Sabbath Drive

This is a post that has been a very long time in the mak­ing. I start­ed this project back in Octo­ber of 2018. Gui­tarPCB had a sale and it looked like their Sab­o­tage Dri­ve would be an inter­est­ing chal­lenge. There were six (!) tran­sis­tors in this cir­cuit. But I want­ed to make this a real­ly fun project so I designed some cus­tom art­work as well, all themed around Black Sab­bath — the inspi­ra­tion of this cir­cuit’s sound. This cir­cuit fur­ther seems to be inspired by Catal­in­bread­’s Sab­bra Cadabra ped­al, anoth­er pre-amp in a box effects that tries to cap­ture Tony Iom­mi’s sound of a Dal­las Range­mas­ter tre­ble boost push­ing a Laney Super­group head1. Or, put it anoth­er way, the sound of doom met­al!

Sabbath Drive Workstation
Sol­der­ing com­po­nents for the Sab­bath Dri­ve project

I did some lay­out in an SVG file for the graph­ics, which you can see above. This is also large­ly where I did the drill hole pat­terns for the enclo­sure, as those go hand-in-hand. My graph­ics incor­po­rat­ed some of the Sab­bath album cov­ers. I was fair­ly proud of the design, if not the actu­al imple­men­ta­tion. I then got to sol­der­ing the cir­cuit com­po­nents. Bar­ry Stein­del of Gui­tarPCB did a great job design­ing this for a rel­a­tive­ly com­plex build, it is a very clean lay­out.

Sabbath Drive PCB Resistors
Resis­tors and tran­sis­tor sock­ets in place

I think I’ve men­tioned this before, but I am in the habit of tap­ing out all the com­po­nents to a parts sheet with labels that cor­re­spond to the PCB silk screen labels. This would­n’t scale up to a large pro­duc­tion, but for one-at-a-time builds, it real­ly takes the stress out of try­ing to find the right com­po­nent for each step.

Sabbath Drive Component Leads
Com­po­nent leads being cut
Sabbath Drive Components
Close-up of the tran­sis­tors being placed in the sock­ets — bend those leads!

Once the com­po­nents were in place, it was time to final­ize the enclo­sure lay­out. The rel­a­tive place­ment of the pots/knobs are fixed since they are sol­dered direct­ly to the PCB. But the place­ment of every­thing else is depen­dent on get­ting it all to fit. I would have loved top-mount­ed jacks as you can see in the orig­i­nal sketch below, but that was­n’t going to hap­pen with this PCB lay­out (in the size of enclo­sure I chose, any­way). I need­ed to for­go that in order to squeeze every­thing in place. Regard­less, no 9v bat­tery in here! I don’t use ’em any­way.

Sabbath Drive Enclosure Layout
“Dry fit­ting” the off board com­po­nents and con­trols for the lay­out

When it comes to drilling the enclo­sure, I use a step bit in my drill press. Anoth­er thing I’ve prob­a­bly men­tioned: I have a small med­i­cine syringe with machine cut­ting flu­id. That way I can use my cen­ter punch to mark the point on my tem­plate and the put 1–2 drops of cut­ting flu­id right at that spot.

Sabbath Drive Drill Press
Drilling the enclo­sure holes

As you can see below, I actu­al­ly test­ed the cir­cuit before I even com­plet­ed drilling all the lay­out holes. I drilled the holes for the pots to get those mount­ed to the PCB in the cor­rect ori­en­ta­tion. I think wired up some leads for sig­nal in/out, the 9v pow­er, and ground to hook up to my test­ing rig.

Sabbath Drive Test Box
Test­ing the effect on the my test­ing rig

Then it was time to fin­ish drilling the holes and wiring up the off board switch, jacks, and LED.

Sabbath Drive Case Layout
Off-board wiring in progress (I don’t recall why there was a third jack!)

It was a bit of a tight fit into the enclo­sure, but part of that was my desire to place the LED near the top of the ped­al I real­ly don’t like LEDs right by the footswitch, where the get cov­ered up by your foot! Sure, they’re a lot eas­i­er to put there, but they don’t make it easy to tell you’ve prop­er­ly engaged the effect.

Sabbath Drive Offboard Wiring
Com­plet­ing the off-board wiring

I tried using our vinyl cut­ting machine to cre­ate paint­ing a paint­ing tem­plate from my SVG file. My first mis­take was using some cheap vinyl which did­n’t stick to the pow­der-coat­ed sur­face well.

Sabbath Drive Vinyl Cutter
Cut­ting the paint tem­plate on our Cri­cut

Then I used acrylic paint which bled under that tem­plate. Also, the tiny let­ter­ing details were just about beyond the scale was which the Cri­cut could suc­cess­ful­ly cut this vinyl. The end result looked about like I’d just hand-paint­ed the whole thing. I was­n’t at all hap­py with the paint job, but know­ing I was­n’t like­ly to improve on it, I went ahead and sealed it with some spray clear coat.

Sabbath Drive Paint Template
Vinyl paint tem­plate trans­ferred to the enclo­sure
Sabbath Drive Painting
Acrylic paint on the tem­plate

So I fin­ished all this Decem­ber of 2018. I nev­er post­ed about it all last year though because I real­ly was­n’t able to get a good sound record­ing of this. My iPhone demos so far have been pret­ty lack­lus­ter. And this effect did­n’t sound as great as I’d liked any­way because it’s real­ly meant to run into a cranked amp. Though I used my pre-amp, pas­sive vol­ume con­trol I could­n’t real­ly push the pow­er amp sec­tion of my tube head. Well, in the past cou­ple of months I got a pow­er atten­u­a­tor and a pret­ty good mic to record some audio with. My ampli­fi­er has a “cab emu­la­tion” out­put, as does the pow­er atten­u­a­tor but both frankly sound pret­ty ter­ri­ble. None of the record­ings with those ever had any of the low end that the amp actu­al­ly pro­duces. But using the atten­u­a­tor with the head vol­ume cranked and the mic into my record­ing inter­face, I’m final­ly hap­py with the sound I can get record­ed.

