Purgasound | Vintage Amplifier Repair, Restoration & Builds

Marshall Amps

Marshall and Celestion Date Codes

No fluff, just the date code charts.

Marshall Amp Identification 1967–1980 — The JMP Era

Cosmetic and construction changes through the JMP era, year by year.

The Ultimate Split Channel JCM800 Guide!

Detailed fixes for the known channel bleed issue and oscillation problems at high gain settings

The Ultimate JCM900 SL-X Guide!

Everything you need to know about Marshall's high-gain SL-X circuit, mods, and maintenance.

Oddball Late 70's Super Bass Circuit Info

Notes and schematics for the unusual late-1970s Super Bass circuit variations.

Mid 70's Super Bass Circuit Info and Schematics

Highlights changes made in early to mid '70s Super Bass amps.

Peavey Amps

Peavey Butcher Adjustable Bias and Service Guide

How to safely adjust the bias and service the Peavey Butcher for reliable stage and studio use.

Technical Info / Knowledge Hub

4x12 Speaker Wiring Tutorials

How to wire a 4x12 cabinet for different impedances and configurations.

1972 Marshall 1959 Super Lead

The Collection

Reference Archive

My personal amp collection along with some others I've serviced or restored, documented for reference. Each amp includes sound clips so you can hear exactly what these circuits do, along with schematics and notes from the bench.

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Watch

On YouTube

Follow along with teardowns, repair walkthroughs, shootouts, and the occasional rant about why your amp sounds the way it does.

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