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. []

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