So here is the full sig­nal chain:

  • My Fend­er Tele­cast­er with a Lace Sen­sor Death­buck­er pick­up in the bridge posi­tion2
  • This runs through a TC Elec­tron­ic P0lytune 3 (I men­tion this because it has a buffer — all oth­er effects are true bypass) and then into the Sab­bath Dri­ve ped­al.
  • The Black­star HT5 Met­al head on the clean chan­nel (cranked to 10) and a TC Elec­tron­ic Hall of Fame 2 reverb ped­al in the effects loop.
  • The head runs through the Bugera PS1 pow­er atten­u­a­tor into the Black­star 1x12” cab­i­net with a Celestion G‑12T speak­er.
  • The cab­i­net is mic’d with a MXR R144 rib­bon mic into the Behringer UMC22 audio inter­face.

I use some of the EQ set­ting in garage band for the gui­tar and the over­all mix. This par­tic­u­lar record­ing was used with one of the “auto” drum­mers in Garage Band. This video is the live record­ing you’re hear­ing; just poor­ly sync’d to the audio. The gui­tar is a sin­gle track.

*cough, cough* Sweet Leaf — Black Sab­bath (with all apolo­gies to Tony Iom­mi)

On the whole, I’m real­ly pleased with the sound of this ped­al. The Range and Pres­ence con­trols give a real­ly wide tonal range. I’ve cranked the dis­tor­tion here (hon­est­ly, not even sure why that knob exists! Just fix it at 10!). The vol­ume is about at noon. I shud­der to think just how loud this ped­al would be with that cranked.

Also, for ref­er­ence, here is a short demo I did of a Sleep song (“The Druid,” only slow­er tem­po) using the cab emu­la­tor from my amp head. The sound is def­i­nite­ly more “fizzy” and flat here.
  1. For the record, even though the old­er Sab­bath records were record­ed using those, it does­n’t appear Tony Iom­mi uses those any more. He has a sig­na­ture Laney head that appears to have the tre­ble boost “built in”. Laney also has a sim­i­lar, sig­na­ture ped­al which claims to box all this up, but appar­ent­ly Iom­mi does­n’t use it at all accord­ing to his site. []
  2. Yes, I need to write an entire post on my gui­tar and the mod­i­fi­ca­tions I’ve made to it. []

Ah, Rats (Pedals)!

The Pro Co Rat is a, if not the, clas­sic dis­tor­tion gui­tar effect1. It’s still around though “vin­tage” effects can go for hun­dreds of dol­lars. There are many vari­ants and, like any clas­sic gui­tar effect, there are many clones. It’s also one of those ped­als that many of the mods and clones have improved upon the orig­i­nal.

Aion Helios Vin­tage Dis­tor­tion Kit

I got a com­plete ped­al kit from Aion effects — the Helios Vin­tage Dis­tor­tion. I have built one of their effects using just a PCB before, and the instruc­tions are top-notch. The kit was equal­ly well done, with qual­i­ty com­po­nents. The Helios is basi­cal­ly a Rat clone that uses an OP07 chip (instead of the hard to find LM308N and most folks who seem to know say they sound the same, any­way). The Helios also includes a cou­ple of very com­mon mod­i­fi­ca­tions to the Rat: an addi­tion­al “sweep” con­trol and a clip­ping diode selec­tion. The for­mer adds an addi­tion­al EQ con­trol to the ped­al where as the lat­ter adds the abil­i­ty to select dif­fer­ent clip­ping diodes that decide the char­ac­ter­is­tics of the dis­tor­tion.

Com­po­nents for the Rat ped­al laid out

I’m not sure if I’ve real­ly men­tioned this in any posts of effects build­ing, but I pre­fer to tape down all of the com­po­nents for each build onto paper along each of their descrip­tions. This is sort of anal­o­gous to “knolling” a LEGO kit, I sup­pose (though tap­ing them down makes the com­po­nents eas­i­er to iden­ti­fy lat­er!).

Aion footswitch board and red resistors
Aion footswitch board and red resis­tors

As I men­tioned, the Aion kit comes with what all seem to be high qual­i­ty com­po­nents. I have to admit, the all red resis­tors had me con­fused. They were clear­ly labeled with text as to each val­ue (which is much bet­ter than try­ing to read col­or bands!). They appear to be 1/4W 1% met­al film resis­tors with a coat­ing and print­ed val­ue is all.

Rat pots and switch­es

The kit comes with lit­er­al­ly every­thing you need, includ­ing pot iso­la­tion cov­ers. The fit-up of the top-mount audio and pow­er jacks is very pre­cise, so I did have to re-work the sol­der joints on one of the jacks. But the result­ing fin­ish of the enclo­sure is that much nicer.

Rat ped­al ready to assem­ble

The wiring in the ped­al is done using head­ers and small rib­bon cables. If you real­ly hate off-board wiring (I don’t mind it so much), this is real­ly nice. Here you can see the cus­tom dress­ing nut used over the stomp switch (there’s a sim­i­lar cus­tom nut for the clip­ping switch!), which gives the ped­al a very high-end made feel.

Rat ped­al guts and signed bot­tom cov­er
Rat ped­al guts shot after final assem­bly

I do have a few com­plaints about the kit, though. First is that the PCB just refused to lay flat on the selec­tor switch and pots. I could have fid­dled with it more, but it seemed like things just did­n’t want to line up. Even though Aion states the 3PDT footswitch is a pre­mi­um switch, with longer life, I’m not a fan of the feel of it (I guess I’m just so used to either a relay or the Tai­wan blue switch!). Last­ly, and this is some­thing I absolute­ly plan to change on this ped­al: the LED is insane­ly bright! I mean, it hurts to look at and is actu­al­ly dis­tract­ing, even when you’re not look­ing direct­ly at the ped­al! I’m going to swap out the LED resis­tor to dim it down. A lot!

