasn’t worth the effort. LED wouldn’t add much anyway since the switch is clearly labeled On and Off.

A small patch of Velcro to hold the breadboard down. For some reason the Velcro was $6 for one foot at the hardware store! Note to self, somethings should not be bought at the hardware store, Velcro topping the list.

Here’s a few pictures of the test rig.

So far the Fuzz section is working on the breadboard. The octave section is not working at the moment. I suspect the bias is off. Note the voltage around Q3. The collector and emitter voltages should be close to 4.5V. So far they are pretty far off.