Electro-Harmonix · Big Muff Pi V4/V5 (Op-Amp) · c. 1978–1980
Around 1978 EHX rebuilt the Big Muff around two op-amp chips to cut costs. Kit Rae calls the result Version 4, plus a Version 5 that traded the on/off switch for a tone bypass switch, and both were sold alongside the red and black transistor Muffs of the day. Howard Davis, the engineer behind the Deluxe Memory Man and Deluxe Electric Mistress, and Michael Abrams both claim the design. It runs three gain stages instead of four, with an RC4558 and a 741, and it sounds grungier and more consistent from unit to unit than the transistor Muffs. For years nobody wanted them. Then in 2009 Billy Corgan posted a photo of the Muff he'd used on Siamese Dream, and Kit Rae identified it as a V4. Both op-amp versions became collector pieces after that, with the V4 the rarer of the two. A V4 looks just like a red and black V3 from the outside, so the circuit board is the proof. If you only want the Siamese Dream sound, EHX's 2017 reissue was built from the original schematic and includes the tone bypass switch.
These aren't true bypass, so some get louder when switched off because the signal still runs through the op-amps. The 3.5mm power jack is tip positive, the reverse of most pedal supplies, so it needs an EHX-style adapter or a converter cable.
Buying guide
Only 5 vintage op-amp Muffs are listed, so the $900–1,025 band is a thin read, and four of them ask $908–1,109 delivered for a 1978–79 V4 or V5. The $496 V4 is the bargain if it's real, but it's titled 1976, earlier than Kit Rae dates these, so get a photo inside showing two small eight-pin chips before you buy. Read the side switch in the photos too, since OFF ON marks the rarer V4 and TONE BYPASS a V5. The 3.5mm power jack is tip positive, so plan on an EHX-style adapter or a converter cable.
$495.80est. delivered
Titled V4 at $496 delivered from a US seller, about half what the others ask. The 1976 date in the title is earlier than Kit Rae dates op-amp Muffs, so ask for a gut shot showing two eight-pin chips.
Vintage 1976 Electro-Harmonix Big Muff Pi V4 Op-Amp Fuzz Guitar Pedal EHX USA
$908.26est. delivered
A V5 with tone bypass, titled 1978, at $908 delivered from the US, the lowest of the four asking the going price. Ask for a clip of the tone bypass switch and all three knobs.
Electro-Harmonix/Big Muff Pi V5. Op Amp Tone Bypass.1978 Vintag Fuzz EH 1322
$1,013.59est. delivered
Titled V4, the rarer op-amp version, at $1,014 delivered from the US, inside the band. A V4 looks like a transistor V3 from outside, so ask for a photo inside before you pay.
Vintage - Electro-Harmonix Big Muff Pi OP-AMP V4 (Rare EH1322 USA circa 1978)
Delivered prices include shipping as eBay quoted it to a US address on Oct 10, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Snapshot
Checked . Some may have sold.
Delivered prices include shipping as eBay quoted it to a US address on Oct 10, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Used$495.80est. delivered
$479.95 + $15.85 shipping
Buy It Now$479.95
Good buy
Titled 1976 V4, about half the going price. Ask for a gut shot.
Seller: drereave
99.6% positive
Used$908.26est. delivered
$900.00 + $8.26 shipping
Buy It Now$900.00
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Good buy
Titled 1978 V5 with tone bypass. In the US.
Seller: marat0-2760
100% positive
Used$1,013.59est. delivered
$1,000.00 + $13.59 shipping
Buy It Now$1,000.00
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Good buy
Titled V4, circa 1978. In the US.
Seller: humblejoy
100% positive
Used$940.80est. delivered
$834.40 + $106.40 shipping
Buy It Now$834.40
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled 1979 V5. $106 shipping from Italy.
Seller: thefuzzisthefuzz
100% positive
Used$1,108.80est. delivered
$1,002.40 + $106.40 shipping
Buy It Now$1,002.40
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled 1978 V5, about $85 over the band. $106 shipping from Italy.
Seller: thefuzzisthefuzz
100% positive
Prices change daily. The live eBay search shows everything listed now, including anything new since Oct 10, 2026.
See every listing on eBay ↗eBay searchPlenty of used pedals turn up without a power supply. Check the power line in the specs above, then match the voltage and plug before you buy one. This searches Amazon for the usual kit.
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