Helios Vin­tage Dis­tor­tion Kit Com­plete

But these are great kits and this is an amaz­ing ped­al for less than $75 (on sale, reg­u­lar­ly $82). The assem­bly took me about 2 hours or so (that includes tak­ing a few min­utes to put my son to bed). Of course, your mileage may vary. Some of their ped­als are sold ful­ly assem­bled on Reverb or you can also reach out to a builder to see about pric­ing an assem­bled ped­al. Even at that price, it’s a good deal! With the clip­ping options, it can cov­er ground from almost a trans­par­ent boost all the way to a medi­um gain dis­tor­tion ped­al (I mean, it’s no Boss Met­al Zone…). It’s hon­est­ly cheap­er than you could pur­chase a used Rat ped­al and mod it, and already mod­ded Rat ped­als go for much more.

Now, none of this mat­ters if it does­n’t sound good, of course. Once again, I’ve man­aged to build a ped­al and write a blog post with­out both­er­ing to record any audio. Part of that is because I don’t yet have a mic and I’m not pleased with the cab­i­net sim­u­la­tor on my amp head. But most­ly, it’s because I’m lazy and not real­ly a great gui­tar play­er! I’ll try to get some audio post­ed soon, though.

  1. Now, when I say “dis­tor­tion effect”, I’m not refer­ring to fuzz ped­als or dis­tort­ed ampli­fiers, I real­ly do just mean dis­tor­tion effects ped­als. Hen­drix nev­er played one of these! []

Guitar Pedal Board

I real­ly make a point to try to learn some­thing new with each mak­er project I do. Whether it’s a wood­work­ing project, a gui­tar effect, or some oth­er hob­by project, I want to add in at least some­thing new to each one. First, it just keeps things from feel­ing redun­dant. But also it helps to expand my skills.

Steel and ply­wood ped­al board

I’ve need­ed to make a gui­tar ped­al board for a cou­ple of years now. Most­ly just to clean up the cor­ner of my office where my amp and effects sit. It’s not like I’m ever going on tour or any­thing. I fig­ured the met­al frame I made in my intro to met­al­work­ing class would be fun to use as a basis for a ped­al board. Up until now, it’s just been sit­ting in our garage; lean­ing against a wall. Of course, the more I start­ed plan­ning, I quick­ly real­ized it was real­ly just a dec­o­ra­tion around an oth­er­wise wood­en stool (albeit a short and slant­ed stool; that’s real­ly all this is). I had want­ed to put a shal­low rab­bet around the edge of the board so the top of the steel frame would be flush with the wood. I tried using both a router bit and my table saw and both were pret­ty much com­plete fail­ures. Odd­ly enough, the sam­ple board I tried on the router worked fine, but that was with the veneer grain run­ning along the direc­tion of the rab­bet. When I tried using par­al­lel grain on the “real” board, it just shred­ded the veneer. The table saw gave a clean­er cut but was just far less accu­rate (and was­n’t much clean­er than the router).1

Cheap router bit and slop­py wood­work­ing don’t result in clean rab­bets, I guess

So, I basi­cal­ly just build my ped­al board out of 3/4″ ply­wood to dimen­sions that I could slide the met­al frame over it. The ped­als don’t sit entire­ly flat, but they work fine for my needs still. I still need to get some more Vel­cro tape to attach them (which would just main­ly help allow me to up the pow­er cords under­neath). It’s prob­a­bly a bit too tall to be very prac­ti­cal and I’ll almost cer­tain­ly replace it at some point. Whether or not I try to include the met­al frame is anoth­er mat­ter…

So it does­n’t real­ly begin to hold all my gui­tar ped­als (note those sit­ting on top of the speak­er cab­i­net)
  1. I ful­ly attribute both of these fail­ures to my own inex­pe­ri­ence. It does­n’t help that I have some very basic setups and things like feath­er­boards, zero clear­ance inserts, etc. would also help actu­al­ly accom­plish what I had in mind. []

The Bazz Fuss

You know a pro­jec­t’s been lin­ger­ing too long when your son — who could­n’t care less about gui­tar or effects ped­als — won­ders into your office one day, points to a jum­ble of wires and com­po­nents, and asks “are you ever going to fin­ish this thing?”

That “thing” is the bazz fuss cir­cuit I sol­dered onto a perf­board sev­er­al months ago. I had watched Paul of DIY Gui­tar Ped­als put togeth­er his “5 minute fuzz” effect and had read an arti­cle on Sey­mour Dun­can’s site about build­ing the effect with some nice mods to the orig­i­nal cir­cuit. Some more details about the orig­i­nal effect are avail­able here, but essen­tial­ly it seems Chris­t­ian Hem­mo devel­oped a fuzz effect for the bass that used the fewest com­po­nents pos­si­ble (and still gen­er­ate a decent effect, any­way). The design is extreme­ly ele­gant and pro­duces a nice “dirt” fuzz effect (prob­a­bly per­fect for bass gui­tar). Hem­mo’s orig­i­nal site is long lost on the inter­net (ah, Angelfire.com! — still avail­able via Archive.org, though, of course) but his cir­cuit lives on.

The bazz fuss effect on a bread­board with labeled con­trols

I built my first attempt at a Bazz Fuss effect by wiring the com­po­nents in my bread­board, fol­low­ing along with the Sey­mour Dun­can arti­cle (seri­ous­ly can­not rec­om­mend that arti­cle enough). I went through the var­i­ous iter­a­tions on the bread­board in the arti­cle and end­ed up with the “mod­ded” ver­sion there-in. I even tried adding a bat­tery sag con­trol as well, to emu­late a bat­tery los­ing its charge which sounds good on some effects. This par­tic­u­lar effect is one in which it basi­cal­ly just no longer has enough volt­age to make any noise, so it just kills the sound below that thresh­old. This is the bread­board­ed effect that I used to demon­strate my test rig, in fact.

