This OG Electro-Harmonix Bad Stone Phase Shifter is from 1978, dating it from the potentiometer code 137 7748 (48th week of 1977)

This 1978 Electro-Harmonix Bad Stone Phase Shifter is an original vintage unit from the golden age of analog modulation. Known for its six-stage phasing circuit and unique Manual Shift knob, the Bad Stone offers everything from slow, swirling sweeps to psychedelic, vocal-like textures. Unlike many phase pedals, it allows you to “freeze” the phase sweep manually for filter-like static tones. This feature made it a favorite among experimental rock, fusion, and early ambient guitarists.

This example is in excellent vintage condition with fully functioning controls, original enclosure, and period-correct hardware. The switch operates smoothly, and the pedal delivers the warm, organic character that modern reissues aim to recreate. With rich analog depth and subtle grit, it pairs beautifully with clean Fender amps, overdrives, or stacked modulation pedals.

At Mahar’s Vintage Guitars, all pedals are tested, photographed accurately, and described honestly. The pedal works perfectly! 

We buy, sell, and accept trades on vintage, boutique, and modern gear.

For related equipment, explore our Huge Vintage & Used Amplifier Collection, Vintage Fender Guitars, or visit the Sell or Trade Your Gear page.

Mahar's Vintage Guitars is a brick-and-mortar and web-based retailer. We are happy to talk with you before you make a purchase.   Please reach out if you feel so inclined! We cross market our items here and on our own site, so items are subject to sale elsewhere at any time (however we will never cancel a sale if it happens here first). See our profile here, our Google reviews as well as our 100% positive Reverb feedback. Also, Reverb limits us to only 25 pictures of our items. There is a good chance we have more. Contact us if you’d like to see them.

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Shipping policy:

Shipments will require signature on delivery, no exceptions.  If there is damage, the buyer must retain all packing materials intact and picture them immediately and send them to .  Less than 1% of our shipments are damaged in transit, and we are committed to making sure your item arrives safely, but we are taking these additional measures to make sure you are happy with your purchase.