Maestro Boomerang BG-2 Wah/Volume Pedal - Technical Data

Created 9/15/06
Last updated 2/28/08
By Paul Marossy



Once again, I found myself frustrated with the general lack of information about something on the internet - in this case, the great sounding Boomerang wah pedal. So, once again, I decided to make a webpage to fill the void.

In a
wah wah article hosted by AnalogMike, Geoffery Teese says that after the Clyde McCoy, he feels that the 1st series Maestro Boomerang sounded next best. Nothing definitive other than they way they sound. I am not sure how to determine what is a first series pedal and what is a later series pedal, but from what I can tell, it looks like the first series spanned from 1968/69 to around 1972/73 and the later series from that point on to the end of production. As I understand it, these Maestro pedals were somehow associated with Gibson - same parent company I think (Norlin). They were apparently license built under patent #3,316,341 , which was filed in 1961. The shell looks exactly like the one in a patent filed in 1958 by Harry DeArmond, patent #2,986,953 . This circuit is a least as old as the famous Vox Clyde McCoy wah, maybe older. The Boomerang shell design appears to pre-date the Vox wah shell design by about ten years. It would be interesting to find out the story behind these similarities. Additionally, according to the operating instructions that originally came with the pedal, the Boomerang was the first wah pedal on the market. If this is true, then I wonder why the Boomerang is such an unknown compared to the Vox Clyde McCoy? My guess is that it's because guys like Jimi Hendrix didn't play one. It is the wah that you hear in the theme from "Shaft", which seems to be its main claim to fame.

Anyhow, here are some differences/similarities in the Boomerang examples that I have seen thus far:

1. Early manufacture Boomerangs have a different PCB design and components than the later ones have. In the later models, the inductor is the same, but the electrolytic caps are a radial type and resistors appear to have been changed to metal film types.

2. Early manufacture Boomerangs have a different bottom plate and battery holder than the later ones.

3. Later manufacture Boomerangs appear to have a DC jack added to the toe end of the shell.

4. All examples that I have seen use the mysterious El-Rad 500mH inductor.

5. All examples appear to use a 25K pot.

6. The earliest ones were a straight wah pedal and was the BG-1 model. They had a black and silver nameplate and are relatively hard to come by.

7. The second production run was the BG-2. Most every Boomerang that I have seen is the BG-2 model, with an orange and silver name plate. Sometimes it's the "Boomer 2", with an orange and silver nameplate, which appears to be the third and final production run of the Boomerang wah pedal.

Regarding the transistors used by the manufacturer, the actual transistors used were marked with Gibson/Maestro's part numbering system and do not directly correspond with any off the shelf transistors that are available. A reliable source has recently informed me that the BG-1 used a P-2356 or 991-002356 transistor, which should cross-reference as a 2N3404 with a Hfe ranging from 75 to 225. The BG-2 used a P-2873 or 991-002873 transistor which should cross-reference to a 2N3391A with a Hfe ranging from 250 to 500.

Sooner or later, the pots in these old wah pedals will need to be reconditioned or replaced. Sometimes you can find NOS 25K pots on ebay that could work, with a little bit of modification. I have also heard reports that the 200K ProPot sounds good in this pedal, as well as standard 100K wah pots. I personally like to use the 100K Dunlop Hot Potz II with a 33K resistor soldered in parallel with it. Some of the old pots can be taken apart and reconditioned, too. See the links at the bottom of this page for more on that.

Here's an update to this page: Recently, I have been contacted by Richard Mintz, who is the one who redesigned the original Boomerang BG-1 wah-only circuit into the Boomerang BG-2 wah/volume circuit. He also designed some other products in the 1970s in a business partnership with another individual. I have seen a few of these products that he shipped to help me in a recent colloborative effort with him and his products were very good for the time. I hope to see Richard do some new things in the near future.

Below are some details about this particular Boomerang example that I have.

Here is a size comparison between the Boomerang and the ubiquitious CryBaby. My only complaint about the Boomerang is the physical size of the shell. But, it has a longer throw than a CryBaby, so that is a plus. It also weighs noticeably less than the CryBaby.

This is the name plate viewed a little closer. This is the BG-2 model, a wah/volume pedal.

Here is the inside of the pedal. Lots of spare room inside. This pedal has the input on the left side vs. the usual input on the right side.

Here is the PCB viewed a little closer. All Boomerangs that I have seen use the El-Rad 500mH inductor. I'm not sure how they are constructed.

This is the bottom of the PCB. It appears to be manufactured by the same place that made the PCBs found in the TDK 5103 inductor equipped CryBabys from the late 70s/early 80s.

The electrolytic caps in this example were made by Callins. The blue caps may have been made by Mallory, but I'm not 100% sure about that. Resistors are carbon comps.

The silicon transistors are labeled "2873B" in this example.

There are two datestamps in this pedal. This one is below the battery holder, and although it's hard to make out, it says "7208", which I assume means that the shell was made in the 8th week of 1972.

When I pulled the PCB out, there was a second date stamp underneath. I can't quite make it out, but I think it says "Aug 21 1972".

I'm not sure if this pot is the one that came with the pedal, but the date code "7246" seems to indicate that it was. This pot was made by CTS in the 46th week of 1972. I had to take it apart and clean it because it started to sound a little scratchy.

Here is the footswitch, a SPDT type with only one pole of the switch being used.

This is the rack and pinion gears. I like this a little better than the CryBaby method. The spring applies pressure to the rack, eliminating the need for the plastic clip and it makes sweep adjustments very simple.

This is the bottom plate. Serial number 18004. This bottom plate has a square-ish raised area. I usually see a circular raised area on the bottom plates.

This is the schematic, which can usually be found on the inside of the bottom plate.

Compared to my Boomerang clone, it sounds pretty close, but my Boomerang clone is still the most expressive wah pedal that I have played so far.

If you have some definitive information on the history of these pedals or corrections to the information that I have provided, please send me an email.

Factory PCB Layout

How To True Bypass The BG-2 Boomerang

Original Boomerang Operating Instructions

Vintage Boomerang Ad

Scratchy Pot? Fix It!

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