Inspired by this Make video on cir­cuit skills on using perf­board to quick­ly build a cir­cuit, I fig­ured I’d try sol­der­ing the com­po­nents down. I just bent over some longer leads and sol­dered them to make more-or-less a ground rail and a pow­er rail, and then built the cir­cuit from there. I sketched it all out on graph paper before hand, but the cir­cuit is so sim­ple I had near­ly half of the perf­board free after sol­der­ing every­thing.

My ini­tial perf­board cir­cuit

And so this sat on my shelf for months until my son asked about it. I fig­ured I real­ly did need to wrap this thing up before mov­ing on to any oth­er projects. I had pur­chased a blue pow­der-coat­ed enclo­sure for my treme­lo kit ped­al and had already trans­ferred the guts of that effect to its new home. So I had an enclo­sure that only need­ed a cou­ple of holes made larg­er.

I should note here that I use exter­nal nut AC jacks on all my builds. Yes, they stick out fur­ther and are less attrac­tive. But, here’s my rea­son­ing:

  • all the oth­er exter­nal com­po­nents (except LEDs) already have exter­nal nuts
  • I found that the extra 1/4″ of depth pro­vid­ed using an exter­nal nut AC jack real­ly helped in a 1590A enclo­sure, such as my Micro Amp clone
  • most impor­tant­ly: I can pull the guts of a ped­al out with­out hav­ing to cut a sin­gle wire; noth­ing is actu­al­ly even nec­es­sar­i­ly wired after going into the enclo­sure at all this way!

In the spir­it of recy­cling old parts, one of the resis­tors I had pulled from my Cry­Ba­by Wah mod was the right val­ue for the LED resis­tor! I don’t even know why I both­ered sav­ing it, but I was glad I did. I use some of the spare space on the perf­board to mount the LED and the resis­tor. I used a bit of hot glue to hold the LED in place (in fact, that’s the only thing hold­ing the entire board in place!).

The LED hot glued into the enclo­sure — note the old tan, 5% tol­er­ance resis­tor

I did use sock­ets for both the diode and the tran­sis­tor. I don’t know that I’ll ever swap them out, but I have that option. In fact, Paul of DIY Gui­tar Ped­als has an entire video just com­par­ing dif­fer­ent com­bi­na­tions. Though my ped­al does­n’t have a ton of gain, it sounds pret­ty good using the BAT41 diode and MPSA13 tran­sis­tor. You can see where I used a sharpie to mark the ori­en­ta­tion for both, as well, because I won’t remem­ber should I ever want to swap them out. On the sub­ject of trou­bleshoot­ing, I spent a lot of time trou­bleshoot­ing this build only to ulti­mate­ly deter­mine the A100k put for the vol­ume was just a bad pot! So I def­i­nite­ly don’t want any more headaches try­ing to fig­ure out the cor­rect ori­en­ta­tion for a diode or tran­sis­tor. I even got so para­noid, I lined the back of the pots and the back of the perf­boad with elec­tri­cal tape to ensure noth­ing shorts!

Over­all, it’s not the pret­ti­est build I’ve done but it is com­plete, works, and sounds pret­ty good. I’m proud that I was able to lay­out the com­po­nents in an effi­cient way (which is of course impor­tant to print­ed cir­cuit board lay­outs, which I hope to try out at some point).

The fin­ished wiring. What a rat’s nest!

Electro-Harmonix Small Stone Mods

This project has been “in the works” for a while. I’ve had the ped­al work­ing for some­time but final­ly got around mak­ing the mod­i­fi­ca­tions to make it a mod­ern ped­al.

EH Small Stone with work­ing LED indi­ca­tor

Let’s start with a bit of back­sto­ry: Last sum­mer, my wife and I were help­ing to clean out my late father-in-laws tool shed. He had a lot of stuff and a lot of that stuff was entire­ly ran­dom. One such item was a late 70’s Elec­to-Har­monix Small Stone phase shifter. It was in decent shape, but upon open­ing it, the 9v bat­tery cor­rod­ed and ruined the bat­tery snap. So it was unus­able as-is. There’s not a defin­i­tive way to date it, but the pot is labeled 1377825, which means it was man­u­fac­tured the week of June 19th (25th week) of 1978 by CTS (man­u­fac­tur­er’s code 137). So the ped­al was like­ly build and sold in late 1978 or 1979.

EH Issue J board: the red (9v for LED), gray (ground), green (sig­nal in) and yel­low (sig­nal out) wires were ones added as part of this mod

The Small Stone is the oth­er phas­er sound from the late 70’s, where as the MXR Phase 90 is the one that Eddie Van Halen made famous (I have some the­o­ries on why that might have been, too.). That being said, it’s a great sound­ing phas­er. I’m not a fan of the col­or switch on, per­son­al­ly1. But with the switch off, the effect has got a rich, space‑y sound. This par­tic­u­lar ped­al just need­ed a bit of love.

The first thing was to put in a new bat­tery snap to pow­er the ped­al. This ped­al had a 1/8″ audio jack-style pow­er jack. There are adapters for using this with a mod­ern, Boss-style (2.1 mm bar­rel) DC pow­er plug. How­ev­er, it was a pret­ty sim­ple oper­a­tion to just drill out the case a bit larg­er and install a mod­ern pow­er jack. That got the ped­al work­ing again and how it stayed for about a year. And it sound­ed great.

