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!