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Here’s the Holly Grail Maestro Boomerang from Joe Gagan personal collection. Thanks Joe for your contribution!

Here’s what Joe says about his unit:

“after careful examination of this unit and another that sold on ebay in feb ’10 ( they had serial numbers only 2 digits apart!), i am convinced that the unit pictured here is 100% original, all solder joints untouched. original pot. unknown inductor mfgr.

gibson seems to have rushed this into production in the same year as the famous vox. disreali gears and hendrix created a huge demand for these suckers. it uses a patent first applied for in 63 by richard petersen, a resonant circuit designed to imitate a voice or trumpet ‘wow-wow sound” ( gibson owned lowry organs had this feature by around 64). even the schematic uses the term wow wow instead of wahwah.it seems that very few actual BG1s were made, however, and the BG2 boomerang came out in 68.

the BG2 used a different inductor, different pot manufacturer, and doubled as a volume pedal when the wah was off. one of the worst tonesucking pedals in history. but for the wah sound- in my direct comparisons the BG2s still do sound very close to the BG1 voicing and response curve.”

Another cherry on the cake from Jan. Rare example of Grey VOX, very first Wah-Wah ever produced. Here’s what Jan says about this pedal:

“The photos #5 and #6 shows the replacement pot with the pop-fixing-resistor(1M). The original pot (dual 100K linear is put away and will follow this pedal) did not perform properly. As it’s very hard (impossible??) to find really good dual wah-pots, I choose to put in a “Wah Potentiometer 50k lin / 500k lin” 4,50 EUR Product No: “ibawahpot” from Musikding (www.musikding.de). The 50K is for the Wah and 500K for the Swell/Volume. I took the opportunity to reverse the Wah to normal (Treble – toe down / Bass – heal down), it was very strange to have it in the opposite way. I have not revealed what’s under the cover, it remains a secret;-) So I do not know what components there are, what type of; inductor, capacitors and resistors, only the two transistors (BC150) is in the open.

Jan”

This is the second one gooped I ever seen. Also I have just a few picts of similar units and none of them had the duplo pot to control wah & volume/swell. There was always just a single potentiometer. AFAIK there was two basic layouts for this model. First one – also called prototype model was assembled by Del Casher (the inventor) himself and his wife. Those was build on tagboard. Later on the full production model with different component layout was issued, and pretty much looks similar to the one we see on picts here. Also AFAIR the early proto units was build with BC150 transistors, and in the production models usually we see Texas Instrument 2N3707, so this is another oddity. The inductor in later units was 250mH, resistors was Iskra brand, two big yellow unbranded 0,22uF 160v capacitors with similar look to WIMA’s, and two 10000pF (0,01uF) Styroflex type caps, as well as one bipolar 4uF. I’m not sure about the brand, but I think I see Lemco on it… Perhaps someone more knowable could add something to complete/verify the info.

Layout for Grey Wah is in “Layouts” -> “Wah & EQ” section on my webpage

Thanks to Jan again!