Well, except for one issue and it’s why I think this ped­al was nev­er near­ly as pop­u­lar as the MXR or, for that mat­ter, many of EH’s oth­er ped­als such as the Big Muff π. That is there is a seri­ous vol­ume drop when the effect is on. Imag­ine Eddie Van Halen turn­ing the effect on for the drop‑C# chug in “Unchained” and then back off for the chord pro­gres­sion. The riff would be ruined! 2. So I real­ly want­ed to fix that. For­tu­nate­ly, 40+ years of his­to­ry with this design and folks have fig­ured out ways to address the issue. There are two resis­tor val­ues that can be changed that dra­mat­i­cal­ly improve the vol­ume drop. I swapped out R11 and R42 and a quick test (out­side of the case) saw the issue improve dra­mat­i­cal­ly.

Mods com­plet­ed: 1) Boss-style AC jack, 2) LED indi­ca­tor, 3) resis­tors swapped for vol­ume drop (blue resis­tors), and 4) true-bypass switch wiring

The bypass­ing mech­a­nism on this ped­al was fair­ly trans­par­ent. I per­son­al­ly can’t tell much of a dif­fer­ence when it’s in my sig­nal chain or not. How­ev­er, I did decide to make it a true bypass ped­al along with the oth­er mod, main­ly just to add an indi­ca­tor LED. Though I’m not a seri­ous gui­tar play­er and nev­er actu­al­ly play live (or record), I do like hav­ing indi­ca­tor lights on effects. If noth­ing else, it just reminds me to turn them all off when I’m done play­ing for a bit as a break dur­ing work hours! The updat­ed switch, even just a cheap­er “Tai­wan blue” is still a lot less of a “ka-chunk!” than the old switch, too.

The last step was to drill out the hole for the LED bezel. Drilling steel is a bit hard­er than alu­minum. I used a step bit as usu­al, but cut­ting flu­id is a must in this case. Unfor­tu­nate­ly, a cou­ple of steel shav­ings scratched rings around the open­ing as I was drilling. I can prob­a­bly buff them out, but a sim­ple piece of painters tape would have pro­tect­ed the sur­face when drilling (and I usu­al­ly think of that when it’s a pow­der-coat­ed enclo­sure!). I boxed up the effect, plugged it in, and SQUEAL-EEE-OOO-EEAAA! Turns out, the out­put jack can rotate just a bit and short out on the col­or switch con­nec­tors. A small piece of black elec­tri­cal tape fixed that, though.

Black elec­tri­cal tape over the col­or switch con­nec­tors to pre­vent it from short­ing on the out­put jack

Reverb has these vin­tage v7 Small Stone ped­als going from between about $150 to $200, depend­ing on their con­di­tion (they retailed for around $80 back in the 70’s). Even non-func­tion­ing, this one could have sold for $75-$100 (which would have eas­i­ly cov­ered the cost of a mod­ern “Nano” re-issue mod­el). So did I reduce its val­ue? Maybe. Maybe not. There are some mod­ded Small Stones also sold on Reverb going for even more. Many of those have addi­tion­al con­trols added or the abil­i­ty to attach expres­sion ped­als or oth­er more sig­nif­i­cant mod­i­fi­ca­tions.

How­ev­er, none of that is real­ly the point for me. I think it’s real­ly cool that this par­tic­u­lar one belonged to some­one in Ange­la’s fam­i­ly (most like­ly her late uncle, John, who played gui­tar some). I think of all the effects in my col­lec­tion, this would be one I’d nev­er real­ly want to part with any­way. It’s got some real his­to­ry; used by peo­ple I knew. And it’s been fun to take it and make it hope­ful­ly even bet­ter than before. It sounds great and though it may not have been the phas­er I would have bought oth­er­wise, it’s even bet­ter to me.

With all apolo­gies to EVH, my incred­i­bly rough take on the intro riff to “Unchained”

Some notes on that demo: first of all, it’s just record­ed from my iPhone X on a tri­pod (as if the leg was­n’t the give­away). The iPhone attempts to lev­el out sound, so try­ing to show that the vol­ume does­n’t drop when the ped­al is engaged in this record­ing isn’t too use­ful. Next, even though you can clear­ly hear the switch click­ing, it’s tru­ly just because the amp vol­ume is rel­a­tive­ly low. There’s no pop through the amp. Last­ly, I’m bare­ly pass­able at play­ing this riff and try­ing to coor­di­nate the ped­al on-and-off with it was a par­tic­u­lar­ly chal­lenge for me.

  1. The col­or switch seems to add sec­ond lay­er of phas­ing at a slow­er rate than the first so there’s a weird­er change ampli­tude. I think this was more pop­u­lar with organ and elec­tric piano play­ers than gui­tarists. I cer­tain­ly can’t think of any record­ings where I may have heard that col­or switch effect. []
  2. I’m not say­ing EVH ever actu­al­ly even used one of these… In fact, after about 5 min of research, EVH actu­al­ly used a flanger rather than a phas­er for that par­tic­u­lar song; but he did and does famous­ly use a phas­er for oth­er songs such as Ain’t Talkin’ Bout Love), but for any­one who did they sure­ly would have noticed the vol­ume drop. []

Amp Channel Footswitch

Most amps have the abil­i­ty to use an exter­nal footswitch to change between a clean and dis­tor­tion chan­nel. Of course, some have more sophis­ti­cat­ed options than this, but the chan­nel switch is a pret­ty com­mon fea­ture. My old­er broth­er recent­ly got an awe­some-look­ing, orange Fend­er Duo-Son­ic and a small Fend­er prac­tice amp to play it through. This lit­tle Mus­tang amp has a lot of pre­sets and he can use a footswitch to select between a pair of them. Of course, it being an afford­able prac­tice amp, the footswitch is sold sep­a­rate­ly.

But a footswitch is a pret­ty easy thing to make your­self. In my case, I had the dou­ble pole sin­gle throw (DPST) footswitch tak­en out of my Dun­lop Wah ped­al when I mod­ded it (post to come some­day!) and an old stereo audio jack. That, a bit of wire, and some­thing to put it in is all you need! In fact, the fact that it was a dou­ble pole switch and a stereo jack made them both overkill for this small project! But why not recy­cle the parts for a good cause?

I pur­chased a pow­der-coat­ed 1590LB enclo­sure from Mam­moth Elec­tron­ics. At 2″ by 2″ by 1″ tall, this is about as small an enclo­sure as you can get, but plen­ty big for a small switch and a jack. I got the orange to match his gui­tar (well, as close as I can get with stock pow­der coat col­ors, any­way). I laid out the switch and jack to ensure I could arrange them how I want­ed; though I could have also just had the jack on the “side” of the enclo­sure. The cir­cuit sol­der­ing here is super-sim­ple: just sol­der the “tip” lug of the jack to the cen­ter lug of one of the poles (three of the lugs in a line make a pole). Then sol­der the “sleeve” lug of the jack to either the left or right lug on the same poll of the switch. That’s it! Did you mess up and wire the sleeve to the cen­ter lug on the switch? It’s still fine! All this does is con­nect the tip to the sleeve when the switch is “on” and then breaks the cir­cuit between the two when it’s off.

Now, this par­tic­u­lar build relies on an instru­ment cable to con­nect the footswitch to your amp. But you don’t have to use a shield­ed cable for this as the gui­tar sig­nal itself isn’t pass­ing through that cable; just a rel­a­tive­ly low volt­age (around 4–5v1) is flow­ing through to tell the amp the gain chan­nel should be on. So you could actu­al­ly skip the jack and just use any old wire (speak­er cable, a lamp cord, etc.) and wire that into a 1/4″ audio cable end. I was just using as many spare parts as I could. In fact, I fin­ished the bot­tom by cut­ting up a kitchen jar grip pad and glu­ing it to the bot­tom with spray adhe­sive (it won’t slide on his hard­wood floor!).

Giv­en that the Fend­er sin­gle footswitch costs around $15, this prob­a­bly is not much of a cheap­er alter­na­tive. But it was a fun gift for my broth­er and if you’re inter­est­ed in prac­tic­ing some sol­der­ing, this is a great and prac­ti­cal project to start with!

So, amaz­ing­ly enough, there’s a video in which YouTube chan­nel Mer­win­Mu­sic makes the exact same footswitch as mine — down to the orange col­or! Check it out! He also does a great job of explain­ing how to test out that this sort of switch works with your amp before you go to the trou­ble of build­ing one, which is a good idea as some amps may vary (but all good amps just copy Leo’s orig­i­nal!).

I built this exact same project almost!
  1. The volt­age is low enough that my Black­star head­’s footswitch does­n’t even have a resis­tor on the LED. []

Mini MicroAmp Build

With each new ped­al build, I try to focus on some aspect that makes it a new chal­lenge or some­thing new to learn. My first ped­al build ever (about 18 months ago) was a boost ped­al. I decid­ed I’d build anoth­er boost: this one using the MXR MicroAmp cir­cuit. I used the Gen­er­al Gui­tar Gad­gets MAMP PCB, which in addi­tion to sell­ing the PCB sells entire kits and has excel­lent doc­u­men­ta­tion1. Since it’s a rel­a­tive­ly sim­ple cir­cuit and, there­fore a fair­ly small PCB, I want­ed to try to fit it into a “mini” enclo­sure (i.e., a 1590A for­mat). This means hav­ing to real­ly think ahead about aspects of the build so that every­thing can squeeze into such a rel­a­tive­ly small enclo­sure.

The com­plet­ed enclo­sure, includ­ing the mis-aligned hole for the input jack on the right side

The first thing is that this ped­al for­mat can’t uti­lize a bat­tery for pow­er; the ped­al will be AC pow­ered only. That’s fine as I don’t use bat­ter­ies in any ped­al any­way and only ever added a bat­tery snap to that first ped­al build. Sec­ond­ly, the height of the com­po­nents real­ly mat­ters. The taller com­po­nents (gen­er­al­ly, the capac­i­tors) had to be bent over. For the elec­trolyt­ic capac­i­tors, I had to remove and replace a cou­ple in order to facil­i­tate this (I had planned ahead oth­er­wise — as my sketched notes on the wiring dia­gram shows below, but I am just so in the habit of sol­der­ing the com­plete­ly ver­ti­cal I for­got!). In the end, the tallest com­po­nent off the PCB was the inte­grat­ed cir­cuit (IC), as it was mount­ed in a sock­et. This way I can poten­tial­ly swap out ICs in the future. Speak­ing of ICs, I went with a low-noise TL071 op-amp (in place of the orig­i­nal ped­al’s TLo61 — which con­sumes less cur­rent but, again, I’m not using a bat­tery so I don’t real­ly care about that). The only oth­er mod­i­fi­ca­tion I made to the GGG cir­cuit was that I swapped out a 10MΩ in place of the 22MΩ pull-down resis­tor (R1). Real­ly, any fair­ly large (<1MΩ) resis­tor val­ue will do here and 22MΩ are a lit­tle hard­er to find.

The com­plet­ed wiring. This was a tight fit! Notice all the taller capac­i­tors look like a strong wind came through.

Last­ly, the arrange­ment of the larg­er off-board com­po­nents such as the footswitch, jacks, LED bezel, and pot real­ly came down to mil­lime­ters. I had to use calipers to mea­sure every last item and metic­u­lous sketch it out on a print­out of the enclo­sure. I still man­aged to mess up drilling one of the jack holes (I locat­ed it 1/2 the diam­e­ter off, which s about the worst place to mess it up!). I was able to re-drill the hole thanks to hav­ing a drill press and some clamp­ing blocks. It’s a bit ugly and the jack­’s nut is a bit crooked, but it worked out fine.

Re-drilling a hole for the out­put jack. Drill press & clamps absolute­ly required to fix this sort of bone-head­ed mis­take.

The ped­al works great. I mean, it’s about as sim­ple an effect as you can get. It sim­ply takes the gui­tar sig­nal and makes it a lot loud­er (prob­a­bly around the order of 20–25db). I’m pret­ty pleased with how clean the wiring worked out, as well.

My build cost around $27 for the parts I had to pur­chase. That’s not includ­ing resis­tors, capac­i­tors, diode, and LED (nor hookup wire and sol­der), all of which I already had in my parts bins but would run you around $3 in total. I also had to pay around $9 in ship­ping. The PCB from GGG for was about $3.50 to ship. I bought parts for sev­er­al builds at once in a large order from Mam­moth Elec­tron­ics (my parts sup­pli­er of choice), but small­er orders from there tend to ship for around $5. They have high-qual­i­ty pow­der-coat­ed enclo­sures for real­ly great prices, along with gen­er­al­ly good prices on oth­er parts and kits. So, in total, this build is roughy around $39 in cost (and I still haven’t added any art­work, so con­sid­er what slide decal or oth­er for­mat might cost).

That being said, unless you real­ly want to build your own, I would not rec­om­mend this build to any­one else. You can pur­chase a TC Elec­tron­ic Spark for about $35 used on Reverb.com (plus ship­ping) right now. It has the exact same size as my build, but has their amaz­ing non-latch­ing (relay) footswitch and essen­tial­ly the same amount of clean boost. If you don’t care about size, you can pur­chase a used MXR MicroAmp for around $49 on Reverb (plus ship­ping). Both of those are sol­id choic­es if you real­ly just want a boost ped­al and are less inter­est­ed in prac­tic­ing your sol­der­ing skills or learn­ing how to lay­out a small ped­al form fac­tor. And hon­est­ly, as much as I think this ped­al sounds great so far, those prob­a­bly sound even bet­ter and have less noise at full gain.

But over­all, I’m pleased with this build. On the clean chan­nel, it just gets loud­er with­out adding any­thing else notice­able. Best of all: with the knob set to about 3 o’clock, it makes my Black­star HT-5R head­’s gain chan­nel absolute­ly breathe fire!

  1. I think I could have pret­ty eas­i­ly build this cir­cuit on perf­board, but prob­a­bly not to fit in the this small of an enclo­sure. So for a bit more cost I opt­ed for the PCB, which has a fair­ly small foot­print. []

Guitar Effect Test Box

I’m in var­i­ous stages of com­ple­tion for sev­er­al gui­tar effects at the moment and I’ll cer­tain­ly try to write a post for each of those in turn. How­ev­er, I first fig­ured I should post about my gui­tar effect PCB test box I put togeth­er. I by no means first came up with the idea. Paul of DIY Gui­tar Ped­als in Aus­tralia is who I first saw use & rec­om­mend one. In search­ing around for fur­ther ideas, I came across some notes on DIY Stomp Box­es about adding the probe, which can be used in diag­nos­ing PCBs that aren’t work­ing.

A MXR MicroAmp cir­cuit hooked up to the test box

As you can see, I went with a fair­ly large enclo­sure for this project. As it’s real­ly just the off-board wiring stan­dard to most any ped­al project, with no cir­cuit board, this is some­what a waste of space. How­ev­er, I want­ed to leave a bit of space for poten­tial­ly adding some more fea­tures at some point in the future1. This is a pow­der-coat­ed, alu­minum enclo­sure which is not at all nec­es­sary for this, as the wiring is out­side so the met­al box isn’t shield­ing any­thing. So the enclo­sure was a bit of a splurge. But as Mam­moth cur­rent­ly sells these 1590BB enclo­sures pow­der coat­ed for under $10, it’s not exact­ly a bank-buster. The entire test box is less than $25, and many of the parts I already had in my parts bin.

I cut up some cheap alli­ga­tor clips I bought off of Amazon.com to use for the con­nec­tors. They have lit­tle cov­ers over the clips, so they work quite well even when con­nect­ing into close­ly spaced wiring leads. I did knot these just inside the box to pro­vide some strain relief (though it’s not as though this thing is get­ting roughed up much). I used a Mam­moth Elec­tron­ics bypass wiring board just to sim­pli­fy things a bit. I tend to use a stan­dard wiring col­ors for all my projects: red for 9v, black for ground, green for sig­nal to board, and yel­low for sig­nal back from board.

The spa­cious guts of my test box

The one trick my box has is that I added a tog­gle switch to use a test­ing probe. This switch basi­cal­ly hi-jacks the sig­nal return (yel­low) and con­nects the probe (white) direct­ly to the box out­put jack. So if sig­nal isn’t com­ing back from the cir­cuit, I can flip this switch and then use the probe (which is noth­ing more than a 1μf capac­i­tor) to touch along the cir­cuit to trace where the fault is. It’s very sim­ple but incred­i­bly help­ful.

So to quote Paul of DY Gui­tar Effects, if you’re going to even build just more than a cou­ple of gui­tar effects your­self, you’re going to want to build some­thing like this. It’s so invalu­able to be able to test your PCB as soon as you get the com­po­nents installed but before you try to com­plete all the off board wiring & stuff­ing it into an enclo­sure. It’s also extreme­ly fun to hook up to a bread­board and test that way!

A Bazz Fuzz bread­board cir­cuit on the test box
My enclo­sure drill pat­tern
Wiring dia­gram for my test box


  1. For exam­ple, I also saw this post where some­one has added in the abil­i­ty to change the volt­age and add a volt­age sag (to sim­u­late a dying bat­tery), which is real­ly cool. []

Tremolo Pedal Build

Christ­mas in 2018 was a lot of fun and my fam­i­ly got me a lot of won­der­ful things. Among them, my broth­er, Dave, got me a gui­tar ped­al effects kit. This was a tremo­lo ped­al, which is def­i­nite­ly some­thing I would­n’t have got­ten myself. If you don’t know, a tremo­lo ped­al mod­u­lates the ampli­tude of the sig­nal. That is, it’s as if some­one is turn­ing the vol­ume knob up and down reg­u­lar­ly. This effect was built into many ear­ly elec­tric gui­tar ampli­fiers. In the late 50’s an Aus­tralian elec­tron­ics mag­a­zine had an arti­cle on a rel­a­tive­ly sim­ple cir­cuit for this effect. That design has since been mod­i­fied and incor­po­rat­ed into many pop­u­lar gui­tar effects. The kit I got is by Arca­dia Elec­tron­ics and uses the EA Tremo­lo design.

This kit has all of the com­po­nents, even jacks and switch, all direct­ly sol­dered onto the print­ed cir­cuit board (or PCB). This sim­pli­fies build­ing and is, in fact, what most com­mer­cial ped­als uti­lize to speed up fab­ri­ca­tion (and even allow for auto­mat­ed com­po­nent sol­der­ing). As such, it was a rel­a­tive­ly straight-for­ward build process that prob­a­bly took me under three hours total. And mind you, I am inten­tion­al­ly slow with this things because I want to real­ly enjoy the process and also to pre­vent mak­ing any easy avoid­able mis­takes.

Pop­u­lat­ed PCB for the Aca­dia Tremo­lo ped­al. You can see that I inten­tion­al­ly bent over a cou­ple of the elec­trolyt­ic capac­i­tors to keep them well clear of the Depth con­trol poten­tiome­ter.

The instruc­tions with the Aca­dia kits are very sparse. They basi­cal­ly include of a print­out of the PCB (which is very nice­ly screen print­ed and clear­ly marked, though) and a com­po­nent list. That’s it, there’s no oth­er instruc­tions or build steps giv­en. So, if this was a kit for a new builder, I’d sug­gest down­load­ing the instruc­tions for one of the oth­er Tremo­lo ped­als at Mam­moth Elec­tron­ics. They’re gen­er­al­ly sim­i­lar builds and pro­vide some good infor­ma­tion if you’re new to ped­al build­ing or elec­tron­ics. The Aca­dia kit came with high qual­i­ty com­po­nents. I test­ed some of the resis­tors and they were clos­er to nom­i­nal val­ues than the ones I pur­chase. The sin­gle diode in the kit had legs that real­ly did­n’t fit into the drilled through holes, but I just swapped it out for anoth­er 1N4001 in my parts bin. It’s not that the part was cheap; just that the pcb design as-drilled can’t accom­mo­date this par­tic­u­lar part. There’s prob­a­bly sev­er­al solu­tions to this, but this would be pret­ty frus­trat­ing for a first-time builder, I think. Oth­er­wise, I real­ly have no issues with this kit. It’s the first ped­al build I’ve done that I did­n’t have to trou­bleshoot at least one mis­take!

I labeled the ped­al once it was all closed up for test­ing. I’ll paint and dec­o­rate the case anoth­er day.

I got the hard­ware all sol­dered onto the board. I did add some elec­tri­cal tape to the back of the pots as well as to the inside of the case back. This is prob­a­bly not nec­es­sary, but I want­ed to pre­vent any pos­si­bil­i­ty of the pots or com­po­nents ground­ing out.

The ped­al sounds great. The vol­ume boost on this was pret­ty sur­pris­ing, in fact. Just dial­ing the Rate and Depth con­trols to zero makes this a pret­ty effec­tive clean boost, even. The range of the tremo­lo is all the way from noth­ing to com­plete vol­ume clip­ping. I record­ed a fair­ly poor sam­ple for this post, but the sound is real­ly great in per­son.

Tremo­lo Ped­al Demo

My First Stomp Box Project

For my birth­day, I decid­ed to work a com­plete­ly new project: build a gui­tar effects ped­al. I pur­chased the “Con­fi­dence Boost” project kit from BuildYourOwnClone.com (as in clones of pop­u­lar gui­tar stomp box­es). It’s a great project for about $15 which comes with detailed instruc­tions and makes a pret­ty decent lit­tle boost effect. The kit itself only comes with the print­ed cir­cuit board, elec­tron­ic com­po­nents, and off-board wiring such as jacks and poten­tiome­ter.

PCB com­po­nents and ini­tial off-board wiring

I sol­dered up the com­po­nents and off-board wiring and plugged-it up. And noth­ing. It did­n’t make any sound! I post­ed a cou­ple of pho­tos to the dis­cus­sion board and quick­ly got a response: the input jack was wired back­ward. In oth­er words, the sig­nal from my gui­tar was just going to ground and noth­ing was going on to the effect (or amp). I quick­ly re-worked the input jack and it worked. The tiny poten­tiome­ter (blue screw dri­ver knob in the pho­to above) was a bit tough to use.

I decid­ed it would be fun to go ahead and wire this up as an actu­al stomp box, so I ordered a few more com­po­nents and an enclo­sure. I spent some time paint­ing and fin­ish­ing the enclo­sure. I just used a white pen to draw out the label­ing, but it turned out just fine for this project. I read up on how to wire a footswitch for true bypass (when it’s off, it does­n’t affect the sig­nal at all) and with an LED indi­ca­tor light.

Enclo­sure design
Ful­ly wired effect in the enclo­sure
Wired up and turned on

But of course, it only real­ly mat­ters how it sounds. I’m far from a capa­ble gui­tar play­er and even worse when try­ing to film my play­ing, but here’s a small sam­ple.